/* ============================================================
   claudex — Midnight Codex
   A private writing study at night: warm umber, parchment ink,
   oxidised brass. Editorial layout. No SaaS aesthetics here.
   ============================================================ */

:root {
  --bg: #181210;
  --bg-tint: #1F1812;
  --surface: #1F1812;
  --raised: #28201A;
  --raised-2: #2F2620;

  --ink: #ECE1CC;
  --ink-soft: #C8BBA0;
  --muted: #8E7E62;
  --faint: #5A4E3C;
  --whisper: #3A3024;

  --brass: #C9A35F;
  --brass-soft: #8A7140;
  --brass-deep: #5E4C2C;

  --vermillion: #B85C3C;
  --moss: #8FA274;

  --border: #382C20;
  --border-soft: #2A2218;
  --code-bg: #0E0A08;

  --selection: #4A3520;

  --font-display: "Fraunces", "Cormorant Garamond", "Times New Roman", serif;
  --font-body: "EB Garamond", "Iowan Old Style", Georgia, serif;
  --font-mono: "JetBrains Mono", "SF Mono", Menlo, monospace;

  --rail: 296px;
  --gutter: 56px;
}

* { box-sizing: border-box; margin: 0; padding: 0; }

[hidden] { display: none !important; }

html, body {
  height: 100%;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--font-display);
  font-variation-settings: "opsz" 14, "wght" 400;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
}

body {
  background-image:
    radial-gradient(ellipse 900px 500px at 18% -10%, rgba(201, 163, 95, 0.05), transparent 70%),
    radial-gradient(ellipse 700px 700px at 110% 110%, rgba(184, 92, 60, 0.04), transparent 60%);
  background-attachment: fixed;
  overflow: hidden;
}

/* paper grain — barely perceptible, lives over everything */
body::before {
  content: "";
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: 9999;
  opacity: 0.035;
  background-image: url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' width='240' height='240'><filter id='n'><feTurbulence type='fractalNoise' baseFrequency='0.85' numOctaves='2' stitchTiles='stitch'/><feColorMatrix values='0 0 0 0 1  0 0 0 0 1  0 0 0 0 1  0 0 0 1 0'/></filter><rect width='100%' height='100%' filter='url(%23n)'/></svg>");
  mix-blend-mode: overlay;
}

::selection {
  background: var(--selection);
  color: var(--ink);
}

button { font: inherit; color: inherit; }

input, textarea {
  color: inherit;
  background: none;
  border: none;
  font: inherit;
  outline: none;
}

/* ============================================================
   APP SHELL
   ============================================================ */

.app {
  display: grid;
  grid-template-columns: var(--rail) 1fr;
  height: 100vh;
}

/* ============================================================
   SIDEBAR — the ledger
   ============================================================ */

.sidebar {
  display: flex;
  flex-direction: column;
  border-right: 1px solid var(--border);
  background: linear-gradient(180deg, var(--bg-tint), var(--bg));
  overflow: hidden;
  position: relative;
}
.sidebar::after {
  /* a faint vertical hairline like a binding crease */
  content: "";
  position: absolute;
  top: 0;
  bottom: 0;
  right: 12px;
  width: 1px;
  background: linear-gradient(to bottom, transparent, var(--border) 20%, var(--border) 80%, transparent);
  opacity: 0.4;
  pointer-events: none;
}

.brand {
  padding: 28px 28px 18px;
}
.brand h1 {
  font-family: var(--font-display);
  font-variation-settings: "opsz" 144, "wght" 350;
  font-style: italic;
  font-size: 44px;
  line-height: 0.95;
  letter-spacing: -0.02em;
  color: var(--ink);
}
.brand h1::after {
  content: "·";
  color: var(--brass);
  margin-left: 6px;
  font-style: normal;
}
.brand p {
  margin-top: 8px;
  font-family: var(--font-display);
  font-variation-settings: "opsz" 9, "wght" 400;
  font-style: italic;
  font-size: 11px;
  letter-spacing: 0.16em;
  color: var(--muted);
  text-transform: lowercase;
}

.sidebar-actions {
  padding: 4px 28px 14px;
  display: flex;
  flex-direction: column;
  gap: 14px;
}
.new-entry {
  background: none;
  border: none;
  cursor: pointer;
  text-align: left;
  padding: 8px 0;
  border-bottom: 1px solid var(--border);
  font-family: var(--font-display);
  font-variation-settings: "opsz" 14, "wght" 600;
  font-size: 11px;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--brass);
  transition: color 150ms ease, border-color 150ms ease;
}
.new-entry::before {
  content: "+  ";
  color: var(--brass);
  font-weight: 400;
}
.new-entry:hover { color: var(--ink); border-bottom-color: var(--brass-soft); }

.search input {
  width: 100%;
  padding: 7px 0;
  border-bottom: 1px solid var(--border);
  font-family: var(--font-display);
  font-variation-settings: "opsz" 14, "wght" 400;
  font-style: italic;
  font-size: 14px;
  color: var(--ink-soft);
  transition: border-color 150ms ease;
}
.search input::placeholder { color: var(--faint); font-style: italic; }
.search input:focus { border-bottom-color: var(--brass); }

.conversations {
  flex: 1;
  overflow-y: auto;
  padding: 6px 0 24px;
}
.conversations ol { list-style: none; }
.ledger-empty {
  padding: 28px;
  font-family: var(--font-display);
  font-style: italic;
  font-size: 13px;
  color: var(--muted);
  line-height: 1.7;
}
.ledger-empty em { color: var(--brass); }

.conv-item {
  display: grid;
  grid-template-columns: 28px 1fr auto;
  column-gap: 12px;
  align-items: baseline;
  padding: 12px 28px 12px 28px;
  cursor: pointer;
  position: relative;
  transition: background 140ms ease;
}
.conv-item:hover { background: rgba(201, 163, 95, 0.04); }
.conv-item.active { background: rgba(201, 163, 95, 0.07); }
.conv-item.active::before {
  content: "";
  position: absolute;
  left: 0;
  top: 14px;
  bottom: 14px;
  width: 2px;
  background: var(--brass);
}
.conv-item .folio {
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.04em;
  color: var(--faint);
  align-self: start;
  margin-top: 4px;
}
.conv-item.active .folio { color: var(--brass-soft); }
.conv-item .title {
  font-family: var(--font-display);
  font-variation-settings: "opsz" 14, "wght" 400;
  font-size: 14px;
  line-height: 1.35;
  color: var(--ink-soft);
  overflow: hidden;
  text-overflow: ellipsis;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  word-break: break-word;
}
.conv-item.active .title { color: var(--ink); }
.conv-item .date {
  font-family: var(--font-display);
  font-variation-settings: "opsz" 9, "wght" 400;
  font-style: italic;
  font-size: 10px;
  color: var(--faint);
  text-transform: lowercase;
  white-space: nowrap;
}

.conv-item .del {
  position: absolute;
  right: 16px;
  bottom: 8px;
  background: none;
  border: none;
  cursor: pointer;
  font-family: var(--font-display);
  font-style: italic;
  font-size: 11px;
  letter-spacing: 0.08em;
  color: var(--faint);
  opacity: 0;
  transition: opacity 120ms ease, color 120ms ease;
}
.conv-item:hover .del { opacity: 1; }
.conv-item .del:hover { color: var(--vermillion); }

.sidebar-foot {
  padding: 12px 28px 20px;
  border-top: 1px solid var(--border-soft);
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  font-family: var(--font-display);
  font-style: italic;
  font-size: 11px;
  color: var(--faint);
}
.sidebar-foot .seal {
  font-style: normal;
  color: var(--brass-soft);
  letter-spacing: 0.2em;
}
.sidebar-foot .seal-meta {
  letter-spacing: 0.08em;
}

/* ============================================================
   CHAT COLUMN
   ============================================================ */

.chat {
  display: flex;
  flex-direction: column;
  overflow: hidden;
  position: relative;
  background:
    linear-gradient(180deg, rgba(201, 163, 95, 0.015), transparent 280px),
    var(--bg);
}

/* chat header — title strip */
.chat-header {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 28px;
  padding: 24px var(--gutter) 18px;
  border-bottom: 1px solid var(--border-soft);
  position: relative;
}
.chat-header::after {
  /* second hairline below for editorial double-rule */
  content: "";
  position: absolute;
  left: var(--gutter);
  right: var(--gutter);
  bottom: -5px;
  height: 1px;
  background: var(--border-soft);
  opacity: 0.5;
}
.chat-header .meta {
  display: flex;
  align-items: baseline;
  gap: 18px;
  min-width: 0;
  flex: 1;
}
.chat-header .folio {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.16em;
  color: var(--muted);
  text-transform: uppercase;
  white-space: nowrap;
}
.chat-header h2 {
  font-family: var(--font-display);
  font-variation-settings: "opsz" 72, "wght" 400;
  font-style: italic;
  font-size: 26px;
  font-weight: 400;
  color: var(--ink);
  letter-spacing: -0.005em;
  min-width: 0;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  padding: 2px 4px;
  margin: -2px -4px;
  border-radius: 2px;
}
.chat-header h2:focus {
  background: rgba(201, 163, 95, 0.06);
  outline: 1px dotted var(--brass-soft);
  outline-offset: 2px;
}

.header-right { display: flex; align-items: center; gap: 14px; }

.model-picker { position: relative; }
.model-picker select {
  font-family: var(--font-display);
  font-variation-settings: "opsz" 14, "wght" 600;
  font-size: 11px;
  letter-spacing: 0.20em;
  text-transform: uppercase;
  color: var(--brass);
  background: none;
  border: 1px solid var(--border);
  padding: 8px 30px 8px 14px;
  cursor: pointer;
  appearance: none;
  -webkit-appearance: none;
  border-radius: 0;
  transition: border-color 150ms ease, color 150ms ease;
}
.model-picker select:hover { border-color: var(--brass-soft); color: var(--ink); }
.model-picker select option {
  background: var(--surface);
  color: var(--ink);
  font-family: var(--font-display);
}
.model-picker::after {
  content: "";
  position: absolute;
  right: 12px;
  top: 50%;
  width: 6px; height: 6px;
  border-right: 1px solid var(--brass);
  border-bottom: 1px solid var(--brass);
  transform: translateY(-70%) rotate(45deg);
  pointer-events: none;
}

/* ============================================================
   MESSAGES
   ============================================================ */

.messages {
  flex: 1;
  overflow-y: auto;
  padding: 48px 0 40px;
}

.empty-state {
  height: 100%;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 40px;
  gap: 16px;
}
.empty-state .glyph {
  font-family: var(--font-display);
  font-variation-settings: "opsz" 144, "wght" 300;
  font-style: italic;
  font-size: 120px;
  color: var(--brass-soft);
  line-height: 1;
  margin-bottom: 8px;
  text-shadow: 0 2px 30px rgba(201, 163, 95, 0.18);
}
.empty-state p {
  font-family: var(--font-display);
  font-style: italic;
  font-size: 18px;
  color: var(--muted);
  font-variation-settings: "opsz" 24, "wght" 400;
}
.empty-state .empty-meta {
  font-size: 11px;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--faint);
  font-variation-settings: "opsz" 9, "wght" 500;
  font-style: italic;
}

.exchange {
  max-width: 760px;
  margin: 0 auto 36px;
  padding: 0 var(--gutter);
  position: relative;
}
.exchange + .exchange {
  margin-top: 36px;
  padding-top: 36px;
}
.exchange + .exchange::before {
  content: "·    ·    ·";
  position: absolute;
  top: 0;
  left: 50%;
  transform: translateX(-50%);
  letter-spacing: 0.2em;
  color: var(--brass-soft);
  font-size: 12px;
  font-family: var(--font-display);
}

.msg { margin-bottom: 24px; }
.msg:last-child { margin-bottom: 0; }

.msg .role {
  display: flex;
  align-items: baseline;
  gap: 12px;
  margin-bottom: 10px;
  font-family: var(--font-display);
  font-variation-settings: "opsz" 9, "wght" 500;
  font-style: italic;
  font-size: 11px;
  letter-spacing: 0.14em;
  color: var(--muted);
  text-transform: lowercase;
}
.msg .role .name {
  color: var(--brass);
  font-style: normal;
  letter-spacing: 0.22em;
  text-transform: uppercase;
}
.msg .role .stamp {
  color: var(--faint);
  font-family: var(--font-mono);
  font-size: 10px;
  font-style: normal;
  letter-spacing: 0.06em;
}
.msg .role .rule {
  flex: 1;
  height: 1px;
  background: var(--border-soft);
  margin-bottom: 4px;
}

/* USER */
.msg.user .body {
  font-family: var(--font-body);
  font-size: 17px;
  line-height: 1.6;
  color: var(--ink-soft);
  font-style: italic;
  padding-left: 18px;
  border-left: 1px solid var(--brass-soft);
  white-space: pre-wrap;
  word-wrap: break-word;
}

/* ASSISTANT */
.msg.assistant .body {
  font-family: var(--font-body);
  font-size: 18px;
  line-height: 1.7;
  color: var(--ink);
  word-wrap: break-word;
}

/* drop cap on the first paragraph of the assistant reply */
.msg.assistant .body > p:first-of-type::first-letter {
  font-family: var(--font-display);
  font-variation-settings: "opsz" 144, "wght" 400;
  font-style: italic;
  font-size: 3.4em;
  line-height: 0.86;
  float: left;
  padding: 8px 10px 0 0;
  color: var(--brass);
}

/* markdown content */
.body p { margin: 0 0 14px; }
.body p:last-child { margin-bottom: 0; }
.body strong { color: var(--ink); font-weight: 700; }
.body em { font-style: italic; }
.body a {
  color: var(--brass);
  text-decoration: underline;
  text-decoration-color: var(--brass-soft);
  text-underline-offset: 3px;
}
.body a:hover { color: var(--ink); text-decoration-color: var(--brass); }
.body h1, .body h2, .body h3, .body h4 {
  font-family: var(--font-display);
  color: var(--ink);
  margin: 22px 0 10px;
  letter-spacing: -0.01em;
  line-height: 1.25;
}
.body h1 { font-size: 28px; font-variation-settings: "opsz" 72, "wght" 500; font-style: italic; }
.body h2 { font-size: 22px; font-variation-settings: "opsz" 48, "wght" 500; }
.body h3 { font-size: 18px; font-variation-settings: "opsz" 24, "wght" 600; letter-spacing: 0.04em; text-transform: uppercase; color: var(--brass); }
.body h4 { font-size: 16px; font-variation-settings: "opsz" 14, "wght" 600; font-style: italic; }
.body ul, .body ol { padding-left: 26px; margin: 0 0 14px; }
.body ul { list-style: none; }
.body ul li { position: relative; }
.body ul li::before {
  content: "·";
  position: absolute;
  left: -16px;
  color: var(--brass);
  font-size: 1.4em;
  line-height: 1;
  top: -2px;
}
.body ol { list-style: none; counter-reset: list; }
.body ol li { counter-increment: list; position: relative; }
.body ol li::before {
  content: counter(list, lower-roman) ".";
  position: absolute;
  left: -28px;
  color: var(--brass-soft);
  font-family: var(--font-mono);
  font-size: 11px;
  top: 5px;
  width: 24px;
  text-align: right;
}
.body li { margin: 4px 0; }
.body blockquote {
  margin: 14px 0;
  padding: 4px 0 4px 18px;
  border-left: 2px solid var(--brass-soft);
  color: var(--muted);
  font-style: italic;
}
.body hr {
  border: none;
  text-align: center;
  margin: 24px 0;
  height: 14px;
}
.body hr::before {
  content: "·   ·   ·";
  letter-spacing: 0.3em;
  color: var(--brass-soft);
  font-size: 13px;
}
.body table {
  border-collapse: collapse;
  margin: 14px 0;
  width: 100%;
  font-family: var(--font-display);
  font-size: 14px;
}
.body th, .body td {
  text-align: left;
  padding: 6px 12px;
  border-bottom: 1px solid var(--border);
}
.body th {
  font-variation-settings: "opsz" 9, "wght" 600;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  font-size: 11px;
  color: var(--brass);
  font-style: italic;
}

/* inline code */
.body :not(pre) > code {
  font-family: var(--font-mono);
  font-size: 0.82em;
  background: var(--code-bg);
  color: var(--brass);
  padding: 2px 6px;
  border: 1px solid var(--border);
  border-radius: 0;
}

/* code blocks */
.body pre {
  background: var(--code-bg);
  border: 1px solid var(--border);
  border-top: 1px solid var(--brass-soft);
  padding: 30px 18px 16px;
  margin: 18px 0;
  overflow-x: auto;
  position: relative;
}
.body pre > code {
  font-family: var(--font-mono);
  font-size: 13px;
  line-height: 1.6;
  color: var(--ink-soft);
  background: none;
  border: none;
  padding: 0;
  display: block;
}
.code-meta {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  padding: 6px 14px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  border-bottom: 1px solid var(--border-soft);
  background: linear-gradient(to bottom, var(--raised), transparent);
  font-family: var(--font-display);
  font-variation-settings: "opsz" 9, "wght" 600;
  font-style: italic;
  font-size: 10px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
}
.code-meta .lang { color: var(--brass); }
.code-meta .copy {
  cursor: pointer;
  background: none;
  border: none;
  color: var(--muted);
  font: inherit;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  font-style: italic;
}
.code-meta .copy:hover { color: var(--brass); }
.code-meta .copy.copied { color: var(--moss); }

/* attachments inside a message */
.attachments-list {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 12px;
}
.attachments-list .att {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 6px 10px;
  border: 1px solid var(--border);
  background: var(--raised);
  font-family: var(--font-display);
  font-style: italic;
  font-size: 12px;
  color: var(--ink-soft);
}
.attachments-list .att .ext {
  font-family: var(--font-mono);
  font-style: normal;
  font-size: 9px;
  color: var(--brass);
  letter-spacing: 0.1em;
  text-transform: uppercase;
}
.attachments-list .att.image {
  padding: 0;
  border: 1px solid var(--border);
}
.attachments-list .att.image img {
  max-width: 220px;
  max-height: 160px;
  display: block;
}

/* streaming caret */
.cursor {
  display: inline-block;
  width: 9px;
  height: 1.1em;
  background: var(--brass);
  margin-left: 3px;
  vertical-align: -0.2em;
  animation: blink 1.05s steps(1) infinite;
}
@keyframes blink {
  0%, 55% { opacity: 1; }
  56%, 100% { opacity: 0; }
}

/* ============================================================
   COMPOSER
   ============================================================ */

.composer {
  padding: 0 var(--gutter) 22px;
  background: linear-gradient(to bottom, transparent, var(--bg) 28%);
  position: relative;
  margin-top: -28px;
  pointer-events: none;
}
.composer * { pointer-events: auto; }

.composer-inner {
  max-width: 760px;
  margin: 0 auto;
  background: var(--surface);
  border: 1px solid var(--border);
  border-top: 1px solid var(--brass-soft);
  position: relative;
  box-shadow: 0 -8px 40px rgba(0, 0, 0, 0.3);
}

.composer-attachments {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  padding: 12px 14px 0;
}
.composer-attachments:empty { display: none; }
.composer-attachments .chip {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 6px 8px 6px 10px;
  background: var(--raised);
  border: 1px solid var(--border);
  font-family: var(--font-display);
  font-style: italic;
  font-size: 12px;
  color: var(--ink-soft);
  max-width: 280px;
}
.composer-attachments .chip .ext {
  font-family: var(--font-mono);
  font-style: normal;
  font-size: 9px;
  color: var(--brass);
  letter-spacing: 0.1em;
  text-transform: uppercase;
}
.composer-attachments .chip .name {
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}
.composer-attachments .chip img {
  width: 38px; height: 38px;
  object-fit: cover;
  border: 1px solid var(--border);
  display: block;
}
.composer-attachments .chip button {
  background: none;
  border: none;
  color: var(--muted);
  cursor: pointer;
  font-family: var(--font-display);
  font-size: 16px;
  line-height: 1;
  padding: 0 0 0 4px;
  font-style: italic;
}
.composer-attachments .chip button:hover { color: var(--vermillion); }

.composer-input {
  display: flex;
  align-items: flex-end;
  gap: 12px;
  padding: 14px 14px 14px 18px;
}
.composer textarea {
  flex: 1;
  font-family: var(--font-body);
  font-size: 17px;
  line-height: 1.55;
  color: var(--ink);
  resize: none;
  min-height: 26px;
  max-height: 280px;
  caret-color: var(--brass);
}
.composer textarea::placeholder {
  color: var(--faint);
  font-style: italic;
}

.composer-buttons {
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  gap: 8px;
}

.composer .icon {
  background: none;
  border: 1px solid var(--border);
  color: var(--muted);
  width: 36px; height: 36px;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-display);
  font-style: italic;
  font-size: 16px;
  transition: color 150ms ease, border-color 150ms ease;
}
.composer .icon:hover {
  color: var(--brass);
  border-color: var(--brass-soft);
}

.composer .send {
  background: var(--brass);
  color: var(--bg);
  border: none;
  padding: 10px 22px;
  cursor: pointer;
  font-family: var(--font-display);
  font-variation-settings: "opsz" 14, "wght" 700;
  font-size: 11px;
  letter-spacing: 0.24em;
  text-transform: uppercase;
  transition: background 140ms ease, color 140ms ease;
}
.composer .send:hover { background: var(--ink); }
.composer .send:disabled {
  opacity: 0.35;
  cursor: not-allowed;
  background: var(--brass-deep);
}
.composer .send.streaming {
  background: var(--vermillion);
  color: var(--ink);
}

.hint {
  margin-top: 10px;
  text-align: center;
  font-family: var(--font-display);
  font-style: italic;
  font-size: 11px;
  color: var(--faint);
  letter-spacing: 0.04em;
}
.hint kbd {
  font-family: var(--font-mono);
  font-style: normal;
  font-size: 9.5px;
  padding: 2px 5px;
  background: var(--raised);
  border: 1px solid var(--border);
  color: var(--muted);
  letter-spacing: 0;
  margin: 0 1px;
}

/* ============================================================
   DRAG VEIL
   ============================================================ */

.drag-veil {
  position: fixed;
  inset: 20px;
  z-index: 1000;
  background: rgba(24, 18, 16, 0.92);
  border: 2px dashed var(--brass);
  display: flex;
  align-items: center;
  justify-content: center;
  backdrop-filter: blur(2px);
  pointer-events: none;
  animation: veilIn 180ms ease;
}
@keyframes veilIn {
  from { opacity: 0; transform: scale(0.99); }
  to { opacity: 1; transform: scale(1); }
}
.drag-veil-inner {
  text-align: center;
}
.drag-glyph {
  font-family: var(--font-display);
  font-variation-settings: "opsz" 144, "wght" 400;
  font-size: 96px;
  font-style: italic;
  color: var(--brass);
  display: block;
  line-height: 1;
  margin-bottom: 8px;
}
.drag-veil p {
  font-family: var(--font-display);
  font-variation-settings: "opsz" 72, "wght" 400;
  font-style: italic;
  font-size: 32px;
  color: var(--ink);
  letter-spacing: 0.02em;
}

/* ============================================================
   SCROLLBAR
   ============================================================ */

::-webkit-scrollbar { width: 10px; height: 10px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb {
  background: var(--border);
  border: 3px solid var(--bg);
  border-radius: 6px;
}
.sidebar ::-webkit-scrollbar-thumb { border-color: var(--bg-tint); }
::-webkit-scrollbar-thumb:hover { background: var(--brass-soft); }

/* ============================================================
   highlight.js — bespoke theme
   ============================================================ */

.hljs { background: var(--code-bg); color: var(--ink-soft); }
.hljs-keyword,
.hljs-built_in,
.hljs-type,
.hljs-selector-tag { color: #C9A35F; font-style: italic; }
.hljs-string,
.hljs-attr,
.hljs-selector-attr,
.hljs-symbol { color: #A8B98D; }
.hljs-number,
.hljs-literal,
.hljs-deletion { color: #D9966B; }
.hljs-comment,
.hljs-quote { color: #6B5E48; font-style: italic; }
.hljs-function,
.hljs-title,
.hljs-section { color: #E8D094; }
.hljs-variable,
.hljs-name,
.hljs-template-variable,
.hljs-selector-class,
.hljs-selector-id { color: #ECE1CC; }
.hljs-tag,
.hljs-meta,
.hljs-doctag,
.hljs-emphasis { color: #B85C3C; }
.hljs-attribute,
.hljs-params { color: #C9A35F; }
.hljs-regexp,
.hljs-link { color: #8FA274; }
.hljs-addition { color: #8FA274; }

/* ============================================================
   ERROR BANNER
   ============================================================ */

.err {
  max-width: 760px;
  margin: 8px auto 18px;
  padding: 10px 18px 10px 18px;
  border-left: 2px solid var(--vermillion);
  background: rgba(184, 92, 60, 0.08);
  font-family: var(--font-display);
  font-style: italic;
  font-size: 13px;
  color: #E8B8A4;
}
.err::before {
  content: "errata · ";
  font-style: normal;
  font-variation-settings: "opsz" 9, "wght" 600;
  font-size: 11px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--vermillion);
  margin-right: 6px;
}

/* ============================================================
   RESPONSIVE
   ============================================================ */

@media (max-width: 900px) {
  :root { --gutter: 24px; --rail: 240px; }
  .brand h1 { font-size: 32px; }
  .chat-header h2 { font-size: 20px; }
}
@media (max-width: 680px) {
  .app { grid-template-columns: 1fr; }
  .sidebar {
    position: fixed;
    inset: 0 auto 0 0;
    width: 280px;
    transform: translateX(-100%);
    transition: transform 220ms ease;
    z-index: 50;
  }
  .sidebar.open { transform: translateX(0); }
}

/* ============================================================
   THEME CYCLE BUTTON (works in all themes, restyled per-theme)
   ============================================================ */
.theme-cycle {
  background: none;
  border: none;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 0;
  color: var(--muted);
  font-family: var(--font-display);
  font-style: italic;
  font-size: 11px;
  letter-spacing: 0.06em;
  transition: color 140ms ease;
}
.theme-cycle:hover { color: var(--brass); }
.theme-cycle .theme-seal {
  font-style: normal;
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--brass-soft);
  letter-spacing: 0;
}
.theme-cycle .theme-name {
  text-transform: lowercase;
  letter-spacing: 0.12em;
}

.gate .foot .theme-cycle {
  font-size: 11px;
  background: none;
  color: var(--muted);
  padding: 0;
  border-radius: 0;
  text-transform: none;
}
.gate .foot .theme-cycle:hover { background: none; color: var(--brass); }

/* ============================================================
   THEME · CLAUDE (claude.ai look)
   warm cream paper, Claude orange, Tiempos-ish serif
   ============================================================ */

[data-theme="claude"] {
  --bg: #FAF9F5;
  --bg-tint: #F4F2EA;
  --surface: #FFFFFF;
  --raised: #F5F3EB;
  --raised-2: #EDEAE0;

  --ink: #1F1E1B;
  --ink-soft: #3D3C37;
  --muted: #76746E;
  --faint: #B0ACA0;
  --whisper: #DCD7C9;

  --brass: #CC785C;
  --brass-soft: #B86747;
  --brass-deep: #8B4F38;

  --vermillion: #C73E1D;
  --moss: #6B8A5C;

  --border: #E2DED2;
  --border-soft: #EDE9DC;
  --code-bg: #F0EEE5;

  --selection: #F6D6C6;

  --font-display: "Newsreader", "Charter", "Iowan Old Style", Georgia, serif;
  --font-body: "Newsreader", "Charter", "Iowan Old Style", Georgia, serif;
  /* keep var(--font-mono) JetBrains Mono */
}

[data-theme="claude"] body {
  background-image:
    radial-gradient(ellipse 900px 500px at 18% -10%, rgba(204, 120, 92, 0.06), transparent 70%);
}
[data-theme="claude"] body::before { display: none; }
[data-theme="claude"] .sidebar::after { display: none; }
[data-theme="claude"] .chat-header::after { display: none; }
[data-theme="claude"] .exchange + .exchange::before { display: none; }
[data-theme="claude"] .exchange + .exchange {
  border-top: 1px solid var(--border-soft);
  padding-top: 30px;
  margin-top: 30px;
}

[data-theme="claude"] .sidebar {
  background: var(--bg-tint);
  border-right: 1px solid var(--border);
}
[data-theme="claude"] .brand h1 {
  font-variation-settings: normal;
  font-weight: 500;
  font-style: normal;
  font-size: 34px;
  letter-spacing: -0.01em;
  color: var(--ink);
}
[data-theme="claude"] .brand h1::after { content: ""; }
[data-theme="claude"] .brand p {
  font-style: normal;
  text-transform: none;
  letter-spacing: 0.02em;
  font-size: 13px;
  color: var(--muted);
}
[data-theme="claude"] .new-entry {
  color: var(--brass);
  border-bottom-color: var(--border);
  font-weight: 600;
  text-transform: none;
  letter-spacing: 0.02em;
  font-size: 13px;
}
[data-theme="claude"] .new-entry:hover { color: var(--ink); }
[data-theme="claude"] .search input { font-style: normal; }
[data-theme="claude"] .conv-item .title { font-style: normal; }
[data-theme="claude"] .conv-item .date { font-style: normal; }
[data-theme="claude"] .conv-item .folio {
  color: var(--faint);
  font-size: 10px;
}
[data-theme="claude"] .ledger-empty { font-style: normal; color: var(--muted); }

[data-theme="claude"] .chat-header {
  background: var(--bg);
  border-bottom: 1px solid var(--border-soft);
}
[data-theme="claude"] .chat-header h2 {
  font-style: normal;
  font-weight: 500;
  letter-spacing: -0.01em;
}
[data-theme="claude"] .chat-header .folio {
  color: var(--muted);
  text-transform: uppercase;
}
[data-theme="claude"] .model-picker select {
  color: var(--ink);
  font-weight: 600;
  text-transform: none;
  letter-spacing: 0.04em;
  border-color: var(--border);
  background: var(--surface);
}
[data-theme="claude"] .model-picker::after {
  border-right-color: var(--ink);
  border-bottom-color: var(--ink);
}

[data-theme="claude"] .msg .role {
  font-style: normal;
  text-transform: none;
  letter-spacing: 0.04em;
  color: var(--muted);
  font-size: 12px;
}
[data-theme="claude"] .msg .role .name {
  color: var(--brass);
  letter-spacing: 0.06em;
  text-transform: none;
  font-weight: 600;
}
[data-theme="claude"] .msg .role .stamp { color: var(--faint); }

[data-theme="claude"] .msg.user .body {
  font-style: normal;
  color: var(--ink-soft);
  border-left: 2px solid var(--brass);
  font-size: 16px;
  padding-left: 16px;
}
[data-theme="claude"] .msg.assistant .body {
  color: var(--ink);
  font-size: 17px;
  line-height: 1.65;
}
[data-theme="claude"] .msg.assistant .body > p:first-of-type::first-letter {
  /* keep a refined drop cap in the Claude theme */
  color: var(--brass);
  font-style: normal;
  font-weight: 600;
}

[data-theme="claude"] .body h1,
[data-theme="claude"] .body h2 { font-style: normal; font-weight: 600; }
[data-theme="claude"] .body h3 {
  text-transform: none;
  letter-spacing: 0;
  color: var(--ink);
  font-style: normal;
  font-weight: 600;
}
[data-theme="claude"] .body a {
  color: var(--brass);
  text-decoration-color: var(--brass-soft);
}
[data-theme="claude"] .body :not(pre) > code {
  background: var(--code-bg);
  color: var(--brass-deep);
  border-color: var(--border);
}
[data-theme="claude"] .body pre {
  background: var(--code-bg);
  border: 1px solid var(--border);
  border-top: 1px solid var(--border);
}
[data-theme="claude"] .body pre > code { color: var(--ink); }
[data-theme="claude"] .code-meta {
  background: linear-gradient(to bottom, var(--raised-2), transparent);
  font-style: normal;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}
[data-theme="claude"] .code-meta .lang { color: var(--brass); }
[data-theme="claude"] .code-meta .copy { color: var(--muted); }
[data-theme="claude"] .code-meta .copy:hover { color: var(--brass); }
[data-theme="claude"] .body blockquote {
  border-left-color: var(--brass);
  color: var(--muted);
}

[data-theme="claude"] .composer {
  background: linear-gradient(to bottom, transparent, var(--bg) 28%);
}
[data-theme="claude"] .composer-inner {
  background: var(--surface);
  border: 1px solid var(--border);
  border-top: 1px solid var(--border);
  border-radius: 12px;
  box-shadow: 0 4px 24px rgba(31, 30, 27, 0.08);
}
[data-theme="claude"] .composer textarea { color: var(--ink); caret-color: var(--brass); }
[data-theme="claude"] .composer textarea::placeholder { color: var(--faint); font-style: normal; }
[data-theme="claude"] .composer .icon {
  border-radius: 8px;
  border-color: var(--border);
}
[data-theme="claude"] .composer .send {
  background: var(--brass);
  color: white;
  border-radius: 8px;
  font-style: normal;
  font-weight: 600;
  letter-spacing: 0.04em;
  text-transform: none;
  padding: 10px 18px;
}
[data-theme="claude"] .composer .send:hover { background: var(--brass-soft); color: white; }
[data-theme="claude"] .hint { font-style: normal; color: var(--muted); }

[data-theme="claude"] .empty-state .glyph {
  font-style: normal;
  font-size: 80px;
  color: var(--brass);
  font-weight: 400;
}
[data-theme="claude"] .empty-state p { font-style: normal; color: var(--muted); }
[data-theme="claude"] .empty-state .empty-meta {
  font-style: normal;
  letter-spacing: 0.1em;
}

[data-theme="claude"] .drag-veil {
  background: rgba(250, 249, 245, 0.92);
  border-color: var(--brass);
}
[data-theme="claude"] .drag-glyph,
[data-theme="claude"] .drag-veil p {
  color: var(--brass);
  font-style: normal;
}

[data-theme="claude"] ::-webkit-scrollbar-thumb {
  background: var(--border);
  border-color: var(--bg);
}

[data-theme="claude"] .body hr::before { content: ""; }
[data-theme="claude"] .body hr {
  border-top: 1px solid var(--border-soft);
  height: 0;
  margin: 22px 0;
}

/* highlight.js — Claude light */
[data-theme="claude"] .hljs { background: var(--code-bg); color: var(--ink); }
[data-theme="claude"] .hljs-keyword,
[data-theme="claude"] .hljs-built_in,
[data-theme="claude"] .hljs-type { color: #B86747; font-style: normal; font-weight: 600; }
[data-theme="claude"] .hljs-string,
[data-theme="claude"] .hljs-attr { color: #5C7A3F; }
[data-theme="claude"] .hljs-number,
[data-theme="claude"] .hljs-literal { color: #B45309; }
[data-theme="claude"] .hljs-comment { color: #8E8B82; font-style: italic; }
[data-theme="claude"] .hljs-function,
[data-theme="claude"] .hljs-title { color: #7F4A2E; }
[data-theme="claude"] .hljs-tag,
[data-theme="claude"] .hljs-meta { color: #A04020; }

/* login gate */
[data-theme="claude"] .gate {
  background: var(--surface);
  border: 1px solid var(--border);
  border-top: 1px solid var(--border);
  border-radius: 16px;
  box-shadow: 0 30px 80px rgba(31, 30, 27, 0.12);
}
[data-theme="claude"] .gate::before { display: none; }
[data-theme="claude"] .gate h1 {
  font-style: normal;
  font-weight: 500;
  font-variation-settings: normal;
  color: var(--ink);
  font-size: 44px;
}
[data-theme="claude"] .gate h1::after { content: ""; }
[data-theme="claude"] .gate .sub { font-style: normal; color: var(--muted); }
[data-theme="claude"] .gate label {
  font-style: normal;
  text-transform: none;
  letter-spacing: 0.02em;
  color: var(--muted);
  font-size: 12px;
  font-weight: 600;
}
[data-theme="claude"] .gate input[type="password"] {
  color: var(--ink);
  border-bottom: 1px solid var(--border);
}
[data-theme="claude"] .gate input[type="password"]::placeholder { font-style: normal; }
[data-theme="claude"] .gate input[type="password"]:focus { border-bottom-color: var(--brass); }
[data-theme="claude"] .gate button {
  background: var(--brass);
  color: white;
  border-radius: 8px;
  font-style: normal;
  font-weight: 600;
  letter-spacing: 0.04em;
  text-transform: none;
}
[data-theme="claude"] .gate button:hover { background: var(--brass-soft); color: white; }
[data-theme="claude"] .gate .foot { color: var(--muted); font-style: normal; }


/* ============================================================
   THEME · DELTAMATH
   Two-column layout: white sidebar with logo + nav list,
   pale gray main area with white card panels.
   Fonts: Lato (UI), Lora (headings).
   ============================================================ */

[data-theme="deltamath"] {
  --bg: #FAFAFB;
  --bg-tint: #FFFFFF;
  --surface: #FFFFFF;
  --raised: #F9FAFB;
  --raised-2: #F3F4F6;

  --ink: #111827;
  --ink-soft: #222222;
  --muted: #6B7280;
  --faint: #9CA3AF;
  --whisper: #E5E7EB;

  --brass: #2F52E9;
  --brass-soft: #4263F0;
  --brass-deep: #1E3FCC;

  --vermillion: #DC2626;
  --moss: #16A34A;

  --border: #E3E8EF;
  --border-soft: #E5E7EB;
  --code-bg: #F3F4F6;

  --selection: #DBEAFE;

  --font-display: "Lato", -apple-system, "Segoe UI", Roboto, Arial, sans-serif;
  --font-body: "Lato", -apple-system, "Segoe UI", Roboto, Arial, sans-serif;
  --font-serif: "Lora", "Georgia", "Times New Roman", serif;
}

[data-theme="deltamath"] body {
  background-image: none;
  background: var(--bg);
  color: var(--ink-soft);
}
[data-theme="deltamath"] body::before { display: none; }
[data-theme="deltamath"] .sidebar::after { display: none; }
[data-theme="deltamath"] .chat-header::after { display: none; }
[data-theme="deltamath"] .exchange + .exchange::before { display: none; }

/* Sidebar — white, right border only */
[data-theme="deltamath"] .sidebar {
  background: var(--surface);
  border-right: 1px solid var(--border);
}

/* Brand = the actual DeltaMath wordmark */
[data-theme="deltamath"] .brand {
  background: transparent;
  padding: 26px 24px 18px;
  margin: 0;
}
[data-theme="deltamath"] .brand h1 {
  display: block;
  width: 156px;
  height: 39px;
  background: url('/dm-logo.png') no-repeat left top / contain;
  font-size: 0;
  color: transparent;
  overflow: hidden;
  font-variation-settings: normal;
  font-style: normal;
  letter-spacing: 0;
  font-weight: 400;
  padding: 0;
  margin: 0;
}
[data-theme="deltamath"] .brand h1::before,
[data-theme="deltamath"] .brand h1::after { content: ""; display: none; }
[data-theme="deltamath"] .brand p { display: none; }

/* "+ New entry" — looks like an inline link/CTA */
[data-theme="deltamath"] .sidebar-actions {
  padding: 0 24px 14px;
  gap: 12px;
}
[data-theme="deltamath"] .new-entry {
  background: transparent;
  color: var(--brass);
  text-align: left;
  padding: 4px 0;
  border: none;
  border-bottom: none;
  border-radius: 0;
  font-weight: 700;
  font-size: 14px;
  text-transform: none;
  letter-spacing: 0;
  font-family: var(--font-display);
}
[data-theme="deltamath"] .new-entry:hover {
  background: transparent;
  color: var(--brass-deep);
}
[data-theme="deltamath"] .new-entry::before {
  content: "+  ";
  color: var(--brass);
}

[data-theme="deltamath"] .search input {
  font-style: normal;
  font-size: 14px;
  color: var(--ink);
  border: 1px solid var(--border-soft);
  border-radius: 6px;
  background: var(--surface);
  padding: 8px 12px;
  font-family: var(--font-display);
}
[data-theme="deltamath"] .search input::placeholder {
  font-style: normal;
  color: var(--faint);
}
[data-theme="deltamath"] .search input:focus {
  border-color: var(--brass);
  box-shadow: 0 0 0 3px rgba(47, 82, 233, 0.15);
}

/* Conversation list = DeltaMath unit list (circle ○ or green ✓) */
[data-theme="deltamath"] .conversations { padding: 4px 12px 24px; }
[data-theme="deltamath"] .conv-item {
  display: grid;
  grid-template-columns: 20px 1fr auto;
  column-gap: 10px;
  align-items: center;
  padding: 9px 14px 9px 10px;
  margin: 2px 0;
  border-radius: 6px;
  font-style: normal;
}
[data-theme="deltamath"] .conv-item::before {
  content: "";
  display: block;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  border: 2px solid #CBD5E1;
  background: transparent;
  position: static;
}
[data-theme="deltamath"] .conv-item.active::before {
  content: "✓";
  border: none;
  color: var(--moss);
  font-size: 17px;
  font-weight: 700;
  line-height: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  width: 18px;
  height: 18px;
}
[data-theme="deltamath"] .conv-item .folio { display: none; }
[data-theme="deltamath"] .conv-item .title {
  font-style: normal;
  font-size: 14px;
  color: var(--ink-soft);
  font-weight: 400;
  font-family: var(--font-display);
}
[data-theme="deltamath"] .conv-item.active .title {
  font-weight: 700;
  color: var(--ink);
}
[data-theme="deltamath"] .conv-item .date {
  font-style: normal;
  font-size: 11px;
  color: var(--faint);
}
[data-theme="deltamath"] .conv-item:hover { background: var(--raised); }
[data-theme="deltamath"] .conv-item.active {
  background: var(--selection);
}
[data-theme="deltamath"] .conv-item.active:hover { background: var(--selection); }
[data-theme="deltamath"] .conv-item .del {
  font-style: normal;
  font-size: 11px;
  text-transform: none;
}
[data-theme="deltamath"] .ledger-empty {
  font-style: normal;
  color: var(--muted);
  padding: 12px 14px;
}

[data-theme="deltamath"] .sidebar-foot {
  background: transparent;
  padding: 16px 24px 22px;
  border-top: 1px solid var(--border-soft);
  font-style: normal;
}
[data-theme="deltamath"] .sidebar-foot,
[data-theme="deltamath"] .sidebar-foot .seal,
[data-theme="deltamath"] .sidebar-foot .seal-meta,
[data-theme="deltamath"] .theme-cycle,
[data-theme="deltamath"] .theme-cycle .theme-name,
[data-theme="deltamath"] .theme-cycle .theme-seal {
  font-style: normal;
  letter-spacing: 0;
  font-family: var(--font-display);
}
[data-theme="deltamath"] .theme-cycle .theme-seal { color: var(--brass); }
[data-theme="deltamath"] .theme-cycle:hover { color: var(--brass); }

/* Main area — pale gray with title in Lora */
[data-theme="deltamath"] .chat {
  background: var(--bg);
  background-image: none;
}
[data-theme="deltamath"] .chat-header {
  background: transparent;
  border-bottom: none;
  color: var(--ink);
  padding: 32px 40px 22px;
}
[data-theme="deltamath"] .chat-header h2 {
  font-family: var(--font-serif);
  font-style: normal;
  font-weight: 700;
  font-size: 24px;
  color: var(--ink);
  letter-spacing: -0.005em;
  font-variation-settings: normal;
}
[data-theme="deltamath"] .chat-header h2:focus {
  background: rgba(47, 82, 233, 0.06);
  outline: 1px dotted var(--brass);
}
[data-theme="deltamath"] .chat-header .folio { display: none; }

[data-theme="deltamath"] .model-picker select {
  background: var(--surface);
  border: 1px solid var(--border-soft);
  color: var(--ink);
  font-weight: 700;
  text-transform: none;
  letter-spacing: 0;
  font-size: 13px;
  border-radius: 6px;
  padding: 8px 30px 8px 14px;
  font-family: var(--font-display);
}
[data-theme="deltamath"] .model-picker select:hover {
  border-color: var(--brass);
  color: var(--ink);
}
[data-theme="deltamath"] .model-picker select option {
  background: var(--surface);
  color: var(--ink);
}
[data-theme="deltamath"] .model-picker::after {
  border-right-color: var(--ink-soft);
  border-bottom-color: var(--ink-soft);
}

/* Messages — each exchange becomes a white card with subtle border */
[data-theme="deltamath"] .messages { padding: 8px 0 40px; }
[data-theme="deltamath"] .exchange {
  background: var(--surface);
  border: 1px solid var(--border-soft);
  border-radius: 8px;
  padding: 22px 28px;
  margin: 0 40px 16px;
  max-width: none;
}
[data-theme="deltamath"] .exchange + .exchange {
  margin-top: 16px;
  padding-top: 22px;
  border-top: 1px solid var(--border-soft);
}

[data-theme="deltamath"] .msg .role {
  font-style: normal;
  text-transform: none;
  letter-spacing: 0;
  color: var(--muted);
  font-size: 12px;
  font-family: var(--font-display);
  font-weight: 400;
}
[data-theme="deltamath"] .msg .role .name {
  color: var(--brass);
  letter-spacing: 0;
  text-transform: none;
  font-weight: 700;
}
[data-theme="deltamath"] .msg .role .stamp { color: var(--faint); font-family: var(--font-display); }

[data-theme="deltamath"] .msg.user .body {
  font-style: normal;
  color: var(--ink-soft);
  border-left: 3px solid var(--brass);
  font-size: 15px;
  padding: 8px 14px;
  background: var(--raised-2);
  border-radius: 0 4px 4px 0;
  font-family: var(--font-display);
}
[data-theme="deltamath"] .msg.assistant .body {
  color: var(--ink-soft);
  font-size: 16px;
  line-height: 1.6;
  font-family: var(--font-display);
}
[data-theme="deltamath"] .msg.assistant .body > p:first-of-type::first-letter {
  font-family: inherit;
  font-variation-settings: normal;
  font-size: inherit;
  font-style: inherit;
  font-weight: inherit;
  line-height: inherit;
  float: none;
  padding: 0;
  color: inherit;
}

[data-theme="deltamath"] .body h1,
[data-theme="deltamath"] .body h2,
[data-theme="deltamath"] .body h3,
[data-theme="deltamath"] .body h4 {
  font-family: var(--font-serif);
  font-style: normal;
  font-weight: 700;
  font-variation-settings: normal;
  text-transform: none;
  letter-spacing: 0;
  color: var(--ink);
}
[data-theme="deltamath"] .body h1 { font-size: 24px; }
[data-theme="deltamath"] .body h2 { font-size: 20px; }
[data-theme="deltamath"] .body h3 { font-size: 17px; color: var(--ink); }
[data-theme="deltamath"] .body h4 { font-size: 15px; }
[data-theme="deltamath"] .body a {
  color: var(--brass);
  text-decoration-color: var(--brass);
  font-weight: 600;
}
[data-theme="deltamath"] .body :not(pre) > code {
  background: var(--code-bg);
  color: #B91C1C;
  border-color: var(--border-soft);
  font-size: 0.88em;
}
[data-theme="deltamath"] .body pre {
  background: var(--code-bg);
  border: 1px solid var(--border-soft);
  border-top: 1px solid var(--border-soft);
  border-radius: 6px;
}
[data-theme="deltamath"] .body pre > code { color: var(--ink); }
[data-theme="deltamath"] .code-meta {
  background: #EEF1F5;
  border-bottom: 1px solid var(--border-soft);
  font-style: normal;
  letter-spacing: 0.02em;
  text-transform: uppercase;
  font-size: 10px;
  font-weight: 700;
  font-family: var(--font-display);
}
[data-theme="deltamath"] .code-meta .lang { color: var(--brass); }
[data-theme="deltamath"] .code-meta .copy { color: var(--muted); font-family: var(--font-display); }
[data-theme="deltamath"] .code-meta .copy:hover { color: var(--brass); }
[data-theme="deltamath"] .body blockquote {
  border-left: 3px solid var(--brass);
  color: var(--muted);
  background: var(--raised);
  padding: 8px 14px;
  border-radius: 0 4px 4px 0;
}
[data-theme="deltamath"] .body hr::before { content: ""; }
[data-theme="deltamath"] .body hr {
  border-top: 1px solid var(--border-soft);
  height: 0;
  margin: 18px 0;
}

/* Composer — bottom panel as white card */
[data-theme="deltamath"] .composer {
  background: linear-gradient(to bottom, transparent, var(--bg) 28%);
  padding: 0 40px 24px;
}
[data-theme="deltamath"] .composer-inner {
  background: var(--surface);
  border: 1px solid var(--border-soft);
  border-top: 1px solid var(--border-soft);
  border-radius: 8px;
  box-shadow: 0 2px 6px rgba(17, 24, 39, 0.04);
}
[data-theme="deltamath"] .composer textarea {
  color: var(--ink);
  caret-color: var(--brass);
  font-size: 15px;
  font-family: var(--font-display);
}
[data-theme="deltamath"] .composer textarea::placeholder {
  font-style: normal;
  color: var(--faint);
}
[data-theme="deltamath"] .composer .icon {
  border-radius: 6px;
  border-color: var(--border-soft);
  color: var(--muted);
}
[data-theme="deltamath"] .composer .icon:hover {
  color: var(--brass);
  border-color: var(--brass);
}

/* Primary action button (Submit Answer style) */
[data-theme="deltamath"] .composer .send {
  background: var(--brass);
  color: white;
  border-radius: 6px;
  font-style: normal;
  font-weight: 700;
  letter-spacing: 0;
  text-transform: none;
  padding: 10px 22px;
  font-size: 14px;
  font-family: var(--font-display);
}
[data-theme="deltamath"] .composer .send:hover { background: var(--brass-deep); color: white; }
[data-theme="deltamath"] .composer .send:disabled {
  background: #C7D2E8;
  color: white;
  opacity: 1;
}
[data-theme="deltamath"] .composer .send.streaming { background: var(--vermillion); }
[data-theme="deltamath"] .hint {
  font-style: normal;
  color: var(--muted);
  font-family: var(--font-display);
}
[data-theme="deltamath"] .hint kbd {
  font-family: var(--font-mono);
  background: var(--raised);
  border: 1px solid var(--border-soft);
  color: var(--muted);
}

/* Empty state */
[data-theme="deltamath"] .empty-state .glyph {
  font-style: normal;
  font-family: var(--font-serif);
  font-size: 72px;
  color: var(--brass);
  font-weight: 400;
  text-shadow: none;
}
[data-theme="deltamath"] .empty-state p {
  font-style: normal;
  font-family: var(--font-display);
  font-variation-settings: normal;
  color: var(--muted);
  font-size: 15px;
}
[data-theme="deltamath"] .empty-state .empty-meta {
  font-style: normal;
  letter-spacing: 0.04em;
  font-size: 11px;
  color: var(--faint);
}

/* Attachment chips */
[data-theme="deltamath"] .composer-attachments .chip,
[data-theme="deltamath"] .attachments-list .att {
  background: var(--raised);
  border: 1px solid var(--border-soft);
  border-radius: 4px;
  font-style: normal;
  color: var(--ink-soft);
  font-family: var(--font-display);
}
[data-theme="deltamath"] .composer-attachments .chip .ext,
[data-theme="deltamath"] .attachments-list .att .ext {
  color: var(--brass);
  background: var(--surface);
  padding: 2px 4px;
  border-radius: 2px;
}

/* Drag veil */
[data-theme="deltamath"] .drag-veil {
  background: rgba(255, 255, 255, 0.94);
  border-color: var(--brass);
}
[data-theme="deltamath"] .drag-glyph,
[data-theme="deltamath"] .drag-veil p {
  color: var(--brass);
  font-style: normal;
  font-variation-settings: normal;
  font-weight: 700;
  font-family: var(--font-display);
}

[data-theme="deltamath"] ::-webkit-scrollbar-thumb {
  background: #D1D5DB;
  border-color: var(--bg);
}
[data-theme="deltamath"] .sidebar ::-webkit-scrollbar-thumb {
  border-color: var(--surface);
}

/* Errors */
[data-theme="deltamath"] .err {
  background: #FEF2F2;
  color: #991B1B;
  border-left-color: var(--vermillion);
  font-style: normal;
  font-family: var(--font-display);
}
[data-theme="deltamath"] .err::before {
  font-style: normal;
  color: var(--vermillion);
  font-family: var(--font-display);
}

/* highlight.js — light theme tuned to DeltaMath palette */
[data-theme="deltamath"] .hljs { background: var(--code-bg); color: var(--ink); }
[data-theme="deltamath"] .hljs-keyword,
[data-theme="deltamath"] .hljs-built_in,
[data-theme="deltamath"] .hljs-type { color: var(--brass); font-style: normal; font-weight: 700; }
[data-theme="deltamath"] .hljs-string,
[data-theme="deltamath"] .hljs-attr { color: #047857; }
[data-theme="deltamath"] .hljs-number,
[data-theme="deltamath"] .hljs-literal { color: #B91C1C; }
[data-theme="deltamath"] .hljs-comment { color: #6B7280; font-style: italic; }
[data-theme="deltamath"] .hljs-function,
[data-theme="deltamath"] .hljs-title { color: #7C3AED; }
[data-theme="deltamath"] .hljs-tag,
[data-theme="deltamath"] .hljs-meta { color: #B45309; }

/* ---------- LOGIN GATE in DeltaMath theme ---------- */
[data-theme="deltamath"] body { background: var(--bg); }
[data-theme="deltamath"] .gate {
  background: var(--surface);
  border: 1px solid var(--border-soft);
  border-top: none;
  border-radius: 8px;
  box-shadow: 0 6px 24px rgba(17, 24, 39, 0.08);
  padding-top: 36px;
}
[data-theme="deltamath"] .gate::before { display: none; }
[data-theme="deltamath"] .gate h1 {
  width: 220px;
  height: 56px;
  background: url('/dm-logo.png') no-repeat left center / contain;
  font-size: 0;
  color: transparent;
  overflow: hidden;
  font-style: normal;
  font-weight: 400;
  font-variation-settings: normal;
  letter-spacing: 0;
  margin: 0 auto;
}
[data-theme="deltamath"] .gate h1::before,
[data-theme="deltamath"] .gate h1::after { content: ""; display: none; }
[data-theme="deltamath"] .gate .sub {
  font-style: normal;
  color: var(--muted);
  letter-spacing: 0;
  font-family: var(--font-display);
  text-align: center;
  margin-top: 10px;
}
[data-theme="deltamath"] .gate label {
  font-style: normal;
  text-transform: none;
  letter-spacing: 0;
  font-size: 13px;
  font-weight: 700;
  color: var(--ink);
  font-family: var(--font-display);
}
[data-theme="deltamath"] .gate input[type="password"] {
  border: 1px solid var(--border-soft);
  background: var(--surface);
  color: var(--ink);
  padding: 10px 12px;
  border-radius: 6px;
  font-size: 15px;
  letter-spacing: 0;
  font-family: var(--font-display);
}
[data-theme="deltamath"] .gate input[type="password"]::placeholder {
  font-style: normal;
  color: var(--faint);
}
[data-theme="deltamath"] .gate input[type="password"]:focus {
  border-color: var(--brass);
  box-shadow: 0 0 0 3px rgba(47, 82, 233, 0.15);
}
[data-theme="deltamath"] .gate button {
  background: var(--brass);
  color: white;
  border-radius: 6px;
  font-style: normal;
  font-weight: 700;
  letter-spacing: 0;
  text-transform: none;
  padding: 10px 22px;
  font-size: 14px;
  font-family: var(--font-display);
}
[data-theme="deltamath"] .gate button:hover { background: var(--brass-deep); }
[data-theme="deltamath"] .gate .foot {
  font-style: normal;
  color: var(--muted);
  font-family: var(--font-display);
}

/* ============================================================
   DELTAMATH DEEP COVER (data-cover + deltamath theme)
   Visible only when both attributes are set on <html>.
   ============================================================ */

.cover-head,
.cover-foot,
.cover-score { display: none; }

[data-cover][data-theme="deltamath"] .cover-head,
[data-cover][data-theme="deltamath"] .cover-foot {
  display: block;
}
[data-cover][data-theme="deltamath"] .cover-score {
  display: block;
}

/* ---- sidebar head (back link + assignment + grade bar) ---- */
[data-cover][data-theme="deltamath"] .cover-head {
  padding: 4px 24px 14px;
  border-bottom: 1px solid var(--border-soft);
  margin-bottom: 14px;
}
[data-cover][data-theme="deltamath"] .cover-back {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  color: var(--brass);
  font-weight: 700;
  font-size: 14px;
  text-decoration: none;
  margin-bottom: 14px;
  font-family: var(--font-display);
}
[data-cover][data-theme="deltamath"] .cover-back:hover { color: var(--brass-deep); }
[data-cover][data-theme="deltamath"] .cover-asg-title {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 15px;
  color: var(--ink);
  line-height: 1.3;
  margin-bottom: 4px;
}
[data-cover][data-theme="deltamath"] .cover-asg-due {
  font-family: var(--font-display);
  font-size: 13px;
  color: var(--ink-soft);
  margin-bottom: 14px;
}
[data-cover][data-theme="deltamath"] .cover-asg-due strong {
  font-weight: 700;
  color: var(--ink);
}
[data-cover][data-theme="deltamath"] .cover-grade {
  margin-top: 4px;
}
[data-cover][data-theme="deltamath"] .cover-grade-label {
  font-family: var(--font-display);
  font-size: 13px;
  color: var(--ink);
  margin-bottom: 6px;
  font-weight: 700;
}
[data-cover][data-theme="deltamath"] .cover-grade-bar {
  height: 8px;
  background: var(--border-soft);
  border-radius: 4px;
  overflow: hidden;
}
[data-cover][data-theme="deltamath"] .cover-grade-bar span {
  display: block;
  height: 100%;
  background: var(--brass);
  border-radius: 4px;
}

/* ---- sidebar foot (calculators + user) ---- */
[data-cover][data-theme="deltamath"] .cover-foot {
  padding: 12px 0 0;
  border-top: 1px solid var(--border-soft);
  margin: 12px 12px 0;
}
[data-cover][data-theme="deltamath"] .cover-tool {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 7px 12px;
  font-family: var(--font-display);
  font-size: 13px;
  color: var(--ink-soft);
  text-decoration: none;
  border-radius: 6px;
}
[data-cover][data-theme="deltamath"] .cover-tool svg {
  color: var(--muted);
  flex-shrink: 0;
}
[data-cover][data-theme="deltamath"] .cover-tool:hover { background: var(--raised); }
[data-cover][data-theme="deltamath"] .cover-user {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 14px 12px 16px;
  margin-top: 8px;
  border-top: 1px solid var(--border-soft);
  font-family: var(--font-display);
  font-size: 13px;
  color: var(--ink-soft);
}
[data-cover][data-theme="deltamath"] .cover-user-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 24px;
  height: 24px;
  color: var(--muted);
}
[data-cover][data-theme="deltamath"] .cover-user-name {
  flex: 1;
  color: var(--ink-soft);
  font-weight: 400;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}
[data-cover][data-theme="deltamath"] .cover-logout {
  color: var(--brass);
  text-decoration: none;
  font-weight: 700;
  font-size: 13px;
}
[data-cover][data-theme="deltamath"] .cover-logout:hover { color: var(--brass-deep); }

/* hide the regular ledger footer in cover mode (theme cycle moves above) */
[data-cover][data-theme="deltamath"] .sidebar-foot { display: none; }

/* ---- main area score card ---- */
[data-cover][data-theme="deltamath"] .cover-score {
  background: var(--surface);
  border: 1px solid var(--border-soft);
  border-radius: 8px;
  padding: 14px 22px 16px;
  margin: 0 40px 14px;
  box-shadow: 0 1px 2px rgba(17, 24, 39, 0.04);
}
[data-cover][data-theme="deltamath"] .cover-score-row {
  display: flex;
  gap: 28px;
  font-family: var(--font-display);
  font-size: 14px;
  color: var(--ink-soft);
  margin-bottom: 10px;
}
[data-cover][data-theme="deltamath"] .cover-score-row strong {
  font-weight: 700;
  color: var(--ink);
  margin-right: 4px;
}
[data-cover][data-theme="deltamath"] .cover-score-bar {
  display: flex;
  gap: 6px;
  height: 10px;
}
[data-cover][data-theme="deltamath"] .cover-score-bar > span {
  flex: 1;
  background: var(--brass);
  border-radius: 5px;
  height: 100%;
}
[data-cover][data-theme="deltamath"] .cover-score-bar > span.empty {
  background: var(--border-soft);
}

/* tighten the chat header in cover mode — title flush, fewer ornaments */
[data-cover][data-theme="deltamath"] .chat-header { padding-top: 28px; padding-bottom: 12px; }
[data-cover][data-theme="deltamath"] .messages { padding-top: 18px; }