/* IGCSE Review Platform — design system (from handoff bundle).
 * Loaded alongside static/css/style.css. The old style.css holds the
 * content-body classes (.topic-card, .formula-box, .tip-box, etc.) that
 * are embedded INSIDE HTML notes in the database — deleting them would
 * strip formatting from 151 note bodies. New chrome + new pages use the
 * tokens + components below; note bodies keep rendering via the legacy
 * classes. Over time those will be migrated to use design.css tokens.
 */

:root {
  /* Paper neutrals — warm, slightly off-white */
  --paper-0: #faf7f2;
  --paper-1: #f3efe7;
  --paper-2: #e8e2d6;
  --paper-3: #d9d2c2;
  --paper-4: #bcb39f;

  /* Ink — deep cool black with a hint of blue */
  --ink-0: #14181f;
  --ink-1: #2a2f38;
  --ink-2: #4a505b;
  --ink-3: #6d7482;
  --ink-4: #9aa0ac;

  /* Accents */
  --indigo: oklch(42% 0.14 264);
  --indigo-soft: oklch(92% 0.035 264);
  --indigo-line: oklch(78% 0.06 264);
  --amber: oklch(72% 0.12 75);
  --amber-soft: oklch(94% 0.05 80);
  --amber-line: oklch(84% 0.09 75);

  --ok: oklch(55% 0.12 155);
  --ok-soft: oklch(93% 0.05 155);
  --err: oklch(55% 0.17 25);
  --err-soft: oklch(94% 0.04 25);

  --serif: "Newsreader", "Source Serif 4", Georgia, serif;
  --sans: "Inter Tight", "Inter", system-ui, sans-serif;
  --mono: "JetBrains Mono", ui-monospace, monospace;

  --r-sm: 6px;
  --r: 10px;
  --r-lg: 16px;
  --r-xl: 22px;

  --shadow-sm: 0 1px 2px rgba(20, 24, 31, 0.04), 0 1px 1px rgba(20, 24, 31, 0.03);
  --shadow: 0 6px 20px -8px rgba(20, 24, 31, 0.12), 0 2px 6px -2px rgba(20, 24, 31, 0.06);
  --shadow-lg: 0 24px 48px -20px rgba(20, 24, 31, 0.22), 0 8px 16px -8px rgba(20, 24, 31, 0.08);
}

/* Dark mode (project already toggles body.dark-mode from app.js). We only
   flip token VALUES — class names stay the same so every template using
   --paper-0 / --ink-0 auto-adapts. */
body.dark-mode {
  --paper-0: #14181f;
  --paper-1: #1a1f28;
  --paper-2: #252b36;
  --paper-3: #323945;
  --paper-4: #4a5160;
  --ink-0: #f0ede4;
  --ink-1: #d8d4c8;
  --ink-2: #a8a8a8;
  --ink-3: #828389;
  --ink-4: #585c63;
  --indigo-soft: oklch(25% 0.04 264);
  --amber-soft: oklch(28% 0.05 75);
  --ok-soft: oklch(25% 0.05 155);
  --err-soft: oklch(25% 0.05 25);
}

/* Note: we don't reset html/body here — the legacy style.css already does. */
body {
  font-family: var(--sans);
  background: var(--paper-1);
  color: var(--ink-0);
  font-feature-settings: "ss01", "cv11";
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

.app {
  min-height: 100vh;
  background:
    radial-gradient(1200px 600px at 80% -10%, rgba(78,90,140,0.06), transparent 60%),
    radial-gradient(800px 400px at -10% 100%, rgba(180,140,70,0.05), transparent 60%),
    var(--paper-1);
}

.serif { font-family: var(--serif); font-weight: 500; letter-spacing: -0.01em; }
.mono { font-family: var(--mono); }

/* ── Topbar chrome ───────────────────────────────────────────────── */

.ds-topbar {
  position: sticky; top: 0; z-index: 30;
  display: flex; align-items: center; gap: 18px;
  padding: 12px 22px;
  background: rgba(250, 247, 242, 0.85);
  backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--paper-3);
}
body.dark-mode .ds-topbar { background: rgba(20, 24, 31, 0.85); }

.ds-brand {
  display: flex; align-items: center; gap: 10px;
  font-family: var(--serif);
  font-weight: 600;
  font-size: 19px;
  letter-spacing: -0.015em;
  color: var(--ink-0);
  text-decoration: none;
}
.ds-brand-mark {
  width: 28px; height: 28px;
  background: var(--ink-0);
  color: var(--paper-0);
  border-radius: 7px;
  display: grid; place-items: center;
  font-family: var(--serif);
  font-weight: 600;
  font-size: 15px;
  font-style: italic;
}

.ds-divider-v { width: 1px; height: 22px; background: var(--paper-3); }

.ds-tabs { display: flex; gap: 2px; margin-left: 8px; }
.ds-tabs a {
  padding: 8px 14px;
  border-radius: 8px;
  font-size: 13.5px;
  font-weight: 500;
  color: var(--ink-3);
  text-decoration: none;
  transition: all 0.15s;
}
.ds-tabs a:hover { color: var(--ink-1); background: var(--paper-2); }
.ds-tabs a.active { color: var(--ink-0); background: var(--paper-2); }

.ds-syllabus-pill {
  display: inline-flex; align-items: center; gap: 10px;
  padding: 6px 6px 6px 14px;
  background: var(--paper-0);
  border: 1px solid var(--paper-3);
  border-radius: 999px;
  font-size: 13px;
  cursor: pointer;
  transition: border-color 0.2s;
  color: var(--ink-1);
}
.ds-syllabus-pill:hover { border-color: var(--ink-3); }
.ds-syllabus-pill .code {
  font-family: var(--mono); font-weight: 600; font-size: 12px; color: var(--ink-2);
}
.ds-syllabus-pill .name { font-weight: 500; }
.ds-syllabus-pill .chev {
  width: 24px; height: 24px; border-radius: 999px;
  background: var(--paper-2);
  display: grid; place-items: center;
  color: var(--ink-2);
}

.ds-user-chip {
  display: inline-flex; align-items: center; gap: 10px;
  padding: 4px 12px 4px 4px;
  border-radius: 999px;
  background: var(--paper-0);
  border: 1px solid var(--paper-3);
  color: var(--ink-1);
  font-size: 13px;
}
.ds-avatar {
  width: 28px; height: 28px; border-radius: 999px;
  background: linear-gradient(135deg, var(--indigo), oklch(58% 0.13 280));
  color: white;
  display: grid; place-items: center;
  font-size: 12px; font-weight: 600;
}

/* ── Buttons ─────────────────────────────────────────────────────── */

.ds-btn {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 9px 16px;
  border-radius: var(--r);
  font-size: 13.5px;
  font-weight: 500;
  transition: all 0.15s;
  border: 1px solid transparent;
  background: none;
  cursor: pointer;
  font-family: inherit;
  text-decoration: none;
  color: inherit;
  line-height: 1;
}
.ds-btn-primary { background: var(--ink-0); color: var(--paper-0); }
.ds-btn-primary:hover { background: var(--ink-1); transform: translateY(-1px); box-shadow: var(--shadow); }
.ds-btn-primary[disabled] { opacity: 0.5; cursor: not-allowed; transform: none; box-shadow: none; }
.ds-btn-ghost { background: transparent; color: var(--ink-1); border-color: var(--paper-3); }
.ds-btn-ghost:hover { background: var(--paper-2); border-color: var(--ink-4); }
.ds-btn-accent { background: var(--indigo); color: white; }
.ds-btn-sm { padding: 6px 10px; font-size: 12.5px; border-radius: 8px; }

/* ── Inputs ──────────────────────────────────────────────────────── */

.ds-input, .ds-textarea, .ds-select {
  width: 100%;
  background: var(--paper-0);
  border: 1px solid var(--paper-3);
  border-radius: var(--r);
  padding: 10px 12px;
  font-size: 14px;
  transition: all 0.15s;
  outline: none;
  color: var(--ink-0);
  font-family: inherit;
}
.ds-input:focus, .ds-textarea:focus, .ds-select:focus {
  border-color: var(--ink-2);
  box-shadow: 0 0 0 3px rgba(20, 24, 31, 0.05);
}
.ds-textarea { resize: vertical; min-height: 80px; font-family: var(--sans); }
.ds-label {
  font-size: 12px; font-weight: 500; color: var(--ink-2);
  letter-spacing: 0.02em; text-transform: uppercase; display: block;
}

/* ── Card + tokens ──────────────────────────────────────────────── */

.ds-card {
  background: var(--paper-0);
  border: 1px solid var(--paper-3);
  border-radius: var(--r-lg);
  box-shadow: var(--shadow-sm);
}

.ds-badge {
  display: inline-flex; align-items: center; gap: 5px;
  padding: 3px 8px;
  border-radius: 999px;
  font-size: 11.5px;
  font-weight: 500;
  background: var(--paper-2);
  color: var(--ink-1);
}
.ds-badge-indigo { background: var(--indigo-soft); color: var(--indigo); }
.ds-badge-amber  { background: var(--amber-soft);  color: oklch(40% 0.1 75); }
.ds-badge-ok     { background: var(--ok-soft);     color: var(--ok); }
.ds-badge-err    { background: var(--err-soft);    color: var(--err); }

/* Segmented control */
.ds-segmented {
  display: inline-flex;
  background: var(--paper-2);
  padding: 3px;
  border-radius: 10px;
  border: 1px solid var(--paper-3);
}
.ds-segmented button, .ds-segmented a {
  padding: 6px 12px;
  border-radius: 7px;
  font-size: 13px;
  color: var(--ink-2);
  font-weight: 500;
  background: none;
  border: 0;
  cursor: pointer;
  text-decoration: none;
  font-family: inherit;
}
.ds-segmented .active {
  background: var(--paper-0);
  color: var(--ink-0);
  box-shadow: var(--shadow-sm);
}

/* ── Page layout ─────────────────────────────────────────────────── */

.ds-page {
  max-width: 1380px;
  margin: 0 auto;
  padding: 28px 32px 60px;
}
.ds-page-head {
  display: flex; align-items: flex-end; justify-content: space-between;
  margin-bottom: 24px;
  gap: 16px;
  flex-wrap: wrap;
}
.ds-page-title {
  font-family: var(--serif);
  font-size: 36px;
  font-weight: 500;
  letter-spacing: -0.02em;
  margin: 0;
  color: var(--ink-0);
}
.ds-page-sub { color: var(--ink-3); font-size: 14px; margin-top: 4px; }

.ds-row { display: flex; gap: 12px; align-items: center; }
.ds-col { display: flex; flex-direction: column; gap: 12px; }

/* ── Animations ──────────────────────────────────────────────────── */

@keyframes ds-fadeIn { from { opacity: 0; transform: translateY(6px); } to { opacity: 1; transform: none; } }
@keyframes ds-slideInUp { from { transform: translateY(20px); opacity: 0; } to { transform: none; opacity: 1; } }
@keyframes ds-pulse { 0%, 100% { opacity: 1; } 50% { opacity: 0.5; } }
@keyframes ds-spin { to { transform: rotate(360deg); } }

.ds-fade-in { animation: ds-fadeIn 0.3s ease; }
.ds-slide-up { animation: ds-slideInUp 0.35s cubic-bezier(0.2, 0.9, 0.3, 1); }

.ds-spinner {
  width: 44px; height: 44px; border-radius: 50%;
  border: 3px solid var(--paper-2); border-top-color: var(--ink-1);
  animation: ds-spin 0.8s linear infinite;
}

/* ── Placeholder visual (for missing diagrams) ───────────────────── */

.ds-placeholder-img {
  background: repeating-linear-gradient(
    45deg, var(--paper-1), var(--paper-1) 8px,
    var(--paper-2) 8px, var(--paper-2) 16px);
  border: 1px solid var(--paper-3);
  border-radius: var(--r);
  display: grid; place-items: center;
  color: var(--ink-3);
  font-family: var(--mono);
  font-size: 11.5px;
  letter-spacing: 0.05em;
  min-height: 160px;
}

/* ── Note reader paper ──────────────────────────────────────────── */

.ds-note-paper {
  background: var(--paper-0);
  border: 1px solid var(--paper-3);
  border-radius: var(--r-lg);
  padding: 48px 56px;
  line-height: 1.7;
  font-size: 15.5px;
  color: var(--ink-1);
  background-image: linear-gradient(var(--paper-2) 1px, transparent 1px);
  background-size: 100% 32px;
  background-position: 0 47px;
}
.ds-note-paper .serif { font-family: var(--serif); }

/* ── Tree picker ─────────────────────────────────────────────────── */

.ds-tree {
  border-bottom: 1px solid var(--paper-2);
}
.ds-tree-head {
  width: 100%;
  padding: 10px 14px;
  display: flex; gap: 10px; align-items: center;
  background: transparent;
  border: 0;
  cursor: pointer;
  font-family: inherit;
}
.ds-tree-head .bar { width: 4px; height: 18px; border-radius: 2px; }
.ds-tree-head .name {
  flex: 1; text-align: left;
  font-weight: 500; font-size: 13.5px;
  color: var(--ink-0);
}
.ds-tree-head .count {
  font-family: var(--mono);
  font-size: 10.5px;
  color: var(--ink-3);
}
.ds-tree-item {
  width: 100%; padding: 6px 14px 6px 30px;
  display: flex; gap: 8px; align-items: center;
  background: transparent;
  border: 0;
  cursor: pointer;
  font-size: 13px;
  color: var(--ink-2);
  text-align: left;
  text-decoration: none;
  font-family: inherit;
}
.ds-tree-item.active { background: var(--paper-2); color: var(--ink-0); font-weight: 500; }
.ds-mastery-dot {
  width: 6px; height: 6px; border-radius: 999px;
  background: var(--paper-4);
  flex-shrink: 0;
}

/* ── Slide-in panel (chat) ──────────────────────────────────────── */

.ds-panel-backdrop {
  position: fixed; inset: 0;
  background: rgba(20, 24, 31, 0.15);
  backdrop-filter: blur(2px);
  z-index: 60;
  animation: ds-fadeIn 0.2s ease;
}
.ds-panel {
  position: fixed; top: 0; right: 0; bottom: 0;
  width: 480px; max-width: 92vw;
  background: var(--paper-0);
  border-left: 1px solid var(--paper-3);
  box-shadow: var(--shadow-lg);
  z-index: 70;
  display: flex; flex-direction: column;
  animation: ds-slideInUp 0.3s cubic-bezier(0.2, 0.9, 0.3, 1);
}

/* ── Topic diagram (inline SVG inside note bodies) ───────────────── */

/* The `> svg` child combinator is critical: MathJax injects its own
   <svg> elements inside <figcaption> for \(...\) math, and a descendant
   selector would stretch those math SVGs to 480px wide via width:100%. */
.topic-diagram {
  margin: 1.2rem 0;
  text-align: center;
}
.topic-diagram > svg {
  max-width: 420px;
  width: 100%;
  height: auto;
  color: var(--ink-1);
  display: block;
  margin: 0 auto;
}
.topic-diagram figcaption {
  font-size: 0.85rem;
  color: var(--ink-3);
  margin-top: 0.4rem;
  font-style: italic;
  max-width: 480px;
  margin-left: auto;
  margin-right: auto;
  line-height: 1.45;
}
/* Keep MathJax output inline inside figcaption even if its <svg> gets
   sized by its own jax stylesheet — guard against any stray width:100%. */
.topic-diagram figcaption mjx-container,
.topic-diagram figcaption svg {
  display: inline;
  width: auto;
  max-width: none;
  vertical-align: -0.15em;
}

/* ── Utility ─────────────────────────────────────────────────────── */

kbd {
  font-family: var(--mono);
  font-size: 11px;
  padding: 2px 6px;
  border-radius: 4px;
  background: var(--paper-2);
  border: 1px solid var(--paper-3);
  color: var(--ink-2);
}