/* ==========================================================================
   Basic Mathematics interactive course
   Design tokens follow the dataviz reference palette (roles, not raw hex,
   throughout the components below).
   ========================================================================== */

:root {
  --surface-1: #fcfcfb;
  --page: #f9f9f7;
  --ink: #0b0b0b;
  --ink-2: #52514e;
  --muted: #898781;
  --grid: #e1e0d9;
  --baseline: #c3c2b7;
  --border: rgba(11, 11, 11, 0.10);

  --series-1: #2a78d6;  /* blue    */
  --series-2: #1baf7a;  /* aqua    */
  --series-3: #eda100;  /* yellow  */
  --series-4: #008300;  /* green   */
  --series-5: #4a3aa7;  /* violet  */
  --series-6: #e34948;  /* red     */
  --series-7: #e87ba4;  /* magenta */
  --series-8: #eb6834;  /* orange  */

  --good: #0ca30c;
  --good-text: #006300;
  --critical: #d03b3b;

  --accent: #8b5e3c;      /* Injectflow wood brown (primary-500) */
  --accent-soft: #eadfce; /* primary-100 */
  --radius: 10px;
  --sidebar-w: 300px;
  --sans: system-ui, -apple-system, "Segoe UI", sans-serif;
}

[data-theme="dark"] {
  --surface-1: #1a1a19;
  --page: #0d0d0d;
  --ink: #ffffff;
  --ink-2: #c3c2b7;
  --muted: #898781;
  --grid: #2c2c2a;
  --baseline: #383835;
  --border: rgba(255, 255, 255, 0.10);

  --series-1: #3987e5;
  --series-2: #199e70;
  --series-3: #c98500;
  --series-4: #008300;
  --series-5: #9085e9;
  --series-6: #e66767;
  --series-7: #d55181;
  --series-8: #d95926;

  --good-text: #0ca30c;
  --accent: #c4a174;      /* Injectflow primary-300, readable on dark */
  --accent-soft: #442b1c; /* primary-800 */
}

/* Dark-mode accent is light, so filled controls need dark text for contrast */
[data-theme="dark"] .widget-controls button.primary,
[data-theme="dark"] .wbtn.primary,
[data-theme="dark"] .quiz-submit {
  color: #2d1c12;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  height: 100%;
  font-family: var(--sans);
  color: var(--ink);
  background: var(--page);
  font-size: 16px;
  line-height: 1.65;
}

#app { display: flex; min-height: 100vh; }

/* ==================== Sidebar ==================== */

#sidebar {
  width: var(--sidebar-w);
  flex: 0 0 var(--sidebar-w);
  background: var(--surface-1);
  border-right: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  position: sticky;
  top: 0;
  height: 100vh;
  z-index: 30;
}

.sidebar-head {
  padding: 18px 16px 12px;
  border-bottom: 1px solid var(--border);
}

.course-title { display: flex; gap: 10px; align-items: flex-start; }
.course-emoji { font-size: 26px; line-height: 1.2; }
.course-title h1 { font-size: 17px; margin: 0; line-height: 1.25; }
.course-title p { margin: 2px 0 0; font-size: 12px; color: var(--muted); }

.overall-progress {
  display: flex; align-items: center; gap: 8px;
  margin-top: 12px;
}
.overall-bar {
  flex: 1; height: 6px; border-radius: 3px;
  background: var(--grid); overflow: hidden;
}
.overall-fill {
  height: 100%; width: 0%;
  background: var(--accent);
  border-radius: 3px;
  transition: width 0.6s cubic-bezier(.22,1,.36,1);
}
#overall-label { font-size: 12px; color: var(--ink-2); min-width: 34px; text-align: right; }

#toc-nav { flex: 1; overflow-y: auto; padding: 8px 0 16px; }

.toc-part {
  margin: 14px 14px 4px;
  font-size: 11px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--muted);
  font-weight: 700;
}

.toc-chapter { margin: 2px 8px; }
.toc-chapter > button {
  width: 100%;
  display: flex; align-items: center; gap: 8px;
  background: none; border: none;
  font: inherit; color: var(--ink);
  font-weight: 600; font-size: 13.5px;
  padding: 7px 8px;
  border-radius: 8px;
  cursor: pointer;
  text-align: left;
}
.toc-chapter > button:hover { background: var(--page); }
.toc-chapter .chev { margin-left: auto; font-size: 10px; color: var(--muted); transition: transform .25s; }
.toc-chapter.open .chev { transform: rotate(90deg); }
.chap-progress { font-size: 11px; color: var(--muted); font-weight: 400; }

.toc-lessons { display: none; padding-left: 10px; }
.toc-chapter.open .toc-lessons { display: block; }

.toc-lesson {
  display: flex; align-items: center; gap: 8px;
  padding: 5px 10px;
  margin: 1px 0;
  font-size: 13px;
  color: var(--ink-2);
  text-decoration: none;
  border-radius: 7px;
  border-left: 2px solid transparent;
}
.toc-lesson:hover { background: var(--page); color: var(--ink); }
.toc-lesson.active {
  background: var(--accent-soft);
  color: var(--ink);
  border-left-color: var(--accent);
  font-weight: 600;
}
.toc-lesson .check {
  width: 16px; height: 16px; flex: 0 0 16px;
  border-radius: 50%;
  border: 1.5px solid var(--baseline);
  display: inline-flex; align-items: center; justify-content: center;
  font-size: 10px; color: transparent;
}
.toc-lesson.done .check {
  background: var(--good);
  border-color: var(--good);
  color: #fff;
}

.sidebar-foot {
  border-top: 1px solid var(--border);
  padding: 10px 14px;
  display: flex; gap: 8px;
}
.sidebar-foot button,
.sidebar-foot a {
  flex: 1;
  font: inherit; font-size: 12.5px;
  color: var(--ink-2);
  background: var(--page);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 6px 8px;
  cursor: pointer;
  text-decoration: none;
  text-align: center;
}
.sidebar-foot button:hover,
.sidebar-foot a:hover { color: var(--ink); }

/* ==================== Main column ==================== */

#main-col { flex: 1; min-width: 0; display: flex; flex-direction: column; }

#topbar {
  display: flex; align-items: center; gap: 12px;
  padding: 10px 22px;
  border-bottom: 1px solid var(--border);
  background: color-mix(in srgb, var(--page) 85%, transparent);
  backdrop-filter: blur(6px);
  position: sticky; top: 0; z-index: 20;
}
#sidebar-toggle {
  display: none;
  font-size: 18px; background: none; border: none; color: var(--ink); cursor: pointer;
}
#crumb { font-size: 13px; color: var(--muted); }
#crumb b { color: var(--ink-2); font-weight: 600; }

#content {
  max-width: 850px;
  width: 100%;
  margin: 0 auto;
  padding: 30px 26px 90px;
  outline: none;
}

/* ==================== Lesson blocks ==================== */

.lesson-head { margin-bottom: 22px; }
.lesson-kicker {
  font-size: 12px; letter-spacing: .07em; text-transform: uppercase;
  color: var(--accent); font-weight: 700;
}
.lesson-head h2 { font-size: 30px; margin: 4px 0 6px; line-height: 1.2; }
.lesson-head .lesson-sub { color: var(--ink-2); font-size: 15px; margin: 0; }

.block { margin: 0 0 20px; }

.block-text p { margin: 0 0 12px; }
.block-text ul, .block-text ol { margin: 0 0 12px; padding-left: 24px; }
.block-text li { margin-bottom: 4px; }

.callout {
  background: var(--surface-1);
  border: 1px solid var(--border);
  border-left: 4px solid var(--accent);
  border-radius: var(--radius);
  padding: 14px 18px;
}
.callout.rule { border-left-color: var(--series-5); }
.callout.warn { border-left-color: var(--series-3); }
.callout .callout-title {
  font-weight: 700; font-size: 13px;
  letter-spacing: .04em; text-transform: uppercase;
  margin-bottom: 6px; color: var(--ink-2);
}
.callout p:last-child { margin-bottom: 0; }

.example-box {
  background: var(--surface-1);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
}
.example-box .ex-head {
  padding: 8px 18px;
  font-size: 12.5px; font-weight: 700;
  letter-spacing: .05em; text-transform: uppercase;
  color: var(--series-2);
  border-bottom: 1px solid var(--border);
}
.example-box .ex-body { padding: 14px 18px; }
.example-box .ex-body p:last-child { margin-bottom: 0; }

/* widget frame */
.widget-frame {
  background: var(--surface-1);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 16px;
}
.widget-frame .widget-caption {
  font-size: 13px; color: var(--muted);
  margin-top: 10px; text-align: center;
}
.widget-frame .widget-hint {
  font-size: 12.5px; color: var(--accent);
  font-weight: 600; margin-bottom: 8px;
}
.widget-controls {
  display: flex; flex-wrap: wrap; gap: 10px 16px;
  align-items: center;
  margin-top: 12px;
  font-size: 13.5px; color: var(--ink-2);
}
.widget-controls label { display: flex; align-items: center; gap: 7px; }
.widget-controls input[type="range"] { accent-color: var(--accent); width: 130px; }
.widget-controls button, .wbtn {
  font: inherit; font-size: 13px; font-weight: 600;
  color: var(--ink);
  background: var(--page);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 6px 12px;
  cursor: pointer;
}
.widget-controls button:hover, .wbtn:hover { border-color: var(--accent); color: var(--accent); }
.widget-controls button.primary, .wbtn.primary {
  background: var(--accent); border-color: var(--accent); color: #fff;
}
.widget-readout {
  font-size: 14px;
  margin-top: 10px;
  color: var(--ink-2);
}
.widget-readout .katex { font-size: 1.05em; }

.jxgbox {
  border: 1px solid var(--grid) !important;
  border-radius: 8px;
  background: var(--surface-1);
  touch-action: none;
}

svg.widget-svg { display: block; max-width: 100%; height: auto; }
svg.widget-svg text { font-family: var(--sans); }

/* ==================== Quiz ==================== */

.quiz-section { margin-top: 42px; }
.quiz-divider {
  display: flex; align-items: center; gap: 12px;
  color: var(--muted); font-size: 12px; letter-spacing: .1em;
  text-transform: uppercase; font-weight: 700;
  margin-bottom: 18px;
}
.quiz-divider::before, .quiz-divider::after {
  content: ""; flex: 1; height: 1px; background: var(--grid);
}

.quiz-card {
  background: var(--surface-1);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 18px 20px;
  margin-bottom: 14px;
}
.quiz-q { font-weight: 600; margin-bottom: 12px; }
.quiz-q .qnum { color: var(--accent); margin-right: 6px; }

.quiz-options { display: flex; flex-direction: column; gap: 8px; }
.quiz-opt {
  display: flex; align-items: center; gap: 10px;
  border: 1.5px solid var(--grid);
  border-radius: 8px;
  padding: 9px 13px;
  cursor: pointer;
  font-size: 15px;
  background: none;
  color: var(--ink);
  text-align: left;
  font-family: inherit;
  transition: border-color .15s, background .15s;
}
.quiz-opt:hover { border-color: var(--accent); }
.quiz-opt.selected { border-color: var(--accent); background: var(--accent-soft); }
.quiz-opt.correct { border-color: var(--good); background: color-mix(in srgb, var(--good) 12%, var(--surface-1)); }
.quiz-opt.wrong { border-color: var(--critical); background: color-mix(in srgb, var(--critical) 10%, var(--surface-1)); }
.quiz-opt:disabled { cursor: default; }
.quiz-opt .opt-key {
  width: 22px; height: 22px; flex: 0 0 22px;
  border-radius: 50%;
  border: 1.5px solid var(--baseline);
  font-size: 11.5px; font-weight: 700;
  display: inline-flex; align-items: center; justify-content: center;
  color: var(--ink-2);
}

.quiz-numeric { display: flex; gap: 10px; align-items: center; }
.quiz-numeric input {
  font: inherit; font-size: 15px;
  color: var(--ink);
  background: var(--page);
  border: 1.5px solid var(--grid);
  border-radius: 8px;
  padding: 8px 12px;
  width: 140px;
}
.quiz-numeric input:focus { outline: none; border-color: var(--accent); }
.quiz-numeric input.correct { border-color: var(--good); }
.quiz-numeric input.wrong { border-color: var(--critical); }

.quiz-feedback {
  margin-top: 12px;
  font-size: 14px;
  border-radius: 8px;
  padding: 10px 14px;
  display: none;
}
.quiz-feedback.show { display: block; }
.quiz-feedback.ok {
  background: color-mix(in srgb, var(--good) 10%, var(--surface-1));
  color: var(--good-text);
}
.quiz-feedback.no {
  background: color-mix(in srgb, var(--critical) 8%, var(--surface-1));
  color: var(--ink);
}
.quiz-feedback b:first-child { display: block; margin-bottom: 2px; }

.quiz-actions { margin-top: 20px; display: flex; gap: 12px; align-items: center; flex-wrap: wrap; }
.quiz-submit {
  font: inherit; font-weight: 700; font-size: 15px;
  color: #fff; background: var(--accent);
  border: none; border-radius: 10px;
  padding: 11px 26px;
  cursor: pointer;
}
.quiz-submit:hover { filter: brightness(1.08); }
.quiz-submit:disabled { opacity: .45; cursor: default; }

.quiz-result {
  font-weight: 700; font-size: 15px;
  display: none;
}
.quiz-result.show { display: inline; }
.quiz-result.pass { color: var(--good-text); }
.quiz-result.fail { color: var(--critical); }

/* ==================== Lesson footer nav ==================== */

.lesson-nav {
  display: flex; justify-content: space-between; gap: 14px;
  margin-top: 46px;
  border-top: 1px solid var(--grid);
  padding-top: 20px;
}
.lesson-nav a {
  text-decoration: none;
  color: var(--ink);
  border: 1px solid var(--border);
  background: var(--surface-1);
  border-radius: var(--radius);
  padding: 12px 18px;
  max-width: 46%;
  display: block;
}
.lesson-nav a:hover { border-color: var(--accent); }
.lesson-nav .nav-dir { font-size: 11.5px; color: var(--muted); text-transform: uppercase; letter-spacing: .06em; }
.lesson-nav .nav-title { font-weight: 600; font-size: 14.5px; color: var(--ink); margin-top: 2px; }
.lesson-nav .spacer { flex: 1; }

/* ==================== Home / part intro ==================== */

.home-hero { text-align: center; padding: 40px 0 26px; }
.home-hero .big-emoji { font-size: 54px; }
.home-hero h2 { font-size: 34px; margin: 12px 0 8px; }
.home-hero p { color: var(--ink-2); max-width: 560px; margin: 0 auto; }

.part-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(230px, 1fr));
  gap: 16px;
  margin-top: 30px;
}
.part-card {
  background: var(--surface-1);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 18px;
  text-decoration: none;
  color: var(--ink);
  display: block;
}
.part-card:hover { border-color: var(--accent); }
.part-card .part-num { font-size: 12px; color: var(--accent); font-weight: 700; text-transform: uppercase; letter-spacing: .07em; }
.part-card h3 { margin: 6px 0 6px; font-size: 18px; }
.part-card p { margin: 0 0 12px; font-size: 13.5px; color: var(--ink-2); }
.part-card .mini-bar { height: 5px; border-radius: 3px; background: var(--grid); overflow: hidden; }
.part-card .mini-fill { height: 100%; background: var(--accent); border-radius: 3px; }
.part-card .mini-label { font-size: 12px; color: var(--muted); margin-top: 5px; }

/* ==================== About (crawlable prose) ==================== */

#about-course {
  max-width: 850px;
  width: 100%;
  margin: 0 auto;
  padding: 28px 26px 70px;
  border-top: 1px solid var(--grid);
  color: var(--ink-2);
  font-size: 14.5px;
}
#about-course h2 { color: var(--ink); font-size: 20px; margin: 0 0 10px; }
#about-course h3 { color: var(--ink); font-size: 15px; margin: 20px 0 6px; }
#about-course p { margin: 0 0 10px; }
#about-course ul { margin: 0; padding-left: 20px; }
#about-course li { margin-bottom: 4px; }
#about-course a { color: var(--accent); text-decoration: none; font-weight: 600; }
#about-course a:hover { text-decoration: underline; }

/* ==================== KaTeX display tweaks ==================== */

.katex-display { margin: 14px 0; overflow-x: auto; overflow-y: hidden; padding: 2px 0; }

/* ==================== Confetti (quiz pass) ==================== */

.confetti-bit {
  position: fixed;
  width: 9px; height: 9px;
  border-radius: 2px;
  pointer-events: none;
  z-index: 999;
}

/* ==================== Responsive ==================== */

#sidebar-scrim {
  display: none;
  position: fixed; inset: 0;
  background: rgba(0,0,0,.4);
  z-index: 25;
}

@media (max-width: 900px) {
  #sidebar {
    position: fixed;
    left: 0; top: 0;
    transform: translateX(-100%);
    transition: transform .3s cubic-bezier(.22,1,.36,1);
    box-shadow: 0 0 40px rgba(0,0,0,.2);
  }
  body.sidebar-open #sidebar { transform: translateX(0); }
  body.sidebar-open #sidebar-scrim { display: block; }
  #sidebar-toggle { display: block; }
  #content { padding: 22px 16px 70px; }
  .lesson-head h2 { font-size: 25px; }
  .lesson-nav a { max-width: 100%; }
}