/* =========================================================================
   CodingClave — Teaching Studio
   One stylesheet, no build step. Rebrand by editing the variables below.
   ========================================================================= */

:root {
  /* Brand — change these to match CodingClave colours anytime */
  --brand:        #4338ca;   /* indigo 700 */
  --brand-strong: #3730a3;   /* indigo 800 */
  --brand-soft:   #eef2ff;   /* indigo 50  */
  --accent:       #06b6d4;   /* cyan 500   */
  --accent-soft:  #ecfeff;

  /* Track colours */
  --t28: #0ea5e9;   /* fast  */
  --t45: #8b5cf6;   /* standard */
  --t6m: #f59e0b;   /* mastery */

  /* Neutrals (light theme) */
  --bg:        #f6f7fb;
  --surface:   #ffffff;
  --surface-2: #fbfbfe;
  --line:      #e6e8f0;
  --line-soft: #eef0f6;
  --text:      #1f2333;
  --text-soft: #5b6178;
  --text-mute: #8b91a7;

  /* Callouts */
  --tip:  #059669;  --tip-bg:  #ecfdf5;
  --warn: #d97706;  --warn-bg: #fffbeb;
  --note: #2563eb;  --note-bg: #eff6ff;
  --teach:#7c3aed;  --teach-bg:#f5f3ff;

  --code-bg: #0f1729;
  --code-text: #e6ebff;

  --radius:   14px;
  --radius-sm: 9px;
  --shadow:   0 1px 2px rgba(20,24,48,.06), 0 8px 24px rgba(20,24,48,.06);
  --shadow-lg:0 12px 40px rgba(20,24,48,.16);

  --sidebar-w: 320px;
  --topbar-h: 60px;
  --maxw: 880px;

  --font: 'Inter', system-ui, -apple-system, Segoe UI, Roboto, sans-serif;
  --mono: 'JetBrains Mono', ui-monospace, SFMono-Regular, Menlo, monospace;
}

body.dark {
  --bg:        #0d1020;
  --surface:   #151a2e;
  --surface-2: #1a2038;
  --line:      #2a3252;
  --line-soft: #232a45;
  --text:      #eef1fb;
  --text-soft: #aeb6d4;
  --text-mute: #7a83a8;
  --brand-soft:#1e2547;
  --accent-soft:#13283a;
  --tip-bg:#0e2a22; --warn-bg:#2c2410; --note-bg:#10203c; --teach-bg:#211a3c;
  --shadow: 0 1px 2px rgba(0,0,0,.4), 0 10px 30px rgba(0,0,0,.35);
}

* { box-sizing: border-box; }
html, body { height: 100%; }
body {
  margin: 0;
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  -webkit-font-smoothing: antialiased;
  line-height: 1.6;
}
a { color: var(--brand); }
button { font-family: inherit; }

/* ---------- Boot splash ---------- */
.boot { height: 100vh; display: grid; place-content: center; gap: 14px; text-align: center; color: var(--text-mute); }
.boot-logo {
  font-family: var(--mono); font-weight: 700; font-size: 34px;
  width: 72px; height: 72px; display: grid; place-content: center; margin: 0 auto;
  background: var(--brand); color: #fff; border-radius: 18px;
}

/* ========================= Layout ========================= */
.layout {
  display: grid;
  grid-template-columns: var(--sidebar-w) 1fr;
  min-height: calc(100vh - var(--topbar-h));
}

/* ========================= Topbar ========================= */
.topbar {
  position: sticky; top: 0; z-index: 40;
  height: var(--topbar-h);
  display: flex; align-items: center; gap: 18px;
  padding: 0 18px;
  background: color-mix(in srgb, var(--surface) 86%, transparent);
  backdrop-filter: saturate(160%) blur(10px);
  border-bottom: 1px solid var(--line);
}
.brand { display: flex; align-items: center; gap: 11px; min-width: 0; }
.brand .logo {
  font-family: var(--mono); font-weight: 700; font-size: 17px;
  width: 38px; height: 38px; flex: 0 0 38px; display: grid; place-content: center;
  background: linear-gradient(135deg, var(--brand), var(--accent));
  color: #fff; border-radius: 11px; letter-spacing: -1px;
}
.brand b { font-size: 15px; font-weight: 700; letter-spacing: -.2px; display: block; line-height: 1.1; }
.brand span { font-size: 11.5px; color: var(--text-mute); letter-spacing: .3px; text-transform: uppercase; }

.topbar .spacer { flex: 1; }

.course-picker select {
  appearance: none; font-family: inherit; font-size: 13.5px; font-weight: 600;
  color: var(--text); background: var(--surface-2);
  border: 1px solid var(--line); border-radius: 10px;
  padding: 8px 32px 8px 12px; cursor: pointer;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 24 24' fill='none' stroke='%238b91a7' stroke-width='3'%3E%3Cpath d='M6 9l6 6 6-6'/%3E%3C/svg%3E");
  background-repeat: no-repeat; background-position: right 11px center;
}

/* Track segmented control */
.track-tabs { display: flex; gap: 4px; background: var(--surface-2); border: 1px solid var(--line); padding: 4px; border-radius: 12px; }
.track-tab {
  border: 0; background: transparent; cursor: pointer;
  font-size: 13px; font-weight: 600; color: var(--text-soft);
  padding: 6px 13px; border-radius: 8px; display: flex; align-items: center; gap: 7px;
  transition: .15s;
}
.track-tab .dot { width: 8px; height: 8px; border-radius: 50%; background: var(--c); }
.track-tab:hover { color: var(--text); }
.track-tab.active { background: var(--surface); color: var(--text); box-shadow: var(--shadow); }
.track-tab.active { border: 0; }

.icon-btn {
  width: 38px; height: 38px; display: grid; place-content: center;
  background: var(--surface-2); border: 1px solid var(--line); border-radius: 10px;
  cursor: pointer; color: var(--text-soft); transition: .15s;
}
.icon-btn:hover { color: var(--text); border-color: var(--text-mute); }
.icon-btn svg { width: 18px; height: 18px; }

/* ========================= Sidebar ========================= */
.sidebar {
  position: sticky; top: var(--topbar-h);
  height: calc(100vh - var(--topbar-h));
  overflow-y: auto;
  background: var(--surface);
  border-right: 1px solid var(--line);
  padding: 18px 14px 60px;
  scrollbar-width: thin;
}
.sidebar-head { padding: 4px 8px 14px; }
.sidebar-head h2 { margin: 0 0 3px; font-size: 16px; letter-spacing: -.3px; }
.sidebar-head .track-meta { font-size: 12.5px; color: var(--text-mute); display: flex; align-items: center; gap: 6px; }
.sidebar-head .track-meta .pill { font-weight: 600; color: var(--c); }

.progress { margin: 12px 8px 6px; }
.progress-bar { height: 7px; border-radius: 99px; background: var(--line); overflow: hidden; }
.progress-bar > i { display: block; height: 100%; background: linear-gradient(90deg, var(--brand), var(--accent)); border-radius: 99px; transition: width .35s; }
.progress small { display: block; margin-top: 6px; font-size: 11.5px; color: var(--text-mute); }

.module { margin-top: 10px; }
.module-head {
  width: 100%; text-align: left; cursor: pointer;
  display: flex; align-items: center; gap: 9px;
  background: transparent; border: 0; padding: 9px 8px; border-radius: 9px;
  font-size: 12px; font-weight: 700; letter-spacing: .4px; text-transform: uppercase; color: var(--text-mute);
}
.module-head:hover { background: var(--surface-2); color: var(--text-soft); }
.module-head .chev { margin-left: auto; transition: .2s; color: var(--text-mute); }
.module.collapsed .chev { transform: rotate(-90deg); }
.module.collapsed .lessons { display: none; }
.module-head .mnum {
  font-size: 11px; width: 20px; height: 20px; border-radius: 6px;
  display: grid; place-content: center; background: var(--brand-soft); color: var(--brand);
}

.lessons { display: flex; flex-direction: column; gap: 2px; padding: 2px 0 6px; }
.lesson-link {
  display: flex; align-items: center; gap: 10px; text-align: left; width: 100%;
  background: transparent; border: 0; cursor: pointer;
  padding: 8px 10px; border-radius: 9px; color: var(--text-soft); font-size: 13.5px;
  transition: .12s;
}
.lesson-link:hover { background: var(--surface-2); color: var(--text); }
.lesson-link.active { background: var(--brand-soft); color: var(--brand-strong); font-weight: 600; }
body.dark .lesson-link.active { color: #c7d0ff; }
.lesson-link .day {
  flex: 0 0 auto; font-size: 10.5px; font-weight: 700; color: var(--text-mute);
  background: var(--surface-2); border: 1px solid var(--line); border-radius: 6px;
  padding: 2px 6px; min-width: 30px; text-align: center; font-feature-settings: "tnum";
}
.lesson-link.active .day { border-color: transparent; background: var(--brand); color: #fff; }
.lesson-link .ltitle { flex: 1; min-width: 0; }
.lesson-link .check { width: 16px; height: 16px; flex: 0 0 16px; color: var(--tip); opacity: 0; }
.lesson-link.done .check { opacity: 1; }
.lesson-link.done .ltitle { color: var(--text-mute); }
.lesson-link .lvl { width: 7px; height: 7px; border-radius: 50%; flex: 0 0 7px; }
.lvl.core { background: var(--brand); }
.lvl.plus { background: var(--t45); }
.lvl.pro  { background: var(--t6m); }

/* ========================= Content ========================= */
.content { padding: 32px clamp(18px, 5vw, 64px) 120px; }
.lesson-wrap { max-width: var(--maxw); margin: 0 auto; }

.crumbs { display: flex; align-items: center; gap: 8px; font-size: 12.5px; color: var(--text-mute); margin-bottom: 14px; flex-wrap: wrap; }
.crumbs .tag { font-weight: 600; }
.crumbs .lvl-tag { padding: 2px 9px; border-radius: 99px; font-weight: 600; font-size: 11px; }
.crumbs .day-chip { background: var(--surface-2); border: 1px solid var(--line); padding: 2px 9px; border-radius: 99px; font-weight: 600; }
.lvl-tag.core { background: var(--brand-soft); color: var(--brand); }
.lvl-tag.plus { background: #f3e8ff; color: #7c3aed; }
.lvl-tag.pro  { background: #fef3c7; color: #b45309; }
body.dark .lvl-tag.plus { background:#2a1f47; } body.dark .lvl-tag.pro { background:#3a2c0d; color:#fcd34d; }

.lesson-title { font-size: clamp(28px, 4vw, 40px); line-height: 1.12; letter-spacing: -1px; margin: 4px 0 8px; font-weight: 800; }
.lesson-lede { font-size: 18px; color: var(--text-soft); margin: 0 0 26px; }

.objectives {
  background: linear-gradient(180deg, var(--brand-soft), transparent 130%);
  border: 1px solid var(--line); border-radius: var(--radius);
  padding: 18px 20px; margin: 0 0 30px;
}
.objectives h4 { margin: 0 0 10px; font-size: 13px; text-transform: uppercase; letter-spacing: .6px; color: var(--brand); display:flex; align-items:center; gap:8px;}
.objectives h4 svg { width: 18px; height: 18px; flex: 0 0 18px; }
.objectives ul { margin: 0; padding-left: 4px; list-style: none; display: grid; gap: 8px; }
.objectives li { display: flex; gap: 10px; font-size: 15px; align-items: baseline; }
.objectives li::before { content: ""; flex: 0 0 8px; height: 8px; margin-top: 7px; border-radius: 3px; background: var(--accent); }

/* Lesson body typography */
.body h3 { font-size: 23px; letter-spacing: -.4px; margin: 38px 0 12px; font-weight: 700; }
.body h4 { font-size: 17px; margin: 26px 0 8px; font-weight: 700; }
.body p  { font-size: 16.5px; margin: 0 0 16px; }
.body ul, .body ol { font-size: 16.5px; margin: 0 0 16px; padding-left: 24px; }
.body li { margin: 6px 0; }
.body code.inline {
  font-family: var(--mono); font-size: .86em; background: var(--brand-soft);
  color: var(--brand-strong); padding: 2px 7px; border-radius: 6px; white-space: nowrap;
}
body.dark .body code.inline { color: #c7d0ff; }
.body strong { font-weight: 700; color: var(--text); }
.body .kbd { font-family: var(--mono); font-size: .82em; background: var(--surface); border: 1px solid var(--line); border-bottom-width: 2px; border-radius: 6px; padding: 1px 7px; }

/* Callouts */
.callout { display: flex; gap: 13px; padding: 15px 17px; border-radius: var(--radius); margin: 22px 0; border: 1px solid var(--line); font-size: 15.5px; }
.callout .ic { flex: 0 0 22px; width: 22px; height: 22px; }
.callout p { margin: 0; }
.callout p + p { margin-top: 8px; }
.callout.tip  { background: var(--tip-bg);  border-color: color-mix(in srgb, var(--tip) 25%, transparent); }
.callout.tip .ic, .callout.tip b  { color: var(--tip); }
.callout.warn { background: var(--warn-bg); border-color: color-mix(in srgb, var(--warn) 30%, transparent); }
.callout.warn .ic, .callout.warn b { color: var(--warn); }
.callout.note { background: var(--note-bg); border-color: color-mix(in srgb, var(--note) 25%, transparent); }
.callout.note .ic, .callout.note b { color: var(--note); }

/* Trainer panel */
.teach {
  border: 1px dashed color-mix(in srgb, var(--teach) 45%, transparent);
  background: var(--teach-bg); border-radius: var(--radius); margin: 26px 0; overflow: hidden;
}
.teach summary {
  cursor: pointer; list-style: none; padding: 13px 17px; font-weight: 700; font-size: 14px;
  color: var(--teach); display: flex; align-items: center; gap: 9px;
}
.teach summary::-webkit-details-marker { display: none; }
.teach summary svg { width: 18px; height: 18px; flex: 0 0 18px; }
.teach[open] summary { border-bottom: 1px dashed color-mix(in srgb, var(--teach) 30%, transparent); }
.teach .teach-body { padding: 14px 17px; display: grid; gap: 12px; font-size: 15px; }
.teach .row { display: grid; grid-template-columns: 92px 1fr; gap: 12px; }
.teach .row .k { font-size: 12px; font-weight: 700; text-transform: uppercase; letter-spacing: .4px; color: var(--teach); padding-top: 2px; }

/* ========================= Code blocks + live preview ========================= */
.snippet { margin: 24px 0; border: 1px solid var(--line); border-radius: var(--radius); overflow: hidden; box-shadow: var(--shadow); background: var(--surface); }
.snippet-bar { display: flex; align-items: center; gap: 8px; padding: 9px 12px; background: var(--surface-2); border-bottom: 1px solid var(--line); }
.snippet-bar .dots { display: flex; gap: 6px; }
.snippet-bar .dots i { width: 11px; height: 11px; border-radius: 50%; display: block; }
.snippet-bar .dots i:nth-child(1){ background:#ff5f57;} .snippet-bar .dots i:nth-child(2){ background:#febc2e;} .snippet-bar .dots i:nth-child(3){ background:#28c840;}
.snippet-bar .cap { font-size: 12.5px; color: var(--text-mute); font-weight: 500; margin-left: 4px; }
.snippet-bar .actions { margin-left: auto; display: flex; gap: 6px; }
.snip-btn {
  font-size: 12px; font-weight: 600; color: var(--text-soft); cursor: pointer;
  background: var(--surface); border: 1px solid var(--line); border-radius: 7px; padding: 5px 10px;
  display: flex; align-items: center; gap: 6px; transition: .12s;
}
.snip-btn:hover { color: var(--brand); border-color: var(--brand); }
.snip-btn svg { width: 13px; height: 13px; }

.snippet pre { margin: 0; padding: 16px 18px; overflow-x: auto; background: var(--code-bg); }
.snippet pre code { font-family: var(--mono); font-size: 13.5px; line-height: 1.7; color: var(--code-text); white-space: pre; }
.snippet textarea.editor {
  width: 100%; border: 0; resize: vertical; min-height: 150px;
  font-family: var(--mono); font-size: 13.5px; line-height: 1.7;
  padding: 16px 18px; background: var(--code-bg); color: var(--code-text); outline: none; display: none;
}
.snippet.editing pre { display: none; }
.snippet.editing textarea.editor { display: block; }

.snippet .preview-wrap { display: none; border-top: 1px solid var(--line); }
.snippet.live .preview-wrap { display: block; }
.preview-label { font-size: 10.5px; font-weight: 700; letter-spacing: .8px; text-transform: uppercase; color: var(--text-mute); padding: 8px 14px 0; display: flex; align-items: center; gap: 7px; }
.preview-label::before { content:""; width:7px; height:7px; border-radius:50%; background: var(--tip); box-shadow: 0 0 0 3px color-mix(in srgb, var(--tip) 25%, transparent); }
.snippet iframe.preview { width: 100%; border: 0; background: #fff; min-height: 60px; display: block; }

/* Syntax highlight (lightweight) */
.tok-tag   { color: #7dd3fc; }
.tok-attr  { color: #fca5a5; }
.tok-val   { color: #fcd34d; }
.tok-punc  { color: #94a3b8; }
.tok-cmt   { color: #64748b; font-style: italic; }
.tok-text  { color: #e6ebff; }
.tok-doctype{ color: #c084fc; }

/* Tables in lessons */
.body table.data { width: 100%; border-collapse: collapse; margin: 22px 0; font-size: 14.5px; border: 1px solid var(--line); border-radius: var(--radius); overflow: hidden; }
.body table.data th { background: var(--surface-2); text-align: left; padding: 11px 14px; font-weight: 700; font-size: 13px; border-bottom: 1px solid var(--line); }
.body table.data td { padding: 11px 14px; border-bottom: 1px solid var(--line-soft); vertical-align: top; }
.body table.data tr:last-child td { border-bottom: 0; }
.body table.data code { font-family: var(--mono); font-size: 12.5px; color: var(--brand-strong); }
body.dark .body table.data code { color:#c7d0ff; }

/* Practice + homework cards */
.do-card { border: 1px solid var(--line); border-radius: var(--radius); padding: 18px 20px; margin: 22px 0; }
.do-card h4 { margin: 0 0 12px; font-size: 15px; display: flex; align-items: center; gap: 9px; }
.do-card.practice { background: var(--accent-soft); border-color: color-mix(in srgb, var(--accent) 30%, transparent); }
.do-card.practice h4 { color: #0e7490; }
.do-card.homework { background: var(--surface-2); }
.do-card ol { margin: 0; padding-left: 20px; display: grid; gap: 9px; font-size: 15.5px; }
.do-card li { padding-left: 4px; }

/* Quiz */
.quiz { border: 1px solid var(--line); border-radius: var(--radius); padding: 18px 20px; margin: 24px 0; background: var(--surface); }
.quiz .q { font-weight: 700; font-size: 16px; margin: 0 0 13px; display: flex; gap: 9px; }
.quiz .q .qmark { color: var(--brand); }
.quiz .opts { display: grid; gap: 8px; }
.quiz .opt {
  text-align: left; cursor: pointer; padding: 11px 14px; border-radius: 10px;
  border: 1px solid var(--line); background: var(--surface-2); font-size: 15px; color: var(--text);
  display: flex; align-items: center; gap: 11px; transition: .12s;
}
.quiz .opt:hover { border-color: var(--brand); }
.quiz .opt .mk { width: 20px; height: 20px; border-radius: 50%; border: 2px solid var(--line); flex: 0 0 20px; display: grid; place-content: center; }
.quiz .opt.correct { border-color: var(--tip); background: var(--tip-bg); }
.quiz .opt.correct .mk { border-color: var(--tip); background: var(--tip); color: #fff; }
.quiz .opt.wrong { border-color: #ef4444; background: #fef2f2; }
body.dark .quiz .opt.wrong { background:#2a1414; }
.quiz .opt.wrong .mk { border-color: #ef4444; background: #ef4444; color: #fff; }
.quiz .explain { margin-top: 12px; font-size: 14.5px; color: var(--text-soft); padding: 11px 14px; background: var(--note-bg); border-radius: 10px; display: none; }
.quiz.answered .explain { display: block; }

/* ========================= Lesson nav (prev/next) ========================= */
.lesson-nav { max-width: var(--maxw); margin: 50px auto 0; display: flex; gap: 14px; }
.nav-card {
  flex: 1; text-align: left; cursor: pointer; background: var(--surface);
  border: 1px solid var(--line); border-radius: var(--radius); padding: 15px 18px; transition: .15s;
  display: flex; flex-direction: column; gap: 3px; min-width: 0;
}
.nav-card:hover { border-color: var(--brand); transform: translateY(-2px); box-shadow: var(--shadow); }
.nav-card.next { text-align: right; }
.nav-card small { font-size: 11.5px; color: var(--text-mute); text-transform: uppercase; letter-spacing: .5px; font-weight: 600; display: flex; align-items: center; gap: 5px; }
.nav-card.next small { justify-content: flex-end; }
.nav-card small svg { width: 13px; height: 13px; }
.nav-card b { font-size: 15px; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.nav-card.disabled { opacity: .4; pointer-events: none; }

.mark-done {
  display: inline-flex; align-items: center; gap: 9px; cursor: pointer; margin-top: 30px;
  background: var(--brand); color: #fff; border: 0; border-radius: 11px; padding: 12px 20px;
  font-size: 14.5px; font-weight: 600; transition: .15s;
}
.mark-done:hover { background: var(--brand-strong); }
.mark-done.is-done { background: var(--tip); }
.mark-done svg { width: 17px; height: 17px; }

/* ========================= Overview (track) page ========================= */
.overview { max-width: 980px; margin: 0 auto; }
.ov-hero { padding: 10px 0 26px; }
.ov-hero h1 { font-size: clamp(30px,5vw,46px); letter-spacing: -1.4px; margin: 0 0 10px; font-weight: 800; }
.ov-hero p { font-size: 18px; color: var(--text-soft); max-width: 640px; margin: 0; }
.track-cards { display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px; margin: 30px 0 10px; }
.tcard { border: 1px solid var(--line); border-radius: var(--radius); padding: 20px; cursor: pointer; background: var(--surface); transition: .15s; border-top: 3px solid var(--c); }
.tcard:hover { transform: translateY(-3px); box-shadow: var(--shadow-lg); }
.tcard.active { box-shadow: 0 0 0 2px var(--c); }
.tcard .big { font-size: 30px; font-weight: 800; letter-spacing: -1px; color: var(--c); }
.tcard h3 { margin: 4px 0 8px; font-size: 17px; }
.tcard p { font-size: 14px; color: var(--text-soft); margin: 0 0 14px; }
.tcard .stat { display: flex; gap: 16px; font-size: 12.5px; color: var(--text-mute); border-top: 1px solid var(--line-soft); padding-top: 12px; }
.tcard .stat b { color: var(--text); font-size: 15px; display: block; }

.ov-modules { margin-top: 36px; }
.ov-modules h2 { font-size: 22px; letter-spacing: -.4px; margin: 0 0 4px; }
.ov-modules .sub { color: var(--text-mute); font-size: 14.5px; margin: 0 0 20px; }
.ovmod { border: 1px solid var(--line); border-radius: var(--radius); margin-bottom: 12px; overflow: hidden; background: var(--surface); }
.ovmod-head { display: flex; align-items: center; gap: 14px; padding: 16px 20px; background: var(--surface-2); }
.ovmod-head .n { width: 34px; height: 34px; border-radius: 9px; background: var(--brand); color: #fff; display: grid; place-content: center; font-weight: 700; }
.ovmod-head h3 { margin: 0; font-size: 16.5px; }
.ovmod-head .meta { margin-left: auto; font-size: 12.5px; color: var(--text-mute); }
.ovmod-list { padding: 6px 10px 12px; }
.ovmod-list a { display: flex; align-items: center; gap: 12px; padding: 9px 12px; border-radius: 9px; color: var(--text-soft); text-decoration: none; font-size: 14.5px; }
.ovmod-list a:hover { background: var(--surface-2); color: var(--text); }
.ovmod-list a .day { font-size: 11px; font-weight: 700; color: var(--text-mute); min-width: 54px; }
.ovmod-list a .ltime { margin-left: auto; font-size: 12px; color: var(--text-mute); }

/* ========================= Playground overlay ========================= */
.pg-overlay { position: fixed; inset: 0; z-index: 80; background: var(--bg); display: none; flex-direction: column; }
.pg-overlay.open { display: flex; }
.pg-bar { height: 54px; display: flex; align-items: center; gap: 14px; padding: 0 16px; border-bottom: 1px solid var(--line); background: var(--surface); }
.pg-bar b { font-size: 15px; }
.pg-bar .spacer { flex: 1; }
.pg-grid { flex: 1; display: grid; grid-template-columns: 1fr 1fr; min-height: 0; }
.pg-pane { display: flex; flex-direction: column; min-height: 0; }
.pg-pane.code { border-right: 1px solid var(--line); }
.pg-pane h5 { margin: 0; padding: 10px 16px; font-size: 11.5px; text-transform: uppercase; letter-spacing: .6px; color: var(--text-mute); border-bottom: 1px solid var(--line-soft); background: var(--surface-2); }
.pg-pane textarea { flex: 1; border: 0; outline: none; resize: none; font-family: var(--mono); font-size: 14.5px; line-height: 1.7; padding: 16px; background: var(--code-bg); color: var(--code-text); }
.pg-pane iframe { flex: 1; border: 0; background: #fff; }
.pg-snippets { display: flex; gap: 7px; flex-wrap: wrap; }
.pg-chip { font-size: 12px; font-weight: 600; padding: 6px 11px; border-radius: 8px; border: 1px solid var(--line); background: var(--surface-2); cursor: pointer; color: var(--text-soft); }
.pg-chip:hover { border-color: var(--brand); color: var(--brand); }

/* ========================= Buttons ========================= */
.btn { display: inline-flex; align-items: center; gap: 8px; cursor: pointer; font-weight: 600; font-size: 13.5px; border-radius: 10px; padding: 8px 14px; border: 1px solid var(--line); background: var(--surface-2); color: var(--text); transition: .14s; }
.btn:hover { border-color: var(--brand); color: var(--brand); }
.btn.primary { background: var(--brand); color: #fff; border-color: var(--brand); }
.btn.primary:hover { background: var(--brand-strong); color: #fff; }
.btn svg { width: 15px; height: 15px; }

/* ========================= Present mode ========================= */
body.present .sidebar { display: none; }
body.present .layout { grid-template-columns: 1fr; }
body.present { --maxw: 1100px; }
body.present .content { padding-top: 40px; }
body.present .body p, body.present .body li { font-size: 21px; }
body.present .lesson-lede { font-size: 23px; }
body.present .body h3 { font-size: 30px; }
body.present .snippet pre code, body.present .snippet textarea.editor { font-size: 17px; }
body.present .objectives li { font-size: 19px; }

/* Mobile menu button (hidden on desktop) */
.menu-btn { display: none; }

/* ========================= Responsive ========================= */
@media (max-width: 1024px) {
  .track-tab span.lbl { display: none; }
  .course-picker { display: none; }
}
@media (max-width: 860px) {
  :root { --sidebar-w: 280px; }
  .layout { grid-template-columns: 1fr; }
  .menu-btn { display: grid; }
  .sidebar {
    position: fixed; top: var(--topbar-h); left: 0; z-index: 60; width: 86%; max-width: 340px;
    transform: translateX(-104%); transition: transform .25s; box-shadow: var(--shadow-lg);
  }
  body.nav-open .sidebar { transform: none; }
  body.nav-open::after { content:""; position: fixed; inset: var(--topbar-h) 0 0; background: rgba(10,12,28,.4); z-index: 50; }
  .track-cards { grid-template-columns: 1fr; }
  .pg-grid { grid-template-columns: 1fr; grid-template-rows: 1fr 1fr; }
  .pg-pane.code { border-right: 0; border-bottom: 1px solid var(--line); }
  .lesson-nav { flex-direction: column; }
}

/* ========================= Print ========================= */
@media print {
  .topbar, .sidebar, .lesson-nav, .mark-done, .snippet-bar .actions, .teach { display: none !important; }
  .layout { grid-template-columns: 1fr; }
  .content { padding: 0; }
  .snippet, .callout, .do-card { break-inside: avoid; }
  body { background: #fff; }
}

/* Scrollbars */
::-webkit-scrollbar { width: 11px; height: 11px; }
::-webkit-scrollbar-thumb { background: color-mix(in srgb, var(--text-mute) 40%, transparent); border-radius: 99px; border: 3px solid var(--bg); }
::-webkit-scrollbar-thumb:hover { background: var(--text-mute); }

.fade-in { animation: fade .3s ease; }
@keyframes fade { from { opacity: 0; transform: translateY(6px); } to { opacity: 1; transform: none; } }