/* ============================================================
   TechStudy — design tokens
   ============================================================ */
@import url('https://fonts.googleapis.com/css2?family=IBM+Plex+Mono:wght@400;500;600;700&family=IBM+Plex+Sans:wght@400;500;600;700&display=swap');

:root {
  --bg: #0A0C14;
  --bg-elevated: #141826;
  --bg-inset: #080a12;
  --border: #262C42;
  --border-soft: #1C2036;
  --text: #F5F7FC;
  --text-muted: #ABB3CC;
  --text-faint: #6E7592;
  --accent: #8B5CF6;        /* vivid violet — primary */
  --accent-dim: #4C3593;
  --accent-2: #22D3EE;      /* electric cyan — secondary / links */
  --accent-2-dim: #0E7490;
  --danger: #FB7185;
  --success: #34D399;
  --radius: 4px;
  --mono: 'IBM Plex Mono', ui-monospace, SFMono-Regular, Menlo, monospace;
  --sans: 'IBM Plex Sans', -apple-system, BlinkMacSystemFont, sans-serif;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: radial-gradient(circle at 15% -5%, #1a1638 0%, var(--bg) 42%);
  background-attachment: fixed;
  color: var(--text);
  font-family: var(--sans);
  font-size: 15px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

body::before {
  content: "";
  position: fixed;
  top: 0; left: 0; right: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--accent) 0%, var(--accent-2) 50%, var(--accent) 100%);
  z-index: 1000;
  opacity: 0.95;
}

a { color: var(--accent-2); text-decoration: none; }
a:hover { text-decoration: underline; }

code, pre, .mono { font-family: var(--mono); }

::selection { background: var(--accent-dim); color: #fff; }

:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

@media (prefers-reduced-motion: reduce) {
  * { animation-duration: 0.01ms !important; transition-duration: 0.01ms !important; }
}

/* ============================================================
   Layout shell
   ============================================================ */
.shell {
  display: grid;
  grid-template-columns: 260px 1fr;
  min-height: 100vh;
}

.sidebar {
  background: var(--bg-inset);
  border-right: 1px solid var(--border);
  padding: 22px 0;
  position: sticky;
  top: 0;
  height: 100vh;
  overflow-y: auto;
}

.brand {
  display: block;
  padding: 0 20px 18px;
  border-bottom: 1px solid var(--border-soft);
  margin-bottom: 14px;
}
.brand-mark {
  font-family: var(--mono);
  font-weight: 700;
  font-size: 16px;
  background: linear-gradient(90deg, var(--accent) 0%, var(--accent-2) 100%);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
.brand-mark span { background: none; -webkit-text-fill-color: initial; color: var(--text); }
.brand-mark .brand-cursor { color: var(--text-faint); -webkit-text-fill-color: var(--text-faint); }
.brand-sub { display: block; font-family: var(--mono); font-size: 11px; color: var(--text-faint); margin-top: 4px; }

.nav-label {
  font-family: var(--mono);
  font-size: 10px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--text-faint);
  padding: 4px 20px;
  margin-top: 10px;
}

.nav-list { list-style: none; margin: 0; padding: 0 10px; }
.nav-item a {
  display: flex;
  align-items: center;
  gap: 9px;
  padding: 7px 10px;
  border-radius: var(--radius);
  color: var(--text-muted);
  font-size: 13.5px;
  text-decoration: none;
  font-family: var(--mono);
}
.nav-item a:hover { background: var(--bg-elevated); color: var(--text); text-decoration: none; }
.nav-item.active a { background: var(--bg-elevated); color: var(--accent); }
.nav-dot {
  width: 6px; height: 6px; border-radius: 50%;
  background: var(--text-faint); flex-shrink: 0;
}
.nav-item.done .nav-dot { background: var(--success); }
.nav-item.active .nav-dot { background: var(--accent); }
.nav-pct {
  margin-left: auto;
  font-size: 10.5px;
  color: var(--text-faint);
}

main { padding: 44px 56px 80px; max-width: 900px; }

/* ============================================================
   Prompt / hero
   ============================================================ */
.prompt-line {
  font-family: var(--mono);
  font-size: 13px;
  color: var(--text-faint);
  margin-bottom: 10px;
}
.prompt-line .p1 { color: var(--accent-2); }
.prompt-line .p2 { color: var(--text-muted); }

.cursor {
  display: inline-block;
  width: 8px; height: 16px;
  background: var(--accent);
  margin-left: 2px;
  vertical-align: middle;
  animation: blink 1s steps(1) infinite;
}
@keyframes blink { 50% { opacity: 0; } }

h1.title {
  font-family: var(--mono);
  font-size: 30px;
  font-weight: 600;
  margin: 0 0 6px;
  letter-spacing: -0.01em;
}
h1.title .title-grad {
  background: linear-gradient(90deg, var(--accent), var(--accent-2));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
p.subtitle { color: var(--text-muted); margin: 0 0 34px; max-width: 60ch; }

/* ============================================================
   Dashboard cards ("ls -la ~/courses")
   ============================================================ */
.listing-head {
  font-family: var(--mono);
  font-size: 11px;
  color: var(--text-faint);
  display: grid;
  grid-template-columns: 1fr 90px 90px 130px;
  padding: 0 16px 8px;
  border-bottom: 1px solid var(--border-soft);
  margin-bottom: 4px;
}

.course-row {
  display: grid;
  grid-template-columns: 1fr 90px 90px 130px;
  align-items: center;
  padding: 14px 16px;
  border-bottom: 1px solid var(--border-soft);
  text-decoration: none;
  color: var(--text);
  transition: background 0.15s ease, transform 0.15s ease;
}
.course-row:hover { background: var(--bg-elevated); text-decoration: none; transform: translateX(3px); }
.course-row .name { display: flex; flex-direction: column; gap: 3px; }
.course-row .name b { font-family: var(--mono); font-size: 14.5px; font-weight: 600; }
.course-row .name span { font-size: 12.5px; color: var(--text-muted); }
.course-row .status { font-family: var(--mono); font-size: 12px; }
.status.locked { color: var(--text-faint); }
.status.active { color: var(--accent); }
.status.done { color: var(--success); }
.course-row .lessons { font-family: var(--mono); font-size: 12px; color: var(--text-faint); }

.bar-track {
  height: 5px;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: 2px;
  overflow: hidden;
}
.bar-fill { height: 100%; background: var(--accent); border-radius: 2px; transition: width 0.4s ease; }

/* ============================================================
   Stat strip
   ============================================================ */
.stat-strip { display: flex; gap: 34px; margin: 30px 0 40px; flex-wrap: wrap; }
.stat b { display: block; font-family: var(--mono); font-size: 24px; color: var(--accent); }
.stat span { font-size: 11.5px; color: var(--text-faint); text-transform: uppercase; letter-spacing: 0.08em; }

/* ============================================================
   Lesson content
   ============================================================ */
.breadcrumb {
  font-family: var(--mono);
  font-size: 12px;
  color: var(--text-faint);
  margin-bottom: 16px;
}
.breadcrumb a { color: var(--text-muted); }

.module-progress {
  display: flex;
  align-items: center;
  gap: 12px;
  margin: 18px 0 38px;
  font-family: var(--mono);
  font-size: 12px;
  color: var(--text-muted);
}
.module-progress .bar-track { flex: 1; max-width: 280px; }

.lesson {
  border-top: 1px solid var(--border-soft);
  padding: 34px 0;
}
.lesson:first-of-type { border-top: none; }

.lesson-eyebrow {
  font-family: var(--mono);
  font-size: 11px;
  color: var(--accent-2);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin-bottom: 8px;
}
.lesson h2 { font-size: 21px; margin: 0 0 14px; font-family: var(--mono); font-weight: 600; }
.lesson h3 { font-size: 15.5px; margin: 26px 0 10px; color: var(--text); }
.lesson p { color: #C6D0DB; margin: 0 0 14px; }
.lesson ul, .lesson ol { color: #C6D0DB; padding-left: 22px; margin: 0 0 14px; }
.lesson li { margin-bottom: 6px; }
.lesson strong { color: var(--text); }

.callout {
  background: var(--bg-elevated);
  border-left: 3px solid var(--accent);
  border-radius: var(--radius);
  padding: 12px 16px;
  margin: 16px 0;
  font-size: 13.5px;
  color: var(--text-muted);
}
.callout.warn { border-left-color: var(--danger); }
.callout.fun { border-left-color: var(--accent-2); }
.callout b { color: var(--text); }

.tryit {
  background: rgba(34,211,238,0.08);
  border: 1px dashed var(--accent-2);
  border-radius: var(--radius);
  padding: 14px 16px;
  margin: 18px 0;
  font-size: 13.5px;
  color: var(--text-muted);
}
.tryit .tryit-label {
  font-family: var(--mono);
  font-size: 10.5px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--accent-2);
  display: block;
  margin-bottom: 6px;
}

.syllabus-item {
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 16px 4px;
  border-top: 1px solid var(--border-soft);
  text-decoration: none;
  color: var(--text);
  transition: background 0.15s ease, transform 0.15s ease;
}
.syllabus-item:first-of-type { border-top: none; }
.syllabus-item:hover { text-decoration: none; background: var(--bg-elevated); transform: translateX(3px); }
.syllabus-num {
  font-family: var(--mono);
  font-size: 13px;
  color: var(--text-faint);
  min-width: 26px;
}
.syllabus-check {
  width: 16px; height: 16px; border-radius: 50%;
  border: 1.5px solid var(--border);
  flex-shrink: 0;
}
.syllabus-check.done { background: var(--success); border-color: var(--success); }
.syllabus-body { flex: 1; }
.syllabus-body h3 { margin: 0 0 3px; font-size: 14.5px; font-family: var(--mono); }
.syllabus-body p { margin: 0; font-size: 12.5px; color: var(--text-muted); }
.syllabus-arrow { color: var(--text-faint); font-family: var(--mono); }

pre.term {
  background: var(--bg-inset);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 14px 16px;
  overflow-x: auto;
  font-family: var(--mono);
  font-size: 12.8px;
  line-height: 1.65;
  margin: 14px 0;
  color: #C6D0DB;
}
pre.term .c1 { color: var(--text-faint); }       /* comment */
pre.term .kw { color: var(--accent-2); }          /* keyword */
pre.term .str { color: var(--success); }          /* string/value */
pre.term .flag { color: var(--accent); }          /* flag */
.term-bar {
  display: flex; gap: 6px; margin: -14px -16px 12px; padding: 8px 12px;
  border-bottom: 1px solid var(--border);
}
.term-bar span { width: 9px; height: 9px; border-radius: 50%; background: var(--border); }

code.inline {
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: 3px;
  padding: 1px 6px;
  font-size: 12.5px;
  color: var(--accent);
}

table.ref { width: 100%; border-collapse: collapse; margin: 14px 0; font-size: 13px; }
table.ref th, table.ref td { text-align: left; padding: 8px 12px; border-bottom: 1px solid var(--border-soft); }
table.ref th { font-family: var(--mono); color: var(--text-faint); font-size: 11px; text-transform: uppercase; letter-spacing: 0.06em; }
table.ref td code { font-family: var(--mono); color: var(--accent); }

/* ============================================================
   Quiz
   ============================================================ */
.quiz-block {
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 22px 24px;
  margin-top: 12px;
}
.quiz-progress { font-family: var(--mono); font-size: 11.5px; color: var(--text-faint); margin-bottom: 14px; }
.q-prompt { font-size: 15px; margin: 0 0 16px; color: var(--text); }
.q-options { display: flex; flex-direction: column; gap: 8px; margin-bottom: 16px; }
.q-option {
  text-align: left;
  background: var(--bg-inset);
  border: 1px solid var(--border);
  color: var(--text-muted);
  border-radius: var(--radius);
  padding: 10px 14px;
  font-family: var(--sans);
  font-size: 13.5px;
  cursor: pointer;
}
.q-option:hover { border-color: var(--accent-dim); color: var(--text); }
.q-option.correct { border-color: var(--success); color: var(--success); background: rgba(52,211,153,0.1); }
.q-option.wrong { border-color: var(--danger); color: var(--danger); background: rgba(251,113,133,0.1); }
.q-option:disabled { cursor: default; }
.q-explain { font-size: 13px; color: var(--text-muted); border-top: 1px solid var(--border); padding-top: 12px; display: none; }
.q-explain.show { display: block; }
.quiz-result { font-family: var(--mono); font-size: 14px; color: var(--accent); }

.btn {
  font-family: var(--mono);
  font-size: 12.5px;
  background: linear-gradient(135deg, var(--accent), #6D3FE0);
  color: #FBFAFF;
  border: none;
  border-radius: var(--radius);
  padding: 9px 16px;
  cursor: pointer;
  font-weight: 600;
  transition: transform 0.15s ease, box-shadow 0.15s ease, filter 0.15s ease;
}
.btn:hover { filter: brightness(1.12); transform: translateY(-1px); box-shadow: 0 6px 24px rgba(139,92,246,0.4); }
.btn.ghost {
  background: transparent;
  border: 1px solid var(--border);
  color: var(--text-muted);
}
.btn.ghost:hover { border-color: var(--accent-dim); color: var(--text); box-shadow: none; transform: none; background: var(--bg-elevated); }
.btn:disabled { opacity: 0.4; cursor: default; transform: none; box-shadow: none; }

/* ============================================================
   Coming-soon / outline pages
   ============================================================ */
.outline-item {
  display: flex;
  gap: 16px;
  padding: 18px 0;
  border-top: 1px solid var(--border-soft);
}
.outline-item:first-of-type { border-top: none; }
.outline-num { font-family: var(--mono); color: var(--text-faint); font-size: 13px; padding-top: 2px; min-width: 24px; }
.outline-body h3 { margin: 0 0 6px; font-size: 15px; font-family: var(--mono); }
.outline-body p { margin: 0; color: var(--text-muted); font-size: 13.5px; }

.badge {
  display: inline-block;
  font-family: var(--mono);
  font-size: 10.5px;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  border: 1px solid var(--accent-dim);
  color: var(--accent);
  border-radius: 20px;
  padding: 3px 10px;
  margin-bottom: 16px;
}
.badge.soon { border-color: var(--border); color: var(--text-faint); }

.lesson-nav {
  display: flex;
  justify-content: space-between;
  margin-top: 46px;
  padding-top: 20px;
  border-top: 1px solid var(--border-soft);
}

/* ============================================================
   Original diagrams & icons (all hand-drawn, no external assets)
   ============================================================ */
.diagram {
  background: var(--bg-inset);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 22px 20px 16px;
  margin: 18px 0 22px;
}
.diagram svg { display: block; width: 100%; height: auto; }
.diagram-caption {
  font-family: var(--mono);
  font-size: 11px;
  color: var(--text-faint);
  text-align: center;
  margin-top: 10px;
  letter-spacing: 0.03em;
}

.course-icon { flex-shrink: 0; color: var(--accent-2); }
.course-row .name { display: flex; flex-direction: row; align-items: center; gap: 12px; }
.course-row .name .name-text { display: flex; flex-direction: column; gap: 3px; }

.hero-art { margin: 6px 0 30px; }
.hero-art svg { display: block; width: 100%; height: auto; }

.title-icon { color: var(--accent); vertical-align: -6px; margin-right: 10px; }

/* ============================================================
   Auth widget (top-right, injected by app.js on every page)
   ============================================================ */
.auth-widget {
  position: fixed;
  top: 14px;
  right: 20px;
  z-index: 900;
  font-family: var(--mono);
}
.auth-btn {
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  color: var(--text-muted);
  border-radius: 20px;
  padding: 7px 16px;
  font-family: var(--mono);
  font-size: 12px;
  cursor: pointer;
  transition: border-color 0.15s ease, color 0.15s ease;
}
.auth-btn:hover { border-color: var(--accent-dim); color: var(--text); }
.auth-btn.primary { background: linear-gradient(135deg, var(--accent), #6D3FE0); color: #FBFAFF; border: none; font-weight: 600; margin-left: 6px; }
.auth-btn.primary:hover { filter: brightness(1.12); }

.auth-account {
  display: flex;
  align-items: center;
  gap: 8px;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: 20px;
  padding: 5px 14px 5px 5px;
  cursor: pointer;
  position: relative;
}
.auth-avatar {
  width: 24px; height: 24px; border-radius: 50%;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  color: #0A0C14;
  display: flex; align-items: center; justify-content: center;
  font-size: 11px; font-weight: 700;
}
.auth-name { font-size: 12px; color: var(--text-muted); }

.auth-dropdown {
  position: absolute;
  top: calc(100% + 8px);
  right: 0;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 6px;
  min-width: 160px;
  box-shadow: 0 12px 30px rgba(0,0,0,0.4);
  display: none;
}
.auth-dropdown.open { display: block; }
.auth-dropdown button {
  width: 100%;
  text-align: left;
  background: none;
  border: none;
  color: var(--text-muted);
  font-family: var(--mono);
  font-size: 12px;
  padding: 8px 10px;
  border-radius: 3px;
  cursor: pointer;
}
.auth-dropdown button:hover { background: var(--bg-inset); color: var(--text); }

.auth-modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(5,7,10,0.7);
  backdrop-filter: blur(2px);
  z-index: 1000;
  display: flex;
  align-items: center;
  justify-content: center;
}
.auth-modal {
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 28px;
  width: 340px;
  max-width: 90vw;
  box-shadow: 0 20px 60px rgba(0,0,0,0.5);
}
.auth-tabs { display: flex; gap: 4px; margin-bottom: 20px; background: var(--bg-inset); border-radius: 6px; padding: 3px; }
.auth-tab {
  flex: 1;
  text-align: center;
  padding: 8px;
  border-radius: 4px;
  font-family: var(--mono);
  font-size: 12px;
  color: var(--text-faint);
  cursor: pointer;
  border: none;
  background: none;
}
.auth-tab.active { background: var(--bg-elevated); color: var(--accent); }
.auth-field { margin-bottom: 12px; }
.auth-field label { display: block; font-family: var(--mono); font-size: 11px; color: var(--text-faint); margin-bottom: 5px; text-transform: uppercase; letter-spacing: 0.06em; }
.auth-field input {
  width: 100%;
  background: var(--bg-inset);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 9px 12px;
  color: var(--text);
  font-family: var(--sans);
  font-size: 13.5px;
  box-sizing: border-box;
}
.auth-field input:focus { outline: none; border-color: var(--accent-dim); }
.auth-error {
  color: var(--danger);
  font-size: 12.5px;
  margin: 4px 0 12px;
  display: none;
}
.auth-error.show { display: block; }
.auth-submit { width: 100%; padding: 11px; margin-top: 6px; }
.auth-close {
  position: absolute;
  top: 14px; right: 18px;
  background: none; border: none;
  color: var(--text-faint);
  font-size: 18px;
  cursor: pointer;
}
.auth-modal { position: relative; }
.auth-note { font-size: 11.5px; color: var(--text-faint); margin-top: 14px; text-align: center; }

/* ============================================================
   Responsive
   ============================================================ */
@media (max-width: 860px) {
  .shell { grid-template-columns: 1fr; }
  .sidebar { position: relative; height: auto; }
  main { padding: 32px 20px 60px; }
  .listing-head { display: none; }
  .course-row { grid-template-columns: 1fr; row-gap: 8px; }
  .stat-strip { gap: 24px; }
  .auth-widget { top: 10px; right: 10px; }
  .auth-name { display: none; }
}