/* ==========================================================================
   DJ NOTES — design system
   Direction: late-night rave flyer meets technical field manual.
   Dark base, neon signal colors, mono type for precision, grain for atmosphere.
   ========================================================================== */

:root {
  --bg: #0a0a0f;
  --bg-raised: #121219;
  --bg-inset: #16161f;
  --fg: #f3f1ea;
  --fg-dim: #948f9c;
  --fg-faint: #5c5964;
  --line: rgba(243, 241, 234, 0.1);
  --line-strong: rgba(243, 241, 234, 0.22);

  --magenta: #ff2e6c;
  --cyan: #2be6c8;
  --amber: #ffb020;

  --font-display: "Unbounded", sans-serif;
  --font-mono: "JetBrains Mono", ui-monospace, monospace;

  --container: 1080px;
  --radius: 3px;
}

* {
  box-sizing: border-box;
}

html {
  background: var(--bg);
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background:
    radial-gradient(900px 420px at 85% -80px, rgba(255, 46, 108, 0.07), transparent 70%),
    radial-gradient(700px 380px at 8% 30px, rgba(43, 230, 200, 0.05), transparent 70%),
    var(--bg);
  color: var(--fg);
  font-family: var(--font-mono);
  font-size: 16px;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  position: relative;
}

/* grain overlay for atmosphere */
.noise-overlay {
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: 999;
  opacity: 0.05;
  mix-blend-mode: overlay;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='120' height='120'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='2' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)'/%3E%3C/svg%3E");
}

a {
  color: inherit;
}

h1, h2, h3, h4 {
  font-family: var(--font-display);
  font-weight: 800;
  line-height: 1.15;
  letter-spacing: -0.01em;
  margin: 0 0 0.6em;
}

p {
  margin: 0 0 1.1em;
}

::selection {
  background: var(--magenta);
  color: #0a0a0f;
}

/* ==========================================================================
   Header
   ========================================================================== */

.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 18px 28px;
  background: rgba(10, 10, 15, 0.82);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--line);
}

.brand {
  font-family: var(--font-display);
  font-weight: 900;
  font-size: 18px;
  letter-spacing: 0.02em;
  text-decoration: none;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  color: var(--fg);
}

.brand-mark {
  color: var(--magenta);
  text-shadow: 0 0 12px rgba(255, 46, 108, 0.7);
  font-size: 10px;
}

.brand-accent {
  color: var(--cyan);
}

.site-nav {
  display: flex;
  gap: 26px;
  font-size: 13px;
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.site-nav a {
  text-decoration: none;
  color: var(--fg-dim);
  transition: color 0.15s ease;
  position: relative;
}

.site-nav a:hover {
  color: var(--cyan);
}

main {
  min-height: 60vh;
}

/* ==========================================================================
   Footer
   ========================================================================== */

.site-footer {
  border-top: 1px solid var(--line);
  padding: 32px 28px 60px;
  text-align: center;
  color: var(--fg-faint);
  font-size: 12px;
  letter-spacing: 0.04em;
}

/* ==========================================================================
   Homepage — hero
   ========================================================================== */

.hero {
  max-width: var(--container);
  margin: 0 auto;
  padding: 88px 28px 40px;
}

.hero-eyebrow {
  font-size: 12px;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--amber);
  margin-bottom: 18px;
}

.hero-title {
  font-size: clamp(48px, 9vw, 104px);
  margin: 0 0 20px;
  background: linear-gradient(120deg, var(--fg) 40%, var(--cyan) 75%, var(--magenta) 100%);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.hero-sub {
  font-size: 16px;
  color: var(--fg-dim);
  max-width: 520px;
  margin-bottom: 40px;
}

.hero-waveform {
  display: flex;
  align-items: flex-end;
  gap: 4px;
  height: 60px;
  margin-bottom: 8px;
}

.hero-waveform span {
  display: block;
  width: 4px;
  background: linear-gradient(to top, var(--magenta), var(--cyan));
  border-radius: 2px;
  animation: waveform-pulse 1.8s ease-in-out infinite;
  opacity: 0.85;
}

@keyframes waveform-pulse {
  0%, 100% { transform: scaleY(0.35); }
  50% { transform: scaleY(1); }
}

.content-prose {
  max-width: var(--container);
  margin: 0 auto;
  padding: 0 28px 20px;
  color: var(--fg-dim);
}

.content-prose a {
  color: var(--cyan);
}

/* ==========================================================================
   Lesson grid (homepage tracklist)
   ========================================================================== */

.lesson-grid {
  max-width: var(--container);
  margin: 0 auto;
  padding: 40px 28px 100px;
}

.section-label {
  font-family: var(--font-mono);
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.18em;
  color: var(--fg-faint);
  font-weight: 700;
  margin-bottom: 24px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--line);
}

.grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(230px, 1fr));
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
}

.lesson-card {
  background: var(--bg);
  padding: 22px 20px;
  text-decoration: none;
  display: flex;
  flex-direction: column;
  gap: 14px;
  position: relative;
  transition: background 0.15s ease;
  overflow: hidden;
}

.lesson-card::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: 3px;
  background: var(--magenta);
  transform: scaleY(0);
  transform-origin: bottom;
  transition: transform 0.2s ease;
}

.lesson-card:hover {
  background: var(--bg-raised);
}

.lesson-card:hover::before {
  transform: scaleY(1);
}

.lesson-num {
  font-family: var(--font-display);
  font-size: 26px;
  font-weight: 900;
  color: var(--fg-faint);
  transition: color 0.15s ease;
}

.lesson-card:hover .lesson-num {
  color: var(--cyan);
}

.lesson-title {
  font-size: 14px;
  color: var(--fg);
  line-height: 1.4;
}

/* career track cards get the amber accent instead of magenta */
.lesson-grid-career {
  padding-top: 0;
}

.section-label-career {
  color: var(--amber);
  border-bottom-color: rgba(255, 176, 32, 0.25);
}

.lesson-card-career::before {
  background: var(--amber);
}

.lesson-card-career:hover .lesson-num {
  color: var(--amber);
}

.resource-cta {
  max-width: var(--container);
  margin: 0 auto;
  padding: 0 28px 100px;
}

.resource-cta a {
  display: inline-block;
  text-decoration: none;
  color: var(--amber);
  border: 1px solid var(--amber);
  padding: 12px 22px;
  border-radius: var(--radius);
  font-size: 13px;
  letter-spacing: 0.04em;
  transition: background 0.15s ease, color 0.15s ease;
}

.resource-cta a:hover {
  background: var(--amber);
  color: #0a0a0f;
}

/* ==========================================================================
   Lesson page layout
   ========================================================================== */

.lesson-layout {
  max-width: var(--container);
  margin: 0 auto;
  padding: 48px 28px 100px;
  display: grid;
  grid-template-columns: 220px 1fr;
  gap: 56px;
  align-items: start;
}

.lesson-sidebar {
  position: sticky;
  top: 90px;
  display: flex;
  gap: 18px;
}

.progress-fader {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 10px;
}

.fader-track {
  width: 4px;
  height: 220px;
  background: var(--bg-inset);
  border: 1px solid var(--line);
  border-radius: 2px;
  position: relative;
  overflow: hidden;
}

.fader-fill {
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  height: var(--progress, 50%);
  background: linear-gradient(to top, var(--magenta), var(--cyan));
  box-shadow: 0 0 10px rgba(43, 230, 200, 0.5);
}

.progress-label {
  font-size: 11px;
  color: var(--fg-faint);
  letter-spacing: 0.05em;
}

.sidebar-list {
  list-style: none;
  margin: 0;
  padding: 0;
  font-size: 13px;
}

.sidebar-list li {
  border-left: 2px solid transparent;
}

.sidebar-list li a {
  display: flex;
  gap: 10px;
  padding: 7px 0 7px 12px;
  text-decoration: none;
  color: var(--fg-faint);
  transition: color 0.15s ease;
}

.sidebar-list li a .num {
  font-family: var(--font-display);
  font-weight: 700;
  color: var(--fg-faint);
  min-width: 16px;
}

.sidebar-list li a:hover {
  color: var(--fg-dim);
}

.sidebar-list li.active {
  border-left-color: var(--magenta);
}

.sidebar-list li.active a,
.sidebar-list li.active a .num {
  color: var(--cyan);
}

.lesson-content {
  min-width: 0;
}

.lesson-kicker {
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.16em;
  color: var(--amber);
  margin-bottom: 10px;
}

.lesson-content h1 {
  font-size: clamp(30px, 4vw, 42px);
  margin-bottom: 28px;
  padding-bottom: 20px;
  border-bottom: 1px solid var(--line);
}

.lesson-content h2 {
  font-size: 19px;
  margin-top: 2.2em;
  color: var(--fg);
  display: flex;
  align-items: center;
  gap: 10px;
}

.lesson-content h2::before {
  content: "";
  width: 8px;
  height: 8px;
  background: var(--cyan);
  border-radius: 1px;
  flex-shrink: 0;
}

.lesson-content p,
.lesson-content li {
  color: var(--fg-dim);
  font-size: 14.5px;
}

.lesson-content strong {
  color: var(--fg);
  font-weight: 700;
}

.lesson-content ul,
.lesson-content ol {
  padding-left: 22px;
}

.lesson-content li {
  margin-bottom: 0.5em;
}

.lesson-content code {
  font-family: var(--font-mono);
  background: var(--bg-inset);
  border: 1px solid var(--line);
  color: var(--cyan);
  padding: 1px 6px;
  border-radius: var(--radius);
  font-size: 0.9em;
}

.lesson-content blockquote {
  margin: 2em 0;
  padding: 16px 20px;
  border: 1px solid rgba(255, 176, 32, 0.35);
  background: rgba(255, 176, 32, 0.06);
  border-left: 3px solid var(--amber);
  border-radius: var(--radius);
  color: var(--fg);
  font-size: 14px;
}

.lesson-content blockquote p:last-child {
  margin-bottom: 0;
}

.lesson-content a {
  color: var(--cyan);
  text-decoration-color: rgba(43, 230, 200, 0.4);
}

.lesson-content hr {
  border: none;
  border-top: 1px solid var(--line);
  margin: 3em 0 2em;
}

/* task checklists */
.lesson-content li:has(input[type="checkbox"]) {
  list-style: none;
  margin-left: -22px;
}

/* ==========================================================================
   Embedded video player
   ========================================================================== */

.video-embed {
  margin: 1.8em 0 2.2em;
}

.video-frame {
  position: relative;
  aspect-ratio: 16 / 9;
  background: #000;
  border: 1px solid var(--line-strong);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow:
    0 0 0 1px rgba(0, 0, 0, 0.6),
    0 18px 46px -18px rgba(255, 46, 108, 0.28),
    0 8px 30px -12px rgba(43, 230, 200, 0.18);
}

.video-frame::before {
  content: "";
  position: absolute;
  top: -1px;
  left: 0;
  right: 0;
  height: 2px;
  background: linear-gradient(90deg, var(--magenta), var(--cyan));
  z-index: 1;
}

.video-frame iframe {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  border: 0;
}

.video-embed figcaption {
  margin-top: 10px;
  font-size: 12.5px;
  color: var(--fg-faint);
  line-height: 1.5;
}

.video-tag {
  display: inline-block;
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.14em;
  color: var(--magenta);
  border: 1px solid rgba(255, 46, 108, 0.45);
  border-radius: 2px;
  padding: 1px 6px;
  margin-right: 10px;
  vertical-align: 1px;
}

/* ==========================================================================
   Manual figures (diagrams cropped from the official user manual)
   ========================================================================== */

.manual-figure {
  margin: 1.8em 0 2.2em;
}

.manual-figure-frame {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: #101018;
  padding: 18px;
}

.manual-figure-frame img {
  display: block;
  width: 100%;
  height: auto;
  /* soft-invert the white manual pages into the dark theme;
     hue-rotate keeps the red callout lines readable (turn cyan) */
  filter: invert(0.92) hue-rotate(180deg);
  opacity: 0.95;
}

.manual-figure figcaption {
  margin-top: 10px;
  font-size: 12.5px;
  color: var(--fg-faint);
  line-height: 1.5;
}

.figure-tag {
  display: inline-block;
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.14em;
  color: var(--amber);
  border: 1px solid rgba(255, 176, 32, 0.45);
  border-radius: 2px;
  padding: 1px 6px;
  margin-right: 10px;
  vertical-align: 1px;
}

/* self-drawn diagrams are dark-native: no invert */
.diagram-figure .manual-figure-frame img {
  filter: none;
  opacity: 1;
}

.diagram-figure .manual-figure-frame {
  padding: 6px;
}

.diagram-tag {
  color: var(--cyan);
  border-color: rgba(43, 230, 200, 0.45);
}

/* ==========================================================================
   老师傅干货 (pro-tip) callout
   ========================================================================== */

.protip {
  margin: 2.2em 0;
  padding: 20px 22px 8px;
  background:
    linear-gradient(var(--bg-raised), var(--bg-raised)) padding-box,
    linear-gradient(135deg, var(--magenta), var(--cyan)) border-box;
  border: 1px solid transparent;
  border-radius: 4px;
  position: relative;
}

.protip::before {
  content: "◉ 老师傅干货";
  display: block;
  font-family: var(--font-display);
  font-size: 12px;
  font-weight: 800;
  letter-spacing: 0.12em;
  color: var(--cyan);
  margin-bottom: 14px;
}

.protip p,
.protip li {
  font-size: 14px;
}

.protip ul,
.protip ol {
  padding-left: 20px;
  margin-top: 0;
}

.protip li {
  margin-bottom: 0.7em;
}

.protip li:last-child {
  margin-bottom: 1em;
}

.protip strong {
  color: var(--amber);
}

/* ==========================================================================
   Prev / Next pager
   ========================================================================== */

.lesson-pager {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  margin-top: 60px;
  padding-top: 24px;
  border-top: 1px solid var(--line);
}

.lesson-pager a {
  flex: 1;
  text-decoration: none;
  font-size: 13px;
  color: var(--fg-dim);
  border: 1px solid var(--line);
  padding: 16px 18px;
  border-radius: var(--radius);
  transition: border-color 0.15s ease, color 0.15s ease;
}

.lesson-pager a:hover {
  border-color: var(--cyan);
  color: var(--cyan);
}

.pager-next {
  text-align: right;
  margin-left: auto;
}

/* ==========================================================================
   Generic prose page (resources, etc.)
   ========================================================================== */

.prose-page {
  max-width: 720px;
  margin: 0 auto;
  padding: 64px 28px 100px;
}

.prose-page h1 {
  font-size: clamp(30px, 4vw, 42px);
  margin-bottom: 24px;
}

.prose-page h2 {
  font-size: 18px;
  margin-top: 2em;
  color: var(--cyan);
}

.prose-page p,
.prose-page li {
  color: var(--fg-dim);
  font-size: 14.5px;
}

.prose-page a {
  color: var(--cyan);
}

.prose-page blockquote {
  margin: 2em 0;
  padding: 16px 20px;
  border-left: 3px solid var(--amber);
  background: rgba(255, 176, 32, 0.06);
  color: var(--fg);
  font-size: 14px;
  border-radius: var(--radius);
}

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

@media (max-width: 760px) {
  .site-nav {
    gap: 16px;
    font-size: 11px;
  }

  .lesson-layout {
    grid-template-columns: 1fr;
    gap: 28px;
  }

  .lesson-sidebar {
    position: static;
    flex-direction: row-reverse;
    justify-content: flex-end;
  }

  .fader-track {
    width: 160px;
    height: 4px;
  }

  .fader-fill {
    top: 0;
    bottom: auto;
    left: 0;
    right: auto;
    width: var(--progress, 50%);
    height: 100%;
    background: linear-gradient(to right, var(--magenta), var(--cyan));
  }

  .progress-fader {
    flex-direction: row;
  }

  .sidebar-list {
    display: none;
  }

  .hero {
    padding-top: 56px;
  }
}