:root {
  --bg: #07090d;
  --surface: #0f141c;
  --surface-raised: #141b25;
  --surface-soft: #0b1017;
  --ink: #f4f7fb;
  --muted: #98a4b3;
  --line: #263242;
  --line-strong: #344459;
  --accent: #00d8ee;
  --accent-strong: #00a9c2;
  --accent-soft: rgba(0, 216, 238, 0.13);
  --gold: #d6a94a;
  --danger: #e35b4f;
  --max-width: 1180px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; background: var(--bg); }
body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: "Microsoft YaHei", "PingFang SC", Arial, sans-serif;
}
button, input, textarea, select { font: inherit; }
button, a { -webkit-tap-highlight-color: transparent; }
button { cursor: pointer; }
a { color: inherit; }
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.tutorial-header {
  position: sticky;
  top: 0;
  z-index: 100;
  min-height: 68px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  padding: 0 max(20px, calc((100vw - var(--max-width)) / 2));
  border-bottom: 1px solid rgba(255, 255, 255, 0.08);
  background: rgba(7, 9, 13, 0.92);
  backdrop-filter: blur(18px);
}
.tutorial-brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  color: #eff7f5;
  font-size: 14px;
  font-weight: 700;
  text-decoration: none;
  white-space: nowrap;
}
.brand-mark {
  width: 30px;
  height: 30px;
  border: 1px solid rgba(32, 199, 167, 0.48);
  border-radius: 6px;
  background: rgba(32, 199, 167, 0.12);
  object-fit: contain;
}
.tutorial-nav { display: flex; align-items: center; gap: 24px; }
.tutorial-nav a {
  color: var(--muted);
  font-size: 13px;
  text-decoration: none;
  transition: color 0.18s ease;
}
.tutorial-nav a:hover { color: var(--ink); }
.tutorial-nav .studio-link { display: inline-flex; align-items: center; gap: 7px; color: #8cebd8; }
.course-progress { position: absolute; left: 0; right: 0; bottom: -1px; height: 2px; background: transparent; }
.course-progress span { display: block; width: 0; height: 100%; background: var(--accent); transition: width 0.24s ease; }

.tutorial-hero {
  position: relative;
  width: min(var(--max-width), calc(100% - 40px));
  min-height: min(560px, calc(78vh - 68px));
  display: flex;
  align-items: center;
  margin-inline: auto;
  overflow: hidden;
  background: url("/brand/share-desktop-2560x1440.webp") center 44% / cover no-repeat;
}
.hero-overlay {
  position: absolute;
  inset: 0;
  background:
    linear-gradient(90deg, rgba(6, 8, 12, 0.97) 0%, rgba(6, 8, 12, 0.89) 42%, rgba(6, 8, 12, 0.47) 72%, rgba(6, 8, 12, 0.58) 100%),
    linear-gradient(180deg, rgba(7, 9, 13, 0.2) 56%, var(--bg) 100%);
}
.hero-content {
  position: relative;
  z-index: 1;
  width: min(var(--max-width), calc(100% - 40px));
  margin: 0 auto;
  padding: 72px 0 74px;
}
.hero-kicker, .section-index, .lesson-number {
  color: var(--accent);
  font-size: 12px;
  font-weight: 800;
  letter-spacing: 0;
}
.hero-content h1 {
  max-width: 760px;
  margin: 14px 0 18px;
  font-size: 68px;
  line-height: 1.06;
  letter-spacing: 0;
}
.hero-lead {
  max-width: 670px;
  margin: 0;
  color: #c3cbd6;
  font-size: 18px;
  line-height: 1.8;
}
.hero-actions, .completion-actions {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px;
  margin-top: 30px;
}
.primary-action, .secondary-action {
  min-height: 44px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  border-radius: 7px;
  padding: 0 18px;
  text-decoration: none;
  transition: background 0.18s ease, border-color 0.18s ease, transform 0.18s ease;
}
.primary-action {
  border: 1px solid var(--accent);
  background: var(--accent);
  color: #031411;
  font-weight: 800;
}
.primary-action:hover { background: #2addbb; transform: translateY(-1px); }
.secondary-action {
  border: 1px solid var(--line-strong);
  background: rgba(13, 18, 26, 0.82);
  color: #e9eef5;
}
.secondary-action:hover { border-color: #52647c; background: #161e29; }
.hero-facts {
  display: flex;
  gap: 34px;
  margin: 40px 0 0;
  padding: 0;
  list-style: none;
}
.hero-facts li { display: flex; flex-direction: column; gap: 5px; }
.hero-facts strong { font-size: 19px; color: #f0f6f5; }
.hero-facts span { color: var(--muted); font-size: 12px; }
.hero-next {
  position: absolute;
  z-index: 1;
  left: 50%;
  bottom: 24px;
  transform: translateX(-50%);
  color: #9ba7b6;
  font-size: 11px;
}

.course-block { padding: 56px 0 0; }
.section-intro, .lesson {
  width: min(var(--max-width), calc(100% - 40px));
  margin-inline: auto;
}
.section-intro { padding-bottom: 34px; }
.section-intro h2 {
  margin: 10px 0 10px;
  font-size: 32px;
  line-height: 1.24;
}
.section-intro > p:last-child { max-width: 720px; margin: 0; color: var(--muted); line-height: 1.75; }
.advanced-block { background: #090d12; }
.lesson {
  display: grid;
  grid-template-columns: minmax(240px, 0.72fr) minmax(0, 1.5fr);
  gap: 34px 44px;
  margin-bottom: 20px;
  padding: 44px 38px;
  border: 1px solid rgba(113, 137, 172, 0.3);
  border-radius: 8px;
  background: linear-gradient(180deg, rgba(24, 32, 47, 0.9), rgba(13, 18, 27, 0.76));
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.045), 0 16px 38px rgba(0, 0, 0, 0.16);
  scroll-margin-top: 84px;
}
.lesson:nth-of-type(even) {
  border-color: rgba(32, 199, 167, 0.27);
  background: linear-gradient(180deg, rgba(14, 43, 40, 0.82), rgba(10, 25, 28, 0.74));
}
.lesson-copy h3 { margin: 12px 0 12px; font-size: 27px; line-height: 1.3; }
.lesson-copy > p { margin: 0; color: var(--muted); font-size: 14px; line-height: 1.8; }
.lesson-tip {
  display: flex;
  gap: 9px;
  margin-top: 20px;
  padding: 12px;
  border-left: 2px solid var(--gold);
  background: rgba(214, 169, 74, 0.08);
  color: #dbc891;
  font-size: 12px;
  line-height: 1.6;
}
.lesson-nav {
  grid-column: 1 / -1;
  display: flex;
  justify-content: space-between;
  padding-top: 2px;
}
.lesson-nav button {
  min-height: 38px;
  display: inline-flex;
  align-items: center;
  gap: 7px;
  border: 1px solid var(--line);
  border-radius: 7px;
  padding: 0 13px;
  background: #101722;
  color: #d7dee8;
}
.lesson-nav button:hover { border-color: var(--accent); color: #b8f5e8; }

.demo-panel, .share-demo-panel, .settings-demo {
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--surface);
  overflow: hidden;
}
.demo-panel-head {
  min-height: 42px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 0 14px;
  border-bottom: 1px solid var(--line);
  color: #e6ebf2;
  font-size: 12px;
  font-weight: 700;
}
.demo-panel-head > span:last-child { color: var(--muted); font-weight: 500; }
.demo-panel textarea, .settings-demo input, .settings-demo textarea, .settings-demo select {
  width: 100%;
  border: 1px solid var(--line);
  border-radius: 6px;
  outline: none;
  background: #090d13;
  color: #edf5f2;
}
.demo-panel textarea { min-height: 126px; padding: 15px; border: 0; border-radius: 0; resize: vertical; line-height: 1.7; }
.demo-panel textarea:focus, .settings-demo input:focus, .settings-demo textarea:focus, .settings-demo select:focus { border-color: var(--accent); box-shadow: inset 0 0 0 1px var(--accent); }
.demo-state, .live-dot { color: #84e9d5 !important; }
.quick-scenes { display: flex; flex-wrap: wrap; gap: 7px; padding: 0 14px 14px; }
.quick-scenes button, .preset-demo-grid button, .created-preset-preview button {
  min-height: 34px;
  border: 1px solid var(--line);
  border-radius: 6px;
  padding: 0 11px;
  background: #151c26;
  color: #d9e0e9;
}
.quick-scenes button:hover, .preset-demo-grid button:hover, .created-preset-preview button:hover { border-color: var(--accent); color: #b9f5e9; }
.two-column-demo { display: grid; grid-template-columns: 0.8fr 1.2fr; gap: 12px; }
.preset-demo-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 8px; padding: 14px; }
.preset-demo-grid button.active { border-color: var(--accent); background: var(--accent-soft); color: #bdf6eb; }
.preset-demo-grid button.negative { border-color: rgba(227, 91, 79, 0.34); color: #ffaaa2; }
.code-panel pre, .prompt-mirror {
  min-height: 225px;
  margin: 0;
  padding: 16px;
  overflow: auto;
  color: #b9f3e7;
  font: 13px/1.75 Consolas, "Microsoft YaHei", monospace;
  white-space: pre-wrap;
  overflow-wrap: anywhere;
}
.prompt-mirror { color: #e6edf3; }
.callout-line { margin: 0 14px 14px; padding-top: 11px; border-top: 1px solid var(--line); color: var(--gold); font-size: 12px; }
.copy-demo { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; }
.copy-choice {
  min-height: 150px;
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 8px;
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 20px;
  background: var(--surface);
  color: var(--ink);
  text-align: left;
}
.copy-choice:hover { border-color: var(--accent); background: #111b22; }
.copy-choice > span:last-child { color: var(--muted); font-size: 12px; line-height: 1.6; }
.copy-icon { width: 34px; height: 34px; display: grid; place-items: center; border-radius: 6px; background: var(--accent-soft); color: #8fedd9; }
.demo-feedback { grid-column: 2; min-height: 20px; margin: 0; color: #8cebd8; font-size: 12px; }
.share-demo-panel { display: grid; grid-template-columns: minmax(0, 1fr) auto; gap: 18px; align-items: center; padding: 20px; }
.share-demo-panel h4 { margin: 10px 0 8px; font-size: 18px; }
.share-demo-panel p { max-width: 560px; margin: 0; color: var(--muted); font-size: 13px; line-height: 1.65; }
.share-tag { display: inline-flex; min-height: 24px; align-items: center; padding: 0 8px; border: 1px solid rgba(32, 199, 167, 0.38); border-radius: 5px; background: var(--accent-soft); color: #92ebd9; font-size: 11px; }
.demo-share-result { grid-column: 1 / -1; display: flex; gap: 8px; padding: 11px 12px; border: 1px solid rgba(32, 199, 167, 0.32); border-radius: 6px; background: rgba(32, 199, 167, 0.08); color: #a7f0e1; font-size: 12px; }
.demo-share-result[hidden] { display: none; }
.completion-actions { grid-column: 2; margin-top: 0; }

.sortable-list { display: grid; gap: 8px; }
.sortable-item {
  min-height: 68px;
  display: grid;
  grid-template-columns: 36px minmax(0, 1fr) auto;
  align-items: center;
  gap: 12px;
  border: 1px solid var(--line);
  border-radius: 7px;
  padding: 10px 12px;
  background: var(--surface);
  transition: border-color 0.16s ease, background 0.16s ease, transform 0.16s ease;
}
.sortable-item.dragging { opacity: 0.68; border-color: var(--accent); background: #10231f; }
.sortable-item strong, .sortable-item span { display: block; }
.sortable-item strong { font-size: 14px; }
.sortable-item span, .sortable-item time { margin-top: 5px; color: var(--muted); font-size: 11px; }
.drag-handle {
  width: 32px;
  height: 32px;
  display: grid;
  place-items: center;
  border: 1px solid var(--line);
  border-radius: 7px;
  background: #171e29;
  color: var(--muted);
  cursor: grab;
  touch-action: none;
}
.drag-handle:hover { border-color: var(--accent); color: #9bf0df; }
.drag-handle:active { cursor: grabbing; }
.sort-layout { display: grid; grid-template-columns: minmax(0, 1fr) 210px; gap: 12px; }
.category-sort-demo .sortable-item { grid-template-columns: 36px minmax(0, 1fr) auto; min-height: 58px; }
.safety-note { border: 1px solid rgba(214, 169, 74, 0.34); border-radius: 7px; padding: 18px; background: rgba(214, 169, 74, 0.06); color: #d9c58f; }
.safety-note .ui-icon { margin-bottom: 14px; }
.safety-note strong { display: block; margin-bottom: 8px; color: #ead9a9; }
.safety-note p { margin: 0; font-size: 12px; line-height: 1.7; }

.settings-demo { display: grid; grid-template-columns: 170px minmax(0, 1fr); }
.settings-demo > nav { display: flex; flex-direction: column; padding: 12px; border-right: 1px solid var(--line); background: #0b1017; }
.settings-demo > nav button { min-height: 38px; border: 0; border-radius: 6px; padding: 0 10px; background: transparent; color: var(--muted); text-align: left; }
.settings-demo > nav button.active { background: var(--accent-soft); color: #a4f0e0; }
.settings-demo form { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; padding: 18px; }
.settings-demo label { display: grid; gap: 7px; color: var(--muted); font-size: 12px; }
.settings-demo input, .settings-demo textarea, .settings-demo select { min-height: 40px; padding: 9px 11px; }
.settings-demo textarea { resize: vertical; }
.settings-demo .wide-field { grid-column: 1 / -1; }
.settings-demo form .primary-action { justify-self: start; }
.created-preset-preview { grid-column: 1 / -1; display: flex; align-items: center; gap: 12px; padding: 12px 18px; border-top: 1px solid var(--line); color: var(--muted); font-size: 12px; }
.created-preset-preview > div { display: flex; flex-wrap: wrap; gap: 7px; }

.shortcut-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 10px; }
.shortcut-grid > div { min-height: 116px; display: block; border: 1px solid var(--line); border-radius: 7px; padding: 16px; background: var(--surface); }
.shortcut-grid kbd { display: inline-grid; min-width: 34px; height: 28px; place-items: center; margin-right: 5px; border: 1px solid #45546a; border-bottom-width: 2px; border-radius: 5px; padding: 0 7px; background: #1a2230; color: #e4eaf1; font: 12px Consolas, monospace; }
.shortcut-grid strong, .shortcut-grid span { display: block; }
.shortcut-grid strong { margin-top: 14px; font-size: 13px; }
.shortcut-grid span { margin-top: 5px; color: var(--muted); font-size: 11px; }

.file-action-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 10px; }
.file-action { min-height: 190px; border: 1px solid var(--line); border-top: 2px solid var(--accent); border-radius: 7px; padding: 18px; background: var(--surface); }
.file-action.merge { border-top-color: var(--gold); }
.file-action.danger { border-top-color: var(--danger); }
.file-action .ui-icon { margin-bottom: 20px; color: #8cebd8; }
.file-action.merge .ui-icon { color: #e2c271; }
.file-action.danger .ui-icon { color: #ff938a; }
.file-action strong { display: block; margin-bottom: 10px; }
.file-action p { margin: 0; color: var(--muted); font-size: 12px; line-height: 1.75; }
.warning-line { grid-column: 2; display: flex; gap: 9px; margin-top: 12px; padding: 12px; border: 1px solid rgba(214, 169, 74, 0.28); background: rgba(214, 169, 74, 0.06); color: #dcc98f; font-size: 12px; line-height: 1.65; }

.final-cta { min-height: 420px; display: flex; flex-direction: column; align-items: center; justify-content: center; padding: 72px 20px; text-align: center; }
.final-cta > p { margin: 0 0 12px; color: var(--accent); font-size: 12px; font-weight: 800; }
.final-cta h2 { margin: 0; font-size: 34px; }
.final-cta > span { margin-top: 12px; color: var(--muted); font-size: 13px; }
.final-cta .primary-action { margin-top: 26px; }
.tutorial-footer { min-height: 70px; display: flex; justify-content: space-between; align-items: center; width: min(var(--max-width), calc(100% - 40px)); margin: 0 auto; border-top: 1px solid var(--line); color: var(--muted); font-size: 11px; }

.ui-icon { width: 17px; height: 17px; display: inline-block; flex: 0 0 17px; background: currentColor; mask-repeat: no-repeat; mask-position: center; mask-size: contain; }
.icon-play { mask-image: url("/icons/play.svg"); }
.icon-external { mask-image: url("/icons/external-link.svg"); }
.icon-pointer { mask-image: url("/icons/mouse-pointer-click.svg"); }
.icon-arrow-right { mask-image: url("/icons/arrow-right.svg"); }
.icon-arrow-left { mask-image: url("/icons/arrow-left.svg"); }
.icon-copy { mask-image: url("/icons/copy.svg"); }
.icon-braces { mask-image: url("/icons/braces.svg"); }
.icon-share { mask-image: url("/icons/share-2.svg"); }
.icon-check { mask-image: url("/icons/check.svg"); }
.icon-grip { mask-image: url("/icons/grip-vertical.svg"); }
.icon-shield { mask-image: url("/icons/shield-check.svg"); }
.icon-download { mask-image: url("/icons/download.svg"); }
.icon-upload { mask-image: url("/icons/upload.svg"); }
.icon-layers { mask-image: url("/icons/layers.svg"); }
.icon-alert { mask-image: url("/icons/triangle-alert.svg"); }
.icon-restart { mask-image: url("/icons/rotate-ccw.svg"); }

@media (max-width: 900px) {
  .lesson { grid-template-columns: 1fr; gap: 24px; }
  .lesson-nav, .demo-feedback, .warning-line, .completion-actions { grid-column: 1; }
  .tutorial-nav > a:not(.studio-link) { display: none; }
  .hero-content h1 { font-size: 50px; }
}

@media (max-width: 640px) {
  .tutorial-header { min-height: 60px; padding-inline: 12px; }
  .tutorial-brand { font-size: 12px; }
  .brand-mark { width: 28px; height: 28px; }
  .tutorial-nav .studio-link { font-size: 0; gap: 0; }
  .tutorial-nav .studio-link .ui-icon { width: 20px; height: 20px; }
  .tutorial-hero {
    width: min(100% - 28px, 600px);
    min-height: min(650px, calc(100vh - 60px));
    background-position: 62% center;
  }
  .hero-content { width: min(100% - 28px, 600px); padding: 70px 0 90px; }
  .hero-content h1 { font-size: 40px; }
  .hero-lead { font-size: 15px; }
  .hero-actions { align-items: stretch; flex-direction: column; }
  .hero-actions > * { width: 100%; }
  .hero-facts { gap: 18px; justify-content: space-between; }
  .hero-facts strong { font-size: 16px; }
  .section-intro, .lesson { width: min(100% - 28px, 600px); }
  .course-block { padding-top: 64px; }
  .section-intro h2 { font-size: 26px; }
  .lesson { margin-bottom: 14px; padding: 32px 20px; }
  .lesson-copy h3 { font-size: 23px; }
  .two-column-demo, .copy-demo, .sort-layout, .file-action-grid, .shortcut-grid { grid-template-columns: 1fr; }
  .share-demo-panel { grid-template-columns: 1fr; }
  .share-demo-panel .primary-action { width: 100%; }
  .settings-demo { grid-template-columns: 1fr; }
  .settings-demo > nav { flex-direction: row; overflow-x: auto; border-right: 0; border-bottom: 1px solid var(--line); }
  .settings-demo > nav button { white-space: nowrap; }
  .settings-demo form { grid-template-columns: 1fr; padding: 14px; }
  .settings-demo .wide-field { grid-column: 1; }
  .sortable-item { grid-template-columns: 34px minmax(0, 1fr); }
  .sortable-item time { grid-column: 2; margin-top: -4px; }
  .lesson-nav button { padding-inline: 10px; font-size: 12px; }
  .completion-actions { align-items: stretch; flex-direction: column; }
  .completion-actions > * { width: 100%; }
  .tutorial-footer { width: calc(100% - 28px); }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { scroll-behavior: auto !important; transition-duration: 0.01ms !important; animation-duration: 0.01ms !important; }
}