:root {
  color-scheme: light;
  --page: #fafafa;
  --surface: #fff;
  --soft: #f1f2f4;
  --text: #121417;
  --muted: #606770;
  --line: #dedfe3;
  --accent: #155cc2;
  --focus: #2274df;
}
@media (prefers-color-scheme: dark) {
  html[data-theme="auto"] {
    color-scheme: dark;
    --page: #101114;
    --surface: #191b20;
    --soft: #22252b;
    --text: #f4f5f7;
    --muted: #b8bdc8;
    --line: #393d47;
    --accent: #8ebcff;
    --focus: #8ebcff;
  }
}
html[data-theme="dark"] {
  color-scheme: dark;
  --page: #101114;
  --surface: #191b20;
  --soft: #22252b;
  --text: #f4f5f7;
  --muted: #b8bdc8;
  --line: #393d47;
  --accent: #8ebcff;
  --focus: #8ebcff;
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 100px; }
body { margin: 0; background: var(--page); color: var(--text); font-family: "OPPO Sans", "Microsoft YaHei", "PingFang SC", system-ui, sans-serif; line-height: 1.8; }
a { color: inherit; }
button { font: inherit; cursor: pointer; }
a, button { -webkit-tap-highlight-color: transparent; }
:focus-visible { outline: 3px solid var(--focus); outline-offset: 4px; }
[hidden] { display: none !important; }
.skip-link { position: fixed; top: -100px; left: 16px; z-index: 60; padding: 10px 16px; background: var(--surface); }
.skip-link:focus { top: 12px; }
.topbar { position: sticky; top: 0; z-index: 20; background: #050505; color: #fff; border-bottom: 1px solid #303238; }
.topbar-inner { max-width: 1180px; min-height: 72px; padding: 12px 24px; margin: auto; display: flex; align-items: center; gap: 16px; }
.brand { margin-right: auto; display: flex; align-items: center; gap: 12px; text-decoration: none; font-weight: 700; line-height: 1.4; }
.brand-mark { display: grid; place-items: center; flex: 0 0 34px; height: 34px; border-radius: 10px; color: #111; background: #fff; }
.theme-toggle { min-height: 42px; padding: 7px 14px; display: flex; align-items: center; gap: 8px; border-radius: 24px; border: 1px solid #565a63; background: #191b20; color: #fff; font-size: 14px; white-space: nowrap; }
.theme-toggle:hover { background: #30343b; border-color: #939ba9; }
.theme-toggle:active { background: #414650; }
.theme-toggle:focus-visible { outline-color: #fff; }
.theme-toggle:disabled { opacity: .5; cursor: not-allowed; }
.container { width: min(1080px, calc(100% - 48px)); margin: auto; }
.hero { padding: 64px 0 38px; }
.breadcrumb { color: var(--muted); font-size: 14px; text-decoration: none; }
.breadcrumb:hover { color: var(--accent); }
.eyebrow { margin: 34px 0 10px; color: var(--accent); font-size: 14px; font-weight: 700; letter-spacing: .06em; }
h1, h2, h3, p { margin-top: 0; }
h1 { margin-bottom: 18px; font-size: clamp(32px, 4vw, 52px); line-height: 1.2; letter-spacing: -.025em; }
.lead { max-width: 820px; margin-bottom: 22px; color: var(--muted); font-size: clamp(17px, 2vw, 20px); }
.hero-links { display: flex; flex-wrap: wrap; gap: 12px 24px; align-items: center; }
.primary-link { display: inline-flex; align-items: center; gap: 12px; padding: 10px 18px; border: 1px solid var(--text); border-radius: 10px; background: var(--text); color: var(--surface); text-decoration: none; font-weight: 700; }
.primary-link:hover { opacity: .83; }
.primary-link:active { transform: translateY(1px); }
.hero-meta { color: var(--muted); font-size: 14px; }
.quick-nav { margin: 0 0 26px; }
.quick-nav ol { margin: 0; padding: 0; list-style: none; display: grid; grid-template-columns: repeat(3, 1fr); gap: 12px; }
.quick-nav a { display: flex; align-items: center; gap: 14px; height: 100%; padding: 20px; border: 1px solid var(--line); border-radius: 14px; background: var(--surface); text-decoration: none; font-size: 15px; font-weight: 700; }
.quick-nav a:hover { background: var(--soft); border-color: var(--muted); }
.quick-nav a:active { background: var(--soft); transform: translateY(1px); }
.nav-number { color: var(--accent); font-size: 18px; }
.source-note { margin-bottom: 52px; font-size: 14px; color: var(--muted); }
.step { margin-bottom: 64px; scroll-margin-top: 100px; }
.step-heading { display: flex; align-items: center; gap: 16px; margin-bottom: 18px; }
.step-number { display: grid; place-items: center; width: 44px; height: 44px; flex-shrink: 0; border-radius: 12px; background: var(--text); color: var(--surface); font-weight: 700; }
h2 { margin: 0; font-size: clamp(24px, 3vw, 32px); line-height: 1.4; }
.step-summary { margin-bottom: 14px; color: var(--muted); }
.instructions { margin: 0 0 24px; padding-left: 24px; }
.instructions li { margin: 6px 0; padding-left: 4px; }
.instructions li::marker { color: var(--muted); font-weight: 600; }
.shot-card { margin: 0; border: 1px solid var(--line); border-radius: 16px; background: var(--surface); overflow: hidden; }
.shot-button { display: block; width: 100%; padding: 0; border: 0; background: var(--surface); cursor: zoom-in; }
.shot-button img { display: block; width: 100%; height: auto; }
.shot-button:hover { opacity: .94; }
.shot-button:active { opacity: .86; }
.shot-button:focus-visible { outline-offset: -4px; }
.shot-caption { display: flex; align-items: center; justify-content: space-between; gap: 16px; padding: 12px 18px; border-top: 1px solid var(--line); color: var(--muted); font-size: 13px; }
.zoom-hint { flex-shrink: 0; border: 1px solid var(--line); background: var(--surface); color: var(--text); padding: 6px 12px; border-radius: 8px; }
.zoom-hint:hover { background: var(--soft); border-color: var(--muted); }
.zoom-hint:active { background: var(--soft); }
.article-footer { display: flex; justify-content: space-between; gap: 20px; padding: 24px 0 48px; border-top: 1px solid var(--line); color: var(--muted); font-size: 14px; }
.article-footer a:hover { color: var(--accent); }
dialog { width: min(1600px, calc(100% - 32px)); max-width: none; max-height: calc(100dvh - 32px); padding: 0; border: 1px solid var(--line); border-radius: 14px; background: var(--surface); color: var(--text); }
dialog::backdrop { background: rgba(0, 0, 0, .8); }
.dialog-bar { position: sticky; top: 0; display: flex; justify-content: space-between; align-items: center; gap: 16px; padding: 12px 18px; background: var(--surface); border-bottom: 1px solid var(--line); }
.dialog-title { margin: 0; font-size: 15px; }
.dialog-close { flex: 0 0 42px; height: 42px; border: 1px solid var(--line); border-radius: 10px; background: var(--surface); color: var(--text); font-size: 26px; line-height: 1; }
.dialog-close:hover, .dialog-close:active { background: var(--soft); }
.dialog-canvas { overflow: auto; }
.dialog-canvas img { display: block; width: 100%; height: auto; }
@media (max-width: 680px) {
  html { scroll-padding-top: 140px; }
  .container { width: calc(100% - 32px); }
  .topbar-inner { gap: 10px; padding: 12px 16px; flex-wrap: wrap; }
  .brand { flex: 1 0 100%; }
  .topbar .i18n-language-switcher { margin-right: auto; }
  .hero { padding-top: 32px; }
  .eyebrow { margin-top: 26px; }
  .quick-nav ol { grid-template-columns: 1fr; gap: 8px; }
  .quick-nav a { padding: 12px 16px; }
  .source-note { margin-bottom: 36px; }
  .step { margin-bottom: 44px; scroll-margin-top: 140px; }
  .step-heading { gap: 12px; }
  .shot-caption { align-items: flex-start; padding: 12px; gap: 10px; }
  .article-footer { flex-wrap: wrap; }
  .dialog-canvas img { width: max(100%, 1000px); max-width: none; }
}
@media (prefers-reduced-motion: reduce) { html { scroll-behavior: auto; } }
@media (forced-colors: active) { .step-number, .primary-link { border: 1px solid ButtonText; } }