/* InSnap 官网样式 —— 「取景框」风格：整站像一次截图——暗场、点阵、白色角标取景框、荧光笔高亮。
   只有一套深色主题；无框架、无外部字体。滚动特效全部是 CSS 滚动驱动动画（animation-timeline），
   不支持的浏览器自动退回静态版式。下拉菜单 / 移动端菜单是纯 CSS。 */
:root {
  color-scheme: dark;
  --bg: #07080c;
  --alt: #0c0e14;
  --card: #10131b;
  --text: #eef0f6;
  --muted: #8f95a9;
  --line: rgba(255, 255, 255, 0.1);
  --link: #6fa8ff;
  --btn: #2f7bff;
  --btn-hover: #5593ff;
  --on-btn: #ffffff;
  --soft: rgba(47, 123, 255, 0.14);
  --hi: #ffe14d;
  --ok: #4cc777;
  --warn-bg: #2a2412;
  --warn-line: #5b4d1c;
  --shadow: 0 1px 2px rgba(0, 0, 0, 0.5), 0 40px 90px -40px rgba(0, 0, 0, 0.9);
  --maxw: 1240px;
  --font: -apple-system, BlinkMacSystemFont, "SF Pro Display", "SF Pro Text", "Segoe UI", system-ui, sans-serif;
  --mono: ui-monospace, "SF Mono", SFMono-Regular, Menlo, Consolas, monospace;
}

*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; background: var(--bg); }
body { margin: 0; background: var(--bg); color: var(--text); font: 400 17px/1.55 var(--font); -webkit-font-smoothing: antialiased; text-rendering: optimizeLegibility; overflow-x: clip; }
img, svg, video { display: block; max-width: 100%; }
a { color: var(--link); text-decoration: none; }
a:hover { text-decoration: underline; }
button { font: inherit; color: inherit; }
:focus-visible { outline: 3px solid var(--btn); outline-offset: 2px; border-radius: 6px; }
h1, h2, h3, h4 { line-height: 1.04; letter-spacing: -0.04em; margin: 0; font-weight: 720; text-wrap: balance; }
p { margin: 0; }
ul, ol { margin: 0; padding: 0; list-style: none; }
.container { width: 100%; max-width: var(--maxw); margin: 0 auto; padding: 0 28px; }
.narrow { max-width: 780px; }
.skip { position: absolute; left: -9999px; top: 0; background: var(--btn); color: var(--on-btn); padding: 10px 14px; z-index: 200; }
.skip:focus { left: 8px; top: 8px; border-radius: 6px; }

/* 荧光笔：关键字下的黄色高亮（Marker 工具的意象） */
.mark { background-image: linear-gradient(transparent 60%, rgba(255, 225, 77, 0.85) 60%); background-repeat: no-repeat; background-size: 100% 100%; color: #fff; padding: 0 0.06em; margin: 0 -0.06em; }
.mono { font-family: var(--mono); }

/* 滚动进度：顶部一根细线 */
.progress { position: fixed; left: 0; right: 0; top: 0; height: 2px; background: var(--btn); transform-origin: 0 50%; transform: scaleX(0); z-index: 120; }

/* ===== 顶栏 ===== */
.site-header { position: sticky; top: 0; z-index: 90; border-bottom: 1px solid transparent; background: color-mix(in srgb, var(--bg) 70%, transparent); -webkit-backdrop-filter: saturate(160%) blur(18px); backdrop-filter: saturate(160%) blur(18px); }
.header-row { display: flex; align-items: center; gap: 8px; height: 64px; }
.brand { display: flex; align-items: center; gap: 10px; color: var(--text); font-weight: 750; font-size: 19px; letter-spacing: -0.03em; margin-right: 20px; }
.brand:hover { text-decoration: none; }
.brand img { width: 30px; height: 30px; border-radius: 8px; }
.nav { display: flex; align-items: center; gap: 2px; }
.nav > a, .nav-trigger { display: inline-flex; align-items: center; gap: 6px; height: 38px; padding: 0 14px; border-radius: 8px; color: var(--text); font-size: 15px; font-weight: 550; background: none; border: 0; cursor: pointer; }
.nav > a:hover, .nav-item:hover > .nav-trigger, .nav-item:focus-within > .nav-trigger { background: var(--soft); text-decoration: none; }
.nav > a[aria-current="page"] { background: var(--soft); }
.nav-trigger svg { width: 14px; height: 14px; opacity: 0.55; transition: transform 0.15s; }
.nav-item:hover .nav-trigger svg, .nav-item:focus-within .nav-trigger svg { transform: rotate(180deg); }
.nav-item { position: relative; }
.menu { position: absolute; top: 100%; left: -8px; min-width: 330px; padding: 10px; margin-top: 6px; background: #12151e; border: 1px solid var(--line); border-radius: 14px; box-shadow: var(--shadow); opacity: 0; visibility: hidden; transform: translateY(6px); transition: opacity 0.14s, transform 0.14s, visibility 0.14s; }
.menu::before { content: ""; position: absolute; left: 0; right: 0; top: -14px; height: 14px; }
.nav-item:hover .menu, .nav-item:focus-within .menu { opacity: 1; visibility: visible; transform: none; }
.menu a.entry { display: flex; gap: 14px; align-items: center; padding: 10px; border-radius: 10px; color: var(--text); }
.menu a.entry:hover, .menu a.plain:hover { background: var(--soft); text-decoration: none; }
.menu .tile { flex: none; width: 42px; height: 42px; border-radius: 10px; display: grid; place-items: center; background: var(--bg); border: 1px solid var(--line); color: var(--btn); }
.menu .tile svg { width: 22px; height: 22px; }
.menu .entry b { display: block; font-size: 15px; line-height: 1.25; }
.menu .entry span { display: block; font-size: 13px; color: var(--muted); line-height: 1.35; margin-top: 2px; }
.menu hr { border: 0; border-top: 1px solid var(--line); margin: 8px 10px; }
.menu a.plain { display: flex; align-items: center; gap: 12px; padding: 10px; border-radius: 10px; color: var(--text); font-size: 15px; font-weight: 550; }
.menu a.plain svg { width: 19px; height: 19px; color: var(--muted); }
.menu.sm { min-width: 240px; }
.header-end { margin-left: auto; display: flex; align-items: center; gap: 10px; }
.burger { display: none; width: 42px; height: 42px; border-radius: 8px; cursor: pointer; place-items: center; }
.burger:hover { background: var(--soft); }
.burger svg { width: 24px; height: 24px; }
.nav-toggle { position: absolute; opacity: 0; pointer-events: none; }
.nav-toggle:focus-visible ~ .header-row .burger { outline: 3px solid var(--btn); }
.mobile-menu { display: none; border-top: 1px solid var(--line); background: var(--bg); padding: 10px 20px 22px; }
.mobile-menu h4 { font-size: 12px; font-family: var(--mono); letter-spacing: 0.08em; text-transform: uppercase; color: var(--muted); margin: 16px 8px 6px; }
.mobile-menu a { display: flex; gap: 12px; align-items: center; padding: 12px 8px; color: var(--text); font-size: 17px; font-weight: 550; border-radius: 8px; }
.mobile-menu a svg { width: 22px; height: 22px; color: var(--btn); }

/* ===== 按钮 ===== */
.btn { display: inline-flex; align-items: center; justify-content: center; gap: 8px; height: 48px; padding: 0 24px; border-radius: 10px; font: 650 16px/1 var(--font); border: 1px solid transparent; cursor: pointer; text-decoration: none !important; transition: background-color 0.15s, transform 0.15s; }
.btn-primary { background: var(--btn); color: var(--on-btn); }
.btn-primary:hover { background: var(--btn-hover); transform: translateY(-1px); }
.btn-ghost { background: transparent; color: var(--text); border-color: rgba(255, 255, 255, 0.22); }
.btn-ghost:hover { background: rgba(255, 255, 255, 0.06); }
.btn-sm { height: 38px; padding: 0 16px; font-size: 14.5px; }
.btn-block { width: 100%; }
.btn-lg { height: 54px; padding: 0 30px; font-size: 17px; }
.btn-disabled { background: var(--soft); color: var(--muted); cursor: not-allowed; border-color: var(--line); }
.btn svg { width: 18px; height: 18px; flex: none; }
.cta-row { display: flex; flex-wrap: wrap; gap: 12px; justify-content: center; margin-top: 32px; }
.fine { font-size: 13.5px; color: var(--muted); margin-top: 18px; font-family: var(--mono); }

/* ===== 取景框：视频的外框（白色角标 + 左上角尺寸标签） ===== */
.frame { position: relative; margin: 38px 0 0; }
.frame video { width: 100%; height: auto; aspect-ratio: 1280 / 800; object-fit: cover; background: #0b0d13; border-radius: 4px; box-shadow: 0 0 0 1px rgba(255, 255, 255, 0.1), 0 50px 120px -50px rgba(47, 123, 255, 0.55), 0 30px 80px -40px rgba(0, 0, 0, 0.9); }
.stage-frame video { transition: opacity 0.25s; }
.stage-frame video.buf { position: absolute; left: 0; top: 0; opacity: 0; }
.stage-frame video.on { opacity: 1; }
.frame .c { position: absolute; width: 22px; height: 22px; border: 2px solid #fff; pointer-events: none; }
.frame .c.tl { left: -9px; top: -9px; border-right: 0; border-bottom: 0; }
.frame .c.tr { right: -9px; top: -9px; border-left: 0; border-bottom: 0; }
.frame .c.bl { left: -9px; bottom: -9px; border-right: 0; border-top: 0; }
.frame .c.br { right: -9px; bottom: -9px; border-left: 0; border-top: 0; }
.frame .size { position: absolute; left: -9px; top: -34px; font: 600 11.5px/1 var(--mono); letter-spacing: 0.02em; color: #0a0a0f; background: #fff; padding: 6px 8px; border-radius: 4px; max-width: 100%; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }

/* ===== 首屏 ===== */
.hero { position: relative; padding: 96px 0 0; text-align: center; overflow: clip; }
.hero::before { content: ""; position: absolute; inset: 0 0 auto 0; height: 760px; z-index: -1; background-image: radial-gradient(rgba(255, 255, 255, 0.11) 1px, transparent 1.5px); background-size: 26px 26px; -webkit-mask-image: radial-gradient(60% 70% at 50% 30%, #000, transparent 75%); mask-image: radial-gradient(60% 70% at 50% 30%, #000, transparent 75%); }
.eyebrow { display: inline-block; font: 600 12.5px/1 var(--mono); letter-spacing: 0.1em; text-transform: uppercase; color: var(--muted); border: 1px solid var(--line); border-radius: 999px; padding: 8px 14px; }
.hero h1 { font-size: clamp(46px, 8vw, 104px); letter-spacing: -0.055em; line-height: 0.98; margin-top: 26px; }
.hero .lead { font-size: clamp(18px, 2vw, 22px); color: var(--muted); max-width: 34em; margin: 26px auto 0; text-wrap: balance; }
.hero-stage { margin-top: 24px; max-width: 1120px; padding-bottom: 8px; }

/* 工具名滚动条带：随页面滚动横向移动 */
.ribbon { overflow: hidden; border-block: 1px solid var(--line); background: var(--alt); margin-top: 90px; }
.ribbon-track { display: flex; gap: 14px; width: max-content; padding: 16px 0; }
.ribbon span { font: 600 14px/1 var(--mono); letter-spacing: 0.04em; text-transform: uppercase; color: var(--muted); border: 1px solid var(--line); border-radius: 6px; padding: 10px 14px; white-space: nowrap; }

/* ===== 首页章节 ===== */
.chapter { padding: 140px 0 0; }
.chapter-grid { display: grid; grid-template-columns: minmax(0, 5fr) minmax(0, 7fr); gap: 80px; align-items: center; }
.chapter.flip .chapter-grid { grid-template-columns: minmax(0, 7fr) minmax(0, 5fr); }
.chapter.flip .chapter-text { order: 2; }
.idx { font: 600 13px/1 var(--mono); letter-spacing: 0.1em; color: var(--hi); }
.chapter h2 { font-size: clamp(36px, 4.6vw, 64px); margin-top: 16px; }
.tag-line { font-size: 21px; color: var(--muted); margin-top: 14px; }
.points { margin-top: 28px; display: grid; gap: 10px; }
.points li { display: flex; gap: 10px; align-items: flex-start; font-size: 16.5px; }
.points svg { width: 20px; height: 20px; flex: none; margin-top: 3px; color: var(--ok); }
.more { display: inline-flex; align-items: center; gap: 8px; margin-top: 32px; font-weight: 650; }
.more svg { width: 18px; height: 18px; transition: transform 0.15s; }
.more:hover { text-decoration: none; }
.more:hover svg { transform: translate(3px, -3px); }
.tag { display: inline-block; vertical-align: middle; margin-left: 10px; padding: 3px 8px; font: 700 11px/1 var(--mono); letter-spacing: 0.06em; text-transform: uppercase; color: #0a0a0f; background: var(--hi); border-radius: 4px; }

/* ===== 产品页：功能列表 + 粘性取景框 ===== */
.page-head { padding: 88px 0 40px; text-align: center; }
.page-head h1 { font-size: clamp(40px, 6.4vw, 84px); letter-spacing: -0.05em; max-width: 13em; margin: 0 auto; }
.page-head p { color: var(--muted); font-size: 21px; max-width: 34em; margin: 20px auto 0; text-wrap: balance; }
.page-head .picon { width: 60px; height: 60px; border-radius: 12px; margin: 0 auto 24px; display: grid; place-items: center; background: var(--alt); border: 1px solid var(--line); color: var(--btn); }
.page-head .picon svg { width: 30px; height: 30px; }
.page-head.lg { padding: 140px 0; }
.explorer { padding: 40px 0 0; }
.explorer-grid { display: grid; grid-template-columns: minmax(0, 5fr) minmax(0, 7fr); gap: 80px; align-items: stretch; }
.group-title { font: 600 12.5px/1 var(--mono); letter-spacing: 0.1em; text-transform: uppercase; color: var(--hi); padding: 16px 0 14px; border-bottom: 1px solid var(--line); margin-top: 40px; }
.group:first-child .group-title { margin-top: 0; }
.step { padding: 30px 0 30px 28px; border-left: 2px solid var(--line); margin-left: 4px; position: relative; }
.step .num { font: 600 12.5px/1 var(--mono); color: var(--muted); letter-spacing: 0.08em; }
.step h4 { font-size: 26px; margin-top: 10px; letter-spacing: -0.03em; }
.step p { color: var(--muted); font-size: 17px; margin-top: 10px; max-width: 30em; }
.step-media .frame { margin-top: 44px; }
.stage-col { display: none; }
@media (min-width: 961px) {
  .js .stage-col { display: block; }
  .js .step-media { display: none; }
  .js .step { min-height: 48vh; display: flex; flex-direction: column; justify-content: center; opacity: 0.4; transition: opacity 0.3s, border-color 0.3s; }
  .js .step.is-active { opacity: 1; border-color: var(--btn); }
  .js .step.is-active .num { color: var(--hi); }
  .stage { position: sticky; top: calc(50vh - 240px); }
}
@media (max-width: 960px) {
  .step { padding-left: 20px; }
  .step-media .frame { margin-top: 40px; }
}
.also { padding: 120px 0 0; text-align: center; }
.also h2 { font-size: clamp(30px, 4vw, 52px); }
.chips { display: flex; flex-wrap: wrap; gap: 10px; justify-content: center; margin-top: 36px; }
.chips li { display: inline-flex; align-items: center; gap: 8px; font-size: 15px; font-weight: 600; padding: 10px 16px; border: 1px solid var(--line); border-radius: 8px; background: var(--card); }
.chips svg { width: 16px; height: 16px; color: var(--ok); }

/* ===== 价格 ===== */
.pricing-sec { padding: 140px 0 0; text-align: center; }
.pricing-sec h2 { font-size: clamp(34px, 4.6vw, 60px); }
.pricing-sec .sub { color: var(--muted); font-size: 19px; margin: 16px auto 0; max-width: 34em; }
.pricing-sec .plans, .pricing-sec .plan { text-align: left; }
.pricing-sec .plans { margin-top: 56px; }
.pricing-sec .container.one { max-width: 480px; }
.plans { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; align-items: stretch; }
.plan { position: relative; display: flex; flex-direction: column; background: var(--card); border: 1px solid var(--line); border-radius: 14px; padding: 32px 28px 28px; }
.plan.featured { border-color: var(--btn); box-shadow: 0 0 0 1px var(--btn), 0 40px 90px -50px rgba(47, 123, 255, 0.7); background: linear-gradient(180deg, #121a2e, var(--card) 60%); }
.plan .badge { position: absolute; top: 18px; right: 18px; background: var(--hi); color: #0a0a0f; font: 700 11px/1 var(--mono); letter-spacing: 0.05em; text-transform: uppercase; padding: 6px 9px; border-radius: 4px; }
.plan h3 { font-size: 22px; letter-spacing: -0.02em; }
.plan .for { color: var(--muted); font-size: 15px; margin-top: 8px; min-height: 46px; }
.price { margin-top: 20px; display: flex; align-items: baseline; gap: 8px; flex-wrap: wrap; }
.price b { font-size: 54px; letter-spacing: -0.05em; line-height: 1; }
.price span { color: var(--muted); font-size: 16px; }
.price-alt { color: var(--muted); font-size: 15px; margin-top: 10px; min-height: 24px; }
.plan .btn { margin-top: 22px; }
.plan .note { font-size: 13.5px; color: var(--muted); margin-top: 12px; text-align: center; }
.plan ul { margin-top: 24px; padding-top: 22px; border-top: 1px solid var(--line); display: grid; gap: 11px; font-size: 15.5px; }
.plan li { display: flex; gap: 10px; }
.plan li svg { width: 19px; height: 19px; flex: none; margin-top: 3px; color: var(--ok); }
.plan li.muted { opacity: 0.7; }
.cap { text-align: center; margin-top: 28px; font-size: 15px; color: var(--muted); }

/* ===== CTA / 页脚 ===== */
.band { padding: 150px 0 130px; text-align: center; }
.band img { width: 72px; height: 72px; border-radius: 16px; margin: 0 auto 28px; }
.band h2 { font-size: clamp(36px, 5.4vw, 72px); max-width: 12em; margin: 0 auto; }
.site-footer { border-top: 1px solid var(--line); background: var(--alt); padding: 64px 0 36px; font-size: 15px; }
.foot-grid { display: grid; grid-template-columns: 1.5fr repeat(4, 1fr); gap: 32px; }
.foot-grid h4 { margin: 0 0 14px; font: 600 12px/1 var(--mono); letter-spacing: 0.1em; text-transform: uppercase; color: var(--muted); }
.foot-grid li { margin: 10px 0; }
.foot-grid a { color: var(--text); opacity: 0.86; }
.foot-note { color: var(--muted); margin-top: 14px; max-width: 24em; }
.foot-bottom { margin-top: 44px; padding-top: 22px; border-top: 1px solid var(--line); color: var(--muted); font-size: 13.5px; display: flex; flex-wrap: wrap; gap: 8px 24px; justify-content: space-between; }

/* ===== 二级页通用 ===== */
.pill { display: inline-block; padding: 6px 10px; border-radius: 4px; background: var(--hi); color: #0a0a0f; font: 700 11.5px/1 var(--mono); letter-spacing: 0.06em; text-transform: uppercase; margin-bottom: 18px; }
.section { padding: 96px 0; }
.section.alt { background: var(--alt); }
.section.pt-sm { padding-top: 16px; }
.section.pt-md { padding-top: 32px; }
.section-head { text-align: center; max-width: 720px; margin: 0 auto 48px; }
.section-head h2 { font-size: clamp(30px, 4vw, 48px); }
.section-head p { font-size: 19px; color: var(--muted); margin-top: 14px; }
.faq-sec { padding: 120px 0 0; }
.faq-sec h2 { text-align: center; font-size: clamp(30px, 4vw, 48px); margin-bottom: 40px; }
.faq { max-width: 820px; margin: 0 auto; display: grid; gap: 10px; }
.faq details { background: var(--card); border: 1px solid var(--line); border-radius: 12px; padding: 0 24px; }
.faq summary { cursor: pointer; list-style: none; padding: 20px 36px 20px 0; font-size: 17.5px; font-weight: 650; position: relative; letter-spacing: -0.01em; }
.faq summary::-webkit-details-marker { display: none; }
.faq summary::after { content: "+"; position: absolute; right: 0; top: 50%; transform: translateY(-50%); width: 26px; height: 26px; border-radius: 6px; background: var(--soft); color: var(--link); display: grid; place-items: center; font-size: 19px; line-height: 1; }
.faq details[open] summary::after { content: "–"; }
.faq .ans { padding: 0 0 22px; color: var(--muted); font-size: 16px; }
.faq .ans p + p { margin-top: 12px; }
.buying { display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px; }
.mini { background: var(--card); border: 1px solid var(--line); border-radius: 12px; padding: 28px; }
.mini h3 { font-size: 19px; letter-spacing: -0.015em; }
.mini p { color: var(--muted); font-size: 16px; margin-top: 10px; }
.callout { background: var(--warn-bg); border: 1px solid var(--warn-line); border-radius: 12px; padding: 18px 22px; font-size: 16px; }
.callout.mt { margin-top: 22px; }
.callout.box { max-width: 660px; margin: 24px auto 0; text-align: left; }
.table-wrap { overflow-x: auto; border: 1px solid var(--line); border-radius: 12px; background: var(--card); }
table.compare { width: 100%; border-collapse: collapse; min-width: 640px; font-size: 15.5px; }
.compare th, .compare td { padding: 14px 20px; text-align: center; border-bottom: 1px solid var(--line); }
.compare th:first-child, .compare td:first-child { text-align: left; }
.compare thead th { font-size: 14.5px; background: var(--alt); }
.compare tbody tr:last-child td { border-bottom: 0; }
.compare .yes { color: var(--ok); font-weight: 800; font-size: 18px; }
.compare .no { color: var(--muted); }
.compare .grp td { background: var(--alt); font: 600 12px/1 var(--mono); letter-spacing: 0.08em; text-transform: uppercase; color: var(--hi); text-align: left; }
.steps { counter-reset: s; display: grid; gap: 12px; max-width: 760px; margin: 0 auto; }
.steps li { counter-increment: s; display: flex; gap: 16px; background: var(--card); border: 1px solid var(--line); border-radius: 12px; padding: 20px 22px; }
.steps li::before { content: counter(s); flex: none; width: 32px; height: 32px; border-radius: 6px; background: var(--btn); color: var(--on-btn); font: 700 15px/1 var(--mono); display: grid; place-items: center; }
.steps b { display: block; font-size: 17px; }
.steps span { color: var(--muted); font-size: 15.5px; }
.perm { width: 100%; border-collapse: collapse; font-size: 15.5px; }
.perm th, .perm td { text-align: left; padding: 14px 18px; border-bottom: 1px solid var(--line); vertical-align: top; }
.perm th { background: var(--alt); font-size: 14px; }
.stack { display: grid; gap: 14px; }
.narrow .section-head { max-width: none; }

/* ===== 法律文本 ===== */
.legal { padding: 40px 0 112px; }
.legal h1 { font-size: clamp(36px, 5vw, 56px); letter-spacing: -0.045em; }
.legal .meta { color: var(--muted); margin-top: 12px; font: 500 13.5px/1.4 var(--mono); }
.legal .intro { margin-top: 26px; font-size: 18px; }
.legal .toc { margin: 30px 0 8px; padding: 18px 22px; background: var(--alt); border: 1px solid var(--line); border-radius: 10px; font-size: 15px; columns: 2; column-gap: 32px; }
.legal .toc a { display: block; padding: 4px 0; break-inside: avoid; }
.legal h2 { font-size: 24px; margin-top: 48px; letter-spacing: -0.025em; scroll-margin-top: 90px; }
.legal p { margin-top: 14px; }
.legal ul { margin-top: 12px; padding-left: 22px; list-style: disc; }
.legal li { margin-top: 8px; }
.legal li::marker { color: var(--muted); }
.legal table { width: 100%; border-collapse: collapse; margin-top: 16px; font-size: 15px; }
.legal th, .legal td { text-align: left; vertical-align: top; padding: 12px 14px; border-bottom: 1px solid var(--line); }
.legal th { background: var(--alt); font-weight: 600; }

/* ===== 滚动驱动动画（CSS animation-timeline；不支持就是静态版式） ===== */
@supports (animation-timeline: view()) {
  @keyframes grow { from { transform: scaleX(0); } to { transform: scaleX(1); } }
  .progress { animation: grow linear both; animation-timeline: scroll(root); }

  @keyframes bar-in { from { border-bottom-color: transparent; background-color: transparent; } to { border-bottom-color: var(--line); background-color: color-mix(in srgb, var(--bg) 82%, transparent); } }
  .site-header { background: transparent; animation: bar-in linear both; animation-timeline: scroll(root); animation-range: 0 140px; }

  /* 首屏取景框：随滚动从「小选区」放大到满幅 */
  @keyframes stage-in { from { transform: scale(0.9) translateY(18px); opacity: 0.7; } to { transform: none; opacity: 1; } }
  .hero-stage .frame { animation: stage-in linear both; animation-timeline: scroll(root); animation-range: 0 520px; transform-origin: 50% 0; }

  /* 工具名条带随滚动横移 */
  @keyframes slide { from { transform: translateX(0); } to { transform: translateX(-50%); } }
  .ribbon-track { animation: slide linear both; animation-timeline: scroll(root); }

  @keyframes rise { from { opacity: 0; transform: translateY(46px); } to { opacity: 1; transform: none; } }
  .reveal, .step-media, .also h2, .chips li { animation: rise linear both; animation-timeline: view(); animation-range: entry 5% entry 60%; }

  /* 章节里的取景框：从略小、略偏下「就位」 */
  @keyframes settle { from { opacity: 0.2; transform: translateY(70px) scale(0.92); } to { opacity: 1; transform: none; } }
  .reveal-frame { animation: settle linear both; animation-timeline: view(); animation-range: entry 0% cover 38%; }

  /* 荧光笔随滚动「划」出来 */
  @keyframes sweep { from { background-size: 0% 100%; } to { background-size: 100% 100%; } }
  .band h2, .pricing-sec h2 { background-image: linear-gradient(transparent 62%, rgba(255, 225, 77, 0.0) 62%); }
}
@keyframes sweep-time { from { background-size: 0% 100%; } to { background-size: 100% 100%; } }
.hero .mark { animation: sweep-time 0.9s 0.35s cubic-bezier(0.3, 0.7, 0.2, 1) both; }

/* ===== 响应式 ===== */
@media (max-width: 1040px) {
  .nav { display: none; }
  .burger { display: grid; }
  .nav-toggle:checked ~ .mobile-menu { display: block; }
  .header-end .btn { display: none; }
}
@media (max-width: 960px) {
  .chapter { padding-top: 96px; }
  .chapter-grid, .chapter.flip .chapter-grid, .explorer-grid { grid-template-columns: 1fr; gap: 44px; }
  .chapter.flip .chapter-text { order: 0; }
  .plans, .buying { grid-template-columns: 1fr; }
  .plan .for { min-height: 0; }
  .foot-grid { grid-template-columns: 1fr 1fr; }
  .legal .toc { columns: 1; }
  .pricing-sec { padding-top: 96px; }
  .band { padding: 96px 0 80px; }
  .section { padding: 72px 0; }
  .ribbon { margin-top: 64px; }
}
@media (max-width: 520px) {
  body { font-size: 16.5px; }
  .container { padding: 0 20px; }
  .hero { padding-top: 60px; }
  .foot-grid { grid-template-columns: 1fr; }
  .btn-lg, .cta-row .btn { width: 100%; }
  .plan { padding: 28px 22px; }
  .price b { font-size: 46px; }
  .legal table { font-size: 14px; }
  .faq details { padding: 0 18px; }
  .frame .c { width: 16px; height: 16px; }
  .frame .size { font-size: 10.5px; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .btn, .menu, .more svg, .step { transition: none; }
  .hero .mark { animation: none; }
}