/* ============================================================
   7FA4 Chat — landing page styles
   Dark-first, glassmorphism, gradient accents, light theme.
   ============================================================ */

/* ---------- tokens（仅浅色主题）---------- */
:root {
  --bg: #f6f8fd;
  --bg-2: #ffffff;
  --surface: rgba(15, 22, 45, .035);
  --surface-2: rgba(15, 22, 45, .06);
  --surface-border: rgba(15, 22, 45, .1);
  --text: #0f1a36;
  --text-soft: #41506f;
  --text-mute: #7a869f;
  --brand: #6d8bff;
  --brand-2: #b06dff;
  --brand-3: #46e0c8;
  --grad: linear-gradient(120deg, #6d8bff 0%, #b06dff 55%, #ff6db0 100%);
  --grad-soft: linear-gradient(120deg, rgba(109,139,255,.18), rgba(176,109,255,.18));
  --good: #2ecc8f;
  --warn: #ffb454;
  --bad: #ff6b6b;
  --info: #56b3ff;
  --shadow: 0 24px 60px -24px rgba(36, 52, 110, .35);
  --radius: 18px;
  --radius-lg: 26px;
  --maxw: 1200px;
  --ease: cubic-bezier(.2, .8, .2, 1);
  --font: 'Inter', system-ui, -apple-system, 'Segoe UI', 'PingFang SC', 'Microsoft YaHei', Roboto, sans-serif;
  --mono: 'JetBrains Mono', ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
}

/* ---------- reset ---------- */
*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}
img { max-width: 100%; display: block; }
a { color: inherit; text-decoration: none; }
button { font-family: inherit; cursor: pointer; }
code, pre { font-family: var(--mono); }
::selection { background: rgba(109, 139, 255, .35); color: #fff; }

.container { width: min(100% - 40px, var(--maxw)); margin-inline: auto; }
.container.narrow { max-width: 820px; }
.muted { color: var(--text-mute); }
.grad {
  background: var(--grad);
  -webkit-background-clip: text; background-clip: text;
  color: transparent;
}
.link { color: var(--brand); font-weight: 600; }
.link:hover { text-decoration: underline; }

/* ---------- ambient background ---------- */
.bg { position: fixed; inset: 0; z-index: -1; overflow: hidden; pointer-events: none; }
.bg-grid {
  position: absolute; inset: -2px;
  background-image:
    linear-gradient(var(--surface-border) 1px, transparent 1px),
    linear-gradient(90deg, var(--surface-border) 1px, transparent 1px);
  background-size: 64px 64px;
  mask-image: radial-gradient(ellipse 90% 70% at 50% 0%, #000 10%, transparent 80%);
  -webkit-mask-image: radial-gradient(ellipse 90% 70% at 50% 0%, #000 10%, transparent 80%);
  opacity: .55;
}
.orb { position: absolute; border-radius: 50%; filter: blur(90px); opacity: .5; }
.orb-a { width: 520px; height: 520px; top: -160px; left: -120px; background: #6d8bff; }
.orb-b { width: 460px; height: 460px; top: 6%; right: -160px; background: #b06dff; opacity: .4; }
.orb-c { width: 380px; height: 380px; top: 40%; left: 40%; background: #46e0c8; opacity: .22; }

/* ---------- buttons ---------- */
.btn {
  --pad-y: .7em; --pad-x: 1.25em;
  display: inline-flex; align-items: center; gap: .55em;
  padding: var(--pad-y) var(--pad-x);
  border-radius: 999px;
  font-weight: 600; font-size: .95rem;
  border: 1px solid transparent;
  transition: transform .2s var(--ease), box-shadow .2s var(--ease), background .2s var(--ease), border-color .2s var(--ease);
  white-space: nowrap; user-select: none;
}
.btn:hover { transform: translateY(-2px); }
.btn:active { transform: translateY(0); }
.btn-sm { --pad-y: .5em; --pad-x: 1em; font-size: .85rem; }
.btn-lg { --pad-y: .95em; --pad-x: 1.6em; font-size: 1.05rem; }
.btn-primary { background: var(--grad); color: #fff; box-shadow: 0 12px 30px -10px rgba(109,139,255,.6); }
.btn-primary:hover { box-shadow: 0 18px 40px -10px rgba(176,109,255,.7); }
.btn-ghost { background: var(--surface); border-color: var(--surface-border); color: var(--text); backdrop-filter: blur(8px); }
.btn-ghost:hover { background: var(--surface-2); }
.icon-btn {
  width: 40px; height: 40px; border-radius: 50%;
  display: inline-grid; place-items: center;
  background: var(--surface); border: 1px solid var(--surface-border);
  color: var(--text); transition: background .2s var(--ease), transform .2s var(--ease);
}
.icon-btn:hover { background: var(--surface-2); transform: translateY(-2px); }

/* ---------- glass ---------- */
.glass {
  background: var(--surface);
  border: 1px solid var(--surface-border);
  border-radius: var(--radius-lg);
  backdrop-filter: blur(20px) saturate(140%);
  -webkit-backdrop-filter: blur(20px) saturate(140%);
  box-shadow: var(--shadow);
}

/* ---------- nav ---------- */
.nav {
  position: sticky; top: 0; z-index: 50;
  transition: background .3s var(--ease), border-color .3s var(--ease), backdrop-filter .3s var(--ease);
  border-bottom: 1px solid transparent;
}
.nav.scrolled {
  background: color-mix(in srgb, var(--bg) 75%, transparent);
  backdrop-filter: blur(16px) saturate(140%);
  -webkit-backdrop-filter: blur(16px) saturate(140%);
  border-bottom-color: var(--surface-border);
}
.nav-inner { display: flex; align-items: center; gap: 20px; height: 68px; }
.brand { display: inline-flex; align-items: center; gap: 10px; font-weight: 800; font-size: 1.15rem; letter-spacing: -.01em; }
.brand-logo { width: 30px; height: 30px; border-radius: 9px; }
.brand-accent { background: var(--grad); -webkit-background-clip: text; background-clip: text; color: transparent; }
.nav-links { display: flex; gap: 6px; margin-left: auto; }
.nav-links a {
  padding: .55rem .9rem; border-radius: 10px;
  color: var(--text-soft); font-weight: 500; font-size: .92rem;
  transition: color .2s var(--ease), background .2s var(--ease);
}
.nav-links a:hover { color: var(--text); background: var(--surface); }
.nav-actions { display: flex; align-items: center; gap: 10px; }
.nav-burger {
  display: none; width: 40px; height: 40px; border-radius: 10px;
  background: var(--surface); border: 1px solid var(--surface-border);
  flex-direction: column; gap: 4px; align-items: center; justify-content: center;
}
.nav-burger span { width: 18px; height: 2px; background: var(--text); border-radius: 2px; transition: transform .25s var(--ease), opacity .2s var(--ease); }
.nav-burger.open span:nth-child(1) { transform: translateY(6px) rotate(45deg); }
.nav-burger.open span:nth-child(2) { opacity: 0; }
.nav-burger.open span:nth-child(3) { transform: translateY(-6px) rotate(-45deg); }

/* ---------- hero ---------- */
.hero { padding: 90px 0 40px; position: relative; }
.hero-inner { display: grid; grid-template-columns: 1.05fr 1fr; gap: 56px; align-items: center; }
.pill {
  display: inline-flex; align-items: center; gap: .55em;
  padding: .4em .95em; border-radius: 999px;
  background: var(--surface); border: 1px solid var(--surface-border);
  font-size: .82rem; color: var(--text-soft); font-weight: 500;
}
.pill .dot { width: 7px; height: 7px; border-radius: 50%; background: var(--good); box-shadow: 0 0 10px var(--good); }
.hero-title {
  font-size: clamp(2.3rem, 5vw, 3.7rem); line-height: 1.05; font-weight: 900;
  letter-spacing: -.025em; margin: 22px 0 18px;
}
.hero-sub { font-size: 1.12rem; color: var(--text-soft); max-width: 540px; }
.hero-sub strong { color: var(--text); font-weight: 700; }
.hero-cta { display: flex; flex-wrap: wrap; gap: 14px; margin: 30px 0 26px; }
.hero-stats { display: flex; flex-wrap: wrap; gap: 28px; list-style: none; padding: 0; margin: 0; }
.hero-stats li { display: flex; flex-direction: column; }
.hero-stats strong { font-size: 1.7rem; font-weight: 800; letter-spacing: -.02em; }
.hero-stats span { font-size: .82rem; color: var(--text-mute); }

/* hero art — 静态截图展示，无交互 */
.hero-art { position: relative; }
.hero-shot {
  padding: 0;
  overflow: hidden;
  border-radius: 18px;
  background: var(--surface-2);
  border: 1px solid var(--surface-border);
  box-shadow: 0 30px 60px -25px rgba(10, 18, 45, .55), 0 8px 20px rgba(10, 18, 45, .25);
}
.hero-shot img {
  display: block;
  width: 100%;
  height: auto;
  user-select: none;
}
.float-card {
  position: absolute; display: flex; align-items: center; gap: 10px;
  padding: 12px 16px; border-radius: 16px; font-size: .85rem;
}
.float-card i { font-size: 1.1rem; color: var(--brand); }
.float-card strong { display: block; font-size: .9rem; }
.float-card small { color: var(--text-mute); }
.float-card[data-float='a'] { top: 12%; left: -8%; animation: floaty 5s ease-in-out infinite; }
.float-card[data-float='b'] { bottom: 14%; right: -6%; animation: floaty 6s ease-in-out infinite reverse; }
@keyframes floaty { 0%,100% { transform: translateY(0); } 50% { transform: translateY(-12px); } }

/* marquee */
.hero-marquee { margin-top: 64px; overflow: hidden; }
.marquee {
  display: flex; align-items: center; gap: 28px;
  white-space: nowrap; width: max-content;
  animation: marquee 28s linear infinite;
  color: var(--text-mute); font-weight: 600; font-size: 1rem;
}
.marquee span:nth-child(3n) { color: var(--brand); }
.marquee i { width: 6px; height: 6px; border-radius: 50%; background: var(--surface-border); }
@keyframes marquee { to { transform: translateX(-50%); } }

/* ---------- sections ---------- */
.section { padding: 96px 0; position: relative; }
.section-head { text-align: center; max-width: 680px; margin: 0 auto 56px; }
.kicker {
  display: inline-block; padding: .35em .9em; border-radius: 999px;
  background: var(--surface); border: 1px solid var(--surface-border);
  color: var(--brand); font-size: .78rem; font-weight: 700; letter-spacing: .12em; text-transform: uppercase;
  margin-bottom: 16px;
}
.section-head h2 { font-size: clamp(1.8rem, 3.5vw, 2.7rem); font-weight: 800; letter-spacing: -.02em; margin: 0 0 12px; }
.section-head p { color: var(--text-soft); margin: 0; font-size: 1.05rem; }

/* features */
.feature-grid {
  display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px;
}
.feature-card {
  padding: 26px 24px; border-radius: var(--radius-lg);
  background: var(--surface); border: 1px solid var(--surface-border);
  transition: transform .25s var(--ease), border-color .25s var(--ease), background .25s var(--ease);
  position: relative; overflow: hidden;
}
.feature-card::before {
  content: ''; position: absolute; inset: 0;
  background: radial-gradient(400px circle at var(--mx,50%) var(--my,0%), var(--grad-soft), transparent 60%);
  opacity: 0; transition: opacity .3s var(--ease);
}
.feature-card:hover { transform: translateY(-4px); border-color: color-mix(in srgb, var(--brand) 35%, var(--surface-border)); }
.feature-card:hover::before { opacity: 1; }
.feature-ico {
  width: 48px; height: 48px; border-radius: 14px; display: grid; place-items: center;
  background: var(--grad-soft); border: 1px solid var(--surface-border);
  font-size: 1.25rem; color: var(--brand); margin-bottom: 16px;
  position: relative;
}
.feature-card h3 { margin: 0 0 8px; font-size: 1.1rem; font-weight: 700; position: relative; }
.feature-card p { margin: 0; color: var(--text-soft); font-size: .92rem; position: relative; }

/* preview */
.section-preview { background:
    radial-gradient(800px 400px at 50% 0%, rgba(176,109,255,.07), transparent 70%);
}
.preview-tabs { display: flex; gap: 8px; justify-content: center; margin-bottom: 24px; flex-wrap: wrap; }
.preview-tabs .tab {
  padding: .55em 1.1em; border-radius: 999px; border: 1px solid var(--surface-border);
  background: var(--surface); color: var(--text-soft); font-weight: 600; font-size: .9rem;
  display: inline-flex; align-items: center; gap: 8px;
  transition: color .2s var(--ease), background .2s var(--ease), border-color .2s var(--ease);
}
.preview-tabs .tab.active { color: #fff; background: var(--grad); border-color: transparent; }
.preview-stage { padding: 18px; }
.preview-window {
  display: grid; grid-template-columns: 260px 1fr; gap: 14px;
  height: 540px; border-radius: var(--radius); overflow: hidden;
}
.pw-sidebar { background: var(--surface); border-right: 1px solid var(--surface-border); padding: 16px 12px; overflow-y: auto; }
.pw-me { display: flex; align-items: center; gap: 10px; font-weight: 700; padding: 6px 8px 14px; }
.pw-search { display: flex; align-items: center; gap: 8px; color: var(--text-mute); font-size: .85rem; padding: .5em .8em; background: var(--surface-2); border-radius: 10px; margin-bottom: 12px; }
.conv { display: flex; align-items: center; gap: 10px; padding: 9px 8px; border-radius: 12px; cursor: pointer; transition: background .2s var(--ease); position: relative; }
.conv:hover { background: var(--surface-2); }
.conv.active { background: var(--grad-soft); }
.conv .avatar { width: 36px; height: 36px; border-radius: 11px; }
.conv div { flex: 1; min-width: 0; }
.conv strong { display: block; font-size: .9rem; font-weight: 600; }
.conv small { display: block; color: var(--text-mute); font-size: .78rem; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.conv .badge { background: var(--bad); color: #fff; font-size: .72rem; font-weight: 700; min-width: 20px; height: 20px; border-radius: 999px; display: grid; place-items: center; padding: 0 6px; }
.conv .badge.dot { background: var(--brand); min-width: 10px; height: 10px; padding: 0; }
.pw-main { display: flex; flex-direction: column; min-width: 0; }
.pw-topbar { display: flex; align-items: center; justify-content: space-between; padding: 14px 18px; border-bottom: 1px solid var(--surface-border); color: var(--text-soft); }
.pw-topbar strong { color: var(--text); font-size: 1.05rem; }
.pw-topbar i { margin-left: 14px; }
.pw-msgs { flex: 1; padding: 18px; display: flex; flex-direction: column; gap: 12px; overflow-y: auto; }
.date-line { text-align: center; color: var(--text-mute); font-size: .75rem; padding: 6px 0; position: relative; }
.date-line::before, .date-line::after { content: ''; position: absolute; top: 50%; width: 30%; height: 1px; background: var(--surface-border); }
.date-line::before { left: 10%; } .date-line::after { right: 10%; }
.pw-input { display: flex; align-items: center; gap: 14px; padding: 12px 18px; border-top: 1px solid var(--surface-border); color: var(--text-mute); }
.pw-input .fake-input { flex: 1; }

/* download */
.download-shell { padding: 36px; }
.download-head { display: flex; align-items: flex-start; justify-content: space-between; flex-wrap: wrap; gap: 20px; margin-bottom: 28px; }
.ver-badge { display: inline-block; padding: .3em .85em; border-radius: 999px; background: var(--grad-soft); color: var(--brand); font-size: .75rem; font-weight: 700; letter-spacing: .08em; text-transform: uppercase; margin-bottom: 8px; }
.download-head h3 { margin: 0; font-size: 1.7rem; font-weight: 800; letter-spacing: -.02em; }
.os-switch { display: inline-flex; gap: 6px; padding: 6px; background: var(--surface); border: 1px solid var(--surface-border); border-radius: 14px; }
.os-btn {
  display: inline-flex; align-items: center; gap: 8px;
  padding: .55em 1.1em; border-radius: 10px; border: none; background: transparent;
  color: var(--text-soft); font-weight: 600; font-size: .9rem;
  transition: background .2s var(--ease), color .2s var(--ease);
}
.os-btn:hover { color: var(--text); }
.os-btn.active { background: var(--grad); color: #fff; }
.download-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 14px; }
.dl-card {
  display: flex; align-items: center; gap: 16px; padding: 20px;
  border-radius: var(--radius); background: var(--surface); border: 1px solid var(--surface-border);
  transition: transform .2s var(--ease), border-color .2s var(--ease);
}
.dl-card:hover { transform: translateY(-3px); border-color: color-mix(in srgb, var(--brand) 40%, var(--surface-border)); }
.dl-ico { width: 48px; height: 48px; border-radius: 13px; display: grid; place-items: center; background: var(--grad-soft); color: var(--brand); font-size: 1.3rem; flex-shrink: 0; }
.dl-card .meta { flex: 1; min-width: 0; }
.dl-card .meta strong { display: block; font-size: .98rem; }
.dl-card .meta small { color: var(--text-mute); font-size: .82rem; }
.dl-go {
  width: 42px; height: 42px; border-radius: 12px; flex-shrink: 0;
  background: var(--surface-2); border: 1px solid var(--surface-border);
  color: var(--text); display: grid; place-items: center;
  transition: background .2s var(--ease), color .2s var(--ease), transform .2s var(--ease);
}
.dl-card:hover .dl-go { background: var(--grad); color: #fff; border-color: transparent; }
.download-note { margin: 26px 0 0; font-size: .85rem; color: var(--text-mute); display: flex; align-items: center; gap: 8px; flex-wrap: wrap; }

/* all versions */
.all-versions { margin-top: 40px; }
.all-versions h3 { display: flex; align-items: center; gap: 10px; font-size: 1.15rem; margin: 0 0 16px; }
.versions-list { padding: 8px; max-height: 420px; overflow-y: auto; }
.ver-row { display: flex; align-items: center; gap: 14px; padding: 12px 14px; border-radius: 12px; transition: background .2s var(--ease); }
.ver-row:hover { background: var(--surface); }
.ver-row .ver-num { font-weight: 700; font-size: .95rem; min-width: 92px; }
.ver-row .ver-latest { font-size: .68rem; padding: 2px 8px; border-radius: 999px; background: var(--good); color: #04231a; font-weight: 700; }
.ver-row .ver-meta { color: var(--text-mute); font-size: .82rem; }
.ver-row .ver-files { margin-left: auto; display: flex; flex-direction: column; gap: 6px; }
.ver-platform { display: flex; align-items: center; gap: 8px; flex-wrap: wrap; min-width: 0; }
.ver-os-label { flex: 0 0 auto; min-width: 62px; font-size: .72rem; font-weight: 700; color: var(--text-soft); }
.ver-os-chips { display: flex; flex-wrap: wrap; gap: 6px; min-width: 0; }
.ver-file-chip { font-size: .72rem; padding: 3px 9px; border-radius: 999px; background: var(--surface-2); border: 1px solid var(--surface-border); color: var(--text-soft); text-decoration: none; transition: background .2s var(--ease), color .2s var(--ease); }
.ver-file-chip:hover { background: var(--grad); color: #fff; border-color: transparent; }

/* changelog */
.changelog { display: flex; flex-direction: column; gap: 18px; }
.cl-entry { padding: 24px 28px; }
.cl-version { display: flex; align-items: center; gap: 12px; margin-bottom: 14px; }
.cl-version h3 { margin: 0; font-size: 1.3rem; font-weight: 800; }
.cl-version .cl-date { color: var(--text-mute); font-size: .85rem; }
.cl-list { list-style: none; padding: 0; margin: 0; display: grid; gap: 8px; }
.cl-item { display: flex; gap: 10px; align-items: flex-start; font-size: .93rem; color: var(--text-soft); }
.cl-tag {
  flex-shrink: 0; font-size: .68rem; font-weight: 700; padding: 2px 8px; border-radius: 6px;
  letter-spacing: .04em; min-width: 48px; text-align: center;
}
.cl-tag.new    { background: rgba(46, 204, 143, .15); color: var(--good); }
.cl-tag.improve{ background: rgba(86, 179, 255, .15); color: var(--info); }
.cl-tag.fix    { background: rgba(255, 107, 107, .15); color: var(--bad); }
.cl-tag.notice { background: rgba(255, 180, 84, .15); color: var(--warn); }
.cl-item .cl-body code { font-size: .85em; background: var(--surface-2); padding: 1px 6px; border-radius: 5px; }
.cl-hidden { display: none; }
.cl-toggle { align-self: center; margin: 6px auto 0; }

/* faq */
.faq-list { display: grid; gap: 12px; }
.faq-item {
  padding: 0; border-radius: var(--radius); background: var(--surface); border: 1px solid var(--surface-border); overflow: hidden;
}
.faq-item summary {
  list-style: none; cursor: pointer; padding: 18px 22px;
  display: flex; align-items: center; justify-content: space-between; gap: 16px;
  font-weight: 600; font-size: 1rem;
}
.faq-item summary::-webkit-details-marker { display: none; }
.faq-item summary i { color: var(--text-mute); transition: transform .25s var(--ease); }
.faq-item[open] summary i { transform: rotate(180deg); }
.faq-a { padding: 0 22px 18px; color: var(--text-soft); font-size: .95rem; }
.faq-a code { background: var(--surface-2); padding: 1px 6px; border-radius: 5px; }

/* cta */
.cta-section { padding: 40px 0 100px; }
.cta {
  padding: 48px; display: flex; align-items: center; justify-content: space-between; gap: 30px; flex-wrap: wrap;
  background:
    linear-gradient(120deg, rgba(109,139,255,.16), rgba(176,109,255,.12)),
    var(--surface);
  position: relative; overflow: hidden;
}
.cta::after {
  content: ''; position: absolute; right: -100px; top: -100px; width: 360px; height: 360px;
  background: var(--grad); filter: blur(120px); opacity: .35; border-radius: 50%;
  pointer-events: none;
}
.cta h2 { margin: 0 0 8px; font-size: clamp(1.6rem, 3vw, 2.2rem); font-weight: 800; position: relative; }
.cta p { margin: 0; color: var(--text-soft); position: relative; }
.cta .btn { position: relative; z-index: 1; }

/* footer */
.footer { border-top: 1px solid var(--surface-border); padding: 40px 0; }
.footer-inner { display: flex; align-items: center; flex-wrap: wrap; gap: 24px; justify-content: space-between; }
.footer-brand { display: flex; align-items: center; gap: 12px; }
.footer-brand strong { font-size: 1.05rem; }
.footer-brand p { margin: 2px 0 0; font-size: .85rem; }
.footer-links { display: flex; gap: 18px; }
.footer-links a { color: var(--text-soft); font-size: .9rem; }
.footer-links a:hover { color: var(--text); }
.footer-meta { display: flex; align-items: center; gap: 14px; font-size: .85rem; }

/* to-top */
.to-top {
  position: fixed; right: 24px; bottom: 24px; z-index: 60;
  width: 46px; height: 46px; border-radius: 14px; border: 1px solid var(--surface-border);
  background: var(--surface-2); backdrop-filter: blur(12px); color: var(--text);
  display: grid; place-items: center; opacity: 0; transform: translateY(16px) scale(.9); pointer-events: none;
  transition: opacity .25s var(--ease), transform .25s var(--ease), background .2s var(--ease);
}
.to-top.show { opacity: 1; transform: none; pointer-events: auto; }
.to-top:hover { background: var(--grad); color: #fff; border-color: transparent; }

/* ---------- reveal animation ---------- */
.reveal { opacity: 0; transform: translateY(24px); transition: opacity .7s var(--ease), transform .7s var(--ease); }
.reveal.in { opacity: 1; transform: none; }

/* ---------- loading dots ---------- */
.loading { display: inline-flex; gap: 6px; padding: 18px; }
.loading span {
  width: 8px; height: 8px; border-radius: 50%; background: var(--brand);
  animation: bob 1s ease-in-out infinite;
}
.loading span:nth-child(2) { animation-delay: .15s; background: var(--brand-2); }
.loading span:nth-child(3) { animation-delay: .3s; background: var(--brand-3); }
@keyframes bob { 0%, 100% { transform: translateY(0); opacity: .5; } 50% { transform: translateY(-6px); opacity: 1; } }



/* ===== 预览截图：错落层叠 ===== */
.preview-stage { padding: 34px; }
.shot-stack {
  position: relative;
  max-width: 860px;
  margin: 0 auto;
  height: 560px;
}
.shot {
  position: absolute;
  width: 60%;
  border-radius: 14px;
  overflow: hidden;
  background: #0d1117;
  border: 1px solid rgba(255, 255, 255, .16);
  box-shadow: 0 18px 40px -20px rgba(10, 18, 45, .5);
  transition: transform .3s var(--ease), box-shadow .3s var(--ease);
}
.shot img {
  display: block;
  width: 100%;
  height: auto;
  user-select: none;
}
.shot:nth-child(1) { left: 0;   top: 150px; z-index: 4; transform: rotate(-2.5deg); }
.shot:nth-child(2) { right: 0;  top: 0;     z-index: 3; transform: rotate(2deg); }
.shot:nth-child(3) { left: 4%;  top: 0;     z-index: 2; transform: rotate(-1.5deg); }
.shot:nth-child(4) { right: 4%; top: 152px; z-index: 1; transform: rotate(2.5deg); }
.shot:hover {
  z-index: 10;
  transform: rotate(0deg) translateY(-6px) scale(1.02);
  box-shadow: 0 26px 54px -18px rgba(10, 18, 45, .65);
}
/* ---------- responsive ---------- */
@media (max-width: 960px) {
  .hero-inner { grid-template-columns: 1fr; gap: 40px; }
  .hero-art { max-width: 460px; margin: 0 auto; }
  .feature-grid { grid-template-columns: repeat(2, 1fr); }
  .float-card[data-float='a'] { left: 0; }
  .float-card[data-float='b'] { right: 0; }
}
@media (max-width: 720px) {
  .nav-links { display: none; }
  .nav-burger { display: flex; }
  .nav-links.open {
    display: flex; flex-direction: column; position: absolute; top: 68px; left: 0; right: 0;
    background: var(--bg-2); border-bottom: 1px solid var(--surface-border);
    padding: 16px; gap: 4px;
  }
  .nav-actions .btn-primary { display: none; }
  .feature-grid { grid-template-columns: 1fr; }
  .download-grid { grid-template-columns: 1fr; }
  .download-shell { padding: 22px; }

  .hero { padding: 50px 0 30px; }
  .section { padding: 64px 0; }
  .cta { padding: 32px; }

  .shot-stack { height: 470px; }
  .shot { width: 78%; }
  .shot:nth-child(1) { left: 0;  top: 112px; }
  .shot:nth-child(2) { right: 0; top: 0; }
  .shot:nth-child(3) { left: 2%; top: 8px; }
  .shot:nth-child(4) { right: 2%; top: 116px; }
  .download-head { flex-direction: column; align-items: stretch; }
  .ver-row { flex-wrap: wrap; }
  .ver-row .ver-files { margin-left: 0; width: 100%; }
}
@media (max-width: 480px) {
  .hero-stats { gap: 18px; }
  .hero-stats strong { font-size: 1.4rem; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation-duration: .001ms !important; transition-duration: .001ms !important; }
  .reveal { opacity: 1; transform: none; }
}