/* ============================================================
   满帧 FullFrame 官网 · 极简正规软件官网版
   白底 · 大留白 · 规整排版 · 橙色仅作强调
   ============================================================ */

:root {
  --bg:        #FFFFFF;
  --bg-soft:   #F8F8F6;
  --ink:       #191A1E;
  --text:      #33343A;
  --dim:       #6B6C74;
  --mute:      #9A9BA3;
  --line:      #E9E8E4;
  --line-soft: #F1F0EC;
  --accent:    #CA5629;
  --accent-hover: #B34A21;
  --accent-soft: #FBF0EA;
  --green:     #1E8E5A;
  --green-soft: #EAF5EF;
  --shadow:    0 1px 2px rgba(20, 20, 30, .04), 0 16px 40px -20px rgba(20, 20, 30, .14);
  --sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
          "Microsoft YaHei", "Helvetica Neue", sans-serif;
  --mono: "SF Mono", "Cascadia Code", Consolas, "Courier New", monospace;
  --maxw: 1080px;
  --r: 14px;
}

* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; scroll-padding-top: 80px; }
body {
  font-family: var(--sans);
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

::selection { background: rgba(202, 86, 41, .16); }
::-webkit-scrollbar { width: 10px; height: 10px; }
::-webkit-scrollbar-track { background: var(--bg-soft); }
::-webkit-scrollbar-thumb { background: #D8D6D0; border-radius: 8px; border: 2px solid var(--bg-soft); }
::-webkit-scrollbar-thumb:hover { background: var(--accent); }

.wrap { max-width: var(--maxw); margin: 0 auto; padding: 0 28px; }
a { color: inherit; text-decoration: none; }
img, svg { display: block; }
h1, h2, h3, h4 { color: var(--ink); font-weight: 700; letter-spacing: -.3px; line-height: 1.35; }

/* ============================================================
   导航
   ============================================================ */
.nav {
  position: fixed; top: 0; left: 0; right: 0; z-index: 100;
  background: rgba(255, 255, 255, .88);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid transparent;
  transition: border-color .25s, background .25s;
}
.nav.scrolled { border-bottom-color: var(--line); background: rgba(255, 255, 255, .96); }
.nav .wrap { display: flex; align-items: center; gap: 32px; height: 64px; }
.brand { display: flex; align-items: center; gap: 9px; font-weight: 700; color: var(--ink); font-size: 15.5px; }
.brand svg { flex: none; }
.nav-links { display: flex; gap: 28px; margin-left: auto; }
.nav-links a { font-size: 14px; color: var(--dim); transition: color .2s; }
.nav-links a:hover { color: var(--ink); }
.nav .btn-sm { margin-left: 4px; }

/* ============================================================
   按钮
   ============================================================ */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 8px;
  height: 46px; padding: 0 24px; border-radius: 10px;
  font-size: 15px; font-weight: 600; cursor: pointer;
  border: 1px solid transparent; white-space: nowrap;
  transition: background .2s, border-color .2s, box-shadow .2s;
}
.btn-primary {
  background: var(--accent); color: #fff;
  box-shadow: 0 1px 2px rgba(202, 86, 41, .3), 0 8px 20px -10px rgba(202, 86, 41, .5);
}
.btn-primary:hover { background: var(--accent-hover); }
.btn-ghost { background: var(--bg); color: var(--ink); border-color: var(--line); }
.btn-ghost:hover { border-color: #C9C7C1; background: var(--bg-soft); }
.btn-sm { height: 36px; padding: 0 18px; font-size: 13.5px; border-radius: 8px; }
.btn-lg { height: 52px; padding: 0 30px; font-size: 16px; }

/* ============================================================
   Hero
   ============================================================ */
.hero { padding: 156px 0 88px; }
.hero-grid {
  display: grid; grid-template-columns: 1fr 1fr;
  gap: 72px; align-items: center;
}
.hero-copy h1 {
  font-size: clamp(34px, 4.4vw, 50px);
  line-height: 1.2; letter-spacing: -1px; font-weight: 800;
}
.lead { margin-top: 20px; font-size: 16px; color: var(--dim); line-height: 1.9; max-width: 30em; }
.actions { display: flex; gap: 14px; margin-top: 32px; flex-wrap: wrap; }
.meta { margin-top: 20px; font-size: 13px; color: var(--mute); }

/* 应用窗口示意 */
.app {
  border: 1px solid var(--line); border-radius: var(--r);
  background: var(--bg);
  box-shadow: var(--shadow);
  overflow: hidden;
}
.app-titlebar {
  display: flex; align-items: center; gap: 6px;
  padding: 11px 14px;
  border-bottom: 1px solid var(--line-soft);
  background: var(--bg-soft);
}
.app-titlebar i { width: 10px; height: 10px; border-radius: 50%; background: #DEDCD6; }
.app-titlebar span { margin-left: 10px; font-size: 12px; color: var(--mute); }
.app-body { padding: 20px 22px 16px; }
.app-head {
  display: flex; align-items: flex-start; justify-content: space-between;
  padding-bottom: 16px; margin-bottom: 6px;
  border-bottom: 1px solid var(--line-soft);
}
.app-plan { font-size: 15px; font-weight: 700; color: var(--ink); }
.app-plan-v { margin-top: 2px; font-size: 12.5px; color: var(--mute); }
.app-badge {
  flex: none; font-size: 11.5px; font-weight: 600; color: var(--green);
  background: var(--green-soft); border-radius: 999px; padding: 4px 11px;
}
.app-row {
  display: flex; align-items: center; gap: 12px;
  padding: 11px 0; border-bottom: 1px solid var(--line-soft);
  font-size: 13.5px;
}
.app-row span { flex: 1; color: var(--ink); font-weight: 550; }
.app-row em { font-style: normal; color: var(--dim); font-size: 12.5px; }
.app-row.is-dim span, .app-row.is-dim em { color: var(--mute); }
.app-row i {
  flex: none; font-style: normal; font-size: 11px; font-weight: 600;
  border-radius: 5px; padding: 2px 8px;
}
.app-row i.ok { color: var(--green); background: var(--green-soft); }
.app-row i.skip { color: var(--mute); background: var(--bg-soft); }
.app-foot {
  display: flex; align-items: center; justify-content: space-between;
  padding-top: 14px; font-size: 12px; color: var(--mute);
}
.app-link { color: var(--accent); font-weight: 600; }
.app-link:hover { text-decoration: underline; }

/* ============================================================
   信任条
   ============================================================ */
.trust { padding: 0 0 26px; }
.trust-grid {
  display: grid; grid-template-columns: repeat(4, 1fr);
  border: 1px solid var(--line); border-radius: var(--r);
  overflow: hidden; background: var(--bg);
}
.trust-item {
  display: flex; align-items: center; gap: 12px;
  padding: 18px 20px;
  border-left: 1px solid var(--line-soft);
  color: var(--accent);
}
.trust-item:first-child { border-left: 0; }
.trust-item b { display: block; font-size: 13.5px; color: var(--ink); font-weight: 650; }
.trust-item span { display: block; font-size: 12px; color: var(--mute); margin-top: 1px; }

/* ============================================================
   区块通用
   ============================================================ */
.section { padding: 96px 0; }
.section-alt { background: var(--bg-soft); }
.section-head { max-width: 600px; margin-bottom: 48px; }
.section h2 { font-size: clamp(26px, 3.2vw, 34px); letter-spacing: -.6px; }
.sub { margin-top: 14px; color: var(--dim); font-size: 15px; line-height: 1.85; }

/* ============================================================
   功能卡
   ============================================================ */
.cards { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; }
.card {
  border: 1px solid var(--line); border-radius: var(--r);
  background: var(--bg); padding: 28px 26px;
  transition: border-color .2s, box-shadow .2s;
}
.card:hover { border-color: #DCDAD4; box-shadow: var(--shadow); }
.card-icon {
  width: 42px; height: 42px; border-radius: 10px;
  display: grid; place-items: center;
  color: var(--accent); background: var(--accent-soft);
  margin-bottom: 18px;
}
.card h3 { font-size: 16.5px; }
.card p { margin-top: 9px; font-size: 14px; color: var(--dim); line-height: 1.75; }

/* ============================================================
   帧率监测
   ============================================================ */
.monitor-grid {
  display: grid; grid-template-columns: .88fr 1.12fr;
  gap: 64px; align-items: center;
}
.monitor-copy h2 { font-size: clamp(24px, 2.8vw, 30px); }
.monitor-copy > p { margin-top: 16px; color: var(--dim); font-size: 15px; line-height: 1.85; }
.check-list { list-style: none; margin-top: 22px; display: grid; gap: 11px; }
.check-list li {
  position: relative; padding-left: 26px;
  font-size: 14px; color: var(--text);
}
.check-list li::before {
  content: "✓"; position: absolute; left: 0; top: 0;
  width: 18px; height: 18px; border-radius: 50%;
  display: grid; place-items: center;
  font-size: 10px; font-weight: 700; color: var(--green);
  background: var(--green-soft);
}
.monitor-panel {
  border: 1px solid var(--line); border-radius: var(--r);
  background: var(--bg); padding: 20px 22px 16px;
  box-shadow: var(--shadow);
}
.monitor-head {
  display: flex; align-items: center; justify-content: space-between;
  font-size: 13px; font-weight: 650; color: var(--ink);
}
.monitor-fps { font-size: 12.5px; color: var(--mute); font-weight: 500; }
.monitor-fps b { font-size: 20px; font-weight: 700; color: var(--accent); font-variant-numeric: tabular-nums; margin-right: 3px; }
#fpsChart { width: 100%; height: 190px; display: block; margin-top: 10px; }
.monitor-foot {
  display: flex; justify-content: space-between; gap: 12px;
  margin-top: 12px; padding-top: 13px;
  border-top: 1px solid var(--line-soft);
  font-size: 12px; color: var(--mute);
}
.monitor-foot b { color: var(--ink); font-weight: 650; }

/* ============================================================
   安全
   ============================================================ */
.safety {
  display: grid; grid-template-columns: .9fr 1.1fr;
  gap: 56px; align-items: center;
}
.safety-copy h2 { font-size: clamp(24px, 2.8vw, 30px); }
.safety-copy .sub { font-size: 14.5px; }
.safety-copy .btn { margin-top: 26px; }
.safety-list { display: grid; gap: 12px; }
.safety-item {
  display: flex; gap: 14px; align-items: flex-start;
  border: 1px solid var(--line); border-radius: 12px;
  background: var(--bg); padding: 16px 18px;
  transition: border-color .2s;
}
.safety-item:hover { border-color: #DCDAD4; }
.safety-item h4 { font-size: 14.5px; }
.safety-item p { margin-top: 4px; font-size: 13px; color: var(--dim); line-height: 1.65; }
.tick {
  flex: none; width: 24px; height: 24px; border-radius: 50%;
  display: grid; place-items: center;
  font-size: 12px; font-weight: 700; color: var(--green);
  background: var(--green-soft);
}

/* ============================================================
   下载
   ============================================================ */
.download { padding: 88px 0; }
.dl { text-align: center; max-width: 560px; margin: 0 auto; }
.dl h2 { font-size: clamp(26px, 3vw, 34px); }
.dl .sub { font-size: 14.5px; }
.dl-actions { display: flex; gap: 14px; justify-content: center; margin-top: 30px; flex-wrap: wrap; }
.dl-meta { margin-top: 24px; font-size: 12.5px; color: var(--mute); line-height: 1.9; }

/* ============================================================
   FAQ
   ============================================================ */
.faq-list { display: grid; gap: 12px; max-width: 760px; }
details.faq {
  border: 1px solid var(--line); border-radius: 12px;
  background: var(--bg);
  transition: border-color .2s;
}
details.faq:hover { border-color: #DCDAD4; }
details.faq[open] { border-color: #DCDAD4; box-shadow: var(--shadow); }
details.faq summary {
  list-style: none; cursor: pointer;
  padding: 17px 22px;
  font-weight: 600; color: var(--ink); font-size: 14.5px;
  display: flex; align-items: center; justify-content: space-between; gap: 14px;
}
details.faq summary::-webkit-details-marker { display: none; }
details.faq summary::after {
  content: "+"; flex: none;
  font-size: 18px; font-weight: 400; color: var(--mute);
  transition: transform .2s;
}
details.faq[open] summary::after { transform: rotate(45deg); }
details.faq p { padding: 0 22px 19px; font-size: 13.8px; color: var(--dim); line-height: 1.85; }

/* ============================================================
   页脚
   ============================================================ */
footer { border-top: 1px solid var(--line); padding: 48px 0 36px; background: var(--bg); }
.foot-top { display: flex; justify-content: space-between; gap: 48px; flex-wrap: wrap; }
.foot-brand { max-width: 320px; }
.foot-brand .brand { font-size: 14.5px; margin-bottom: 12px; }
.foot-brand p { font-size: 12.5px; color: var(--mute); line-height: 1.8; }
.foot-links { display: flex; gap: 64px; flex-wrap: wrap; }
.foot-col h5 {
  font-size: 12px; font-weight: 650; color: var(--mute);
  letter-spacing: .5px; margin-bottom: 12px;
}
.foot-col a { display: block; font-size: 13px; color: var(--dim); padding: 4px 0; transition: color .2s; }
.foot-col a:hover { color: var(--accent); }
.foot-bottom {
  margin-top: 40px; padding-top: 20px;
  border-top: 1px solid var(--line-soft);
  display: flex; justify-content: space-between; gap: 14px; flex-wrap: wrap;
  font-size: 12px; color: var(--mute);
}
.foot-bottom a:hover { color: var(--accent); }

/* ============================================================
   Reveal 进场
   ============================================================ */
.reveal { opacity: 0; transform: translateY(16px); transition: opacity .6s ease, transform .6s ease; }
.reveal.in { opacity: 1; transform: none; }

/* ============================================================
   响应式
   ============================================================ */
@media (max-width: 960px) {
  .hero { padding: 128px 0 64px; }
  .hero-grid { grid-template-columns: 1fr; gap: 44px; }
  .monitor-grid { grid-template-columns: 1fr; gap: 36px; }
  .safety { grid-template-columns: 1fr; gap: 32px; }
  .cards { grid-template-columns: repeat(2, 1fr); }
  .trust-grid { grid-template-columns: repeat(2, 1fr); }
  .trust-item:nth-child(3) { border-left: 0; }
  .trust-item:nth-child(n+3) { border-top: 1px solid var(--line-soft); }
  .nav-links { display: none; }
}
@media (max-width: 640px) {
  .cards { grid-template-columns: 1fr; }
  .trust-grid { grid-template-columns: 1fr; }
  .trust-item { border-left: 0 !important; }
  .trust-item:nth-child(n+2) { border-top: 1px solid var(--line-soft); }
  .section { padding: 68px 0; }
  .wrap { padding: 0 20px; }
  #fpsChart { height: 150px; }
  .monitor-foot { flex-wrap: wrap; gap: 8px; }
}

/* 减少动效 */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .reveal { opacity: 1; transform: none; transition: none; }
}