/* ============ NadChat 官网 ============ */
:root {
  --green: #6b8e7f; --green-deep: #5a7d6e; --green-soft: #e6efe9;
  --bg: #f2f3f0; --card: #ffffff; --text: #2c2c2a; --sub: #8a8a86;
  --line: #e6e7e2; --danger: #b06060;
  --shadow: 0 1px 2px rgba(0,0,0,.04), 0 12px 32px rgba(0,0,0,.07);
  --shadow-lg: 0 24px 64px rgba(0,0,0,.13);
  --radius: 20px;
  --ease: cubic-bezier(.22, 1, .36, 1);
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #161716; --card: #21231f; --text: #e4e4df; --sub: #8f9089;
    --line: #2e302b; --green: #7fa392; --green-deep: #6b8e7f; --green-soft: #27312c;
    --shadow: 0 1px 2px rgba(0,0,0,.2), 0 12px 32px rgba(0,0,0,.32);
    --shadow-lg: 0 24px 64px rgba(0,0,0,.5);
  }
}
* { margin: 0; padding: 0; box-sizing: border-box; -webkit-tap-highlight-color: transparent; }
html { scroll-behavior: smooth; }
body {
  font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  background: var(--bg); color: var(--text); line-height: 1.6; overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
}
a { color: inherit; text-decoration: none; }
button { font: inherit; cursor: pointer; border: none; background: none; color: inherit; }
button:focus-visible, a:focus-visible { outline: 2px solid var(--green); outline-offset: 3px; border-radius: 6px; }
::selection { background: var(--green); color: #fff; }
::-webkit-scrollbar { width: 8px; }
::-webkit-scrollbar-thumb { background: var(--line); border-radius: 4px; }
::-webkit-scrollbar-thumb:hover { background: var(--sub); }

.wrap { max-width: 1120px; margin: 0 auto; padding: 0 24px; }
.sub { color: var(--sub); }
.center { text-align: center; }

/* ---------- 滚动进度条 ---------- */
.progress { position: fixed; top: 0; left: 0; height: 3px; width: 0; z-index: 200;
  background: linear-gradient(90deg, var(--green), var(--green-deep)); border-radius: 0 3px 3px 0;
  transition: width .1s linear; }

/* ---------- 回到顶部 ---------- */
.to-top { position: fixed; right: 26px; bottom: 26px; z-index: 150; width: 44px; height: 44px;
  border-radius: 50%; background: var(--card); border: 1px solid var(--line); color: var(--green-deep);
  display: flex; align-items: center; justify-content: center; box-shadow: var(--shadow);
  opacity: 0; pointer-events: none; transform: translateY(12px); transition: all .3s var(--ease); }
.to-top.show { opacity: 1; pointer-events: auto; transform: none; }
.to-top:hover { background: var(--green); color: #fff; border-color: transparent; transform: translateY(-2px); }
.to-top svg { width: 18px; height: 18px; }

/* ---------- 滚动显现（带轻微模糊，更柔和） ---------- */
.reveal { opacity: 0; transform: translateY(26px); filter: blur(5px);
  transition: opacity .8s var(--ease), transform .8s var(--ease), filter .8s var(--ease); }
.reveal.in { opacity: 1; transform: none; filter: blur(0); }
.reveal.d1 { transition-delay: .08s; } .reveal.d2 { transition-delay: .16s; }
.reveal.d3 { transition-delay: .24s; } .reveal.d4 { transition-delay: .32s; }
.reveal.d5 { transition-delay: .4s; } .reveal.d6 { transition-delay: .48s; }

/* ---------- 导航 ---------- */
.nav { position: fixed; top: 0; left: 0; right: 0; z-index: 100; transition: all .3s ease; }
.nav .inner { display: flex; align-items: center; gap: 28px; height: 64px; }
.nav.scrolled { background: color-mix(in srgb, var(--bg) 82%, transparent); backdrop-filter: blur(14px); border-bottom: 1px solid var(--line); }
.nav .logo { display: flex; align-items: center; gap: 10px; font-weight: 600; font-size: 17px; letter-spacing: .3px; }
.nav .logo .icon { width: 32px; height: 32px; border-radius: 10px; overflow: hidden; flex: none;
  box-shadow: 0 4px 12px rgba(107,142,127,.28); transition: transform .3s var(--ease); }
.nav .logo:hover .icon { transform: rotate(-6deg) scale(1.06); }
.nav .logo .icon svg { width: 100%; height: 100%; display: block; }
.nav .links { display: flex; gap: 24px; margin-left: auto; font-size: 14px; color: var(--sub); }
.nav .links a { position: relative; transition: color .2s ease; padding: 4px 0; }
.nav .links a:hover, .nav .links a.active { color: var(--green-deep); }
.nav .links a::after { content: ''; position: absolute; left: 0; right: 100%; bottom: -2px; height: 2px;
  background: var(--green); border-radius: 2px; transition: right .25s var(--ease); }
.nav .links a:hover::after, .nav .links a.active::after { right: 0; }
.nav-cta { padding: 8px 18px; border-radius: 999px; background: var(--green); color: #fff;
  font-size: 13.5px; font-weight: 500; transition: all .2s ease; flex: none;
  box-shadow: 0 4px 14px rgba(107,142,127,.3); animation: ctaGlow 3.2s ease-in-out infinite; }
@keyframes ctaGlow { 50% { box-shadow: 0 4px 14px rgba(107,142,127,.3), 0 0 0 5px rgba(107,142,127,.12); } }
.nav-cta:hover { background: var(--green-deep); transform: translateY(-1px); box-shadow: 0 8px 20px rgba(107,142,127,.4); }

/* ---------- Hero ---------- */
.hero { position: relative; padding: 158px 0 96px; overflow: hidden; }
.hero-bg { position: absolute; inset: 0; pointer-events: none; }
.hero-bg::before, .hero-bg::after { content: ''; position: absolute; border-radius: 50%; filter: blur(90px); opacity: .5; }
.hero-bg::before { width: 560px; height: 560px; background: var(--green-soft); top: -180px; right: -120px; animation: drift 14s ease-in-out infinite alternate; }
.hero-bg::after { width: 420px; height: 420px; background: #d8e4dc; top: 220px; left: -160px; animation: drift 18s ease-in-out infinite alternate-reverse; }
@media (prefers-color-scheme: dark) { .hero-bg::after { background: #1f2a25; } }
.hero-bg .orb.c3 { position: absolute; width: 300px; height: 300px; border-radius: 50%; filter: blur(80px);
  opacity: .32; background: var(--green); bottom: -140px; left: 44%; animation: drift 22s ease-in-out infinite alternate; }
@keyframes drift { to { transform: translate(50px, 36px) scale(1.08); } }
.hero .grid { position: relative; display: grid; grid-template-columns: 1.15fr .85fr; gap: 48px; align-items: center; }
.hero .badge { display: inline-flex; align-items: center; gap: 8px; font-size: 13px; color: var(--green-deep);
  background: var(--green-soft); border: 1px solid color-mix(in srgb, var(--green) 22%, transparent);
  border-radius: 999px; padding: 6px 14px; margin-bottom: 22px; }
.hero .badge .dot { width: 7px; height: 7px; border-radius: 50%; background: var(--green); animation: pulse 1.6s infinite; }
@keyframes pulse { 50% { opacity: .3; } }
.hero h1 { font-size: clamp(38px, 5.2vw, 58px); line-height: 1.16; font-weight: 700; letter-spacing: .5px; }
.hero h1 em { font-style: normal; background: linear-gradient(120deg, var(--green), var(--green-deep) 60%, var(--green));
  -webkit-background-clip: text; background-clip: text; -webkit-text-fill-color: transparent;
  background-size: 200% 100%; animation: hueSlide 5s ease-in-out infinite; position: relative; }
@keyframes hueSlide { 50% { background-position: 100% 0; } }
.hero p.lead { margin: 22px 0 32px; font-size: 17px; color: var(--sub); max-width: 30em; }
.hero .cta-row { display: flex; gap: 14px; flex-wrap: wrap; }
.btn { display: inline-flex; align-items: center; gap: 8px; padding: 13px 26px; border-radius: 14px;
  font-size: 15px; font-weight: 500; transition: all .22s ease; }
.btn svg { width: 17px; height: 17px; flex: none; }
.btn-primary { background: var(--green); color: #fff; box-shadow: 0 8px 24px rgba(107,142,127,.32); }
.btn-primary:hover { background: var(--green-deep); transform: translateY(-2px); box-shadow: 0 12px 32px rgba(107,142,127,.4); }
.btn-ghost { border: 1px solid var(--line); background: var(--card); color: var(--text); }
.btn-ghost:hover { border-color: var(--green); color: var(--green-deep); transform: translateY(-2px); }
.hero .stats { display: flex; gap: 36px; margin-top: 46px; }
.hero .stats .num { font-size: 26px; font-weight: 700; color: var(--green-deep); font-variant-numeric: tabular-nums; }
.hero .stats .lbl { font-size: 12.5px; color: var(--sub); margin-top: 2px; }

/* ---------- Hero 手机模型 ---------- */
.phone-stage { perspective: 1200px; display: flex; justify-content: center; }
.phone { width: 264px; height: 540px; background: #1c1c1a; border-radius: 42px; padding: 11px;
  box-shadow: var(--shadow-lg), inset 0 0 0 2px rgba(255,255,255,.06); position: relative;
  animation: phoneFloat 6s ease-in-out infinite; transform-style: preserve-3d; }
@keyframes phoneFloat { 0%,100% { transform: translateY(0) rotateY(-6deg) rotateX(2deg); } 50% { transform: translateY(-14px) rotateY(-2deg) rotateX(0deg); } }
.phone::before { content: ''; position: absolute; top: 21px; left: 50%; transform: translateX(-50%);
  width: 74px; height: 20px; background: #1c1c1a; border-radius: 999px; z-index: 2; }
.phone::after { content: ''; position: absolute; inset: -14px -22px; border-radius: 56px;
  background: radial-gradient(60% 50% at 50% 40%, rgba(107,142,127,.18), transparent 70%); z-index: -1; }
.phone-screen { width: 100%; height: 100%; background: var(--bg); border-radius: 32px; overflow: hidden;
  display: flex; flex-direction: column; position: relative; }
.mini-status { display: flex; justify-content: space-between; align-items: center; padding: 16px 16px 6px;
  font-size: 11px; font-weight: 600; color: var(--text); }
.mini-status .tm { margin-right: auto; }
.mini-status .sic { display: inline-flex; align-items: center; gap: 6px; }
.mini-status .sic svg { display: block; flex: none; overflow: visible; }
.mini-status .i-sig { width: 13px; height: 9px; }
.mini-status .i-wifi { width: 11px; height: 9px; }
.mini-status .i-bat { width: 17px; height: 9px; }
.mini-head { display: flex; align-items: center; gap: 9px; padding: 8px 14px 11px; background: var(--card);
  border-bottom: 1px solid var(--line); }
.mini-head .av { width: 30px; height: 30px; border-radius: 10px; background: var(--green-soft);
  display: flex; align-items: center; justify-content: center; color: var(--green-deep);
  font-weight: 600; font-size: 13px; flex: none; }
.mini-head .nm { font-size: 13.5px; font-weight: 600; }
.mini-head .st { font-size: 10.5px; color: var(--green-deep); }
.mini-head .st::before { content: '● '; font-size: 7px; }
.mini-msgs { flex: 1; padding: 14px 12px; display: flex; flex-direction: column; gap: 9px; overflow: hidden; }
.mini-bubble { max-width: 78%; padding: 8px 12px; font-size: 12.5px; border-radius: 15px;
  opacity: 0; transform: translateY(10px) scale(.9); animation: bubbleIn .5s var(--ease) forwards;
  display: inline-flex; align-items: center; gap: 5px; }
.mini-bubble.l { align-self: flex-start; background: var(--card); border: 1px solid var(--line); border-bottom-left-radius: 4px; }
.mini-bubble.r { align-self: flex-end; background: var(--green); color: #fff; border-bottom-right-radius: 4px; }
.mini-bubble .ic-inline { width: 13px; height: 13px; flex: none; }
.mini-bubble:nth-child(1) { animation-delay: .5s; } .mini-bubble:nth-child(2) { animation-delay: 1.3s; }
.mini-bubble:nth-child(3) { animation-delay: 2.1s; } .mini-bubble:nth-child(4) { animation-delay: 2.9s; }
@keyframes bubbleIn { to { opacity: 1; transform: none; } }
.mini-typing { align-self: flex-start; display: flex; gap: 4px; padding: 10px 13px; background: var(--card);
  border: 1px solid var(--line); border-radius: 15px; border-bottom-left-radius: 4px;
  opacity: 0; animation: bubbleIn .5s 3.7s forwards; }
.mini-typing i { width: 6px; height: 6px; border-radius: 50%; background: var(--sub); animation: typing 1.2s infinite; }
.mini-typing i:nth-child(2) { animation-delay: .18s; } .mini-typing i:nth-child(3) { animation-delay: .36s; }
@keyframes typing { 30% { transform: translateY(-4px); opacity: 1; } 60% { opacity: .5; } }
.mini-input { margin: 10px 12px 4px; padding: 9px 14px; background: var(--card); border: 1px solid var(--line);
  border-radius: 999px; font-size: 11.5px; color: var(--sub); display: flex; justify-content: space-between; align-items: center; }
.mini-input .send { width: 24px; height: 24px; border-radius: 50%; background: var(--green);
  display: flex; align-items: center; justify-content: center; flex: none; }
.mini-input .send svg { width: 11px; height: 11px; color: #fff; }
.mini-home { width: 108px; height: 4px; border-radius: 999px; background: var(--sub); opacity: .35;
  margin: 0 auto 8px; flex: none; }

/* ---------- 通用区块 ---------- */
section { padding: 88px 0; position: relative; scroll-margin-top: 72px; }

/* ---------- 全局细腻噪点纹理 ---------- */
body::after { content: ''; position: fixed; inset: 0; z-index: 999; pointer-events: none; opacity: .03;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='140' height='140'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.85' numOctaves='2' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='140' height='140' filter='url(%23n)'/%3E%3C/svg%3E"); }
@media (prefers-color-scheme: dark) { body::after { opacity: .05; } }
.sec-head { text-align: center; max-width: 620px; margin: 0 auto 56px; }
.sec-head .kicker { font-size: 13px; font-weight: 600; color: var(--green-deep); letter-spacing: 2px; text-transform: uppercase; }
.sec-head .kicker::after { content: ''; display: block; width: 34px; height: 3px; border-radius: 2px;
  background: linear-gradient(90deg, var(--green), transparent); margin: 10px auto 0;
  transform: scaleX(0); transform-origin: left; transition: transform .6s var(--ease) .25s; }
.sec-head .kicker.in::after { transform: scaleX(1); }
.sec-head h2 { font-size: clamp(26px, 3.4vw, 36px); font-weight: 700; margin: 12px 0 14px; letter-spacing: .3px; }
.sec-head p { color: var(--sub); font-size: 15.5px; }

/* ---------- 功能卡片 ---------- */
.features .grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 22px; }
.feature-card { background: var(--card); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 30px 28px; transition: transform .3s var(--ease), box-shadow .3s ease, border-color .3s ease;
  position: relative; overflow: hidden; will-change: transform; }
.feature-card:hover { box-shadow: var(--shadow); border-color: transparent; }
.feature-card::before { content: ''; position: absolute; top: 0; left: 0; right: 0; height: 3px;
  background: linear-gradient(90deg, var(--green), var(--green-deep)); transform: scaleX(0);
  transform-origin: left; transition: transform .35s ease; }
.feature-card:hover::before { transform: scaleX(1); }
/* 悬停光斑（跟随鼠标） */
.feature-card::after, .step-card::after, .sec-card::after { content: ''; position: absolute; inset: 0;
  border-radius: inherit; pointer-events: none; opacity: 0; transition: opacity .35s ease;
  background: radial-gradient(260px circle at var(--mx, 50%) var(--my, 50%),
    color-mix(in srgb, var(--green) 12%, transparent), transparent 68%); }
.feature-card:hover::after, .step-card:hover::after, .sec-card:hover::after { opacity: 1; }
/* 入场时图标轻弹（ backwards 填充，避免动画驻留影响悬停 ） */
.feature-card.in .fic, .step-card.in .fic { animation: iconPop .7s var(--ease) .2s backwards; }
@keyframes iconPop { 0% { transform: scale(.6) rotate(-8deg); opacity: 0; } 60% { transform: scale(1.1) rotate(2deg); }
  100% { transform: scale(1) rotate(0); opacity: 1; } }
.feature-card .fic { width: 48px; height: 48px; border-radius: 14px; background: var(--green-soft);
  display: flex; align-items: center; justify-content: center; margin-bottom: 18px; transition: transform .3s var(--ease); }
.feature-card:hover .fic { transform: scale(1.08) rotate(-4deg); }
.feature-card .fic svg { width: 23px; height: 23px; color: var(--green-deep); }
.feature-card h3 { font-size: 17px; font-weight: 600; margin-bottom: 8px; }
.feature-card p { font-size: 14px; color: var(--sub); }

/* ---------- 文件传输助手专区 ---------- */
.transfer { background: var(--card); border-block: 1px solid var(--line); }
.transfer .grid { display: grid; grid-template-columns: 1fr 1fr; gap: 56px; align-items: center; }
.transfer h2 { font-size: clamp(26px, 3.2vw, 34px); font-weight: 700; line-height: 1.3; }
.transfer .lead { color: var(--sub); font-size: 15.5px; margin: 18px 0 26px; }
.transfer ul { list-style: none; display: flex; flex-direction: column; gap: 14px; }
.transfer li { display: flex; gap: 12px; align-items: flex-start; font-size: 14.5px; }
.transfer li .ck { width: 22px; height: 22px; border-radius: 50%; background: var(--green-soft);
  color: var(--green-deep); display: flex; align-items: center; justify-content: center; flex: none; margin-top: 2px; }
.transfer li .ck svg { width: 12px; height: 12px; }
.transfer li b { font-weight: 600; }
.transfer-demo { background: var(--bg); border: 1px solid var(--line); border-radius: 24px; padding: 22px;
  display: flex; flex-direction: column; gap: 14px; box-shadow: var(--shadow); }
.transfer-demo .row { display: flex; gap: 12px; align-items: center; background: var(--card);
  border: 1px solid var(--line); border-radius: 16px; padding: 14px 16px; transition: transform .25s var(--ease); }
.transfer-demo .row:hover { transform: translateX(4px); }
.transfer-demo .row .ic { width: 40px; height: 40px; border-radius: 12px; background: var(--green-soft);
  display: flex; align-items: center; justify-content: center; color: var(--green-deep); flex: none; }
.transfer-demo .row .ic svg { width: 19px; height: 19px; }
.transfer-demo .row .nm { font-size: 14px; font-weight: 500; }
.transfer-demo .row .dt { font-size: 12px; color: var(--sub); }
.transfer-demo .row .go { margin-left: auto; color: var(--green-deep); font-weight: 500; display: flex;
  align-items: center; gap: 5px; font-size: 12.5px; }
.transfer-demo .row .go svg { width: 15px; height: 15px; }
.transfer-demo .flow { display: flex; align-items: center; justify-content: center; gap: 10px;
  font-size: 12.5px; color: var(--sub); padding: 4px 0; flex-wrap: wrap; }
.transfer-demo .flow .dev { padding: 6px 13px; background: var(--card); border: 1px solid var(--line);
  border-radius: 999px; display: inline-flex; align-items: center; gap: 6px; }
.transfer-demo .flow .dev svg { width: 14px; height: 14px; color: var(--green-deep); }
.transfer-demo .flow .arrow { color: var(--green-deep); display: inline-flex; animation: flowX 1.8s ease-in-out infinite; }
.transfer-demo .flow .arrow svg { width: 15px; height: 15px; }
.transfer-demo .flow .arrow:nth-of-type(2) { animation-delay: .9s; }
@keyframes flowX { 50% { transform: translateX(5px); } }

/* ---------- 三步上手 ---------- */
.steps { display: grid; grid-template-columns: repeat(3, 1fr); gap: 22px; position: relative; }
.steps::before { content: ''; position: absolute; top: 44px; left: 12%; right: 12%; height: 2px;
  background: repeating-linear-gradient(90deg, var(--green) 0 10px, transparent 10px 20px); z-index: 0;
  opacity: .45; transform: scaleX(0); transform-origin: left;
  transition: transform 1.1s var(--ease) .35s, opacity .6s ease; }
.steps.in::before { transform: scaleX(1); }
.step-card { background: var(--card); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 30px 28px; position: relative; z-index: 1; transition: transform .3s var(--ease), box-shadow .3s ease; }
.step-card:hover { transform: translateY(-6px); box-shadow: var(--shadow); }
.step-num { position: absolute; top: -15px; left: 24px; width: 32px; height: 32px; border-radius: 50%;
  background: linear-gradient(135deg, var(--green), var(--green-deep)); color: #fff; font-weight: 700;
  font-size: 15px; display: flex; align-items: center; justify-content: center;
  box-shadow: 0 6px 16px rgba(107,142,127,.35); }
.step-ic { width: 48px; height: 48px; border-radius: 14px; background: var(--green-soft);
  display: flex; align-items: center; justify-content: center; margin: 8px 0 18px; }
.step-ic svg { width: 23px; height: 23px; color: var(--green-deep); }
.step-card h3 { font-size: 17px; font-weight: 600; margin-bottom: 8px; }
.step-card p { font-size: 14px; color: var(--sub); }

/* ---------- 安全与隐私 ---------- */
.security { background: var(--card); border-block: 1px solid var(--line); }
.sec-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 18px; }
.sec-card { background: var(--bg); border: 1px solid var(--line); border-radius: 18px; padding: 26px 22px;
  transition: transform .3s var(--ease), box-shadow .3s ease, border-color .3s ease; }
.sec-card:hover { transform: translateY(-5px); box-shadow: var(--shadow); border-color: color-mix(in srgb, var(--green) 35%, transparent); }
.sec-card .sic2 { width: 42px; height: 42px; border-radius: 12px; background: var(--green-soft);
  display: flex; align-items: center; justify-content: center; margin-bottom: 16px; }
.sec-card .sic2 svg { width: 20px; height: 20px; color: var(--green-deep); }
.sec-card h3 { font-size: 15.5px; font-weight: 600; margin-bottom: 6px; }
.sec-card p { font-size: 13px; color: var(--sub); }

/* ---------- 多端同步 ---------- */
.devices { display: grid; grid-template-columns: repeat(3, 1fr); gap: 22px; }
.device-card { background: var(--card); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 26px; text-align: center; transition: transform .3s var(--ease), box-shadow .3s ease; }
.device-card:hover { box-shadow: var(--shadow); }
.device-card .mock { height: 150px; display: flex; align-items: center; justify-content: center; margin-bottom: 20px; }
.device-card .mock .frame { background: var(--bg); border: 1px solid var(--line); border-radius: 14px;
  overflow: hidden; transition: transform .35s var(--ease); }
.device-card:hover .mock .frame { transform: scale(1.05); }
.device-card .mock .bar { height: 22px; background: var(--green-soft); display: flex; align-items: center;
  padding: 0 8px; gap: 4px; }
.device-card .mock .bar i { width: 5px; height: 5px; border-radius: 50%; background: var(--green); }
.device-card .mock .body { padding: 10px; display: flex; flex-direction: column; gap: 6px; width: 150px; }
.device-card .mock .ln { height: 7px; border-radius: 4px; background: var(--line); }
.device-card .mock .ln.g { background: var(--green-soft); width: 70%; }
.device-card .mock .ln.s { width: 45%; }
.device-card h3 { font-size: 16.5px; font-weight: 600; }
.device-card p { font-size: 13.5px; color: var(--sub); margin-top: 6px; }
.device-card.phone-m .frame { width: 96px; height: 130px; border-radius: 18px; }
.device-card.desktop-m .frame { width: 180px; }
.device-card.web-m .frame { width: 160px; }

/* ---------- 下载 ---------- */
.download .grid { display: grid; grid-template-columns: 1fr 1fr; gap: 22px; }
.dl-card { background: var(--card); border: 1px solid var(--line); border-radius: 24px; padding: 36px;
  display: flex; flex-direction: column; gap: 14px; transition: transform .3s var(--ease), box-shadow .3s ease;
  position: relative; overflow: hidden; }
.dl-card:hover { box-shadow: var(--shadow); }
.dl-card .tag { align-self: flex-start; font-size: 12px; color: var(--green-deep); background: var(--green-soft);
  padding: 4px 12px; border-radius: 999px; font-weight: 500; }
.dl-card h3 { font-size: 22px; font-weight: 700; }
.dl-card p { font-size: 14px; color: var(--sub); max-width: 24em; }
.dl-card .meta { font-size: 12.5px; color: var(--sub); display: flex; gap: 16px; flex-wrap: wrap; }
.dl-card .meta span { display: inline-flex; align-items: center; gap: 5px; }
.dl-card .meta span::before { content: ''; width: 4px; height: 4px; border-radius: 50%; background: var(--green); }
.dl-card .btn { align-self: flex-start; margin-top: 6px; }
.dl-card .qr { position: absolute; right: 26px; top: 50%; transform: translateY(-50%);
  width: 104px; height: 104px; border-radius: 16px; background: var(--bg); border: 1px solid var(--line);
  display: flex; align-items: center; justify-content: center; transition: transform .3s var(--ease); }
.dl-card:hover .qr { transform: translateY(-50%) scale(1.05); }
.dl-card .qr svg { width: 76px; height: 76px; }

/* ---------- FAQ ---------- */
.faq-list { max-width: 720px; margin: 0 auto; display: flex; flex-direction: column; gap: 12px; }
.faq-item { background: var(--card); border: 1px solid var(--line); border-radius: 16px; overflow: hidden;
  transition: border-color .25s ease, box-shadow .25s ease; }
.faq-item.open { border-color: color-mix(in srgb, var(--green) 40%, transparent); box-shadow: var(--shadow); }
.faq-item .q { width: 100%; display: flex; align-items: center; justify-content: space-between;
  padding: 18px 22px; font-size: 15.5px; font-weight: 500; text-align: left; gap: 16px; }
.faq-item .q .ind { width: 26px; height: 26px; border-radius: 50%; background: var(--green-soft);
  color: var(--green-deep); display: flex; align-items: center; justify-content: center;
  flex: none; transition: transform .3s var(--ease); font-size: 15px; font-weight: 400; }
.faq-item.open .q .ind { transform: rotate(45deg); }
.faq-item .a { max-height: 0; overflow: hidden; transition: max-height .35s ease; }
.faq-item .a p { padding: 0 22px 20px; font-size: 14.5px; color: var(--sub); }

/* ---------- Footer ---------- */
footer { border-top: 1px solid var(--line); padding: 48px 0 36px; background: var(--card); }
footer .grid { display: flex; justify-content: space-between; gap: 40px; flex-wrap: wrap; }
footer .brand { max-width: 300px; }
footer .brand .logo { display: flex; align-items: center; gap: 10px; font-weight: 600; font-size: 16px; margin-bottom: 12px; }
footer .brand .logo .icon { width: 30px; height: 30px; border-radius: 9px; overflow: hidden; }
footer .brand .logo .icon svg { width: 100%; height: 100%; display: block; }
footer .brand p { font-size: 13.5px; color: var(--sub); }
footer .col h4 { font-size: 14px; margin-bottom: 14px; }
footer .col a { display: block; font-size: 13.5px; color: var(--sub); padding: 4px 0; transition: color .2s ease; }
footer .col a:hover { color: var(--green-deep); }
footer .copy { margin-top: 36px; padding-top: 22px; border-top: 1px solid var(--line);
  font-size: 12.5px; color: var(--sub); display: flex; justify-content: space-between; flex-wrap: wrap; gap: 10px; }

/* ---------- 汉堡菜单按钮（默认隐藏，移动端显示） ---------- */
.nav-toggle { display: none; flex-direction: column; justify-content: center; gap: 5px;
  width: 38px; height: 38px; border-radius: 10px; flex: none; }
.nav-toggle i { display: block; width: 18px; height: 2px; background: var(--text); border-radius: 2px;
  transition: transform .3s var(--ease), opacity .2s ease; }
.nav-toggle i:nth-child(2) { width: 13px; }
.nav.open .nav-toggle i:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav.open .nav-toggle i:nth-child(2) { opacity: 0; }
.nav.open .nav-toggle i:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* ---------- 移动端下拉菜单 ---------- */
.nav-menu { position: absolute; top: 64px; left: 0; right: 0;
  background: color-mix(in srgb, var(--bg) 94%, transparent); backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--line); padding: 6px 24px 14px;
  display: flex; flex-direction: column;
  opacity: 0; transform: translateY(-10px); pointer-events: none;
  transition: opacity .28s var(--ease), transform .28s var(--ease); }
.nav.open .nav-menu { opacity: 1; transform: none; pointer-events: auto; }
.nav-menu a { padding: 13px 2px; font-size: 15px; color: var(--sub); border-bottom: 1px solid var(--line);
  opacity: 0; transform: translateX(-10px); transition: opacity .25s ease, transform .25s ease, color .2s ease; }
.nav-menu a:last-child { border-bottom: none; }
.nav-menu a:active { color: var(--green-deep); }
.nav.open .nav-menu a { opacity: 1; transform: none; }
.nav.open .nav-menu a:nth-child(1) { transition-delay: .04s; }
.nav.open .nav-menu a:nth-child(2) { transition-delay: .08s; }
.nav.open .nav-menu a:nth-child(3) { transition-delay: .12s; }
.nav.open .nav-menu a:nth-child(4) { transition-delay: .16s; }
.nav.open .nav-menu a:nth-child(5) { transition-delay: .2s; }
.nav.open .nav-menu a:nth-child(6) { transition-delay: .24s; }
.nav.open .nav-menu a:nth-child(7) { transition-delay: .28s; }
@media (min-width: 901px) { .nav-menu { display: none; } }

/* ---------- 响应式 ---------- */
@media (max-width: 900px) {
  .hero .grid { grid-template-columns: 1fr; gap: 40px; }
  .hero { padding-top: 118px; }
  .phone-stage { order: -1; }
  .features .grid, .devices, .steps, .sec-grid { grid-template-columns: repeat(2, 1fr); }
  .steps::before { display: none; }
  .transfer .grid, .download .grid { grid-template-columns: 1fr; }
  .nav .links { display: none; }
  .nav-toggle { display: flex; margin-left: auto; }
  .nav.open { background: color-mix(in srgb, var(--bg) 88%, transparent); backdrop-filter: blur(14px);
    border-bottom: 1px solid var(--line); }
  .dl-card .qr { display: none; }
  section { padding: 64px 0; }
}

/* ---------- 平板 / 大屏手机 ---------- */
@media (max-width: 640px) {
  section { padding: 54px 0; }
  .hero { padding: 104px 0 56px; }
  .hero .lead { font-size: 15.5px; }
  .features .grid, .devices, .steps, .sec-grid { grid-template-columns: 1fr; }
  .sec-head { margin-bottom: 42px; }
  .feature-card, .step-card { padding: 24px 20px; }
  .feature-card .fic, .step-ic { margin-bottom: 14px; }
  .hero .stats { flex-wrap: wrap; gap: 16px 28px; margin-top: 36px; }
  .hero .stats .num { font-size: 23px; }
  .transfer .grid { gap: 36px; }
  .transfer-demo { padding: 16px; border-radius: 20px; }
  .transfer-demo .row { padding: 12px 13px; }
  .transfer-demo .flow { gap: 7px; }
  .transfer-demo .flow .dev { padding: 5px 11px; font-size: 12px; }
  .device-card { padding: 22px; }
  .device-card .mock { height: 132px; margin-bottom: 16px; }
  .dl-card { padding: 26px 22px; border-radius: 20px; }
  .faq-item .q { padding: 16px 18px; font-size: 14.5px; }
  .faq-item .a p { padding: 0 18px 18px; }
  footer { padding: 40px 0 30px; }
  footer .grid { gap: 26px; }
  footer .copy { margin-top: 28px; }
  .to-top { right: 16px; bottom: calc(16px + env(safe-area-inset-bottom)); width: 40px; height: 40px; }
  .nav .inner { height: 58px; gap: 12px; }
  .nav-menu { top: 58px; }
  .progress { height: 2.5px; }
}

/* ---------- 小屏手机 ---------- */
@media (max-width: 400px) {
  .wrap { padding: 0 18px; }
  .hero h1 { font-size: 33px; }
  .hero .badge { font-size: 12px; }
  .btn { padding: 12px 20px; font-size: 14px; }
  .hero .cta-row .btn { flex: 1; justify-content: center; }
  .nav-cta { padding: 7px 14px; font-size: 12.5px; }
  .nav .logo { font-size: 16px; }
  .phone { width: 236px; height: 486px; }
  .phone::before { width: 66px; height: 18px; top: 19px; }
  .mini-status { padding: 14px 14px 5px; }
  .sec-head h2 { font-size: 24px; }
  .transfer h2 { font-size: 25px; }
  .dl-card h3 { font-size: 19px; }
}

/* ---------- 减少动画偏好 ---------- */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation-duration: .01ms !important; animation-iteration-count: 1 !important;
    transition-duration: .01ms !important; }
  html { scroll-behavior: auto; }
  .reveal { opacity: 1; transform: none; }
}