:root {
  --navy: #0b3d5c;
  --navy-2: #072a40;
  --teal: #1a7a6d;
  --mint: #5fd3bc;
  --gold: #e8b54a;
  --text: #16232f;
  --muted: #5c6b78;
  --line: rgba(11, 61, 92, .08);
  --bg-alt: #f3f8f7;
  --radius: 22px;
  --shadow: 0 24px 60px -24px rgba(11, 61, 92, .28);
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font: 16px/1.75 -apple-system, BlinkMacSystemFont, "PingFang SC", "HarmonyOS Sans SC", "Microsoft YaHei", sans-serif;
  color: var(--text);
  background: #fff;
  -webkit-font-smoothing: antialiased;
}
img { max-width: 100%; display: block; }
a { color: inherit; text-decoration: none; }
.wrap { max-width: 1200px; margin: 0 auto; padding: 0 24px; }
.muted { color: var(--muted); }
.center { text-align: center; justify-content: center; }

/* 导航 */
.nav { position: fixed; inset: 0 0 auto; z-index: 50; transition: background .3s, box-shadow .3s; }
.nav.solid { background: rgba(255, 255, 255, .86); backdrop-filter: saturate(1.6) blur(14px); box-shadow: 0 1px 0 var(--line); }
.nav-inner { display: flex; align-items: center; justify-content: space-between; height: 72px; }
.brand { display: flex; align-items: center; gap: 10px; font-weight: 800; font-size: 21px; color: var(--navy); letter-spacing: .02em; }
.brand img { border-radius: 10px; box-shadow: 0 6px 16px -6px rgba(11,61,92,.5); }
.nav nav { display: flex; align-items: center; gap: 30px; font-size: 15px; font-weight: 500; color: #2b3b48; }
.nav nav a:not(.btn) { position: relative; }
.nav nav a:not(.btn)::after { content: ""; position: absolute; left: 0; right: 0; bottom: -6px; height: 2px; border-radius: 2px; background: var(--teal); transform: scaleX(0); transition: transform .25s; }
.nav nav a:not(.btn):hover::after { transform: scaleX(1); }

/* 按钮 */
.btn { display: inline-flex; align-items: center; gap: 8px; padding: 12px 26px; border-radius: 999px; font-weight: 600; color: #fff;
  background: linear-gradient(135deg, var(--teal), var(--navy)); box-shadow: 0 12px 28px -12px rgba(26,122,109,.7); transition: transform .2s, box-shadow .2s; }
.btn:hover { transform: translateY(-2px); box-shadow: 0 18px 36px -14px rgba(26,122,109,.8); }
.btn-lg { padding: 15px 32px; font-size: 17px; }
.btn-small { padding: 8px 20px; font-size: 14px; }
.btn-glass { background: rgba(255,255,255,.55); color: var(--navy); border: 1px solid rgba(11,61,92,.15); backdrop-filter: blur(10px); box-shadow: none; }
.btn-white { background: #fff; color: var(--navy); }
.btn[aria-disabled="true"] { cursor: default; }

/* 首屏 */
.hero { position: relative; min-height: 760px; display: flex; align-items: center; overflow: hidden; padding: 120px 0 80px; }
.hero-bg { position: absolute; inset: 0; width: 100%; height: 100%; object-fit: cover; object-position: right center; }
.hero-shade { position: absolute; inset: 0; background: linear-gradient(90deg, rgba(247,252,251,.97) 0%, rgba(247,252,251,.9) 34%, rgba(247,252,251,.25) 58%, rgba(247,252,251,0) 75%); }
.hero-inner { position: relative; width: 100%; }
.hero-copy { max-width: 560px; }
.pill { display: inline-flex; align-items: center; gap: 8px; padding: 6px 14px; border-radius: 999px; background: rgba(26,122,109,.1); color: var(--teal); font-size: 14px; font-weight: 600; }
.pill i { width: 8px; height: 8px; border-radius: 50%; background: var(--mint); box-shadow: 0 0 0 4px rgba(95,211,188,.25); }
h1 { font-size: 60px; line-height: 1.15; margin: 22px 0 22px; color: var(--navy); letter-spacing: -.01em; }
h1 em { font-style: normal; background: linear-gradient(120deg, var(--teal), #2aa58f 50%, var(--navy)); -webkit-background-clip: text; background-clip: text; color: transparent; }
.lead { font-size: 19px; color: #31424f; margin: 0 0 32px; }
.cta { display: flex; gap: 14px; flex-wrap: wrap; }
.hero-stats { list-style: none; padding: 0; margin: 44px 0 0; display: flex; gap: 40px; }
.hero-stats b { display: block; font-size: 30px; color: var(--navy); line-height: 1.1; }
.hero-stats span { font-size: 14px; color: var(--muted); }

/* 区块 */
.section { padding: 112px 0; position: relative; }
.section.alt { background: var(--bg-alt); }
.head { text-align: center; max-width: 720px; margin: 0 auto 56px; }
.kicker { display: inline-flex; align-items: center; gap: 8px; color: var(--teal); font-weight: 700; font-size: 14px; letter-spacing: .12em; }
.kicker.light { color: var(--mint); }
h2 { font-size: 40px; line-height: 1.25; margin: 12px 0 16px; color: var(--navy); letter-spacing: -.01em; }
h3 { font-size: 19px; margin: 18px 0 8px; color: var(--navy); }
.sub { color: var(--muted); font-size: 17px; margin: 0; }
.sub.light { color: #bcd3df; }

.grid4 { display: grid; grid-template-columns: repeat(4, 1fr); gap: 22px; }
.feature { background: #fff; border: 1px solid var(--line); border-radius: var(--radius); padding: 30px 26px 32px; transition: transform .3s, box-shadow .3s; }
.feature:hover { transform: translateY(-6px); box-shadow: var(--shadow); }
.feature img { width: 96px; height: 96px; object-fit: contain; border-radius: 24px; mix-blend-mode: multiply; }
.feature p { margin: 0; color: var(--muted); font-size: 15px; }
.feature.soft { background: linear-gradient(180deg, #fff, #f6fbfa); }
.feature.soft img { width: 88px; height: 88px; }

.split { display: grid; grid-template-columns: 1fr 1fr; gap: 72px; align-items: center; }
.split.rev > :first-child { order: 0; }
.art img { border-radius: 28px; box-shadow: var(--shadow); }

/* 手机与对话 */
.showcase { background: radial-gradient(1000px 500px at 15% 50%, rgba(95,211,188,.16), transparent 70%); }
.phone-wrap { display: flex; justify-content: center; }
.phone-wrap img { width: min(460px, 100%); filter: drop-shadow(0 40px 60px rgba(11,61,92,.25)); }
.chat { display: flex; flex-direction: column; gap: 12px; margin: 24px 0 24px; }
.msg { padding: 13px 18px; border-radius: 18px; max-width: 88%; font-size: 15.5px; line-height: 1.6; }
.msg.me { align-self: flex-end; background: linear-gradient(135deg, var(--navy), #135575); color: #fff; border-bottom-right-radius: 6px; }
.msg.ai { align-self: flex-start; background: #fff; border: 1px solid var(--line); box-shadow: 0 10px 30px -18px rgba(11,61,92,.4); border-bottom-left-radius: 6px; }
.msg.ai b { display: block; font-size: 12px; color: var(--teal); letter-spacing: .06em; margin-bottom: 2px; }

/* 路径横幅 */
.banner { background: linear-gradient(140deg, var(--navy-2), var(--navy) 55%, #0f5a62); color: #fff; overflow: hidden; }
.banner::before { content: ""; position: absolute; width: 640px; height: 640px; right: -200px; top: -240px; border-radius: 50%; background: radial-gradient(circle, rgba(95,211,188,.25), transparent 65%); }
.banner h2, .banner h3 { color: #fff; }
.steps { list-style: none; margin: 32px 0 0; padding: 0; display: grid; gap: 18px; }
.steps li { display: flex; gap: 18px; padding: 20px 22px; border-radius: 18px; background: rgba(255,255,255,.06); border: 1px solid rgba(255,255,255,.1); }
.steps span { flex: none; font-size: 22px; font-weight: 800; color: var(--mint); line-height: 1.4; }
.steps h3 { margin: 0 0 4px; }
.steps p { margin: 0; color: #bcd3df; font-size: 15px; }
.banner .art img { box-shadow: 0 40px 80px -30px rgba(0,0,0,.6); }

/* 自主学习 */
.checks { list-style: none; padding: 0; margin: 22px 0 28px; display: grid; gap: 12px; }
.checks li { position: relative; padding-left: 32px; font-size: 16.5px; }
.checks li::before { content: ""; position: absolute; left: 0; top: 5px; width: 20px; height: 20px; border-radius: 50%;
  background: var(--teal) url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 20 20'%3E%3Cpath d='M5 10.5l3 3 7-7' fill='none' stroke='white' stroke-width='2.4' stroke-linecap='round' stroke-linejoin='round'/%3E%3C/svg%3E") center/14px no-repeat; }
.meter { background: #fff; border-radius: 18px; padding: 20px 22px; box-shadow: var(--shadow); }
.meter-row { display: flex; justify-content: space-between; font-size: 14px; }
.meter-row b { color: var(--navy); font-size: 16px; }
.bar { height: 10px; border-radius: 999px; background: #e3efed; margin: 12px 0; overflow: hidden; }
.bar i { display: block; height: 100%; border-radius: 999px; background: linear-gradient(90deg, var(--mint), var(--teal)); }

/* 下载 */
.cta-band { background: linear-gradient(135deg, var(--teal), var(--navy)); color: #fff; }
.cta-band h2 { color: #fff; }
.cta-logo { margin: 0 auto 18px; border-radius: 24px; box-shadow: 0 20px 40px -16px rgba(0,0,0,.5); }
.cta-band .cta { margin-top: 30px; }
.cta-band .btn-glass { color: #fff; background: rgba(255,255,255,.12); border-color: rgba(255,255,255,.3); }

/* 页脚 */
.foot { padding: 34px 0; background: var(--navy-2); color: #a9bfcc; font-size: 14px; }
.foot-inner { display: flex; justify-content: space-between; align-items: center; gap: 16px; flex-wrap: wrap; }
.foot .brand { color: #fff; font-size: 17px; }
.foot .brand em { font-style: normal; font-weight: 400; color: #a9bfcc; font-size: 14px; margin-left: 6px; }
.foot .muted { color: #8aa3b2; }

/* 进入动画 */
.reveal { opacity: 0; transform: translateY(24px); transition: opacity .8s ease, transform .8s ease; }
.reveal.in { opacity: 1; transform: none; }
@media (prefers-reduced-motion: reduce) { .reveal { opacity: 1; transform: none; transition: none; } }

@media (max-width: 1000px) {
  .grid4 { grid-template-columns: repeat(2, 1fr); }
  .split { grid-template-columns: 1fr; gap: 40px; }
  .split.rev > .art { order: -1; }
  h1 { font-size: 46px; }
  h2 { font-size: 32px; }
  .nav nav a:not(.btn) { display: none; }
}
@media (max-width: 640px) {
  .hero { min-height: auto; padding: 96px 0 56px; flex-direction: column; }
  .hero-bg { position: relative; height: 300px; order: 2; margin-top: 28px; border-radius: 0; object-position: 75% center; }
  .hero-shade { display: none; }
  .hero { background: linear-gradient(180deg, #f2faf8, #fff); }
  .hero-inner { order: 1; }
  h1 { font-size: 38px; }
  .hero-stats { gap: 24px; }
  .grid4 { grid-template-columns: 1fr; }
  .section { padding: 76px 0; }
}