/* 小海豚学习 · 设计系统 theme.css —— 海洋玻璃拟态 + Liquid Glass */
:root{
  --ground:#eaf3f9; --ground2:#d6e8f2; --surface:#ffffff;
  --glass:rgba(255,255,255,.62); --glass-brd:rgba(255,255,255,.7);
  --ink:#11243a; --muted:#5b7284; --line:#d9e5ef;
  --brand1:#2f6fdb; --brand2:#3fc7bd; --deep:#14345f; --coral:#ff6a45; --aqua:#12a99c;
  --glow1:rgba(63,199,189,.45); --glow2:rgba(47,111,219,.4);
  --shadow:0 2px 6px rgba(20,50,80,.06),0 26px 60px -30px rgba(20,50,80,.32);
  --r:22px;
}
@media (prefers-color-scheme:dark){
  :root{
    --ground:#07111b; --ground2:#0c1c2c; --surface:#0f1d2e;
    --glass:rgba(18,34,54,.55); --glass-brd:rgba(120,160,200,.16);
    --ink:#eaf2f8; --muted:#8ba1b3; --line:#22374d;
    --brand1:#4f8ff0; --brand2:#4fd1c5; --deep:#bcd4f0; --coral:#ff7a59; --aqua:#4fd1c5;
    --glow1:rgba(79,209,197,.28); --glow2:rgba(79,143,240,.26);
    --shadow:0 2px 6px rgba(0,0,0,.4),0 30px 66px -30px rgba(0,0,0,.75);
  }
}
:root[data-theme="light"]{--ground:#eaf3f9;--ground2:#d6e8f2;--surface:#fff;--glass:rgba(255,255,255,.62);--glass-brd:rgba(255,255,255,.7);--ink:#11243a;--muted:#5b7284;--line:#d9e5ef;--brand1:#2f6fdb;--brand2:#3fc7bd;--deep:#14345f;--coral:#ff6a45;--aqua:#12a99c;--glow1:rgba(63,199,189,.45);--glow2:rgba(47,111,219,.4);--shadow:0 2px 6px rgba(20,50,80,.06),0 26px 60px -30px rgba(20,50,80,.32);}
:root[data-theme="dark"]{--ground:#07111b;--ground2:#0c1c2c;--surface:#0f1d2e;--glass:rgba(18,34,54,.55);--glass-brd:rgba(120,160,200,.16);--ink:#eaf2f8;--muted:#8ba1b3;--line:#22374d;--brand1:#4f8ff0;--brand2:#4fd1c5;--deep:#bcd4f0;--coral:#ff7a59;--aqua:#4fd1c5;--glow1:rgba(79,209,197,.28);--glow2:rgba(79,143,240,.26);--shadow:0 2px 6px rgba(0,0,0,.4),0 30px 66px -30px rgba(0,0,0,.75);}

*{box-sizing:border-box}
body{margin:0;background:var(--ground);color:var(--ink);
  font-family:"PingFang SC","Microsoft YaHei","Source Han Sans SC",system-ui,sans-serif;
  line-height:1.6;-webkit-font-smoothing:antialiased}
a{text-decoration:none;color:inherit}
img{max-width:100%}
.wrap{max-width:1180px;margin:0 auto;padding:0 clamp(18px,4vw,36px)}

/* nav */
.site-nav{position:sticky;top:0;z-index:20;backdrop-filter:blur(16px);-webkit-backdrop-filter:blur(16px);
  background:color-mix(in srgb,var(--ground) 72%,transparent);border-bottom:1px solid var(--line)}
.nav-in{max-width:1180px;margin:0 auto;padding:12px clamp(18px,4vw,36px);display:flex;align-items:center;gap:12px}
.brand{display:flex;align-items:center;gap:11px}
.brand img{width:38px;height:auto;display:block}
.brand .zh{font-size:1.16rem;font-weight:800;letter-spacing:.03em}
.brand .en{display:block;font-size:.58rem;letter-spacing:.3em;color:var(--muted);text-transform:uppercase;margin-top:1px}
.nav-cta{margin-left:auto;font-size:.85rem;font-weight:650;padding:9px 20px;border-radius:99px;color:#fff;position:relative;isolation:isolate;
  background:linear-gradient(135deg,rgba(47,111,219,.6),rgba(79,209,197,.48));
  backdrop-filter:blur(16px) saturate(185%);-webkit-backdrop-filter:blur(16px) saturate(185%);
  box-shadow:inset 0 1px 1px rgba(255,255,255,.55),0 10px 24px -10px rgba(47,111,219,.5);transition:transform .2s ease}
.nav-cta::before,.btn::before,.feature .go::before{content:"";position:absolute;inset:0;border-radius:inherit;padding:1px;pointer-events:none;
  background:linear-gradient(155deg,rgba(255,255,255,.82),rgba(255,255,255,.06) 45%,transparent 72%);
  -webkit-mask:linear-gradient(#000 0 0) content-box,linear-gradient(#000 0 0);-webkit-mask-composite:xor;
  mask:linear-gradient(#000 0 0) content-box,linear-gradient(#000 0 0);mask-composite:exclude}
.nav-cta:hover{transform:translateY(-1px)}

/* Liquid Glass 按钮 */
.btn{font-size:.95rem;font-weight:700;padding:14px 30px;border-radius:99px;display:inline-flex;align-items:center;gap:8px;
  position:relative;isolation:isolate;cursor:pointer;border:0;
  transition:transform .22s cubic-bezier(.2,.7,.3,1),box-shadow .22s ease,background .22s ease}
.btn.primary{color:#fff;background:linear-gradient(135deg,rgba(47,111,219,.62),rgba(79,209,197,.5));
  backdrop-filter:blur(18px) saturate(185%);-webkit-backdrop-filter:blur(18px) saturate(185%);
  box-shadow:inset 0 1px 1px rgba(255,255,255,.6),inset 0 -9px 18px -12px rgba(0,40,80,.55),0 14px 34px -12px rgba(47,111,219,.5)}
.btn.ghost{color:var(--ink);background:color-mix(in srgb,var(--surface) 32%,transparent);
  backdrop-filter:blur(18px) saturate(165%);-webkit-backdrop-filter:blur(18px) saturate(165%);
  box-shadow:inset 0 1px 1px rgba(255,255,255,.5),0 12px 28px -14px rgba(10,30,60,.32)}
.btn:hover{transform:translateY(-2px)}
.btn.primary:hover{box-shadow:inset 0 1px 1px rgba(255,255,255,.65),0 20px 44px -12px rgba(47,111,219,.62)}
.btn:active,.nav-cta:active{transform:translateY(0) scale(.97)}

/* 玻璃卡片（通用） */
.gcard{background:var(--glass);border:1px solid var(--glass-brd);border-radius:var(--r);
  backdrop-filter:blur(14px) saturate(150%);-webkit-backdrop-filter:blur(14px) saturate(150%);
  box-shadow:var(--shadow);transition:transform .22s ease,box-shadow .22s ease}
.gcard:hover{transform:translateY(-5px)}

/* sections */
.section{padding:clamp(30px,5vw,58px) 0}
.sec-head{display:flex;align-items:baseline;gap:14px;margin-bottom:22px}
.sec-head h2{font-size:1.5rem;font-weight:800;margin:0;letter-spacing:-.01em}
.sec-head .tag{font-size:.72rem;color:var(--muted);border:1px solid var(--line);border-radius:99px;padding:3px 11px}
.sec-head .line{flex:1;height:1px;background:var(--line)}

/* hero */
.hero{position:relative;overflow:hidden}
.hero .glow{position:absolute;inset:-20% -10% auto -10%;height:120%;pointer-events:none;
  background:radial-gradient(60% 60% at 72% 34%,var(--glow1),transparent 60%),radial-gradient(50% 50% at 20% 20%,var(--glow2),transparent 62%)}
.hero-in{position:relative;display:grid;grid-template-columns:1.05fr .95fr;gap:24px;align-items:center;padding:clamp(40px,6vw,86px) 0 clamp(30px,4vw,50px)}
.eyebrow{font-size:.76rem;letter-spacing:.24em;text-transform:uppercase;font-weight:700;color:var(--aqua);margin:0 0 16px}
.hero h1{font-size:clamp(2.2rem,6vw,4rem);line-height:1.08;margin:0 0 18px;font-weight:850;letter-spacing:-.02em;text-wrap:balance}
.hero h1 .g{background:linear-gradient(115deg,var(--brand1),var(--brand2));-webkit-background-clip:text;background-clip:text;color:transparent}
.hero p.lead{color:var(--muted);font-size:clamp(1rem,2vw,1.16rem);max-width:44ch;margin:0 0 28px}
.btns{display:flex;gap:14px;flex-wrap:wrap}
.hero-art{position:relative;display:flex;justify-content:center;align-items:center;min-height:340px}
.hero-art img{width:min(100%,520px);height:auto;filter:drop-shadow(0 30px 50px rgba(20,60,90,.4));animation:float 6s ease-in-out infinite}
@keyframes float{0%,100%{transform:translateY(-6px)}50%{transform:translateY(10px)}}
@media(prefers-reduced-motion:reduce){.hero-art img{animation:none}}
.scroll-hint{position:relative;text-align:center;color:var(--muted);font-size:.82rem;padding:6px 0 30px;letter-spacing:.02em}
.scroll-hint .dot{display:inline-block;margin-right:8px;color:var(--aqua)}

/* feature 大卡 */
.feature{position:relative;overflow:hidden;border-radius:26px;padding:clamp(26px,4vw,44px);
  background:linear-gradient(120deg,color-mix(in srgb,var(--brand1) 92%,#000),var(--brand2));color:#fff;
  display:grid;grid-template-columns:1.3fr .7fr;gap:20px;align-items:center;box-shadow:var(--shadow)}
.feature h3{font-size:clamp(1.5rem,3vw,2rem);margin:0 0 10px;font-weight:850}
.feature p{margin:0 0 22px;opacity:.92;max-width:40ch}
.feature .go{display:inline-flex;align-items:center;gap:8px;color:#fff;font-weight:700;padding:13px 26px;border-radius:99px;
  position:relative;isolation:isolate;background:rgba(255,255,255,.2);
  backdrop-filter:blur(16px) saturate(165%);-webkit-backdrop-filter:blur(16px) saturate(165%);
  box-shadow:inset 0 1px 1px rgba(255,255,255,.65),0 12px 28px -12px rgba(0,20,40,.35);transition:transform .2s ease,background .2s ease}
.feature .go:hover{transform:translateY(-2px);background:rgba(255,255,255,.28)}
.feature .pills{margin-top:16px;display:flex;gap:8px;flex-wrap:wrap}
.feature .pill{font-size:.76rem;background:rgba(255,255,255,.18);border:1px solid rgba(255,255,255,.28);border-radius:99px;padding:4px 12px}
.feature-art{display:flex;justify-content:center}
.feature-art img{width:min(100%,300px);filter:drop-shadow(0 20px 34px rgba(0,0,0,.3))}

/* footer */
.site-footer{padding:40px 0 60px;text-align:center;color:var(--muted);font-size:.82rem}
.site-footer .fmark{display:flex;align-items:center;justify-content:center;gap:9px;margin-bottom:8px}
.site-footer .fmark img{width:30px}
.site-footer .fmark b{font-size:1rem;color:var(--ink)}

@media(max-width:860px){
  .hero-in{grid-template-columns:1fr;text-align:center}
  .hero-art{order:-1;min-height:auto}.btns{justify-content:center}.hero p.lead{margin-inline:auto}
  .feature{grid-template-columns:1fr;text-align:center}.feature-art{order:-1}
}

/* 统一功能图标 tile（品牌渐变玻璃 + 白色线性图标，取代 emoji） */
.icotile{width:52px;height:52px;border-radius:15px;display:flex;align-items:center;justify-content:center;color:#fff;flex:none;
  background:linear-gradient(135deg,var(--brand1),var(--brand2));
  box-shadow:inset 0 1px 1px rgba(255,255,255,.5),0 12px 24px -10px var(--glow2)}
.icotile svg{width:26px;height:26px}
.btn svg,.nav-cta svg,.feature .go svg{width:18px;height:18px;flex:none}

/* ===== 滚动叙事 v4：海豚主角·滚动换动作·看鼠标（姿势序列擦除 + 鼠标微交互）===== */
.scene{position:relative;height:270vh;display:none}
.js-motion .scene{display:block}
.js-motion .hero-static{display:none}
.scene-stage{position:sticky;top:0;height:100vh;overflow:hidden;
  background:radial-gradient(92% 70% at 50% 16%,#0f3856,transparent 62%),linear-gradient(180deg,#06131f,#0a2438 58%,#0c3550)}
.scene-bubbles{position:absolute;inset:0;pointer-events:none;overflow:hidden}
.scene-bubbles i{position:absolute;bottom:-6%;border-radius:50%;
  background:radial-gradient(circle at 35% 30%,rgba(255,255,255,.55),rgba(150,220,230,.1));animation:rise linear infinite}
.scene-bubbles i:nth-child(1){left:16%;width:9px;height:9px;animation-duration:9s;animation-delay:-1s}
.scene-bubbles i:nth-child(2){left:30%;width:6px;height:6px;animation-duration:7s;animation-delay:-3s}
.scene-bubbles i:nth-child(3){left:46%;width:13px;height:13px;animation-duration:12s;animation-delay:-6s}
.scene-bubbles i:nth-child(4){left:62%;width:7px;height:7px;animation-duration:8s;animation-delay:-2s}
.scene-bubbles i:nth-child(5){left:78%;width:10px;height:10px;animation-duration:10s;animation-delay:-4.5s}
.scene-bubbles i:nth-child(6){left:88%;width:5px;height:5px;animation-duration:6.5s;animation-delay:-1.5s}
@keyframes rise{0%{transform:translateY(0);opacity:0}14%{opacity:.6}100%{transform:translateY(-104vh);opacity:0}}
.dolphin-wrap{position:absolute;left:50%;top:41%;transform:translate(-50%,-50%);
  width:min(46vw,440px);height:min(46vw,440px);perspective:1000px;z-index:3;pointer-events:none}
.dolphin-tilt{position:absolute;inset:0;transform-style:preserve-3d;will-change:transform;
  filter:drop-shadow(0 26px 46px rgba(0,30,50,.55))}
.pose{position:absolute;left:50%;top:50%;transform:translate(-50%,-50%);max-width:100%;max-height:100%;opacity:0;will-change:opacity}
.scene-copy{position:absolute;left:50%;bottom:11%;transform:translateX(-50%);width:min(94%,860px);text-align:center;z-index:4}
.scene-copy .eyebrow{opacity:0;color:#bfeef0;margin-bottom:14px}
.scene-copy h1{font-size:clamp(2rem,5.4vw,3.6rem);line-height:1.1;font-weight:850;letter-spacing:-.02em;margin:0 0 20px;opacity:0;white-space:nowrap;color:#fff}
.scene-copy h1 .g{background:linear-gradient(115deg,#8fd0ff,#4fe0d0);-webkit-background-clip:text;background-clip:text;color:transparent}
.scene-copy .btns{justify-content:center;opacity:0}
.scene-hint{position:absolute;bottom:26px;left:50%;transform:translateX(-50%);color:#cfe6ee;opacity:.85;z-index:4}
.scene-hint svg{width:26px;height:26px;animation:bob 1.6s ease-in-out infinite}
@keyframes bob{0%,100%{transform:translateY(0)}50%{transform:translateY(7px)}}
@media(max-width:860px){.dolphin-wrap{width:72vw;height:72vw;top:39%}}
@media (prefers-reduced-motion:reduce){.scene{display:none!important}.hero-static{display:block!important}}