:root{
  --bg:#04050a; --bg2:#0a0f1e;
  --blue:#3fa9ff; --cyan:#7fe0ff; --deep:#1a49b8;
  --text:#eaf2ff; --muted:#9fb2d6; --card:rgba(30,52,110,.28);
  --line:rgba(120,175,255,.22);
}
*{box-sizing:border-box}
html,body{margin:0;padding:0}
body{
  background:
    radial-gradient(1200px 700px at 50% -10%, rgba(40,110,255,.20), transparent 60%),
    radial-gradient(900px 600px at 80% 20%, rgba(0,220,255,.10), transparent 55%),
    var(--bg);
  color:var(--text);
  font-family:-apple-system,BlinkMacSystemFont,"Segoe UI","PingFang SC","Hiragino Sans","Noto Sans CJK SC",sans-serif;
  line-height:1.7; min-height:100vh;
  -webkit-font-smoothing:antialiased;
}
a{color:var(--cyan);text-decoration:none}
a:hover{text-decoration:underline}
.wrap{max-width:860px;margin:0 auto;padding:0 22px}

/* top bar */
.nav{display:flex;align-items:center;justify-content:space-between;padding:22px 0}
.brand{display:flex;align-items:center;gap:12px;font-weight:700;letter-spacing:.3px}
.brand img{width:38px;height:38px;border-radius:10px;box-shadow:0 0 18px rgba(63,169,255,.55)}
/* 语言下拉：点击展开列表 */
.lang{position:relative}
.lang-btn{
  display:flex;align-items:center;gap:7px;
  background:transparent;border:1px solid var(--line);color:var(--text);
  padding:7px 13px;border-radius:999px;cursor:pointer;font-size:14px;transition:.2s;
}
.lang-btn:hover{border-color:var(--blue)}
.lang-btn .arrow{font-size:10px;color:var(--muted);transition:transform .2s}
.lang.open .lang-btn .arrow{transform:rotate(180deg)}
.lang-menu{
  position:absolute;right:0;top:calc(100% + 8px);min-width:132px;z-index:20;
  background:#0b1226;border:1px solid var(--line);border-radius:14px;padding:6px;
  box-shadow:0 14px 40px rgba(0,0,0,.55);display:none;
}
.lang.open .lang-menu{display:block}
.lang-menu button{
  display:block;width:100%;text-align:left;background:transparent;border:0;color:var(--muted);
  padding:9px 12px;border-radius:9px;cursor:pointer;font-size:14px;transition:.15s;
}
.lang-menu button:hover{background:rgba(63,169,255,.14);color:var(--text)}
.lang-menu button.on{color:#fff;background:linear-gradient(180deg,var(--blue),var(--deep))}

/* hero */
.hero{text-align:center;padding:46px 0 30px}
.hero .gem{width:132px;height:132px;border-radius:28px;box-shadow:0 0 60px rgba(63,169,255,.55),0 0 120px rgba(0,180,255,.28)}
.hero h1{font-size:38px;margin:22px 0 6px;letter-spacing:.5px;
  background:linear-gradient(180deg,#fff,#bcd8ff);-webkit-background-clip:text;background-clip:text;color:transparent}
.hero p.sub{color:var(--muted);font-size:17px;margin:0 auto;max-width:520px}
.cta{display:flex;gap:14px;justify-content:center;flex-wrap:wrap;margin:30px 0 4px}
.btn{
  display:inline-block;padding:12px 26px;border-radius:999px;font-weight:600;font-size:15px;
  background:linear-gradient(180deg,var(--blue),var(--deep));color:#fff;
  box-shadow:0 6px 26px rgba(40,110,255,.45);transition:.2s;border:1px solid transparent;
}
.btn:hover{transform:translateY(-2px);text-decoration:none;box-shadow:0 10px 34px rgba(40,110,255,.6)}
.btn.ghost{background:transparent;border-color:var(--line);color:var(--text);box-shadow:none}
.btn.ghost:hover{border-color:var(--blue)}

/* features */
.grid{display:grid;grid-template-columns:repeat(2,1fr);gap:16px;margin:40px 0}
.card{background:var(--card);border:1px solid var(--line);border-radius:18px;padding:20px 22px;backdrop-filter:blur(6px)}
.card h3{margin:0 0 6px;font-size:17px}
.card p{margin:0;color:var(--muted);font-size:14.5px}

/* content pages */
.page{padding:30px 0 10px}
.page h2{font-size:27px;margin:6px 0 4px;
  background:linear-gradient(180deg,#fff,#bcd8ff);-webkit-background-clip:text;background-clip:text;color:transparent}
.page .updated{color:var(--muted);font-size:13px;margin-bottom:22px}
.page h3{font-size:18px;margin:26px 0 6px}
.page p{color:#d3e2ff}
.page ul{color:#d3e2ff;padding-left:20px}
.page li{margin:5px 0}

/* footer */
.foot{border-top:1px solid var(--line);margin-top:46px;padding:26px 0 40px;text-align:center;color:var(--muted);font-size:13.5px}
.foot a{margin:0 10px}
.hide{display:none}
@media(max-width:640px){.grid{grid-template-columns:1fr}.hero h1{font-size:31px}}