*{box-sizing:border-box}html{color-scheme:light;scroll-behavior:smooth}body{margin:0;background:#f5f5f7;color:#1d1d1f;font:17px/1.65 -apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif;-webkit-font-smoothing:antialiased}a{color:#a71829;text-underline-offset:.19em}a:hover{text-decoration-thickness:2px}a:focus-visible{outline:3px solid #b82032;outline-offset:5px;border-radius:3px}.skip{position:absolute;left:16px;top:-90px;background:white;padding:10px 16px;z-index:3}.skip:focus{top:12px}.bar{background:#101013;color:#f5f5f7;border-bottom:1px solid #343438}.bar-inner{max-width:1020px;min-height:88px;margin:auto;padding:18px 32px;display:flex;gap:24px;align-items:center;justify-content:space-between}.brand{display:flex;gap:13px;align-items:center;text-decoration:none;color:inherit;font-weight:650;letter-spacing:-.025em;line-height:1.25}.brand img{width:48px;height:48px;border-radius:12px}.brand small{display:block;color:#a8a8af;font-weight:400;font-size:12px;letter-spacing:.01em;margin-top:4px}nav{display:flex;gap:26px;font-size:14px}nav a{color:#c8c8cf;text-decoration:none}nav a[aria-current=page]{color:#fff;text-decoration:underline;text-decoration-color:#fb344d;text-underline-offset:8px}main{max-width:900px;margin:48px auto 72px;padding:48px 64px;background:#fff;border:1px solid #e8e8ed;border-radius:24px}article>header{padding-bottom:28px;border-bottom:1px solid #e8e8ed}article>header>p:first-child{font-weight:600;color:#b0182b;font-size:14px;letter-spacing:.015em;margin-top:0}h1{font-size:clamp(36px,6vw,52px);line-height:1.08;letter-spacing:-.045em;font-weight:700;margin:10px 0 22px}article>header p{color:#606068}article>header p:last-child{margin-bottom:0}section{margin-top:38px}h2{font-size:25px;letter-spacing:-.025em;line-height:1.25;margin:0 0 15px}h3{font-size:18px;letter-spacing:-.015em;line-height:1.4;margin:28px 0 8px}p{margin:0 0 17px}li{margin-bottom:12px}ul{padding-left:24px}code{font:14px ui-monospace,monospace;overflow-wrap:anywhere;background:#f5f5f7;padding:2px 5px;border-radius:4px}article a{overflow-wrap:anywhere}.footer{max-width:900px;padding:0 32px 40px;margin:auto;display:flex;flex-wrap:wrap;justify-content:space-between;gap:16px;color:#6e6e73;font-size:13px}.footer p{margin:0}.footer a{color:inherit}.footer-links{display:flex;gap:22px}@media(max-width:640px){.bar-inner{padding:16px 20px;flex-wrap:wrap;gap:18px}.brand img{width:42px;height:42px}.brand{font-size:16px}nav{gap:24px}main{margin:24px 12px 40px;padding:30px 24px;border-radius:20px}h2{font-size:23px}.footer{padding:0 24px 28px}}@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}}
/* Shared language preference and public testing invitation. */
[hidden]{display:none!important}
nav{align-items:center;flex-wrap:wrap;gap:20px}
.language-control{display:flex;align-items:center}
.language-switch{min-height:38px;max-width:150px;padding:7px 30px 7px 12px;border:1px solid #66666e;border-radius:9px;background:#232328;color:#fff;font:inherit;line-height:1.35;cursor:pointer}
.language-switch option{background:#232328;color:#fff}
.language-switch:focus-visible{outline:3px solid #ff6980;outline-offset:4px}
.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}
.testflight-callout{padding:24px;border:1px solid #edc9cf;border-left:4px solid #b0182b;border-radius:14px;background:#fff7f8}
.testflight-callout h2{font-size:23px}
.testflight-callout p:last-child{margin-bottom:0}
html[lang^="zh"] body{line-height:1.8}
html[lang^="zh"] h1,html[lang^="zh"] h2,html[lang^="zh"] h3{letter-spacing:0;line-height:1.4}
@media(max-width:640px){.bar-inner{gap:20px}nav{width:100%;gap:22px}.language-control{margin-left:auto}.language-switch{max-width:145px}.testflight-callout{padding:20px}html[lang^="zh"] main{padding:28px 22px}}
@media(max-width:360px){nav{gap:16px}.language-switch{max-width:138px;padding-left:10px}}