:root { color-scheme: light dark; --bg: #f6f8f9; --surface: #fff; --text: #23303c; --muted: #52646b; --accent: #345c69; }
* { box-sizing: border-box; }
body { margin: 0; background: var(--bg); color: var(--text); font: 16px/1.8 -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif; }
nav { max-width: 960px; margin: auto; padding: 24px; display: flex; justify-content: space-between; align-items: center; gap: 24px; }
.brand { font-size: 27px; letter-spacing: -1px; color: var(--text); text-decoration: none; }
a { color: var(--accent); text-underline-offset: 4px; overflow-wrap: anywhere; }
a:focus-visible { outline: 2px solid var(--accent); outline-offset: 6px; }
.skip { position: absolute; left: 24px; top: -100px; padding: 10px 16px; background: var(--surface); z-index: 2; }
.skip:focus { top: 8px; }
main { max-width: 900px; margin: 36px auto; padding: 0 24px 40px; }
h1 { font-family: ui-serif, Georgia, serif; font-weight: 500; font-size: clamp(32px, 6vw, 62px); line-height: 1.2; letter-spacing: -1px; }
h1 span { font-size: .68em; line-height: 1.6; }
h2 { font-size: 21px; line-height: 1.5; margin: 0 0 14px; }
section { padding-top: 32px; }
p, li { max-width: 72ch; }
section p { margin: 10px 0; }
section p[lang="zh-Hans"] { color: var(--muted); }
.lead { font-size: 19px; color: var(--muted); }
.notice { font-size: 14px; color: var(--muted); margin-top: 36px; }
.study { height: clamp(220px, 40vw, 360px); border-radius: 24px; overflow: hidden; background: linear-gradient(#d3e7e8, #81a8b5); position: relative; margin: 40px 0 16px; }
.sun { position: absolute; right: 20%; top: 15%; width: 65px; height: 65px; background: #e6eee7; border-radius: 50%; }
.wave { position: absolute; inset: 60% -15% -70%; background: #4c7487; border-radius: 45%; transform: rotate(-8deg); box-shadow: 0 -24px 0 #769eac, 0 25px 0 #244654; }
footer { display: flex; flex-wrap: wrap; gap: 16px 25px; padding-top: 30px; border-top: 1px solid #dce2e4; margin-top: 48px; font-size: 14px; }
footer span { color: var(--muted); }
@media (prefers-color-scheme: dark) { :root { --bg: #171d22; --surface: #222b31; --text: #e3ebed; --muted: #b0bec3; --accent: #9dc9cf; } footer { border-color: #39464e; } }
@media (prefers-reduced-motion: reduce) { * { scroll-behavior: auto !important; } }