:root{color-scheme:light;--paper:#faf9f6;--ink:#191c20;--body:#50565d;--muted:#6d7277;--line:#e5e3de;--accent:#344f5a;font-family:-apple-system,BlinkMacSystemFont,"Segoe UI","PingFang SC","Hiragino Sans GB","Microsoft YaHei",sans-serif;font-synthesis:none}
*{box-sizing:border-box}
html{scroll-padding-top:28px}
body{margin:0;background:var(--paper);color:var(--ink);font-size:16px;line-height:1.8;-webkit-font-smoothing:antialiased}
a{color:inherit;text-decoration:none}
a:focus-visible,summary:focus-visible{outline:2px solid var(--accent);outline-offset:5px;border-radius:4px}
::selection{background:#dbe6e6;color:#152d32}
.page-width{width:min(1040px,calc(100% - 64px));margin-inline:auto}
.skip-link{position:absolute;left:20px;top:12px;z-index:10;transform:translateY(-180%);padding:8px 16px;background:white;border:1px solid var(--line)}
.skip-link:focus{transform:none}
.site-header{min-height:100px;display:flex;align-items:center;justify-content:space-between;gap:24px;border-bottom:1px solid var(--line)}
.wordmark{display:inline-flex;align-items:center;gap:11px;font-size:15px;letter-spacing:.05em;font-weight:500;white-space:nowrap}
.wordmark-icon{display:grid;place-items:center;width:28px;height:28px;border:1px solid #b7c1c1;border-radius:6px;font-size:15px;line-height:1;color:var(--accent)}
.site-header nav{display:flex;gap:29px;color:var(--muted);font-size:14px}
.site-header nav a:hover,.icp-link:hover{color:var(--ink);text-decoration:underline;text-underline-offset:5px}
.intro{padding:62px 0 72px}
.site-kind{display:inline-block;margin:0 0 23px;border:1px solid var(--line);border-radius:999px;padding:3px 13px;color:var(--muted);font-size:13px;line-height:1.8}
h1{margin:0 0 23px;font-size:clamp(38px,4.5vw,52px);line-height:1.3;letter-spacing:-.035em;font-weight:650}
.intro-copy{max-width:960px;margin:0;color:var(--body);font-size:22px;line-height:1.9;letter-spacing:.005em}
.section{border-top:1px solid var(--line);padding:56px 0 64px;scroll-margin-top:25px}
.section-title{margin:0 0 29px;font-size:17px;line-height:1.5;font-weight:600;letter-spacing:.04em;color:var(--muted)}
.topic-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:20px}
.topic-card{padding:27px 29px 24px;background:#fff;border:1px solid var(--line);border-radius:14px}
.topic-card h3{margin:0 0 13px;font-size:22px;line-height:1.5;letter-spacing:-.02em;font-weight:600}
.topic-card p{margin:0;color:var(--body);font-size:17px;line-height:1.9}
.topic-tags{display:block;margin-top:20px;padding-top:14px;border-top:1px solid #efeeea;color:var(--muted);font-size:12px;letter-spacing:.025em}
.section-heading{display:flex;align-items:baseline;justify-content:space-between;gap:20px;margin-bottom:12px}
.section-heading .section-title{margin-bottom:16px}
.section-caption{color:var(--muted);font-size:13px}
.note-list{border-bottom:1px solid var(--line)}
.note{border-top:1px solid var(--line)}
.note summary{display:flex;align-items:center;gap:24px;padding:25px 0;cursor:pointer;list-style:none}
.note summary::-webkit-details-marker{display:none}
.note-category{width:84px;flex:none;font-size:13px;color:var(--muted)}
.note-title{flex:1;font-size:17px;color:#3f464c;line-height:1.7}
.note-toggle{position:relative;flex:none;width:20px;height:20px;margin-left:14px;color:#69777a}
.note-toggle::before,.note-toggle::after{content:"";position:absolute;background:currentColor;left:4px;top:9px;width:12px;height:1px}
.note-toggle::after{transform:rotate(90deg)}
.note[open] .note-toggle::after{transform:none}
.note[open] .note-title{color:#192e35}
.note-content{margin:0 40px 27px 108px;color:var(--body);font-size:16px;line-height:1.95;max-width:800px}
.note-content p{margin:0 0 16px}
.note-content p:last-child{margin-bottom:0}
.note-content ul{padding-left:1.25em;margin:0 0 16px}
.note-content li+li{margin-top:7px}
.note-content strong{font-weight:550;color:#353d43}
.about-section{padding-bottom:58px}
.about-section .section-title{margin-bottom:23px}
.about-section p{max-width:820px;color:var(--body);font-size:17px;margin:0;line-height:1.95}
.about-section p+p{margin-top:8px}
.site-footer{border-top:1px solid var(--line);padding:27px 0 38px;color:var(--muted);font-size:13px;line-height:1.8}
.footer-top{display:flex;justify-content:space-between;gap:12px;margin-bottom:9px}
.icp-link{font-size:13px}
.error-page{min-height:100svh;display:flex;flex-direction:column;justify-content:center;align-items:flex-start;padding-block:70px}
.error-page h1{font-size:36px}.error-page p{max-width:500px;color:var(--body);font-size:17px}
.return-link{display:inline-block;margin-top:15px;border-bottom:1px solid #839398;color:var(--accent)}
@media(max-width:640px){
  .page-width{width:calc(100% - 40px)}
  .site-header{min-height:82px;gap:14px}.wordmark{font-size:14px;gap:8px}.wordmark-icon{width:25px;height:25px;font-size:14px}
  .site-header nav{gap:16px;font-size:12px}.site-header nav a:first-child{display:none}
  .intro{padding:43px 0 46px}.site-kind{font-size:12px;margin-bottom:20px}h1{font-size:38px;margin-bottom:20px}.intro-copy{font-size:18px;line-height:1.95}
  .section{padding:38px 0 42px}.section-title{margin-bottom:23px;font-size:16px}
  .topic-grid{grid-template-columns:1fr;gap:14px}.topic-card{padding:22px 23px 20px}.topic-card h3{font-size:20px;margin-bottom:11px}.topic-card p{font-size:16px}.topic-tags{margin-top:16px;padding-top:12px;font-size:11px}
  .section-heading{display:block;margin-bottom:20px}.section-heading .section-title{margin-bottom:5px}.section-caption{font-size:12px}
  .note summary{flex-wrap:wrap;column-gap:12px;row-gap:8px;padding:21px 0}.note-category{width:100%;font-size:12px}.note-title{font-size:16px}.note-toggle{margin-left:0}
  .note-content{margin:0 0 23px;font-size:15px}.note-content ul{padding-left:1.3em}
  .about-section p{font-size:16px}.site-footer{padding:24px 0 30px;font-size:12px}.footer-top{flex-direction:column;gap:2px}.icp-link{font-size:12px}
}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}}
@media print{body{background:#fff;color:#000}.site-header nav,.skip-link{display:none}.page-width{width:100%}.intro{padding-block:25px}.section{padding-block:25px}.topic-card{break-inside:avoid}.note-content{display:block}.site-footer{padding-bottom:0}}