:root{
  --ink:#0b2033;
  --muted:#66798a;
  --line:#dce5eb;
  --paper:#fbfcfd;
  --surface:#ffffff;
  --accent:#2472b5;
  --max:1180px;
  --sans:ui-sans-serif,-apple-system,BlinkMacSystemFont,"SF Pro Text","Segoe UI","PingFang SC","Hiragino Sans GB","Noto Sans CJK SC","Microsoft YaHei","Helvetica Neue",Arial,sans-serif;
  --display:ui-sans-serif,-apple-system,BlinkMacSystemFont,"SF Pro Display","Segoe UI","PingFang SC","Hiragino Sans GB","Noto Sans CJK SC","Microsoft YaHei","Helvetica Neue",Arial,sans-serif;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;background:var(--paper);color:var(--ink);font-family:var(--sans);font-size:16px;line-height:1.85;-webkit-font-smoothing:antialiased;text-rendering:optimizeLegibility}
body.lang-zh [data-en]{display:none!important}
body.lang-en [data-zh]{display:none!important}
body.lang-en{font-family:-apple-system,BlinkMacSystemFont,"Segoe UI","Helvetica Neue",Arial,sans-serif}
a{color:inherit;text-decoration:none}
img{display:block;max-width:100%}
button{font-family:inherit}
:focus-visible{outline:3px solid rgba(36,114,181,.38);outline-offset:3px}
.skip-link{position:fixed;left:16px;top:12px;z-index:1000;padding:10px 14px;background:var(--ink);color:#fff;border-radius:6px;transform:translateY(-160%);transition:transform .18s ease}
.skip-link:focus{transform:translateY(0)}
.wrap{max-width:var(--max);margin:0 auto;padding:0 42px}
.topbar{position:sticky;top:0;z-index:50;background:rgba(255,255,255,.9);backdrop-filter:blur(18px);border-bottom:1px solid rgba(11,32,51,.08)}
nav{height:76px;display:flex;align-items:center;justify-content:space-between;gap:28px}
.identity{display:flex;align-items:center;gap:12px;min-width:220px}
.wordmark{font-family:var(--display);font-size:18px;font-weight:740;letter-spacing:-.025em;line-height:1.1;color:var(--ink);white-space:nowrap}
.wordmark .brand-i{color:var(--accent);font-weight:760}
.identity small{display:block;font-size:10.5px;line-height:1.2;color:var(--muted);margin-top:5px;letter-spacing:.04em}
.navlinks{display:flex;align-items:center;gap:23px;font-size:12.5px;color:#4d5660}
.navlinks a{transition:color .18s ease}
.navlinks a:hover{color:var(--accent)}
.lang-switch{display:flex;gap:3px;padding:3px;border:1px solid #cccdc9;border-radius:999px;background:rgba(255,255,255,.6)}
.lang-switch button{border:0;background:transparent;border-radius:999px;padding:6px 9px;font-size:11px;color:var(--muted);cursor:pointer}
.lang-switch button.active{background:var(--ink);color:#fff}
.menu-toggle{display:none;border:0;background:transparent;padding:7px;cursor:pointer;color:var(--ink)}
.menu-toggle span{display:block;width:20px;height:1.5px;background:currentColor;margin:4px 0}
.mobile-menu{display:none;border-top:1px solid rgba(11,32,51,.08);padding:8px 0 16px}
.mobile-menu a{display:block;padding:10px 0;font-size:13px;color:#405565;border-bottom:1px solid rgba(11,32,51,.06)}
.mobile-menu a:last-child{border-bottom:0}
.article{max-width:760px;margin:0 auto;padding:54px 0 28px}
.crumb{font-size:12.5px;color:var(--muted);margin:0 0 22px;line-height:1.6}
.crumb a:hover{color:var(--accent)}
.kicker{font-size:11px;letter-spacing:.14em;text-transform:uppercase;color:var(--accent);font-weight:760;margin:0 0 14px}
.article h1{font-family:var(--display);font-size:34px;line-height:1.35;letter-spacing:-.02em;font-weight:680;margin:0 0 22px;overflow-wrap:break-word}
.lede{font-size:17px;line-height:1.85;color:#31485a;margin:0 0 28px}
.article h2{font-family:var(--display);font-size:22px;line-height:1.45;font-weight:650;margin:34px 0 12px}
.article p{margin:0 0 18px;color:#3e4953;overflow-wrap:break-word}
.article a{color:var(--accent);font-weight:650}
.article a:hover{text-decoration:underline}
.note-boundary{margin:8px 0 0;font-size:13px;line-height:1.75;color:#66798a}
.note-end{display:flex;flex-wrap:wrap;gap:10px 22px;margin-top:28px;padding-top:18px;border-top:1px solid var(--line)}
.note-end a{color:var(--accent);font-size:13.5px;font-weight:650}
.note-end a:hover{text-decoration:underline}
footer{padding:36px 0 44px;border-top:1px solid var(--line)}
.footer{display:flex;justify-content:space-between;align-items:center;gap:30px;font-size:11px;color:var(--muted)}
.footer-person{display:flex;align-items:center;gap:10px}
.footer-person img{width:34px;height:34px;border-radius:50%;object-fit:cover;object-position:center 17%}
.footer-person strong{font-size:12px;color:var(--ink)}
.footer-note{max-width:430px;text-align:right;line-height:1.65}
@media(max-width:980px){
  .navlinks>a{display:none}
  .menu-toggle{display:inline-flex;flex-direction:column;justify-content:center}
  .mobile-menu.open{display:block}
}
@media(max-width:700px){
  .wrap{padding:0 22px}
  nav{height:68px}
  .identity{min-width:0}
  .identity small{display:none}
  .article{padding-top:36px}
  .article h1{font-size:28px;line-height:1.4}
  .lede,.article p{font-size:16px}
  .footer{flex-direction:column;align-items:flex-start}
  .footer-note{text-align:left;max-width:none}
}