/* System fonts only; consistent across macOS, Windows, Android. */
:root{--sans:-apple-system,BlinkMacSystemFont,"PingFang SC","HarmonyOS Sans SC","MiSans","Hiragino Sans GB","Microsoft YaHei UI","Microsoft YaHei","Noto Sans CJK SC",sans-serif;--mono:ui-monospace,"SF Mono","JetBrains Mono",Menlo,Consolas,monospace;--ink:#111;--soft:#555;--mute:#999;--rule:#e4e4e2;--hot:#ff4a1c;--bg:#fafaf9}
*{box-sizing:border-box}body,h1,h2,p,ul,figure,blockquote{margin:0;padding:0}ul{list-style:none}a{color:inherit;text-decoration:none}img{display:block;max-width:100%;height:auto}
html{scroll-behavior:smooth;scroll-padding-top:24px}body{font-family:var(--sans);background:var(--bg);color:var(--ink);-webkit-font-smoothing:antialiased;font-synthesis:none}
::selection{background:#ffe0d6}a:focus-visible,summary:focus-visible,button:focus-visible{outline:2px solid var(--hot);outline-offset:4px}
.skip{position:absolute;left:16px;top:12px;padding:10px 16px;background:var(--ink);color:#fff;z-index:9;transform:translateY(-200%)}.skip:focus{transform:none}
.t{text-wrap:pretty;line-break:strict}.nw{white-space:nowrap}
.mono{font-family:var(--mono);font-size:12px;letter-spacing:.01em}
.w{width:min(1200px,calc(100% - 80px));margin:0 auto}
.g{display:grid;grid-template-columns:repeat(12,1fr);column-gap:24px}

.top{display:flex;justify-content:space-between;align-items:center;height:64px;border-bottom:1px solid var(--ink)}
.top.home{justify-content:flex-end}
.mark{font-size:14px;font-weight:600}
.top nav{display:flex;gap:28px;color:#666}.top nav a{padding:14px 0}.top nav a:hover,.top nav a[aria-current]{color:var(--ink)}
.top nav a[aria-current]{box-shadow:inset 0 -1px var(--ink)}

.hero{padding:clamp(64px,8vh,96px) 0 48px;border-bottom:1px solid #ddd}
.hero h1{font-size:clamp(80px,7vw,96px);line-height:1.05;font-weight:700;letter-spacing:-.035em}
.focus{margin-top:24px;font-size:18px;line-height:1.6;font-weight:400}

section{padding:56px 0;border-bottom:1px solid #ddd}
section>h2{grid-column:1/4;font-weight:400;color:#6b6b68}
.tbl{grid-column:4/-1}
.yr{color:var(--mute);padding:0 0 12px}.yr~.yr{padding-top:36px}
.r{display:grid;grid-template-columns:96px 1fr 24px;gap:24px;align-items:baseline;padding:16px 0;border-top:1px solid var(--rule)}
.r time{color:var(--ink)}
.r .ti{font-size:17px;line-height:1.6;font-weight:500}
.r .ar{color:var(--hot);opacity:0;transform:translateX(-4px);transition:.2s;text-align:right}
.r:hover .ar,.r:focus-visible .ar{opacity:1;transform:none}
.pr{grid-template-columns:1fr 1fr 24px}.pr .s{color:#777;font-size:14px}

.about{padding:16vh 0 12vh}
.about h1{font-size:clamp(40px,6vw,80px);line-height:1.1;font-weight:700;letter-spacing:-.04em}
.about blockquote{margin-top:12vh;max-width:20em;font-size:clamp(22px,2.6vw,32px);line-height:1.6;font-weight:500;letter-spacing:-.01em}
.about blockquote p+p{margin-top:.4em}
.wx{margin-top:12vh;display:flex;gap:20px;align-items:center;font-size:15px;line-height:1.9}.wx img{mix-blend-mode:multiply}.wx .n{color:var(--mute);font-size:13px}

.reader{padding:72px 0 56px;border-bottom:1px solid #ddd}
.side{grid-column:1/4;color:var(--mute)}
.toc{position:sticky;top:32px;margin-top:40px}.toc summary{cursor:pointer;list-style:none;color:var(--mute);margin-bottom:12px}.toc summary::-webkit-details-marker{display:none}
.toc nav{display:flex;flex-direction:column;gap:10px;font-size:13px;line-height:1.6;max-width:16em}.toc a:hover,.toc a[aria-current="location"]{color:var(--ink)}
.col{grid-column:4/11;min-width:0}
.col h1{font-size:clamp(28px,3.2vw,40px);line-height:1.35;font-weight:700;letter-spacing:-.02em}
.body{margin-top:56px;font-size:18px;line-height:1.9;color:#2a2a2a;overflow-wrap:anywhere}
.body>p{margin-bottom:1.3em}
.body h2{font-size:1.2em;font-weight:700;line-height:1.5;margin:2.4em 0 .9em;color:var(--ink)}
.body figure{margin:2em 0}.body figure img{margin:0 auto}
.body .caption{text-align:center;color:var(--mute);font-size:13px;margin:-1em 0 2em}
.body .table-scroll{overflow-x:auto;margin:2em 0}.body table{border-collapse:collapse;width:100%;font-size:.8em;line-height:1.7}.body th,.body td{border:1px solid var(--rule);padding:10px 12px;text-align:left;vertical-align:top}.body th{background:#f1f1ef;font-weight:600}
.src{margin-top:56px;padding-top:20px;border-top:1px solid var(--rule);font-size:14px;color:var(--mute)}.src a{color:var(--ink)}.src a:hover{text-decoration:underline;text-underline-offset:4px}
.next{display:block;margin-top:40px}.next .mono{display:block;color:var(--mute);margin-bottom:8px}.next .ti{font-size:20px;font-weight:600;line-height:1.5}.next:hover .ti{color:#000;text-decoration:underline;text-decoration-thickness:1px;text-underline-offset:6px}

footer{display:flex;justify-content:space-between;padding:28px 0 48px;color:var(--mute)}footer nav{display:flex;gap:24px}footer a{padding:6px 0}footer a:hover{color:var(--ink)}

@media(max-width:820px){.w{width:calc(100% - 40px)}.top nav{gap:20px}
.hero{padding:48px 0 36px}.hero h1{font-size:clamp(46px,12vw,54px)}.focus{margin-top:20px;font-size:16px}
section{display:block;padding:40px 0}section>h2{margin-bottom:20px}
.r{grid-template-columns:1fr 20px;gap:4px 12px}.r time{grid-column:1/-1;color:var(--mute)}.r .ti{grid-column:1}.r .ar{opacity:1;transform:none;grid-row:2;grid-column:2}
.pr{grid-template-columns:1fr 20px}.pr .ar{grid-row:1}.pr .s{grid-column:1}
.about{padding:9vh 0}.about h1{font-size:40px}.about blockquote{margin-top:64px;font-size:22px}.wx{margin-top:64px}
.reader{display:flex;flex-direction:column;padding:40px 0}.side,.col{display:contents}.side time{order:1}.col h1{order:2;margin-top:12px}.toc{order:3}.body{order:4}.src{order:5}.next{order:6}
.toc{position:static;margin:24px 0 0;padding:12px 0;border-top:1px solid var(--rule);border-bottom:1px solid var(--rule)}.toc summary{margin:0}.toc nav{padding-top:12px;max-width:none}
.col h1{font-size:28px}.body{margin-top:32px;font-size:17px}}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}}
@media(min-width:821px){.col h1,.about h1{word-break:keep-all;overflow-wrap:anywhere}}
@media(max-width:820px){section.g{display:block}}
footer{align-items:center}
@media(max-width:820px){.r .ar{color:#bbb}}
/* Article content, rebuilt from the original WeChat structure */
.body strong{font-weight:600;color:var(--ink)}
.body a{color:var(--ink);border-bottom:1px solid #ccc}.body a:hover{border-color:var(--ink)}
.body h2 .n{font-family:var(--mono);font-size:.7em;font-weight:400;color:var(--mute);margin-right:12px;vertical-align:.12em}
.body h3{font-size:1em;font-weight:600;line-height:1.6;margin:2.2em 0 .8em;color:var(--ink)}
.body .c{text-align:center}
.body .note{font-size:14px;color:var(--mute);margin-top:-.6em}
.body .cap,.body figcaption{font-size:13px;line-height:1.7;color:var(--mute);text-align:center}
.body .cap{margin:-.4em 0 2em}.body figcaption{margin-top:10px}
.body figure{margin:2em 0}.body figure img{margin:0 auto}
.body blockquote{margin:1.6em 0;padding:2px 0 2px 20px;border-left:2px solid var(--ink);font-size:.89em;line-height:1.85;color:var(--soft)}
.body blockquote p{margin:0 0 .7em}.body blockquote p:last-child{margin-bottom:0}
.body ul,.body ol{margin:0 0 1.3em;padding-left:1.4em}.body ul{list-style:disc}.body li{margin:.3em 0}.body li.fig{list-style:none}
.body pre{margin:1.6em 0;padding:16px 18px;background:#f1f1ef;overflow-x:auto;font-size:13px;line-height:1.7}.body pre code{font-family:var(--mono)}
.body :not(pre)>code{font-family:var(--mono);font-size:.88em;background:#f1f1ef;padding:1px 5px}
.body .tbl-x{overflow-x:auto;margin:1.6em 0}.body table{border-collapse:collapse;width:100%;font-size:.82em;line-height:1.7}.body td{border:1px solid var(--rule);padding:8px 12px;vertical-align:top}.body tr:first-child td{background:#f1f1ef;font-weight:600}
.body .video{margin:1.6em 0;padding:18px 20px;border:1px solid var(--rule);font-size:14px}.body .video a{border:0;color:var(--soft)}.body .video a:hover{color:var(--ink)}
.body hr{border:0;border-top:1px solid var(--rule);margin:2.4em 0}
@media(max-width:820px){.body,.src,.next,.col h1,.toc{min-width:0;max-width:100%;width:100%}}
.body>h2:first-child,.body>h3:first-child{margin-top:0}

/* Home: lead-in, more link */
.focus .lead{color:var(--mute);font-weight:400;margin-right:.6em}
.hero .focus .lead{color:#6b6b68}
.more{display:inline-block;margin-top:24px;color:var(--ink)}.more span{color:var(--hot)}.more:hover{text-decoration:underline;text-underline-offset:4px}
.yr span{color:#bbb}
/* Page head shared by 文章 / 关于 */
.ph{padding:12vh 0 56px;border-bottom:1px solid #ddd}
.ph h1{font-size:clamp(40px,6vw,72px);line-height:1;font-weight:700;letter-spacing:-.04em}
.ph p{margin-top:20px;color:var(--mute)}
section.first{border-top:0}
/* About: same grid as home, quiet type */
.prose2 .focus{margin:0;font-size:17px;font-weight:500}
.prose2 blockquote{margin-top:28px;max-width:30em;font-size:16px;line-height:2;color:var(--soft)}
.links li{display:grid;grid-template-columns:96px 1fr;gap:24px;align-items:baseline;padding:16px 0;border-top:1px solid var(--rule);font-size:15px}
.links .k{color:var(--mute)}
.links a:hover{text-decoration:underline;text-underline-offset:4px}
.email-reveal{display:none;font:inherit;color:var(--soft);text-align:left;border:0;padding:0;background:none;cursor:pointer}
.email-reveal:hover{color:var(--ink)}
.email-reveal.ready{display:inline}
.email-address{color:var(--soft);overflow-wrap:anywhere}
.wxl .id{color:var(--mute)}
.qr-wrap{position:relative;display:inline-block;margin-left:14px}
.qr-btn{border:0;background:none;padding:4px 0;color:var(--mute);cursor:pointer;border-bottom:1px dashed #bbb}.qr-btn:hover,.qr-btn[aria-expanded="true"]{color:var(--ink);border-color:var(--ink)}
.qr-pop{position:absolute;left:0;top:calc(100% + 10px);z-index:5;display:flex;flex-direction:column;align-items:center;gap:8px;padding:14px 14px 10px;background:#fff;border:1px solid var(--rule);box-shadow:0 8px 24px rgba(0,0,0,.06);color:var(--mute)}
.qr-pop[hidden]{display:none}.qr-pop img{display:block}

@media(max-width:820px){.ph{padding:8vh 0 36px}.ph h1{font-size:44px}.links li{grid-template-columns:72px 1fr;gap:12px}.qr-wrap{margin-left:0;display:block;margin-top:4px}.qr-pop{left:0}.focus .lead{display:block;margin:0 0 4px}}
.qr-pop{width:max-content}
.ph{padding:10vh 0 40px}.ph h1{font-size:32px;line-height:1.2;font-weight:600;letter-spacing:-.01em}
@media(max-width:820px){.ph{padding:6vh 0 28px}.ph h1{font-size:28px}}
.top nav .lang{margin-left:12px}
footer .qr-btn{font:inherit;color:inherit;border:0;background:none;padding:6px 0;cursor:pointer}footer .qr-btn:hover,footer .qr-btn[aria-expanded="true"]{color:var(--ink)}
.qr-wrap.up{margin-left:0}.qr-wrap.up .qr-pop{top:auto;bottom:calc(100% + 12px);left:auto;right:0}
@media(max-width:820px){.top nav .lang{margin-left:4px}.qr-wrap.up{display:inline-block;margin-top:0}.qr-wrap.up .qr-pop{left:auto;right:0}}

/* Keep the about-page QR code inside the mobile viewport when opened. */
@media(max-width:820px){.links .qr-pop{top:auto;bottom:calc(100% + 10px)}}