:root{--ink:#14233a;--muted:#617086;--paper:#f5f7fa;--card:#fff;--line:#dfe6ee;--blue:#1769d2;--cyan:#0fa9b8;--orange:#ec7b35;--navy:#102844;--soft-blue:#eaf3ff;--soft-cyan:#e8f9fa;--soft-orange:#fff2e7;--shadow:0 12px 35px rgba(24,46,78,.08)}
*{box-sizing:border-box}html{scroll-behavior:smooth;scroll-padding-top:84px}body{margin:0;background:var(--paper);color:var(--ink);font:16px/1.75 "Microsoft YaHei","PingFang SC",system-ui,sans-serif;transition:.25s}a{color:inherit}code{font-family:"Cascadia Code",Consolas,monospace;font-size:.91em;background:#edf2f7;padding:2px 6px;border-radius:5px;color:#b24e1b}button{font:inherit}.progress-line{position:fixed;left:0;top:0;height:3px;background:linear-gradient(90deg,var(--cyan),var(--blue));z-index:100;width:0}.topbar{height:68px;position:sticky;top:0;z-index:50;padding:0 max(4vw,24px);display:flex;align-items:center;background:rgba(255,255,255,.9);backdrop-filter:blur(15px);border-bottom:1px solid rgba(223,230,238,.9)}.brand{text-decoration:none;font-weight:800;margin-right:auto}.brand-dot{display:inline-block;width:10px;height:10px;border-radius:50%;background:var(--cyan);margin-right:9px;box-shadow:0 0 0 5px #0fa9b81b}.topnav{display:flex;gap:25px}.topnav a{text-decoration:none;color:var(--muted);font-size:14px}.topnav a:hover{color:var(--blue)}.theme-btn{width:36px;height:36px;margin-left:25px;border:1px solid var(--line);border-radius:10px;background:var(--card);color:var(--ink);cursor:pointer}
.hero{color:#fff;background:radial-gradient(circle at 78% 12%,rgba(15,169,184,.24),transparent 25%),linear-gradient(125deg,#0d2038,#11345a 70%,#0d4754);overflow:hidden}.hero-inner{max-width:1220px;margin:auto;padding:84px 30px 55px;display:grid;grid-template-columns:.9fr 1.1fr;align-items:center;gap:65px}.kicker,.eyebrow{font-size:12px;font-weight:800;letter-spacing:2.2px;color:#39c8d5}.hero h1{font-size:clamp(48px,6vw,76px);line-height:1.08;letter-spacing:-3px;margin:14px 0 22px}.hero-copy>p{font-size:18px;color:#c3d4e5;max-width:540px}.hero-actions{display:flex;align-items:center;gap:20px;margin-top:28px}.hero-actions span{font-size:13px;color:#95adc5}.primary-btn{text-decoration:none;background:#fff;color:#123356;padding:12px 22px;border-radius:10px;font-weight:800;box-shadow:0 9px 30px #0003}.hero-visual{display:flex;align-items:center;min-height:270px;position:relative}.visual-label{position:absolute;top:5px;left:50%;transform:translateX(-50%);font-size:11px;letter-spacing:1.7px;color:#86a8c6}.device{width:120px;height:145px;border:1px solid #ffffff32;border-radius:18px;background:#ffffff10;display:flex;flex-direction:column;align-items:center;justify-content:center;text-align:center;backdrop-filter:blur(6px)}.device>span{font-size:35px}.device small,.cloud-core small{font-size:10px;color:#91abc2}.device b,.cloud-core b{font-size:13px;margin-top:6px}.cloud-core{width:155px;height:155px;flex:none;border:1px solid #37c8d24d;border-radius:50%;background:radial-gradient(circle,#15506b,#102c4b);display:flex;flex-direction:column;align-items:center;justify-content:center;box-shadow:0 0 50px #11a5b52e}.cloud-core>span{font-size:28px}.signal{flex:1;min-width:55px;height:4px;display:flex;align-items:center;justify-content:space-around;position:relative}.signal:before{content:"";position:absolute;left:0;right:0;height:1px;background:#78dbe5}.signal i{width:5px;height:5px;border-radius:50%;background:#78dbe5}.moving-packet{position:absolute;width:28px;height:20px;background:#ec7b35;border-radius:5px;text-align:center;font-size:9px;line-height:20px;animation:travel 2.8s infinite ease-in-out;box-shadow:0 0 15px #ec7b35}@keyframes travel{0%,12%{left:-5%}85%,100%{left:90%}}.hero-stats{max-width:1160px;margin:auto;display:grid;grid-template-columns:repeat(4,1fr);border-top:1px solid #ffffff18}.hero-stats div{display:flex;align-items:baseline;gap:11px;padding:22px 28px;border-right:1px solid #ffffff18}.hero-stats div:last-child{border:0}.hero-stats b{font-size:22px}.hero-stats span{color:#9bb2ca;font-size:12px}
.page-shell{max-width:1220px;margin:0 auto;display:grid;grid-template-columns:220px minmax(0,1fr);gap:58px;padding:65px 30px}.sidebar{position:sticky;top:98px;align-self:start;max-height:calc(100vh - 115px);overflow:auto;padding-right:12px}.toc-title{font-size:11px;color:#8b98aa;font-weight:bold;letter-spacing:1.5px;margin:0 0 13px 10px}.sidebar>a{display:flex;gap:12px;align-items:center;text-decoration:none;color:#68778b;font-size:13px;padding:7px 10px;border-left:2px solid transparent}.sidebar>a span{font-size:10px;font-family:monospace;color:#9caaba}.sidebar>a:hover,.sidebar>a.active{color:var(--blue);background:var(--soft-blue);border-left-color:var(--blue)}.sidebar>a.active span{color:var(--blue)}.toc-progress{margin:22px 9px 0;padding-top:18px;border-top:1px solid var(--line)}.toc-progress>div:first-child{display:flex;justify-content:space-between;font-size:11px;color:#8491a3}.mini-track{height:4px;background:var(--line);border-radius:4px;margin-top:8px;overflow:hidden}.mini-track i{display:block;width:0;height:100%;background:var(--blue)}.content{min-width:0}.intro-note{display:flex;gap:18px;border:1px solid #c9e7ec;background:var(--soft-cyan);padding:22px 25px;border-radius:14px;margin-bottom:85px}.note-icon{flex:none;width:38px;height:38px;border-radius:50%;background:var(--cyan);color:#fff;display:grid;place-items:center}.intro-note p{margin:4px 0 0;color:#536f77;font-size:14px}
.chapter{margin-bottom:115px;scroll-margin-top:85px}.chapter-head{display:flex;gap:24px;align-items:flex-start;padding-bottom:20px;border-bottom:1px solid var(--line);margin-bottom:30px}.chapter-head.compact{align-items:center}.chapter-no{flex:none;width:58px;height:58px;display:grid;place-items:center;border-radius:17px;background:var(--navy);color:#fff;font-size:20px;font-weight:800;box-shadow:0 9px 25px #10284427}.chapter-head h2{font-size:34px;letter-spacing:-1.2px;line-height:1.2;margin:6px 0 4px}.chapter-head p{margin:0;color:var(--muted)}.content>.chapter>p{color:#46566b}.subhead{font-size:20px;margin:38px 0 16px}.concept-grid{display:grid;gap:15px;margin:27px 0}.concept-grid.three{grid-template-columns:repeat(3,1fr)}.concept-grid article,.panel{background:var(--card);border:1px solid var(--line);padding:23px;border-radius:14px}.concept-grid h3,.panel h3{margin:13px 0 6px;font-size:17px}.concept-grid p,.panel p{font-size:13px;color:var(--muted);margin:0}.concept-icon{display:grid;place-items:center;width:37px;height:37px;border-radius:10px;color:#fff;font-weight:bold}.concept-icon.blue{background:var(--blue)}.concept-icon.cyan{background:var(--cyan)}.concept-icon.orange{background:var(--orange)}.metric-list{display:grid;grid-template-columns:1fr 1fr;background:var(--card);border:1px solid var(--line);border-radius:15px;overflow:hidden}.metric-list div{padding:19px 22px;border-bottom:1px solid var(--line)}.metric-list div:nth-child(odd){border-right:1px solid var(--line)}.metric-list div:nth-last-child(-n+2){border-bottom:0}.metric-list b{display:block;font-size:14px}.metric-list span{font-size:12px;color:var(--muted)}.callout{padding:20px 24px;margin:25px 0;border-left:4px solid;border-radius:6px 12px 12px 6px}.callout p{margin:3px 0 0;font-size:14px}.callout.analogy{background:var(--soft-orange);border-color:var(--orange);color:#6c4529}.callout.key{background:var(--soft-blue);border-color:var(--blue);color:#2e527a}.callout.warning{background:#fff4e9;border-color:#e79a44;color:#74491f}
.layer-stack{background:var(--navy);border-radius:18px;padding:22px;margin:28px 0;color:#fff}.stack-row{display:grid;grid-template-columns:100px 1fr 170px 110px;align-items:center;gap:15px;padding:14px 18px;border-radius:9px}.stack-row strong{font-size:15px}.stack-row span{font-size:12px;color:#d7e4f1}.stack-row code{color:#fff;background:#ffffff18;text-align:center}.stack-row small{text-align:right;color:#c8dae9}.stack-row.app{background:#1769d2}.stack-row.transport{background:#1b7dad}.stack-row.network{background:#278085}.stack-row.link{background:#376d75}.stack-row.physical{background:#495f6b}.stack-arrow{text-align:center;font-size:10px;color:#8ca9c1;padding:4px}.packet-demo{display:flex;flex-direction:column;gap:8px;font-size:11px;font-weight:bold}.packet-demo>div{min-height:40px;display:flex;align-items:center}.payload{background:#f0b168!important;color:#563419;padding:10px 14px;border-radius:5px}.header{padding:5px 5px 5px 14px;border-radius:6px;color:#fff;gap:7px}.tcp-h{background:#0fa9b8}.ip-h{background:#1769d2}.frame-h{background:#102844}.frame-h>i{margin-left:auto;padding:0 13px;font-style:normal}
.timeline{position:relative;margin:15px 0}.timeline:before{content:"";position:absolute;left:22px;top:24px;bottom:24px;width:2px;background:linear-gradient(var(--blue),var(--cyan))}.timeline article{display:grid;grid-template-columns:46px 1fr;gap:20px;position:relative;margin:0 0 9px}.timeline article>span{width:46px;height:46px;border-radius:50%;display:grid;place-items:center;background:var(--card);border:2px solid var(--blue);color:var(--blue);font-weight:800;z-index:1}.timeline article>div{background:var(--card);border:1px solid var(--line);border-radius:13px;padding:15px 20px}.timeline h3{font-size:15px;margin:0}.timeline p{font-size:13px;color:var(--muted);margin:3px 0}.address-card{display:flex;align-items:flex-end;justify-content:center;gap:8px;background:var(--navy);color:#fff;padding:30px;border-radius:16px;margin:26px 0 8px}.address-card div span{display:block;font-size:10px;color:#91abc3;text-align:center}.address-card b{font:700 30px/1.2 "Cascadia Code",monospace}.address-card i{font-size:30px;font-style:normal}.address-card em{font:700 17px monospace;background:var(--orange);padding:6px 9px;border-radius:7px;margin-left:7px}.caption{text-align:center!important;font-size:12px;color:var(--muted)!important}.split-grid{display:grid;grid-template-columns:1fr 1fr;gap:17px}.nat-diagram{display:grid;grid-template-columns:1.4fr .8fr 1fr;align-items:stretch;gap:13px;margin:25px 0}.lan,.nat-router,.internet-box{border-radius:14px;padding:20px;text-align:center}.lan{background:var(--soft-blue);display:grid;grid-template-columns:1fr 1fr;gap:8px}.lan>b{grid-column:1/-1}.lan span{background:var(--card);padding:10px;border-radius:8px;font-size:12px}.nat-router{background:var(--navy);color:#fff;display:flex;flex-direction:column;justify-content:center}.nat-router small{color:#93abc2}.nat-router span{font-size:10px;color:#46d3dc}.internet-box{background:var(--soft-cyan);display:flex;flex-direction:column;justify-content:center;font-weight:bold}.internet-box small{font-weight:normal;color:var(--muted)}.experiment{border:1px solid var(--line);border-radius:12px;margin-top:25px;background:var(--card)}.experiment summary{cursor:pointer;padding:16px 20px;font-weight:bold;font-size:14px}.experiment summary span{color:var(--blue);font-size:11px;margin-right:12px}.experiment>div{border-top:1px solid var(--line);padding:4px 20px;color:var(--muted);font-size:13px}
.sequence{display:grid;grid-template-columns:110px 1fr 110px;align-items:center;background:var(--navy);border-radius:16px;color:#fff;padding:25px 20px;margin:20px 0}.seq-party{text-align:center}.seq-party b,.seq-party span{display:block}.seq-party span{font-size:10px;color:#86a1b9}.seq-lines{border-left:1px solid #ffffff24;border-right:1px solid #ffffff24;padding:8px 20px}.seq-lines>div{height:54px;position:relative}.seq-lines>div:before{content:"";position:absolute;top:27px;height:1px;background:#4bc8d3;left:0;right:0}.seq-lines>div:after{content:"";position:absolute;top:23px;border:5px solid transparent}.seq-lines .to-right:after{right:-3px;border-left-color:#4bc8d3}.seq-lines .to-left:after{left:-3px;border-right-color:#4bc8d3}.seq-lines code{position:absolute;z-index:1;left:50%;transform:translateX(-50%);background:#1b4a68;color:#fff;white-space:nowrap}.seq-lines i{position:absolute;top:31px;left:50%;transform:translateX(-50%);font-size:9px;color:#88a9c2;white-space:nowrap}.mechanism-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:12px}.mechanism-grid article{background:var(--card);border:1px solid var(--line);border-top:3px solid var(--cyan);border-radius:11px;padding:18px}.mechanism-grid b{font-size:14px}.mechanism-grid p{margin:4px 0 0;font-size:12px;color:var(--muted)}.compare-table{border:1px solid var(--line);border-radius:13px;overflow:hidden;margin:25px 0}.compare-table>div{display:grid;grid-template-columns:.7fr 1fr 1fr;background:var(--card);border-bottom:1px solid var(--line);align-items:center}.compare-table>div:last-child{border:0}.compare-table span,.compare-table p,.compare-table b{padding:11px 16px;margin:0;font-size:13px}.compare-head{background:var(--soft-blue)!important}.compare-head b{color:var(--blue)}
.dns-path{display:flex;align-items:stretch;gap:7px;margin:25px 0}.dns-path>div{flex:1;min-width:0;background:var(--card);border:1px solid var(--line);border-radius:11px;padding:15px 11px}.dns-path>div span{display:grid;place-items:center;width:23px;height:23px;border-radius:50%;background:var(--blue);color:#fff;font-size:10px}.dns-path b,.dns-path small{display:block}.dns-path b{font-size:12px;margin-top:10px}.dns-path small{font-size:9px;color:var(--muted)}.dns-path>i{align-self:center;color:var(--cyan);font-style:normal}.record-list{background:var(--card);border:1px solid var(--line);border-radius:13px;overflow:hidden}.record-list>div{display:grid;grid-template-columns:90px 1fr 1fr;padding:13px 18px;border-bottom:1px solid var(--line);align-items:center}.record-list>div:last-child{border:0}.record-list code{width:max-content;color:var(--blue);font-weight:bold}.record-list span{font-size:13px}.record-list small{color:var(--muted)}
.code-window,.terminal{background:#10233b;color:#d8e5f2;border-radius:14px;overflow:hidden;margin:19px 0;box-shadow:var(--shadow)}.code-title,.terminal-bar{height:40px;display:flex;align-items:center;gap:7px;padding:0 15px;background:#0a1a2c}.code-title>span,.terminal-bar>span{width:9px;height:9px;border-radius:50%;background:#ee6a58}.code-title>span:nth-child(2),.terminal-bar>span:nth-child(2){background:#e9bd51}.code-title>span:nth-child(3),.terminal-bar>span:nth-child(3){background:#56bd70}.code-title b,.terminal-bar b{margin-left:7px;font-size:10px;color:#7e99b2}.code-window pre,.terminal pre{padding:22px;margin:0;overflow:auto;font-size:13px;line-height:1.8}.code-window code,.terminal code{background:none;color:inherit;padding:0}.code-window mark{background:none;color:#61d6df;font-weight:bold}.code-notes{display:flex;gap:17px;padding:12px 20px;background:#0c1e32}.code-notes span{font-size:9px;color:#829cb4}.code-notes b{color:#e4edf5}.response{margin-top:13px}.method-list,.status-list{background:var(--card);border:1px solid var(--line);border-radius:12px;overflow:hidden}.method-list p,.status-list p{display:flex;align-items:center;gap:12px;margin:0;padding:10px 15px;border-bottom:1px solid var(--line);font-size:12px}.method-list p:last-child,.status-list p:last-child{border:0}.method-list code{width:60px;color:var(--blue);font-weight:bold}.status-list b{width:42px;padding:2px 7px;border-radius:4px;color:#fff}.s2{background:#29966d}.s3{background:#2878c7}.s4{background:#d68a2c}.s5{background:#d45454}.version-road{display:flex;align-items:center;gap:13px}.version-road>div{flex:1;background:var(--card);border:1px solid var(--line);padding:18px;border-radius:11px}.version-road b,.version-road span{display:block}.version-road span{font-size:11px;color:var(--muted)}.version-road i{font-style:normal;color:var(--cyan)}
.security-triad{display:grid;grid-template-columns:repeat(3,1fr);gap:14px}.security-triad article{text-align:center;background:var(--card);border:1px solid var(--line);border-radius:13px;padding:23px}.security-triad article>span{font-size:25px;color:var(--blue)}.security-triad h3{font-size:15px;margin:5px}.security-triad p{font-size:11px;color:var(--muted);margin:0}.tls-flow{display:grid;grid-template-columns:120px 1fr 120px;align-items:stretch;margin:22px 0;background:var(--navy);color:#fff;border-radius:16px;padding:20px}.tls-side{display:flex;flex-direction:column;align-items:center;justify-content:center;text-align:center}.tls-side small{color:#89a5bd;font-size:9px}.tls-middle{padding:0 20px;border-left:1px solid #ffffff22;border-right:1px solid #ffffff22}.tls-middle p{padding:9px 13px;margin:7px 0;background:#173b5b;border-radius:8px}.tls-middle b,.tls-middle span{display:block;font-size:11px}.tls-middle span{color:#95aec4;font-size:9px}.tls-middle .center{text-align:center;background:#7d5c25;color:#ffe1a3;font-size:10px}.tls-middle .both{text-align:center;background:#146273}
.terminal pre i{color:#50d2dc;font-style:normal}.terminal pre em{color:#f2c05f}.terminal pre strong{color:#7ade9d}.ssh-auth{display:grid;grid-template-columns:1fr 1fr;gap:15px}.ssh-auth article{background:var(--card);border:1px solid var(--line);padding:22px;border-radius:13px}.ssh-auth article>span{font-size:11px;color:var(--blue);font-weight:bold}.ssh-auth h3{font-size:16px;margin:7px 0}.ssh-auth p{font-size:12px;color:var(--muted);margin:0}.key-pair{display:grid;grid-template-columns:1fr 150px 1fr;align-items:center;margin:28px 0}.private-key,.public-key{padding:20px;border-radius:13px}.private-key{background:#fff0e6;border:1px solid #f2c4a4}.public-key{background:var(--soft-blue);border:1px solid #bcd7f7}.private-key span,.public-key span,.private-key b,.public-key b,.private-key small,.public-key small{display:block}.private-key span,.public-key span{font-size:9px;font-weight:bold}.private-key b,.public-key b{font-size:14px}.private-key small,.public-key small{font-size:10px;color:var(--muted)}.key-action{text-align:center;font-size:11px;color:var(--muted)}.key-action i{display:block;color:var(--blue)}.key-action small{font-size:8px}.command-list{border:1px solid var(--line);border-radius:12px;overflow:hidden;background:var(--card)}.command-list>div{display:grid;grid-template-columns:1.1fr 1fr;gap:15px;padding:12px 17px;border-bottom:1px solid var(--line);align-items:center}.command-list>div:last-child{border:0}.command-list code{width:max-content}.command-list span{font-size:12px;color:var(--muted)}
.diagnose-flow{display:flex;align-items:stretch;gap:7px}.diagnose-flow>div{flex:1;min-width:0;background:var(--card);border:1px solid var(--line);border-radius:11px;padding:13px}.diagnose-flow span{display:grid;place-items:center;width:22px;height:22px;border-radius:50%;background:var(--cyan);color:#fff;font-size:9px}.diagnose-flow b,.diagnose-flow code,.diagnose-flow small{display:block}.diagnose-flow b{font-size:12px;margin-top:7px}.diagnose-flow code{font-size:9px;margin:5px 0}.diagnose-flow small{font-size:9px;color:var(--muted)}.diagnose-flow>i{align-self:center;font-style:normal;color:var(--cyan)}.toolbox{margin-top:20px}.quiz-section{background:linear-gradient(145deg,var(--soft-blue),var(--soft-cyan));padding:34px;border-radius:22px}.quiz-card{background:var(--card);border:1px solid var(--line);border-radius:13px;padding:22px;margin:12px 0;position:relative}.quiz-number{position:absolute;right:18px;top:15px;font:bold 12px monospace;color:#a9b6c5}.quiz-card h3{font-size:15px;margin:0 0 13px}.options{display:flex;gap:8px;flex-wrap:wrap}.options button{border:1px solid var(--line);background:var(--paper);color:var(--ink);padding:8px 12px;border-radius:8px;cursor:pointer;font-size:12px}.options button:hover{border-color:var(--blue);color:var(--blue)}.options button.correct{background:#e5f8ef;border-color:#45ad7f;color:#247350}.options button.wrong{background:#fff0ec;border-color:#e88972;color:#a94c3a}.feedback{min-height:20px;margin:8px 0 0;font-size:11px;color:var(--muted)}.quiz-score{display:flex;align-items:center;gap:12px;margin-top:20px}.quiz-score span{font-size:12px}.quiz-score b{font-size:20px;margin-right:auto}.quiz-score i{font-style:normal;color:var(--blue)}.quiz-score button{border:0;background:var(--navy);color:#fff;padding:8px 14px;border-radius:8px;cursor:pointer;font-size:12px}.next-step{display:flex;align-items:center;gap:30px;padding:35px;background:var(--navy);color:#fff;border-radius:18px}.next-step div{margin-right:auto}.next-step span{color:#51d1dc;font-size:11px;font-weight:bold}.next-step h2{font-size:22px;margin:5px 0}.next-step p{font-size:12px;color:#a9bfd2;margin:0}.next-step>a{flex:none;background:#fff;color:var(--navy);padding:10px 15px;border-radius:8px;text-decoration:none;font-size:12px;font-weight:bold}footer{display:flex;justify-content:space-between;align-items:center;padding:35px max(5vw,30px);background:#0b1c30;color:#fff}footer div b,footer div span{display:block}footer div span,footer p{font-size:11px;color:#8da6bd}
body.dark{--ink:#e7eef6;--muted:#9caec1;--paper:#0c1828;--card:#13243a;--line:#283b52;--navy:#071524;--soft-blue:#142b45;--soft-cyan:#123137;--soft-orange:#39271b;--shadow:none}.dark .topbar{background:rgba(12,24,40,.91)}.dark code{background:#1d3249;color:#f0a977}.dark .theme-btn{background:#17283d}.dark .content>.chapter>p{color:#b7c3d1}.dark .callout.warning{background:#34261b;color:#e6bc8b}.dark .callout.analogy{color:#e7bd96}.dark .callout.key{color:#afcdef}.dark .private-key{background:#32231b;border-color:#62432d}.dark .public-key{background:#142b45;border-color:#294d72}.dark .options button{background:#172a41}
@media(max-width:1000px){.hero-inner{grid-template-columns:1fr}.hero-visual{max-width:650px}.page-shell{grid-template-columns:1fr}.sidebar{display:none}.content{max-width:800px;margin:auto}.dns-path,.diagnose-flow{flex-wrap:wrap}.dns-path>div,.diagnose-flow>div{min-width:145px}.dns-path>i,.diagnose-flow>i{display:none}}
@media(max-width:700px){.topnav{display:none}.hero-inner{padding-top:55px}.hero h1{font-size:48px}.hero-visual{transform:scale(.8);transform-origin:left center;width:125%;margin-bottom:-25px}.hero-stats{grid-template-columns:1fr 1fr}.hero-stats div:nth-child(2){border-right:0}.page-shell{padding:45px 18px}.chapter{margin-bottom:85px}.chapter-head h2{font-size:28px}.chapter-no{width:48px;height:48px}.concept-grid.three,.metric-list,.split-grid,.mechanism-grid,.security-triad,.ssh-auth{grid-template-columns:1fr}.metric-list div{border-right:0!important;border-bottom:1px solid var(--line)!important}.metric-list div:last-child{border-bottom:0!important}.stack-row{grid-template-columns:75px 1fr}.stack-row code,.stack-row small{display:none}.nat-diagram{grid-template-columns:1fr}.sequence{grid-template-columns:65px 1fr 65px;padding:18px 8px}.seq-lines{padding:5px}.compare-table>div{grid-template-columns:.55fr 1fr 1fr}.record-list>div{grid-template-columns:60px 1fr}.record-list small{display:none}.version-road{flex-direction:column;align-items:stretch}.version-road i{transform:rotate(90deg);align-self:center}.tls-flow{grid-template-columns:60px 1fr 60px;padding:15px 5px}.tls-middle{padding:0 7px}.key-pair{grid-template-columns:1fr}.key-action{padding:12px}.key-action i{transform:rotate(90deg)}.command-list>div{grid-template-columns:1fr}.next-step{align-items:flex-start;flex-direction:column}.options{flex-direction:column}.options button{text-align:left}footer{display:block}.packet-demo{overflow:auto}.address-card b{font-size:20px}}
/* ===== 通用规范表格（新增） ===== */
.spec-table{background:var(--card);border:1px solid var(--line);border-radius:13px;overflow:hidden;margin:22px 0}
.spec-table table{width:100%;border-collapse:collapse;font-size:13px}
.spec-table th,.spec-table td{padding:11px 15px;border-bottom:1px solid var(--line);text-align:left;vertical-align:top;line-height:1.65}
.spec-table thead th{background:var(--soft-blue);color:var(--blue);font-size:12px;letter-spacing:.3px;white-space:nowrap}
.spec-table tbody tr:last-child td{border-bottom:0}
.spec-table td:first-child{color:#33537a;font-weight:600;white-space:nowrap}
.spec-table code{white-space:nowrap}
.spec-table td code{background:#e8f1fb;color:#1769d2}
body.dark .spec-table td:first-child{color:#9ec5f2}
@media(max-width:700px){.spec-table{overflow-x:auto}.spec-table table{min-width:540px}}