:root{--ink:#223139;--ink2:#52626b;--muted:#839095;--paper:#f5f6f3;--panel:#fff;--line:#dce3e3;--line2:#e9eeee;--navy:#143b48;--teal:#0d787f;--teal-light:#e7f4f3;--gold:#dca547;--rose:#bd687f;--radius:9px;font-family:Inter,-apple-system,BlinkMacSystemFont,"Segoe UI","Noto Sans SC","PingFang SC",sans-serif;color:var(--ink);background:var(--paper);font-synthesis:none}
*{box-sizing:border-box}body{margin:0;font-size:14px;line-height:1.5}button,input,select{font:inherit}button{cursor:pointer}button:disabled{opacity:.35;cursor:default}button:focus-visible,input:focus-visible,select:focus-visible{outline:3px solid #50b1b3;outline-offset:2px}.hidden{display:none!important}.sr-only{position:absolute;width:1px;height:1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap}.app{display:grid;grid-template-columns:248px minmax(0,1fr) 382px;max-width:2000px;margin:auto;min-height:100vh}.overline,.nav-overline,.intro-eyebrow,.diagram-head,.detail-label,.explain-label{font-size:10px;font-weight:800;letter-spacing:1.8px;color:var(--teal)}.sidebar{height:100dvh;position:sticky;top:0;display:flex;flex-direction:column;padding:27px 14px 18px;background:#fafbf9;border-right:1px solid var(--line);overflow:hidden}.brand{display:flex;align-items:center;gap:11px;padding:0 11px 32px}.brand-sign{width:42px;height:42px;background:var(--navy);color:white;border-radius:9px;font:800 26px/42px Georgia,serif;text-align:center}.brand-sign span{color:#55c4c0}.brand strong{font-weight:850;letter-spacing:1.4px;font-size:13px}.brand small{display:block;font-size:9px;letter-spacing:1.3px;color:var(--muted);margin-top:2px}.nav-overline{display:flex;justify-content:space-between;padding:0 10px 12px;color:#677a80}.nav-overline span{letter-spacing:0;font-size:10px}.search{height:37px;background:#f3f7f5;border:1px solid #e0e8e5;border-radius:7px;padding:0 12px;margin:0 4px 14px;outline:none;width:calc(100% - 8px);font-size:12px;color:var(--ink)}.scenario-nav{overflow:auto;flex:1;scrollbar-width:thin}.nav-group{color:#95a1a3;font-size:10px;font-weight:750;letter-spacing:1.4px;padding:20px 12px 7px}.nav-button{width:100%;border:1px solid transparent;border-radius:6px;padding:11px 11px;display:flex;text-align:left;align-items:center;gap:10px;background:transparent;color:#607079;font-size:12px;margin:2px 0}.nav-button:hover{background:#f0f5f2}.nav-button[aria-current="true"]{background:#e9f3f2;border-color:#d2e7e6;color:#0d6770;font-weight:750}.nav-number{font:650 11px/1.5 ui-monospace,SFMono-Regular,Consolas,monospace;color:#9daaad;min-width:22px}.nav-button[aria-current="true"] .nav-number{color:#0b7f85}.nav-title{font-weight:inherit;line-height:1.35}.nav-steps{display:block;font-size:10px;margin-top:4px;color:#a1adb1;font-weight:450}.sidebar-footer{border-top:1px solid var(--line2);padding:16px 10px 1px;font-size:10px;color:#849297}.sidebar-footer div{margin:3px 0 0 11px}.status-dot{display:inline-block;width:6px;height:6px;background:#53a78e;border-radius:50%}
.workspace{padding:0 32px 18px;min-width:0}.topbar{height:60px;display:flex;justify-content:space-between;align-items:center;border-bottom:1px solid var(--line)}.breadcrumb{font-size:11px;color:#62717a;display:flex;gap:10px}.crumb-slash{color:#bac6c6}.top-links{font-size:11px;display:flex;gap:12px;align-items:center}.top-links a{color:var(--teal);text-decoration:none}.version{border:1px solid #d4e1dd;border-radius:4px;padding:3px 7px;font-size:9px;font-weight:750;color:#537772;letter-spacing:.7px}.intro{padding:29px 0 23px}.intro-eyebrow{display:flex;align-items:center;gap:9px}.eyebrow-line{width:19px;height:2px;background:var(--teal)}h1,h2,p{margin:0}h1{font-size:clamp(24px,2.1vw,34px);font-weight:750;letter-spacing:-.9px;margin:9px 0 10px;color:#142d35;line-height:1.28}.intro>p{font-size:12.5px;color:#64737a;max-width:770px;line-height:1.8}.meta{font-size:10px;color:#77918d;display:flex;gap:9px;margin-top:15px}.meta-separator{color:#c1cccc}.controlbar{display:flex;justify-content:space-between;gap:12px;align-items:center;background:white;border:1px solid var(--line);border-radius:8px;padding:9px 12px;margin-bottom:20px}.play-controls,.control-extras{display:flex;gap:8px;align-items:center}.control-square{width:33px;height:33px;border:1px solid var(--line);background:#fff;color:var(--ink);border-radius:5px;font-size:18px}.play-button{min-width:116px;padding:8px 13px;border:1px solid var(--navy);background:var(--navy);border-radius:5px;color:white;display:flex;align-items:center;justify-content:center;gap:7px;font-size:12px;font-weight:750}.control-text{border:0;background:none;color:var(--ink2);padding:6px 8px;font-size:11px}.control-text:hover{color:var(--teal)}.control-extras label{font-size:11px;color:var(--muted)}.small-select{padding:7px;background:#fff;border:1px solid var(--line);border-radius:4px;font-size:11px;color:var(--ink)}.section-heading{display:flex;justify-content:space-between;align-items:end;gap:12px;margin-bottom:12px}.section-heading h2{font-size:16px;letter-spacing:-.2px;color:#1b343b;margin-top:3px}.section-actions{display:flex;gap:2px;background:#e9efec;border-radius:6px;padding:3px}.tab{border:0;background:transparent;border-radius:4px;color:#697b7e;font-size:11px;padding:6px 10px}.tab.selected{background:white;color:var(--teal);box-shadow:0 1px 3px #273a3214;font-weight:750}.paper-controls{font-size:11px;background:#eaf3f1;padding:9px 12px;border:1px solid #cddfdb;margin:0 0 10px;border-radius:6px;display:flex;align-items:center;gap:10px;flex-wrap:wrap;color:#4a6768}.paper-controls input{font-size:10px;max-width:230px}.paper-controls span{color:#819a95}.stage-wrap{height:clamp(350px,49vh,650px);position:relative;background:#fbfdfc;border:1px solid #dce6e4;border-radius:7px;overflow:hidden}.stage-wrap svg{height:100%;width:100%;display:block;touch-action:pan-y}.stage-top,.stage-bottom{position:absolute;left:14px;right:14px;display:flex;justify-content:space-between;pointer-events:none;align-items:center}.stage-top{top:12px}.stage-bottom{bottom:11px}.stage-top span{font:650 10px/1.5 ui-monospace,Consolas,monospace;letter-spacing:.5px;color:#6d858b}.stage-live{color:#188b8c!important;background:#eef8f5;padding:5px 8px;border:1px solid #d6ede6;border-radius:4px}.legend{display:flex;gap:11px;background:#ffffffef;padding:7px 9px;border:1px solid #e6efed;border-radius:5px}.legend span{font-size:10px;color:#586d73;display:flex;align-items:center;gap:5px}.lg{display:inline-block;width:8px;height:8px;border-radius:50%}.blue{background:#0e93b3}.gold{background:#dca547}.rose{background:#bd687f}.stage-tools{display:flex;gap:2px;pointer-events:auto;background:#fff;border:1px solid var(--line);border-radius:4px;padding:2px}.stage-tools button{background:transparent;border:0;font-size:15px;color:#506871;width:26px;height:26px}.stage-tools button:hover{background:#eaf4f3}.stage-footer{display:flex;justify-content:space-between;margin-top:8px;color:#849395;font-size:10px}.stage-footer label{white-space:nowrap}.stage-footer input{accent-color:var(--teal);vertical-align:middle}.timeline-section{margin-top:29px}.section-heading.compact{align-items:center;margin-bottom:12px}.section-heading.compact h2{font-size:16px}.step-count{font-size:11px;color:#607980;font-family:ui-monospace,Consolas,monospace}.timeline-track{display:flex;overflow-x:auto;gap:7px;padding:3px 0 12px;scrollbar-width:thin}.step-marker{flex:0 0 33px;height:33px;border:1px solid #d3dfdd;border-radius:5px;background:#fff;color:#708084;font:650 11px ui-monospace,Consolas,monospace}.step-marker.done{background:#e9f4f1;border-color:#c8e4dc;color:#0d817d}.step-marker.now{background:#0d787f;color:white;border-color:#0d787f}.explain-card{border:1px solid var(--line);border-radius:7px;background:#fff;padding:15px 17px;border-left:3px solid #0d787f}.explain-label{margin-bottom:7px}.explain-card p{font-weight:650;font-size:13px;color:#29424b}.explain-why{font-size:11px;color:#647981;line-height:1.8;margin-top:7px}.main-footer{font-size:10px;color:#99a8a9;margin-top:23px;padding-top:13px;border-top:1px solid var(--line)}
.inspector{height:100dvh;position:sticky;top:0;overflow:auto;background:#fff;border-left:1px solid var(--line);padding:26px 20px 18px;scrollbar-width:thin}.inspector-heading{display:flex;justify-content:space-between;align-items:center}.analyze-pill{font-size:9px;letter-spacing:1px;background:#eaf5f2;color:#12817b;padding:4px 7px;border-radius:3px;font-weight:800}.inspector h2{font-size:19px;color:#18353d;margin-top:10px}.inspector-lead{font-size:11px;color:#829194;line-height:1.8;margin-top:7px}.diagram-head{display:flex;justify-content:space-between;color:#819294;margin:24px 0 10px}.diagram-head span:first-child{color:var(--teal)}.packet-diagram{min-height:132px}.envelope{border:1.5px solid var(--edge);background:var(--wash);border-radius:6px;padding:10px 10px 11px;margin-bottom:6px;transition:box-shadow .2s}.envelope.application{--edge:#c78b97;--wash:#fff2f5}.envelope.transport{--edge:#d7aa61;--wash:#fff8ec}.envelope.network{--edge:#70ab92;--wash:#f0faf4}.envelope.link{--edge:#7b9fbc;--wash:#eef6fc}.envelope.active{box-shadow:0 0 0 2px var(--edge)}.envelope-head{width:100%;border:0;padding:0;background:transparent;text-align:left;display:block;cursor:pointer}.layer-name{display:flex;align-items:center;justify-content:space-between;font-size:10px;font-weight:800;letter-spacing:.1px;color:#3f5961}.layer-name small{font:500 9px ui-monospace,Consolas,monospace;color:#6b7f83}.layer-address{display:flex;gap:4px;margin:6px 0 1px;font:600 11px/1.3 ui-monospace,Consolas,monospace;overflow-wrap:anywhere;color:#294950}.layer-address .from,.layer-address .to{flex:1;min-width:0}.layer-address .arrow{color:#8b9b9d;flex:0 0 auto}.layer-nest{margin:9px 0 0 9px}.layer-nest .envelope:last-child{margin-bottom:0}.empty-packet{background:#f4f7f5;border:1px dashed #d1dcd8;padding:18px 14px;border-radius:6px;font-size:11px;color:#6c7e80;line-height:1.75}.packet-note{font-size:10px;line-height:1.65;color:#7a8a88;margin-top:8px}.layer-detail{margin-top:18px;background:#f7faf8;border:1px solid #e7eeeb;border-radius:6px;padding:11px}.detail-label{font-size:9px}.detail-content{color:#5d7275;font-size:11px;line-height:1.8;margin-top:7px;overflow-wrap:anywhere}.detail-content b{color:#24484c}.inspector-divider{height:1px;background:var(--line);margin:24px 0 17px}.inspector-heading.small{color:#8ba0a1;font-size:10px}.field-evidence{display:flex;flex-direction:column;gap:7px;margin-top:11px}.evidence-row{border-bottom:1px solid #f0f2ef;padding:7px 0}.evidence-key{font-size:10px;font-weight:800;color:#778d91;margin-bottom:3px}.evidence-values{display:flex;align-items:center;gap:7px;font-size:11px;color:#304e55;overflow-wrap:anywhere}.evidence-values strong{font-weight:700;max-width:45%;word-break:break-word}.evidence-values span{color:#9cafad}.evidence-desc{font-size:10px;color:#a0aead;margin-top:3px}.info-table{margin-top:15px;border:1px solid #e2ebea;border-radius:6px;overflow:auto}.info-table-caption{font-size:10px;color:#55777a;padding:9px;font-weight:750;background:#f2f8f6}.info-table table{border-collapse:collapse;width:100%;font-size:10px}.info-table th,.info-table td{padding:7px;border-bottom:1px solid #e9efeb;text-align:left;white-space:nowrap}.info-table th{font-weight:750;color:#5c8280;background:#fafcfb}.note-box,.quiz-box{font-size:11px;line-height:1.75;background:#fff9ee;border:1px solid #eee1c6;border-radius:6px;margin-top:12px;padding:11px;color:#8b7148}.quiz-box{background:#f1f8f6;border-color:#cfe3dc;color:#52746c}.quiz-box button{background:#fff;border:1px solid #c5ded7;border-radius:4px;font-size:10px;padding:6px;margin-top:7px;color:#306f69}.quiz-answer{border-top:1px solid #d7e9e3;margin-top:8px;padding-top:7px}.inspector-foot{font-size:10px;color:#a1adac;margin-top:20px;padding-top:12px;border-top:1px solid var(--line);line-height:1.7}.toast{position:fixed;bottom:22px;left:50%;transform:translateX(-50%);background:#213e45;color:white;padding:10px 14px;border-radius:6px;box-shadow:0 5px 20px #2239;font-size:12px;z-index:30}
@media(max-width:1370px){.app{grid-template-columns:216px minmax(0,1fr) 344px}.workspace{padding:0 20px 18px}.sidebar{padding:22px 10px 15px}.inspector{padding:23px 14px}.stage-wrap{height:clamp(340px,47vh,590px)}}
@media(max-width:1080px){.app{grid-template-columns:204px minmax(0,1fr)}.inspector{height:auto;position:static;overflow:visible;grid-column:2;border-left:0;border-top:1px solid var(--line);display:block;padding:24px 24px}.packet-diagram{max-width:720px}.sidebar{grid-row:1/3}.stage-wrap{height:430px}}
@media(max-width:700px){.app{display:block}.sidebar{height:auto;position:relative;padding:13px;overflow:visible}.brand{padding:0 0 11px}.nav-overline,.sidebar-footer{display:none}.search{margin:0 0 8px;width:100%}.scenario-nav{display:flex;gap:6px;overflow-x:auto}.nav-group{display:none}.nav-button{flex:0 0 160px;margin:0;padding:8px;align-items:flex-start}.workspace{padding:0 13px}.topbar{height:44px}.breadcrumb{font-size:10px}.top-links a{display:none}.intro{padding:21px 0}.intro h1{font-size:24px}.intro>p{font-size:11px}.controlbar{padding:8px;flex-wrap:wrap;gap:7px}.control-extras{flex:1;justify-content:space-between}.control-text{font-size:10px}.section-heading h2{font-size:14px}.tab{font-size:10px;padding:5px}.stage-wrap{height:clamp(300px,45vh,440px)}.stage-top{left:7px;right:7px}.stage-bottom{left:5px;right:5px}.legend{gap:6px;padding:6px}.legend span{font-size:9px}.stage-footer span{max-width:65%}.inspector{padding:23px 13px}.timeline-section{margin-top:22px}}
@media(prefers-reduced-motion:reduce){*,*:before,*:after{animation:none!important;transition:none!important;scroll-behavior:auto!important}}

.local-note{color:#78918e;font-size:10px}