:root{color-scheme:dark;--bg:#07100f;--surface:#0d1a18;--surface2:#11211e;--ink:#effbf5;--muted:#9db5ab;--line:#2a4039;--mint:#65e6b4;--cyan:#66c9e8;--amber:#ffc56b;--danger:#ff8078;--blocked:#b8c7c1;font-family:Inter,ui-sans-serif,system-ui,-apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;background:var(--bg);color:var(--ink)}
main{width:min(1320px,calc(100% - 32px));margin:auto;padding:42px 0 80px}
.intro{max-width:900px;margin-bottom:30px}
.eyebrow,.kicker,.control-label{margin:0 0 8px;color:var(--mint);font-size:.72rem;font-weight:800;letter-spacing:.14em}
.intro h1{font-size:clamp(2rem,5vw,4.2rem);line-height:1.02;letter-spacing:-.055em;margin:0 0 18px}
.intro>p:last-child{max-width:760px;color:var(--muted);font-size:1.08rem;line-height:1.6}
.instrument{background:var(--surface);border:1px solid var(--line);border-radius:20px;overflow:hidden}
.controls{display:flex;align-items:end;justify-content:space-between;gap:28px;min-height:85px;padding:18px 22px;border-bottom:1px solid var(--line)}
.network-builder{min-width:0;width:100%}.stage-heading{display:flex;align-items:center;justify-content:space-between;gap:14px}.stage-heading strong{display:block}.stage-actions{display:flex;gap:6px}.stage-actions button{width:38px;height:34px;border:1px solid var(--line);border-radius:8px;background:#091310;color:var(--ink);cursor:pointer}.stage-actions button:disabled{color:#53665f;cursor:default}.stage-actions button:not(:disabled):hover,.stage-actions button:not(:disabled):focus-visible{border-color:var(--mint);outline:none}#stage-list{display:flex;gap:6px;margin:12px 0 0;padding:0;overflow-x:auto;list-style:none;scrollbar-color:var(--line) transparent}#stage-list button{white-space:nowrap;border:1px solid var(--line);border-radius:999px;padding:6px 9px;background:#091310;color:var(--muted);font:inherit;font-size:.72rem;cursor:pointer}#stage-list button[aria-current=step]{border-color:var(--mint);background:#0a2b22;color:var(--mint)}#stage-list button:hover,#stage-list button:focus-visible{border-color:var(--mint);outline:none}
.workspace{display:grid;grid-template-columns:minmax(310px,34%) 1fr;min-height:0}
.explanation{padding:28px;border-right:1px solid var(--line);background:var(--surface)}
.method-title{display:flex;align-items:center;gap:14px}
.method-title>span{width:42px;height:42px;border:1px solid var(--line);border-radius:12px;display:grid;place-items:center;color:var(--mint);font-weight:900}
.method-title h2{margin:0;font-size:1.55rem}
.summary{color:var(--muted);line-height:1.55;margin:22px 0}
.model-links{display:flex;flex-wrap:wrap;gap:8px;margin-top:16px}
.model-links:empty{display:none}
.model-links a{color:var(--mint);font-size:.82rem;text-decoration:none;border-bottom:1px solid #65e6b466}
.diagram-wrap{position:relative;padding:48px 18px 16px;background-image:linear-gradient(#ffffff08 1px,transparent 1px),linear-gradient(90deg,#ffffff08 1px,transparent 1px);background-size:24px 24px}
.legend{position:absolute;right:18px;top:16px;display:flex;gap:16px;color:var(--muted);font-size:.72rem}
.legend span{display:flex;align-items:center;gap:6px}
.legend b{font-weight:inherit}
.legend i{display:block;width:18px;border-top:2px solid}
.legend .internet{border-color:var(--cyan)}
.legend .private{border-color:var(--mint)}
.legend .blocked{border-color:var(--danger);border-top-style:dashed}
svg{width:100%;height:auto;min-height:0}
.node rect{fill:var(--surface2);stroke:var(--line);stroke-width:2}
.stage-hidden{display:none}
.node-title{fill:var(--ink);font-size:17px;font-weight:750}
.node-sub{fill:var(--muted);font-size:12px}
.helper rect{stroke:var(--mint)}
.finance-vps rect{stroke:var(--amber)}
.finance-vps.threatened rect,.public-vps.compromised rect{stroke:var(--danger)}
.state-pill{fill:var(--mint);font-size:11px;font-weight:800}
.public-vps.compromised .state-pill,.finance-vps.threatened .state-pill{fill:var(--danger)}
.port-label{fill:var(--muted);font-size:10px;font-weight:800}
.ports{fill:var(--ink);font-size:11px;font-weight:800}
.edge{fill:none;stroke-width:3;opacity:0;marker-end:none}
.edge.visible{opacity:1}
.public-edge{stroke:var(--cyan);marker-end:url(#arrow-public)}
.private-edge{stroke:var(--mint);marker-end:url(#arrow-private)}
.control-edge{stroke:var(--amber);stroke-width:2;stroke-dasharray:7 6;marker-end:none}
.risk-edge{stroke:var(--danger);stroke-width:3;stroke-dasharray:6 5;marker-end:url(#arrow-risk)}
.arrow-public{fill:var(--cyan)}
.arrow-private{fill:var(--mint)}
.arrow-risk{fill:var(--danger)}
.edge-label{fill:var(--ink);font-size:11px;font-weight:750;paint-order:stroke;stroke:var(--bg);stroke-width:7px;stroke-linejoin:round}
.risk-label{fill:var(--danger)}
#blocked-mark{display:none}
#blocked-mark circle{fill:var(--bg);stroke:var(--blocked);stroke-width:2}
#blocked-mark path{stroke:var(--blocked);stroke-width:3}
.table-link{display:inline-block;margin-bottom:16px;color:var(--mint);font-weight:750;text-decoration:none;border:1px solid var(--line);border-radius:9px;padding:10px 13px}
.table-link:hover,.table-link:focus-visible{border-color:var(--mint);outline:none}
@media(max-width:850px){main{width:min(100% - 18px,1320px);padding-top:24px}.intro h1{letter-spacing:-.04em}.controls{align-items:stretch;flex-direction:column}.workspace{grid-template-columns:1fr}.explanation{border-right:0;border-bottom:1px solid var(--line)}.diagram-wrap{overflow-x:auto}.diagram-wrap svg{min-width:720px}.legend{left:18px;right:auto}}
@media(prefers-reduced-motion:no-preference){.edge{transition:opacity .18s ease}.node rect{transition:stroke .18s ease}}

.workspace.compact-example{min-height:0}
.compact-example .diagram-wrap{display:flex;align-items:center;padding:24px 12px;overflow:hidden}
.compact-example #topology{width:100%;min-width:0;max-width:840px;margin:auto;display:block}
.compact-example .legend,.first-example #port-label,.first-example #ports{display:none}
.compact-example #primary-label,.compact-example #reply-label{text-anchor:middle}

.edge.exchange.public-edge{marker-start:url(#arrow-public)}
.edge.exchange.private-edge{marker-start:url(#arrow-private)}
.edge.exchange.control-edge{marker-start:url(#arrow-private)}

#port-label{display:none}

.defined-term{font:inherit;color:inherit;fill:inherit;text-decoration:underline dotted;text-underline-offset:3px;cursor:help;user-select:text}
.defined-term:focus-visible{outline:2px solid var(--mint);outline-offset:3px;border-radius:2px}
.term-definition{position:fixed;z-index:10000;box-sizing:border-box;width:max-content;max-width:min(330px,calc(100vw - 16px));padding:11px 13px;border:1px solid #638779;border-radius:9px;background:#10241e;color:#edf6f1;font:14px/1.5 system-ui,sans-serif;user-select:text}
.term-definition[hidden]{display:none}
@media(prefers-color-scheme:light){.term-definition{background:#f4faf6;color:#172e24;border-color:#779889}}

@media(prefers-color-scheme:light){
 :root{color-scheme:light;--bg:#f1f5ef;--surface:#ffffff;--surface2:#e8f0e9;--ink:#19332b;--muted:#48645a;--line:#a7bbb0;--mint:#17684d;--cyan:#126681;--amber:#835408;--danger:#ac3028;--blocked:#596e64}
 .stage-actions button,#stage-list button{background:var(--surface);color:var(--ink)}
 .stage-actions button:disabled{color:#63756c;background:#e4ece6}
 #stage-list button[aria-current=step]{background:#d9eee1;color:var(--mint)}
 .diagram-wrap{background-image:linear-gradient(#19332b08 1px,transparent 1px),linear-gradient(90deg,#19332b08 1px,transparent 1px)}
}

.ethernet-history{padding:22px 28px;border-top:1px solid var(--line);background:var(--surface);color:var(--ink)}
.ethernet-history[hidden]{display:none}
.ethernet-history h3{margin:0 0 10px;font-size:1.05rem}
.ethernet-history p{margin:8px 0;color:var(--muted);line-height:1.55}
.ethernet-history a{color:var(--mint);text-underline-offset:3px}
.ethernet-timeline{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:22px;padding:16px 0;margin:12px 0;list-style:none;border-top:1px solid var(--line);border-bottom:1px solid var(--line)}
.ethernet-timeline strong{font-size:.9rem}
.ethernet-timeline p{font-size:.9rem}
@media(max-width:700px){.ethernet-timeline{grid-template-columns:1fr;gap:12px}.ethernet-history{padding:20px}}

.ieee-reference{margin-top:24px;padding-top:22px;border-top:1px solid var(--line)}
.standards-scroll{max-width:100%;overflow-x:auto;margin:18px 0}
.standards-scroll:focus-visible{outline:2px solid var(--mint);outline-offset:3px}
.standards-table{width:100%;border-collapse:collapse;font-size:.9rem;text-align:left;background:var(--surface);color:var(--ink)}
.standards-table caption{text-align:left;font-weight:750;margin-bottom:10px;color:var(--ink)}
.standards-table th,.standards-table td{padding:9px 12px;border-bottom:1px solid var(--line);vertical-align:top;line-height:1.45}
.standards-table thead{background:var(--surface2);color:var(--ink)}
.standards-table th:first-child{white-space:nowrap}
.standards-table td{color:var(--muted)}
@media(max-width:700px){.standards-table{font-size:.82rem}.standards-table th,.standards-table td{padding:8px 6px}.standards-table th:first-child{white-space:normal}}

.notebook-main{padding-top:24px}
.notebook-index,.notebook-context{background:var(--surface);color:var(--ink);border:1px solid var(--line);padding:20px 24px}
.notebook-index h1{font-size:1.15rem;margin:0 0 12px}
.notebook-index .standards-scroll{margin:0}
.notebook-description{font-size:.85rem;line-height:1.5;color:var(--muted);margin:14px 0 0}
.notebook-context h3{font-size:1.05rem;margin:0 0 10px}
.notebook-context p{color:var(--muted);line-height:1.55}
.notebook-main a{color:var(--mint)}
.note-status{font-size:.82rem}
@media(max-width:700px){.notebook-index,.notebook-context{padding:16px 12px}.notebook-index .standards-table th:first-child{width:34%}.notebook-index .note-status{width:22%}}

.standard-name{display:block;font-weight:400;color:var(--muted);margin-top:3px;white-space:normal}

.workspace.history-slide{grid-template-columns:minmax(280px,.85fr) minmax(0,1.3fr)}.history-slide .explanation{max-width:none}.diagram-wrap[hidden]{display:none}

#history-illustration{margin:0;padding:20px;background:var(--surface);color:var(--muted);align-self:center}
#history-illustration[hidden]{display:none}
#history-illustration img{display:block;width:100%;height:auto;border-radius:8px}
#history-illustration figcaption{font-size:11px;line-height:1.4;margin-top:8px}
@media(max-width:760px){.workspace.history-slide{grid-template-columns:1fr}#history-illustration{padding:16px}}

#access-retry{font:inherit;border:1px solid var(--line);border-radius:7px;background:var(--surface);color:var(--ink);padding:6px 12px;cursor:pointer}#access-retry:disabled{opacity:.6;cursor:wait}