/* Fonts are self-hosted. The previous build pulled them from Google Fonts with
   @import, which sent every visitor's IP address to a third party and chained
   a render-blocking request. Local files also let the CSP stay at 'self'. */
@font-face{font-family:'IBM Plex Sans';font-style:normal;font-weight:400;font-display:swap;src:url(fonts/ibm-plex-sans-latin-400-normal.woff2) format('woff2')}
@font-face{font-family:'IBM Plex Sans';font-style:normal;font-weight:500;font-display:swap;src:url(fonts/ibm-plex-sans-latin-500-normal.woff2) format('woff2')}
@font-face{font-family:'IBM Plex Sans';font-style:normal;font-weight:600;font-display:swap;src:url(fonts/ibm-plex-sans-latin-600-normal.woff2) format('woff2')}
@font-face{font-family:'IBM Plex Mono';font-style:normal;font-weight:400;font-display:swap;src:url(fonts/ibm-plex-mono-latin-400-normal.woff2) format('woff2')}
@font-face{font-family:'IBM Plex Mono';font-style:normal;font-weight:500;font-display:swap;src:url(fonts/ibm-plex-mono-latin-500-normal.woff2) format('woff2')}

/* Night blueprint. Each accent has one meaning and is used for nothing else:
   flow = data path and selection, tele = security events (always dashed),
   gap = a switched-off layer, ok = good practice and a completed trace.
   Every text colour passes 4.5:1 on ink, surface and raised. The old build
   had labels at 3.3 to 4.3:1 and sizes down to 7px, so 12px is the floor. */
:root{
  --ink:#0E1116;--surface:#151A21;--raised:#1C232C;--line:#2A3340;
  --text:#E8EDF2;--muted:#A3AEBB;--subtle:#8592A1;
  --flow:#4FA3FF;--flow-hover:#8CC4FF;--tele:#A99BF0;--gap:#FFB266;--gap-bg:#241D17;--gap-line:#5C4632;--ok:#5FD0B5;
  --sans:'IBM Plex Sans',system-ui,-apple-system,'Segoe UI',Roboto,Arial,sans-serif;
  --mono:'IBM Plex Mono',ui-monospace,SFMono-Regular,Consolas,monospace;
  color-scheme:dark;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth;scroll-padding-top:16px;-webkit-text-size-adjust:100%}
body{margin:0;background:var(--ink);color:var(--text);font-family:var(--sans);font-size:15px;line-height:1.5}
h1,h2,h3,h4,p{margin:0}
a{color:var(--flow)}a:hover{color:var(--flow-hover)}
button,select{font:inherit;color:inherit}
button{cursor:pointer}
:focus-visible{outline:2px solid var(--flow);outline-offset:3px}
[hidden]{display:none!important}

.skip{position:absolute;left:16px;top:-60px;background:var(--flow);color:var(--ink);padding:10px 14px;border-radius:6px;font-weight:600;z-index:10}
.skip:focus{top:12px}
.wrap{max-width:1440px;margin:0 auto;padding:0 48px}
.eyebrow{font-family:var(--mono);font-size:12px;font-weight:400;letter-spacing:1.1px;color:var(--muted)}
.eyebrow-accent{color:var(--flow)}

/* Header */
.site-header{display:flex;flex-wrap:wrap;align-items:center;justify-content:space-between;gap:8px 32px;padding:20px 0;border-bottom:1px solid var(--line)}
.brand{display:flex;align-items:center;gap:10px;color:var(--text);text-decoration:none;font-size:26px;font-weight:600;letter-spacing:-.8px;min-height:44px}
.brand:hover{color:var(--text)}
.brand svg{fill:none;stroke:var(--flow);stroke-width:2}
.site-nav{display:flex;flex-wrap:wrap;gap:0 28px;font-size:14px}
.site-nav a,.byline{color:var(--muted);text-decoration:none;padding:12px 0;display:inline-block}
.site-nav a:hover,.byline:hover{color:var(--text)}

/* Intro */
.intro{display:flex;flex-wrap:wrap;justify-content:space-between;align-items:flex-end;gap:24px;padding:56px 0 40px}
.intro-copy{display:flex;flex-direction:column;gap:14px;max-width:760px}
h1{font-size:clamp(34px,4.2vw,52px);font-weight:500;letter-spacing:-1.5px;line-height:1.08}
.lede{font-size:17px;line-height:1.6;color:var(--muted);max-width:620px}
.intro-meta{font-family:var(--mono);font-size:12px;color:var(--subtle);line-height:1.8;text-align:right}

/* Explorer shell */
.explorer{border:1px solid var(--line);border-radius:12px;background:var(--surface);overflow:hidden}
.explorer-bar{display:flex;flex-wrap:wrap;align-items:center;justify-content:space-between;gap:12px;padding:14px 20px;border-bottom:1px solid var(--line)}
.segmented{display:flex;gap:4px;padding:4px;background:var(--ink);border:1px solid var(--line);border-radius:8px}
.segmented button{min-height:40px;padding:0 18px;border:0;border-radius:5px;background:transparent;color:var(--muted);font-size:14px}
.segmented button:hover{color:var(--text)}
.segmented button[aria-pressed=true]{background:var(--flow);color:var(--ink);font-weight:600}
.text-btn{min-height:40px;padding:0 12px;border:0;background:transparent;color:var(--muted);font-size:14px}
.text-btn:hover{color:var(--text)}
.explorer-body{display:grid;grid-template-columns:248px minmax(0,1fr) 320px}

/* Layer list */
.layers{border-right:1px solid var(--line);padding:20px 12px;display:flex;flex-direction:column;gap:2px}
#controls{display:flex;flex-direction:column;gap:2px}
.layer-group{font-family:var(--mono);font-size:12px;letter-spacing:1px;color:var(--subtle);padding:18px 12px 8px}
.layer-btn{display:flex;gap:12px;align-items:center;text-align:left;min-height:40px;padding:6px 12px;border:1px solid transparent;border-radius:6px;background:transparent;color:var(--muted);font-size:14px;width:100%}
.layer-btn:hover{color:var(--text);background:var(--raised)}
.layer-btn .num{font-family:var(--mono);font-size:12px;color:var(--subtle);flex:none}
.layer-btn[aria-pressed=true]{border-color:var(--flow);background:var(--raised);color:var(--text);font-weight:500}
.layer-btn[aria-pressed=true] .num{color:var(--flow)}
.layer-overview{min-height:44px}

/* Centre */
.centre{min-width:0;display:flex;flex-direction:column}
.canvas-heading{display:flex;flex-wrap:wrap;justify-content:space-between;align-items:flex-end;gap:12px;padding:24px 28px 8px}
.canvas-heading>div{display:flex;flex-direction:column;gap:8px}
h2{font-size:26px;font-weight:500;letter-spacing:-.5px}
.tag{font-family:var(--mono);font-size:12px;color:var(--muted);border:1px solid var(--line);border-radius:6px;padding:6px 10px}
.flow-hint{font-family:var(--mono);font-size:12px;color:var(--subtle);padding:8px 28px 0}
.diagram{margin:14px 28px 0;scroll-margin-top:16px}

/* Nodes. These are real buttons now, not <g> elements inside an SVG with
   role="img": ARIA treats an image's children as presentational, so the
   old interactive parts could vanish for some screen readers. */
.node{display:flex;flex-direction:column;justify-content:space-between;gap:8px;min-height:92px;width:100%;padding:12px 14px;border:1px solid var(--line);border-radius:10px;background:var(--raised);color:var(--text);text-align:left;transition:border-color .2s,background .2s}
.node:hover{border-color:var(--muted)}
.node-name{font-size:15px;font-weight:500;line-height:1.3}
.node-sub{font-family:var(--mono);font-size:12px;color:var(--subtle)}
.node.tele{border-style:dashed;border-color:var(--tele)}
.node.tele .node-sub{color:var(--tele)}
.node[aria-pressed=true]{border:2px solid var(--flow);padding:11px 13px}
.node.lit{border:2px solid var(--flow);padding:11px 13px;box-shadow:0 0 0 4px rgba(79,163,255,.18)}
.node.off{border:2px dashed var(--gap);padding:11px 13px;background:var(--gap-bg)}
.node.off .node-sub{color:var(--gap)}

/* Overview */
.arch{display:flex;flex-direction:column;gap:18px}
.arch-row{display:grid;grid-template-columns:minmax(0,.8fr) repeat(3,minmax(0,1fr));gap:12px;align-items:end}
.zone{border:1px dashed var(--line);border-radius:10px;padding:10px;display:flex;flex-direction:column;gap:10px;min-width:0}
.zone-plain{border-color:transparent;padding-left:0}
.zone-label{font-family:var(--mono);font-size:12px;letter-spacing:1px;color:var(--subtle)}
.hops{list-style:none;margin:0;padding:0;display:flex;flex-wrap:wrap;gap:8px 24px;font-family:var(--mono);font-size:12px;color:var(--muted)}
.hops li{display:flex;align-items:center;gap:8px}
.arrow{fill:none;stroke:var(--flow);stroke-width:2;stroke-linecap:round;stroke-linejoin:round}
.planes-title{display:block;margin-bottom:10px}
.planes{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:12px}

/* Control deep dive */
.flow-box{border:1px dashed var(--line);border-radius:10px;padding:20px;display:flex;flex-direction:column;gap:20px}
.flow-row{display:flex;align-items:stretch}
.step{flex:1 1 0;min-width:0;display:flex;flex-direction:column;justify-content:space-between;gap:12px;min-height:140px;padding:14px;border:1px solid var(--line);border-radius:10px;background:var(--raised)}
.step.selected{border:2px solid var(--flow);padding:13px}
.step.lit{border:2px solid var(--flow);padding:13px;box-shadow:0 0 0 4px rgba(79,163,255,.18)}
.step.off{border:2px dashed var(--gap);padding:13px;background:var(--gap-bg)}
.step-main{display:flex;flex-direction:column;gap:6px;padding:0;border:0;background:transparent;color:var(--text);text-align:left;min-height:44px}
.step-meta{font-family:var(--mono);font-size:12px;color:var(--subtle)}
.step-name{font-size:16px;font-weight:500;line-height:1.3}
.step-arrow{flex:0 0 36px;display:flex;align-items:center;justify-content:center}
.step-via{font-family:var(--mono);font-size:12px;color:var(--muted)}
.switch{align-self:flex-start;min-height:36px;padding:4px 10px;border:1px solid var(--line);border-radius:5px;background:transparent;color:var(--muted);font-size:13px}
.switch:hover{color:var(--text);border-color:var(--muted)}
.switch[aria-pressed=true]{border-color:var(--gap);color:var(--gap)}
.evidence-row{display:flex;flex-wrap:wrap;align-items:center;gap:14px}
.evidence-row .tele-label{font-family:var(--mono);font-size:12px;color:var(--tele)}
.evidence-row .step{flex:0 1 300px;min-height:0}
.tele-line{fill:none;stroke:var(--tele);stroke-width:2;stroke-dasharray:5 5}

/* Key */
.legend{display:flex;flex-wrap:wrap;gap:8px 20px;padding:18px 28px 20px;font-size:13px;color:var(--muted);border-bottom:1px solid var(--line)}
.legend span{display:flex;align-items:center;gap:8px}
.k-flow{stroke:var(--flow);stroke-width:2}
.k-tele{stroke:var(--tele);stroke-width:2;stroke-dasharray:4 4}
.k-bound{fill:none;stroke:var(--subtle);stroke-width:1.5;stroke-dasharray:4 3}
.k-gap{fill:none;stroke:var(--gap);stroke-width:2;stroke-dasharray:4 3}

/* Journey */
.journey{padding:22px 28px 28px;display:flex;flex-direction:column;gap:14px}
.journey-controls{display:flex;flex-wrap:wrap;gap:10px;align-items:flex-end}
.journey-label{flex:1 1 260px;display:flex;flex-direction:column;gap:6px;font-size:13px;color:var(--muted)}
select{min-height:44px;padding:0 12px;background:var(--ink);border:1px solid var(--line);border-radius:6px;color:var(--text);font-size:15px}
.primary{min-height:44px;padding:0 22px;border:0;border-radius:6px;background:var(--flow);color:var(--ink);font-size:15px;font-weight:600}
.primary:hover{background:var(--flow-hover)}
.primary:disabled{opacity:.7;cursor:progress}
.result{display:flex;flex-direction:column;gap:6px;padding:14px 16px;border-radius:8px;border:1px solid var(--line);background:var(--raised);color:var(--muted)}
.result.done{color:var(--ok)}
.result.warn{color:var(--gap);border-color:var(--gap-line);background:var(--gap-bg)}
.result-label{font-family:var(--mono);font-size:12px;letter-spacing:1px}
.result-text{font-size:15px;line-height:1.6;color:var(--text)}

/* Inspector */
.inspector{border-left:1px solid var(--line);background:var(--raised);padding:24px;display:flex;flex-direction:column;gap:18px;outline:none}
.inspector h3{font-size:22px;font-weight:500;letter-spacing:-.3px;line-height:1.3}
.detail-text{font-size:15px;line-height:1.65;color:var(--muted)}
.detail-section{border-top:1px solid var(--line);padding-top:16px;display:flex;flex-direction:column;gap:10px}
.good-list{list-style:none;margin:0;padding:0;display:flex;flex-direction:column;gap:10px}
.good-list li{display:flex;gap:10px;font-size:14px;line-height:1.55}
.good-list svg{flex:none;margin-top:3px;fill:none;stroke:var(--ok);stroke-width:2}
.chips{display:flex;flex-wrap:wrap;gap:6px}
.chips span{font-size:13px;border:1px solid var(--line);border-radius:4px;padding:5px 9px}
.callout{border:1px solid var(--line);background:var(--surface);border-radius:8px;padding:14px;display:flex;flex-direction:column;gap:6px;font-size:14px;line-height:1.6}
.callout.risk{border-color:var(--gap-line);background:var(--gap-bg)}
.callout.risk .eyebrow{color:var(--gap)}
.secondary{min-height:44px;border:1px solid var(--flow);border-radius:6px;background:transparent;color:var(--text);font-size:14px}
.secondary:hover{background:var(--surface)}
.gap-btn{min-height:44px;border:1px solid var(--line);border-radius:6px;background:transparent;color:var(--muted);font-size:14px}
.gap-btn[aria-pressed=true]{border-color:var(--gap);color:var(--gap);background:var(--gap-bg)}
.back-link{display:none;font-size:14px;min-height:44px;align-items:center}

/* Principles */
.principles{padding:72px 0 24px;display:flex;flex-direction:column;gap:12px}
.principles h2{font-size:34px;letter-spacing:-.8px;margin-bottom:16px}
.cards{display:grid;grid-template-columns:repeat(auto-fit,minmax(280px,1fr));gap:16px}
.card{border:1px solid var(--line);border-radius:10px;background:var(--surface);padding:26px;display:flex;flex-direction:column;gap:14px}
.card h3{font-size:22px;font-weight:500}
.card p:not(.eyebrow){font-size:15px;line-height:1.65;color:var(--muted)}
.card-link{margin-top:auto;padding:14px 0 0;border:0;border-top:1px solid var(--line);background:transparent;color:var(--flow);text-align:left;font-size:15px;min-height:44px}
.card-link:hover{color:var(--flow-hover)}
.review{border-top:1px solid var(--line);border-bottom:1px solid var(--line);margin-top:28px}
.review summary{display:flex;justify-content:space-between;align-items:center;gap:16px;padding:20px 0;font-size:16px;cursor:pointer;list-style:none;min-height:44px}
.review summary::-webkit-details-marker{display:none}
.summary-icon{flex:none;fill:none;stroke:var(--muted);stroke-width:2;stroke-linecap:round}
.review[open] .plus-bar{display:none}
.review-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(240px,1fr));gap:28px;padding-bottom:28px}
.review-grid h3{font-size:15px;font-weight:500;color:var(--flow);margin-bottom:8px}
.review-grid p{font-size:14px;line-height:1.65;color:var(--muted)}

/* About and footer */
.about{padding:48px 0 56px;display:grid;grid-template-columns:repeat(auto-fit,minmax(320px,1fr));gap:32px;align-items:start}
.about>div:first-child{display:flex;flex-direction:column;gap:12px}
.about h2{font-size:30px;letter-spacing:-.6px}
.about-copy{display:flex;flex-direction:column;gap:14px;font-size:15px;line-height:1.7;color:var(--muted)}
.about-links{display:flex;flex-wrap:wrap;gap:20px}
.site-footer{display:flex;flex-wrap:wrap;justify-content:space-between;gap:16px;padding:28px 0 40px;border-top:1px solid var(--line);font-size:13px;color:var(--subtle)}
.footer-links{display:flex;flex-wrap:wrap;gap:20px}

/* Inspector drops below the diagram once three columns would squeeze the
   step cards under about 110px each. */
@media (max-width:1320px){
  .explorer-body{grid-template-columns:232px minmax(0,1fr)}
  .inspector{grid-column:1/-1;border-left:0;border-top:1px solid var(--line)}
  .back-link{display:inline-flex}
}

/* Phone. The old build scaled an 820px SVG down to about 44%, which put
   labels at 3.5px. Here the diagram reflows into a vertical stack instead. */
@media (max-width:760px){
  .wrap{padding:0 16px}
  .intro{padding:32px 0 24px}
  .intro-meta{text-align:left}
  .site-nav{gap:0 18px}
  .byline{display:none}
  .explorer{border-radius:10px;margin:0 -8px}
  .explorer-bar{padding:12px}
  .explorer-bar>.eyebrow{display:none}
  .segmented{order:3;width:100%}
  .segmented button{flex:1;padding:0 8px;min-height:44px}
  .explorer-body{display:block}
  .layers{border-right:0;border-bottom:1px solid var(--line);padding:12px;flex-direction:row;overflow-x:auto;gap:8px}
  #controls{flex-direction:row;gap:8px}
  .layer-group{display:none}
  .layer-btn{width:auto;flex:none;white-space:nowrap;border-color:var(--line);border-radius:22px;min-height:44px;background:var(--raised)}
  .canvas-heading{padding:18px 16px 4px}
  .tag{display:none}
  .flow-hint{padding:6px 16px 0}
  .diagram{margin:12px 16px 0}
  .arch-row{grid-template-columns:1fr;gap:10px}
  .zone-plain{padding:0}
  .hops{flex-direction:column}
  .planes{grid-template-columns:repeat(2,minmax(0,1fr))}
  .flow-box{padding:14px}
  .flow-row{flex-direction:column}
  .step{flex:none;min-height:0;flex-direction:row;align-items:center}
  .step-main{flex:1}
  .switch{align-self:center;min-height:44px}
  .step-arrow{flex:none;height:36px}
  .step-arrow svg{transform:rotate(90deg)}
  .legend{padding:14px 16px}
  .journey{padding:18px 16px 22px}
  .inspector{padding:20px 16px}
  .principles{padding-top:48px}
  .principles h2{font-size:26px}
}

@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  .node,.step{transition:none}
}