:root {
  color-scheme: dark;
  --bg: #090b10;
  --panel: rgba(18, 21, 29, 0.88);
  --panel-strong: #151923;
  --line: rgba(255, 255, 255, 0.1);
  --line-strong: rgba(255, 255, 255, 0.18);
  --text: #f3f5f7;
  --muted: #949ba8;
  --lime: #c8ff3d;
  --lime-soft: rgba(200, 255, 61, 0.13);
  --cyan: #65dce7;
  --orange: #ff9060;
  --radius: 18px;
  font-family: "DM Sans", system-ui, sans-serif;
}

* { box-sizing: border-box; }
[hidden] { display: none !important; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  min-width: 320px;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  overflow-x: hidden;
}
button, input { font: inherit; }
button { color: inherit; }

.ambient { position: fixed; border-radius: 999px; filter: blur(120px); pointer-events: none; opacity: 0.11; }
.ambient-one { width: 420px; height: 420px; background: var(--lime); top: -240px; right: 8%; }
.ambient-two { width: 380px; height: 380px; background: #4e67ff; top: 45%; left: -280px; }
.app-shell { width: min(1480px, calc(100% - 48px)); margin: 0 auto; padding: 38px 0 30px; position: relative; }

.hero { display: flex; align-items: flex-end; justify-content: space-between; gap: 24px; margin-bottom: 30px; }
.hero h1 { font-family: "Space Grotesk", sans-serif; font-size: clamp(42px, 5vw, 74px); line-height: .92; letter-spacing: -.055em; margin: 14px 0 16px; }
.hero h1 span { color: var(--lime); }
.hero p { color: var(--muted); font-size: clamp(16px, 1.4vw, 20px); margin: 0; max-width: 680px; }
.eyebrow, .section-kicker { text-transform: uppercase; letter-spacing: .17em; font-size: 11px; font-weight: 700; color: var(--muted); margin: 0; }
.status-dot { display: inline-block; width: 7px; height: 7px; border-radius: 50%; background: var(--lime); box-shadow: 0 0 14px var(--lime); margin-right: 8px; }
.hero-actions { display: flex; align-items: center; justify-content: flex-end; gap: 9px; flex-wrap: wrap; }
.reset-button { border: 1px solid var(--line-strong); background: rgba(255,255,255,.04); border-radius: 999px; padding: 11px 17px; cursor: pointer; transition: .2s ease; }
.reset-button:hover, .reset-button:focus-visible { border-color: var(--lime); color: var(--lime); outline: none; }
.surprise-button { border: 1px solid rgba(101,220,231,.48); background: rgba(101,220,231,.09); color: var(--cyan); border-radius: 999px; padding: 11px 17px; cursor: pointer; font-weight: 700; transition: .2s ease; }
.surprise-button:hover, .surprise-button:focus-visible { border-color: var(--cyan); background: var(--cyan); color: #071315; outline: none; box-shadow: 0 0 24px rgba(101,220,231,.13); }
.visually-hidden { position: absolute !important; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0, 0, 0, 0); white-space: nowrap; border: 0; }

.lesson-strip { display: grid; grid-template-columns: auto 1fr auto; align-items: center; gap: 18px; border-block: 1px solid var(--line); padding: 14px 4px; margin-bottom: 40px; }
.lesson-strip p { margin: 0; color: #c5cad2; }
.lesson-number { color: var(--lime); font-family: "Space Grotesk"; font-weight: 700; }
.lesson-hint { border: 1px solid var(--line); border-radius: 999px; color: var(--muted); padding: 6px 11px; font-size: 12px; }

.section-heading, .panel-heading, .result-topline { display: flex; align-items: flex-end; justify-content: space-between; gap: 20px; }
.section-heading { margin-bottom: 18px; }
.section-heading h2, .panel-heading h2, .result-topline h2 { font-family: "Space Grotesk"; letter-spacing: -.03em; margin: 5px 0 0; font-size: 26px; }
.legend { display: flex; gap: 16px; flex-wrap: wrap; color: var(--muted); font-size: 12px; }
.legend span { display: inline-flex; align-items: center; gap: 7px; }
.legend-dot { width: 7px; height: 7px; border-radius: 50%; background: #777; }
.legend-dot.effective { background: var(--cyan); }
.legend-dot.bottleneck { background: var(--lime); box-shadow: 0 0 8px var(--lime); }

.chain { display: grid; grid-template-columns: repeat(8, minmax(132px, 1fr)); gap: 10px; align-items: stretch; }
.chain-card { position: relative; z-index: 1; min-height: 374px; border: 1px solid var(--line); background: linear-gradient(150deg, rgba(255,255,255,.055), rgba(255,255,255,.018)), #0d1016; border-radius: var(--radius); padding: 10px 14px 13px; display: flex; flex-direction: column; transition: border-color .25s, background .25s, transform .25s, box-shadow .25s, opacity .25s, filter .25s; }
.chain-card::after { content: "→"; position: absolute; color: #4c5360; right: -11px; top: 50%; transform: translateY(-50%); z-index: 3; font-size: 15px; }
.chain-card:last-child::after { display: none; }
.chain-card.is-bottleneck { border-color: var(--lime); background: linear-gradient(150deg, rgba(200,255,61,.15), rgba(200,255,61,.035)); box-shadow: inset 0 0 0 1px rgba(200,255,61,.08), 0 0 32px rgba(200,255,61,.06); }
.chain-card.is-bottleneck .node-visual { border-color: rgba(200,255,61,.42); background: linear-gradient(145deg, rgba(200,255,61,.09), rgba(255,255,255,.025)); color: var(--lime); }
.chain-card.is-bottleneck .node-visual::before { background: radial-gradient(ellipse, rgba(200,255,61,.42) 0%, rgba(200,255,61,.12) 46%, transparent 72%); }
.chain-card.is-bottleneck .node-photo { filter: drop-shadow(0 9px 11px rgba(0,0,0,.55)) drop-shadow(0 0 11px rgba(200,255,61,.32)); }
.chain-card.is-bottleneck .node-number { color: var(--lime); }
.node-visual { position: relative; display: grid; place-items: center; height: 112px; margin-bottom: 12px; border: 1px solid rgba(255,255,255,.075); border-radius: 13px; background: linear-gradient(145deg, rgba(255,255,255,.065), rgba(255,255,255,.018)); color: #d8dce3; transition: border-color .25s, background .25s, color .25s; overflow: hidden; isolation: isolate; }
.node-visual::before { content: ""; position: absolute; inset: 13% 7%; border-radius: 50%; background: radial-gradient(ellipse, rgba(220,235,242,.27) 0%, rgba(101,220,231,.13) 43%, transparent 72%); filter: blur(6px); z-index: -1; transition: background .25s; }
.node-number { position: absolute; top: 8px; left: 9px; font: 600 9px "Space Grotesk"; color: #6f7784; letter-spacing: .1em; z-index: 1; }
.node-photo { position: absolute; inset: 0; z-index: 0; display: block; width: 100%; height: 100%; min-width: 0; min-height: 0; padding: 5px 7px 3px; object-fit: contain; filter: drop-shadow(0 9px 11px rgba(0,0,0,.58)) drop-shadow(0 0 10px rgba(165,220,232,.2)); }
.node-icon-fallback { display: grid; place-items: center; width: 88px; height: 74px; }
.node-visual.image-failed::before { opacity: .65; }
.node-svg { width: 82px; height: 68px; stroke: currentColor; stroke-width: 2; stroke-linecap: round; stroke-linejoin: round; }
.node-svg .svg-accent { stroke: var(--cyan); }
.node-svg .svg-accent-fill { fill: var(--cyan); stroke: none; }
.chain-card.is-bottleneck .node-svg .svg-accent { stroke: var(--lime); }
.chain-card.is-bottleneck .node-svg .svg-accent-fill { fill: var(--lime); }
.node-type { color: var(--muted); text-transform: uppercase; letter-spacing: .13em; font-size: 9px; font-weight: 700; margin: 0 0 5px; }
.node-name { font: 600 15px/1.15 "Space Grotesk"; min-height: 35px; margin: 0; }
.node-detail { color: var(--muted); font-size: 11px; min-height: 29px; margin: 4px 0 12px; line-height: 1.25; }
.speed-module { border-top: 1px solid var(--line); padding-top: 8px; margin-top: auto; min-height: 75px; }
.speed-content { min-height: 31px; display: grid; align-content: center; }
.speed-hidden { margin: 0; color: #6f7784; text-align: center; font-size: 10px; letter-spacing: .04em; }
.speed-pair { display: grid; gap: 3px; }
.speed-pair span { display: flex; justify-content: space-between; color: var(--muted); font-size: 10px; }
.speed-pair strong { color: #dfe3e8; font-weight: 600; }
.speed-pair .effective-speed strong { color: var(--cyan); }
.speed-toggle { width: 100%; height: 27px; margin-top: 7px; border: 1px solid rgba(101,220,231,.2); border-radius: 8px; background: rgba(101,220,231,.055); color: #8fbcc2; cursor: pointer; font-size: 9px; font-weight: 700; transition: .15s ease; }
.speed-toggle span { display: inline-block; margin-right: 3px; color: var(--cyan); }
.speed-toggle:hover, .speed-toggle:focus-visible { outline: none; color: var(--text); border-color: rgba(101,220,231,.55); background: rgba(101,220,231,.12); }
.speed-module[data-speed-revealed="true"] .speed-toggle { color: var(--muted); border-color: var(--line); background: rgba(255,255,255,.025); }
.arrow-control { display: grid; grid-template-columns: 32px 1fr 32px; gap: 5px; align-items: center; margin-top: 10px; }
.arrow-button { border: 1px solid var(--line); background: rgba(255,255,255,.035); border-radius: 8px; height: 29px; cursor: pointer; color: #9ca4af; transition: .15s; }
.arrow-button:hover, .arrow-button:focus-visible { color: var(--lime); border-color: rgba(200,255,61,.5); outline: none; background: var(--lime-soft); }
.option-count { font-size: 9px; color: #686f7c; text-align: center; }
.compatibility-note { margin: 12px 3px 0; color: var(--muted); font-size: 12px; display: flex; align-items: center; gap: 8px; }
.compatibility-note::before { content: "✓"; display: grid; place-items: center; color: var(--lime); border: 1px solid rgba(200,255,61,.35); border-radius: 50%; width: 17px; height: 17px; font-size: 10px; }

.controls-results-grid { display: grid; grid-template-columns: .8fr 1.2fr; gap: 18px; margin-top: 42px; }
.side-panel, .result-panel { border: 1px solid var(--line); border-radius: 22px; padding: 24px; background: var(--panel); backdrop-filter: blur(18px); }
.panel-icon { width: 38px; height: 38px; border: 1px solid var(--line); display: grid; place-items: center; border-radius: 11px; color: var(--lime); }
.task-controls { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; margin-top: 24px; }
.task-control { border: 1px solid var(--line); border-radius: 14px; padding: 13px; background: rgba(255,255,255,.025); }
.task-control > span { display: block; color: var(--muted); font-size: 11px; margin-bottom: 5px; }
.task-value { font: 600 19px "Space Grotesk"; }
.task-control .arrow-control { margin-top: 9px; }
.checksum-explainer { margin-top: 13px; padding: 12px 14px; border-left: 2px solid var(--cyan); background: rgba(101,220,231,.06); color: #aab2bd; font-size: 12px; line-height: 1.45; }

.result-panel { background: radial-gradient(circle at 90% 0%, rgba(200,255,61,.09), transparent 33%), var(--panel-strong); }
.result-panel[data-diagnosis-state="hidden"] { background: radial-gradient(circle at 90% 0%, rgba(101,220,231,.07), transparent 33%), var(--panel-strong); }
.diagnosis-action { display: flex; justify-content: flex-end; align-items: center; }
.bottleneck-badge { font-size: 10px; letter-spacing: .13em; font-weight: 700; color: #101407; background: var(--lime); border-radius: 999px; padding: 7px 10px; }
.diagnose-button { border: 1px solid rgba(200,255,61,.48); background: var(--lime-soft); color: var(--lime); border-radius: 999px; padding: 10px 15px; cursor: pointer; font-size: 12px; font-weight: 700; white-space: nowrap; transition: .18s ease; }
.diagnose-button:hover, .diagnose-button:focus-visible { background: var(--lime); color: #101407; outline: none; box-shadow: 0 0 24px rgba(200,255,61,.12); }
.speed-hero { display: flex; align-items: baseline; justify-content: space-between; margin: 26px 0 20px; }
.speed-number { font: 700 clamp(62px, 8vw, 100px)/.85 "Space Grotesk"; letter-spacing: -.07em; }
.speed-unit { color: var(--muted); margin-left: 8px; }
.speed-gbps { color: var(--cyan); font: 600 15px "Space Grotesk"; }
.time-grid { display: grid; grid-template-columns: repeat(3, 1fr); border-block: 1px solid var(--line); }
.time-grid > div { padding: 14px 12px; border-right: 1px solid var(--line); }
.time-grid > div:first-child { padding-left: 0; }
.time-grid > div:last-child { border-right: 0; }
.time-grid span { display: block; color: var(--muted); font-size: 11px; margin-bottom: 5px; }
.time-grid strong { font: 600 18px "Space Grotesk"; }
.time-grid .total strong { color: var(--lime); }
.meter { height: 4px; border-radius: 99px; background: rgba(255,255,255,.07); margin: 20px 0 14px; overflow: hidden; }
.meter span { display: block; height: 100%; border-radius: inherit; background: linear-gradient(90deg, var(--cyan), var(--lime)); transition: width .4s ease; }
.result-explanation { color: #a8afb9; font-size: 13px; line-height: 1.5; margin: 0; }
#diagnosis-content:not(:empty) { margin-top: 14px; }

.improvements-section { margin-top: 44px; }
.section-note { color: var(--muted); margin: 0; font-size: 13px; }
.recommendations { display: grid; grid-template-columns: repeat(3, 1fr); gap: 12px; }
.recommendation { border: 1px solid var(--line); border-radius: var(--radius); background: linear-gradient(145deg, rgba(255,255,255,.045), rgba(255,255,255,.015)); padding: 18px; display: flex; flex-direction: column; min-height: 190px; }
.recommendation-rank { color: var(--lime); font: 600 11px "Space Grotesk"; letter-spacing: .12em; }
.recommendation h3 { font: 600 18px/1.2 "Space Grotesk"; margin: 10px 0 5px; }
.recommendation p { color: var(--muted); font-size: 12px; margin: 0 0 16px; }
.recommendation-bottom { display: flex; justify-content: space-between; align-items: center; margin-top: auto; gap: 12px; }
.gain strong { display: block; color: var(--lime); font: 700 18px "Space Grotesk"; }
.gain span { font-size: 10px; color: var(--muted); }
.apply-button { border: 1px solid rgba(200,255,61,.45); background: var(--lime-soft); color: var(--lime); border-radius: 10px; padding: 9px 12px; cursor: pointer; font-size: 12px; font-weight: 700; }
.apply-button:hover, .apply-button:focus-visible { background: var(--lime); color: #101407; outline: none; }
.no-recommendations { grid-column: 1 / -1; border: 1px solid var(--line); border-radius: var(--radius); padding: 22px; color: var(--muted); }
.recommendations-locked { grid-column: 1 / -1; min-height: 132px; display: grid; place-items: center; align-content: center; gap: 9px; border: 1px dashed var(--line-strong); border-radius: var(--radius); color: var(--muted); text-align: center; background: rgba(255,255,255,.018); }
.recommendations-locked span { display: grid; place-items: center; width: 32px; height: 32px; border: 1px solid var(--line-strong); border-radius: 50%; color: var(--cyan); font: 600 15px "Space Grotesk"; }
.recommendations-locked p { margin: 0; font-size: 13px; }

.methodology { margin-top: 38px; border-block: 1px solid var(--line); }
.methodology summary { cursor: pointer; list-style: none; padding: 18px 2px; display: flex; justify-content: space-between; font: 600 14px "Space Grotesk"; }
.methodology summary::-webkit-details-marker { display: none; }
.methodology-content { color: var(--muted); font-size: 13px; line-height: 1.6; padding: 0 2px 20px; max-width: 900px; }
.methodology-content a { color: var(--cyan); text-decoration: none; }
.sources-list { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 13px; }
.sources-list a { border: 1px solid var(--line); border-radius: 999px; padding: 5px 9px; font-size: 11px; }
footer { display: flex; justify-content: space-between; gap: 20px; color: #666e7a; font-size: 11px; padding-top: 24px; }

@media (min-width: 1181px) and (hover: hover) and (pointer: fine) and (prefers-reduced-motion: no-preference) {
  .chain { overflow: visible; isolation: isolate; }
  .chain:has(.chain-card:hover) .chain-card:not(:hover),
  .chain:has(.chain-card:focus-within) .chain-card:not(:focus-within) { opacity: .58; filter: saturate(.65); }
  .chain-card:hover,
  .chain-card:focus-within { z-index: 20; transform: scale(1.35); box-shadow: 0 24px 65px rgba(0,0,0,.72), 0 0 0 1px rgba(101,220,231,.17); }
  .chain-card:first-child { transform-origin: left center; }
  .chain-card:last-child { transform-origin: right center; }
}

@media (max-width: 1180px) {
  .chain { overflow-x: auto; grid-template-columns: repeat(8, 150px); padding-bottom: 10px; scrollbar-color: #303642 transparent; }
}

@media (max-width: 760px) {
  .app-shell { width: min(100% - 28px, 600px); padding-top: 24px; }
  .hero { align-items: flex-start; }
  .hero h1 { font-size: 48px; }
  .hero-actions { max-width: 260px; }
  .reset-button, .surprise-button { padding: 9px 11px; font-size: 12px; }
  .lesson-strip { grid-template-columns: auto 1fr; }
  .lesson-hint { display: none; }
  .section-heading { align-items: flex-start; flex-direction: column; }
  .legend { gap: 10px; }
  .chain { display: flex; flex-direction: column; overflow: visible; }
  .chain-card { min-height: 348px; }
  .node-visual { height: 124px; }
  .chain-card::after { content: "↓"; top: auto; bottom: -16px; right: 50%; transform: translateX(50%); }
  .node-name { min-height: auto; }
  .controls-results-grid { grid-template-columns: 1fr; }
  .speed-hero { align-items: flex-end; }
  .speed-number { font-size: 64px; }
  .recommendations { grid-template-columns: 1fr; }
  .recommendation { min-height: 170px; }
  footer { flex-direction: column; }
}

@media (max-width: 430px) {
  .hero { display: block; }
  .hero-actions { justify-content: flex-start; max-width: none; margin-top: 18px; }
  .task-controls { grid-template-columns: 1fr; }
  .time-grid { grid-template-columns: 1fr; }
  .time-grid > div, .time-grid > div:first-child { padding: 10px 0; border-right: 0; border-bottom: 1px solid var(--line); }
  .time-grid > div:last-child { border-bottom: 0; }
  .speed-gbps { font-size: 12px; }
  .result-topline { align-items: flex-start; flex-direction: column; }
  .diagnosis-action { justify-content: flex-start; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { scroll-behavior: auto !important; transition: none !important; }
}