:root {
  --bg: #0f172a;
  --bg-2: #111c36;
  --panel: #1a2547;
  --ink: #e8eefc;
  --ink-dim: #9aa8c7;
  --accent: #5eead4;
  --accent-2: #818cf8;
  --warn: #fbbf24;
  --good: #34d399;
  --bad: #f87171;
  --line: rgba(255,255,255,0.08);
  --radius: 14px;
  --maxw: 1080px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  background: var(--bg);
  color: var(--ink);
  line-height: 1.55;
  -webkit-font-smoothing: antialiased;
}
h1, h2, h3, h4 { line-height: 1.15; margin: 0 0 0.6em; }
h2 { font-size: clamp(1.8rem, 3vw, 2.6rem); }
p { margin: 0 0 1em; }
em { font-style: italic; color: var(--accent); }

/* Aim indicator */
#aim-indicator {
  position: fixed;
  top: 18px; left: 50%;
  transform: translate(-50%, -12px);
  background: rgba(20, 30, 60, 0.45);
  border: 1px solid rgba(94, 234, 212, 0.35);
  color: rgba(232, 238, 252, 0.75);
  padding: 7px 18px;
  border-radius: 999px;
  font-size: 0.82rem;
  z-index: 60;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.35s ease, transform 0.35s ease;
  backdrop-filter: blur(6px);
  -webkit-backdrop-filter: blur(6px);
  text-align: center;
  line-height: 1.2;
  white-space: nowrap;
  max-width: calc(100vw - 40px);
  overflow: hidden;
  text-overflow: ellipsis;
}
#aim-indicator.visible { opacity: 0.85; transform: translate(-50%, 0); }
#aim-indicator::before { content: "🎯 Aim: "; color: rgba(94, 234, 212, 0.85); font-weight: 600; }
@media (max-width: 700px) {
  #aim-indicator { font-size: 0.72rem; padding: 5px 12px; }
}

/* Progress bar */
#progress-bar {
  position: fixed; top: 0; left: 0;
  height: 4px; width: 0%;
  background: linear-gradient(90deg, var(--accent), var(--accent-2));
  z-index: 100;
  transition: width 0.1s linear;
}

/* Side nav */
#side-nav {
  position: fixed;
  left: 22px; top: 50%;
  transform: translateY(-50%);
  display: flex; flex-direction: column; gap: 12px;
  z-index: 50;
}
#side-nav a {
  position: relative;
  width: 12px; height: 12px;
  border-radius: 50%;
  background: rgba(255,255,255,0.18);
  transition: background 0.2s, transform 0.2s;
}
#side-nav a:hover { background: var(--accent); transform: scale(1.2); }
#side-nav a.active { background: var(--accent); transform: scale(1.3); }
#side-nav a::after {
  content: attr(data-label);
  position: absolute;
  left: 22px; top: 50%;
  transform: translateY(-50%);
  background: var(--panel);
  color: var(--ink);
  font-size: 0.78rem;
  padding: 4px 10px;
  border-radius: 6px;
  white-space: nowrap;
  opacity: 0; pointer-events: none;
  transition: opacity 0.18s;
}
#side-nav a:hover::after { opacity: 1; }

/* Sections */
.section {
  min-height: 100vh;
  display: flex;
  align-items: center;
  padding: 80px 24px;
  border-bottom: 1px solid var(--line);
}
.container { width: 100%; max-width: var(--maxw); margin: 0 auto; }
.sub { color: var(--ink-dim); font-size: 1.1rem; max-width: 70ch; }
.feedback { min-height: 1.5em; font-weight: 500; color: var(--ink-dim); }
.feedback.good { color: var(--good); }
.feedback.bad  { color: var(--bad); }
.feedback.warn { color: var(--warn); }

/* Hero */
.hero {
  background:
    radial-gradient(1200px 600px at 80% 10%, rgba(94,234,212,0.15), transparent 60%),
    radial-gradient(900px 500px at 10% 80%, rgba(129,140,248,0.18), transparent 60%),
    var(--bg);
}
.hero-inner { max-width: 900px; margin: 0 auto; text-align: center; }
.hero h1 { font-size: clamp(2.8rem, 7vw, 5.5rem); letter-spacing: -0.02em; }
.accent { color: var(--accent); }
.eyebrow {
  text-transform: uppercase;
  letter-spacing: 0.2em;
  color: var(--accent-2);
  font-size: 0.85rem;
  margin-bottom: 1em;
}
.scroll-cue {
  display: inline-block;
  padding: 12px 22px;
  border: 1px solid var(--accent);
  color: var(--accent);
  border-radius: 999px;
  text-decoration: none;
  font-weight: 500;
  transition: background 0.2s, color 0.2s;
}
.scroll-cue:hover { background: var(--accent); color: var(--bg); }

/* Objectives */
.objectives-list {
  list-style: none; padding: 0;
  display: grid; gap: 12px;
  margin-top: 1.5em;
}
.objectives-list li {
  background: var(--panel);
  padding: 16px 20px;
  border-radius: var(--radius);
  border-left: 4px solid var(--accent);
  font-size: 1.05rem;
}

/* Flip cards */
.flip-card {
  perspective: 1200px;
  background: transparent;
  border: none;
  padding: 0;
  cursor: pointer;
  font: inherit;
  color: inherit;
  text-align: left;
  min-height: 200px;
}
.flip-card.small { min-height: 180px; }
.flip-card.small .flip-face { padding: 16px; }
.flip-card.small .flip-front h3 { font-size: 1.05rem; }
.flip-card.small .flip-back p { font-size: 0.88rem; line-height: 1.4; margin: 0; }
.flip-inner {
  position: relative;
  width: 100%;
  height: 100%;
  min-height: inherit;
  transition: transform 0.6s;
  transform-style: preserve-3d;
}
.flip-card[aria-pressed="true"] .flip-inner { transform: rotateY(180deg); }
.flip-face {
  position: absolute;
  inset: 0;
  padding: 22px;
  border-radius: var(--radius);
  backface-visibility: hidden;
  display: flex;
  flex-direction: column;
  justify-content: center;
  background: var(--panel);
  border: 1px solid var(--line);
}
.flip-back {
  background: linear-gradient(135deg, #1f2a55 0%, #1a2547 100%);
  transform: rotateY(180deg);
  border-color: var(--accent);
}
.flip-back p { margin: 0; }

/* Callouts */
.callout {
  margin-top: 1.5em;
  padding: 16px 20px;
  background: rgba(94,234,212,0.06);
  border: 1px dashed rgba(94,234,212,0.4);
  border-radius: var(--radius);
}
.callout.note {
  background: rgba(251,191,36,0.06);
  border-color: rgba(251,191,36,0.4);
}
.worksheet-callout {
  margin-top: 2em;
  padding: 16px 20px;
  background: rgba(129,140,248,0.1);
  border: 1px solid rgba(129,140,248,0.4);
  border-radius: var(--radius);
  font-size: 1.05rem;
}

.btn {
  background: var(--accent);
  color: var(--bg);
  border: none;
  padding: 10px 18px;
  font: inherit;
  font-weight: 600;
  border-radius: 8px;
  cursor: pointer;
  transition: transform 0.1s, opacity 0.2s, background 0.2s;
}
.btn:hover { transform: translateY(-1px); }
.btn:active { transform: translateY(0); }
.btn.ghost {
  background: transparent;
  color: var(--ink);
  border: 1px solid var(--line);
}
.btn.ghost:hover { border-color: var(--accent); }
.btn:disabled { opacity: 0.45; cursor: not-allowed; transform: none; }

/* Pros / Cons reveal */
.proscons {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
  margin: 1.5em 0;
}
.proscons-col h3 { font-size: 1.1rem; margin-bottom: 12px; }
.pros-h { color: var(--good); }
.cons-h { color: var(--warn); }
.reveal-list { display: flex; flex-direction: column; gap: 10px; }
.reveal-item {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 14px 18px;
  cursor: pointer;
  font: inherit;
  color: var(--ink-dim);
  text-align: left;
  transition: all 0.2s;
}
.reveal-item:hover { border-color: var(--accent); }
.reveal-item.revealed { color: var(--ink); cursor: default; }
.reveal-item .reveal-hint {
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--ink-dim);
  opacity: 0.6;
}
.reveal-item.revealed .reveal-hint { display: none; }
.reveal-item.revealed.pro { border-left: 4px solid var(--good); background: rgba(52,211,153,0.06); }
.reveal-item.revealed.con { border-left: 4px solid var(--warn); background: rgba(251,191,36,0.06); }

/* Analogy */
.analogy-details {
  background: var(--panel);
  border: 1px solid var(--line);
  border-left: 4px solid var(--accent-2);
  border-radius: var(--radius);
  margin: 12px 0;
  overflow: hidden;
}
.analogy-details[open] { border-color: var(--accent); }
.analogy-details summary {
  cursor: pointer;
  padding: 16px 20px;
  font-weight: 600;
  font-size: 1.05rem;
  list-style: none;
  display: flex;
  align-items: center;
  gap: 12px;
  user-select: none;
}
.analogy-details summary::-webkit-details-marker { display: none; }
.analogy-details summary::after {
  content: "▾";
  margin-left: auto;
  color: var(--ink-dim);
  transition: transform 0.2s;
}
.analogy-details[open] summary::after { transform: rotate(180deg); }
.analogy-card {
  padding: 8px 22px 22px;
  display: grid;
  grid-template-columns: 1fr 1.2fr;
  gap: 28px;
  align-items: center;
}
.tube-svg { width: 100%; height: auto; max-height: 220px; }

/* ===== LAN diagram ===== */
.lan-diagram, .topo-stage, .wan-stage {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 22px;
  margin: 1.5em 0;
  position: relative;
}
.lan-svg, .wan-svg, .topo-svg {
  width: 100%;
  height: auto;
  display: block;
  max-height: 460px;
}
.lan-controls, .topo-controls {
  display: flex;
  gap: 10px;
  margin-top: 14px;
  flex-wrap: wrap;
}
.lan-device circle,
.lan-switch rect {
  transition: filter 0.25s, transform 0.25s;
  transform-box: fill-box;
  transform-origin: center;
}
.lan-device.active circle {
  filter: drop-shadow(0 0 8px rgba(94,234,212,0.9));
}
.lan-switch.active rect {
  filter: drop-shadow(0 0 10px rgba(129,140,248,0.9));
}
.lan-packet {
  fill: var(--warn);
  stroke: #0f172a;
  stroke-width: 1.5;
  transition: cx 1s ease-in-out, cy 1s ease-in-out, opacity 0.3s;
}

/* WAN */
.wan-stage { padding-bottom: 30px; }
#wan-packet { transition: cx 2s ease-in-out, opacity 0.3s; }
.wan-overlay { text-align: center; }
.wan-tag {
  display: inline-block;
  padding: 6px 14px;
  background: rgba(251,191,36,0.12);
  border: 1px solid rgba(251,191,36,0.4);
  color: var(--warn);
  border-radius: 999px;
  font-weight: 600;
  font-size: 0.95rem;
  margin-bottom: 10px;
}

/* WAN media (cable types) */
.wan-media-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 16px;
  margin: 1.2em 0 2em;
}
.wan-media {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 18px;
}
.wan-media-icon {
  background: rgba(0,0,0,0.2);
  border-radius: 8px;
  padding: 10px;
  margin-bottom: 10px;
  display: flex;
  justify-content: center;
}
.wan-media-icon svg { width: 100%; height: 50px; }
.wan-media h4 { color: var(--accent); font-size: 1rem; margin: 0 0 4px; }
.wan-media p { font-size: 0.92rem; color: var(--ink-dim); margin: 0; }

/* ISP flow */
.isp-flow {
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin: 1em 0 1.5em;
  align-items: stretch;
}
.isp-step {
  display: grid;
  grid-template-columns: 56px 1fr;
  gap: 16px;
  background: var(--panel);
  border: 1px solid var(--line);
  border-left: 4px solid var(--accent-2);
  border-radius: var(--radius);
  padding: 16px 20px;
  cursor: pointer;
  text-align: left;
  font: inherit;
  color: inherit;
  transition: border-color 0.2s, background 0.2s;
  align-items: center;
}
.isp-step:hover { border-color: var(--accent); }
.isp-step.open { background: rgba(94,234,212,0.05); border-left-color: var(--accent); }
.isp-num {
  width: 44px; height: 44px;
  border-radius: 50%;
  background: var(--bg-2);
  border: 2px solid var(--accent-2);
  color: var(--accent);
  font-weight: 700;
  font-size: 1.3rem;
  display: flex;
  align-items: center;
  justify-content: center;
}
.isp-step.open .isp-num {
  background: var(--accent);
  color: var(--bg);
  border-color: var(--accent);
}
.isp-text h4 {
  margin: 0;
  color: var(--ink);
  font-size: 1.05rem;
}
.isp-body {
  font-size: 0.95rem;
  color: var(--ink-dim);
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.4s ease, margin-top 0.4s ease;
}
.isp-step.open .isp-body {
  max-height: 260px;
  margin-top: 8px;
  color: var(--ink);
}
.isp-arrow {
  text-align: center;
  color: var(--accent-2);
  font-size: 1.3rem;
  line-height: 1;
}

/* NIC cards */
.nic-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 18px;
  margin: 1.5em 0;
}
.nic-card {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 20px;
  cursor: pointer;
  text-align: left;
  font: inherit;
  color: inherit;
  transition: border-color 0.2s, transform 0.15s;
}
.nic-card:hover { border-color: var(--accent); transform: translateY(-2px); }
.nic-card.active { border-color: var(--accent); background: rgba(94,234,212,0.06); }
.nic-card[data-img] { position: relative; }
.nic-card[data-img]::after {
  content: "🔍 Click to see a real one";
  position: absolute;
  top: 12px; right: 12px;
  font-size: 0.7rem;
  color: var(--accent);
  background: rgba(94,234,212,0.1);
  border: 1px solid rgba(94,234,212,0.35);
  padding: 3px 8px;
  border-radius: 999px;
  letter-spacing: 0.02em;
  pointer-events: none;
}

/* Lightbox */
.lightbox[hidden] { display: none; }
.lightbox {
  position: fixed;
  inset: 0;
  background: rgba(8, 12, 28, 0.88);
  z-index: 200;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 40px;
  backdrop-filter: blur(6px);
  -webkit-backdrop-filter: blur(6px);
  animation: fadeIn 0.2s ease;
}
@keyframes fadeIn { from { opacity: 0; } to { opacity: 1; } }
.lightbox-inner {
  margin: 0;
  max-width: min(90vw, 900px);
  max-height: 88vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 14px;
}
.lightbox-inner img {
  max-width: 100%;
  max-height: 78vh;
  border-radius: var(--radius);
  box-shadow: 0 20px 60px rgba(0,0,0,0.6);
  background: #fff;
}
.lightbox-inner figcaption {
  color: var(--ink);
  font-size: 1rem;
  text-align: center;
  max-width: 70ch;
  line-height: 1.5;
}
.lightbox-close {
  position: absolute;
  top: 20px; right: 24px;
  width: 44px; height: 44px;
  border-radius: 50%;
  background: var(--panel);
  color: var(--ink);
  border: 1px solid var(--line);
  font-size: 1.8rem;
  line-height: 1;
  cursor: pointer;
  transition: all 0.15s;
}
.lightbox-close:hover {
  background: var(--accent);
  color: var(--bg);
  transform: rotate(90deg);
}
.nic-icon {
  background: rgba(0,0,0,0.25);
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 10px;
  margin-bottom: 12px;
  display: flex;
  justify-content: center;
}
.nic-icon svg { width: 100%; height: auto; max-height: 160px; }
.nic-card h3 { font-size: 1.05rem; color: var(--ink); }
.nic-card p { font-size: 0.92rem; color: var(--ink-dim); margin: 0; }

/* Topology preview cards */
.topo-preview {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 20px;
  margin: 1.5em 0;
}
.topo-preview-card {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 20px;
  text-decoration: none;
  color: inherit;
  transition: all 0.2s;
  display: block;
}
.topo-preview-card:hover {
  border-color: var(--accent);
  transform: translateY(-3px);
  box-shadow: 0 10px 30px rgba(0,0,0,0.3);
}
.topo-preview-card h3 { color: var(--accent); font-size: 1.15rem; margin: 8px 0 6px; }
.topo-preview-card p { color: var(--ink-dim); margin: 0; font-size: 0.95rem; }
.topo-mini { background: rgba(0,0,0,0.2); border-radius: 8px; padding: 8px; }
.topo-mini svg { width: 100%; height: 80px; }

/* Topology stages */
.topo-stage { padding: 24px; }
.topo-svg { max-height: 420px; }

/* Bus cable: clickable to break */
.bus-seg {
  cursor: pointer;
  transition: stroke 0.25s, opacity 0.25s, stroke-dasharray 0.25s;
}
.bus-seg:hover { stroke: var(--warn); }
.bus-seg.broken {
  stroke: var(--bad);
  stroke-dasharray: 8 8;
  opacity: 0.55;
  animation: dashShift 1.5s linear infinite;
}
@keyframes dashShift {
  to { stroke-dashoffset: -32; }
}

/* Star cable clickable */
.star-cable {
  cursor: pointer;
  transition: stroke 0.25s, opacity 0.25s;
}
.star-cable:hover { stroke: var(--warn); }
.star-cable.broken {
  stroke: var(--bad);
  stroke-dasharray: 8 8;
  opacity: 0.5;
  animation: dashShift 1.5s linear infinite;
}
.star-dev.offline circle {
  stroke: var(--bad);
  filter: grayscale(0.6);
}
.star-dev.offline text { opacity: 0.55; }

#bus-packet, #star-packet {
  transition: opacity 0.3s;
}
#bus-packet text, #star-packet text { pointer-events: none; }

/* Compare table */
.compare-controls {
  display: flex;
  gap: 10px;
  margin: 1em 0;
  flex-wrap: wrap;
}
.compare-table {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
  margin: 1em 0 1.5em;
}
.cr-side-head {
  display: flex;
  align-items: center;
  gap: 8px;
  font-weight: 700;
  font-size: 0.95rem;
  margin-bottom: 10px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--line);
  letter-spacing: 0.02em;
}
.cr-side-head span { font-size: 1.15rem; }
.cr-side-head.bus  { color: var(--warn); }
.cr-side-head.star { color: var(--accent-2); }

.compare-row {
  border-bottom: 1px solid var(--line);
  transition: background 0.2s;
}
.compare-row:last-child { border-bottom: none; }
.compare-row:hover { background: rgba(94,234,212,0.03); }

.cr-toggle {
  width: 100%;
  display: grid;
  grid-template-columns: 40px 1fr auto auto;
  align-items: center;
  gap: 14px;
  background: transparent;
  border: none;
  font: inherit;
  color: inherit;
  text-align: left;
  padding: 16px 20px;
  cursor: pointer;
}
.cr-num {
  width: 30px; height: 30px;
  border-radius: 50%;
  background: var(--bg-2);
  border: 1.5px solid var(--accent-2);
  color: var(--accent);
  font-weight: 700;
  font-size: 0.9rem;
  display: flex;
  align-items: center;
  justify-content: center;
}
.cr-label {
  font-weight: 600;
  font-size: 1.05rem;
  color: var(--ink);
}
.cr-hint {
  color: var(--ink-dim);
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
}
.cr-toggle::after {
  content: "▾";
  color: var(--ink-dim);
  font-size: 0.9rem;
  transition: transform 0.25s;
}
.compare-row.open .cr-toggle::after { transform: rotate(180deg); }
.compare-row.open .cr-num {
  background: var(--accent);
  color: var(--bg);
  border-color: var(--accent);
}
.compare-row.open .cr-hint { color: var(--accent); }

/* Body that reveals */
.cr-body {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
  padding: 0 20px;
  max-height: 0;
  overflow: hidden;
  opacity: 0;
  transition: max-height 0.45s ease, opacity 0.3s ease, padding 0.45s ease;
}
.compare-row.open .cr-body {
  max-height: 360px;
  opacity: 1;
  padding: 4px 20px 20px;
}
.cr-cell {
  background: rgba(0,0,0,0.18);
  border-radius: 10px;
  padding: 14px 16px;
  border: 1px solid var(--line);
  position: relative;
  transform: translateY(8px);
  transition: transform 0.4s ease, border-color 0.3s;
}
.compare-row.open .cr-cell { transform: translateY(0); }
.cr-cell[data-side="bus"]  { border-left: 3px solid var(--warn); }
.cr-cell[data-side="star"] { border-left: 3px solid var(--accent-2); }
.compare-row[data-winner="bus"].open  .cr-cell[data-side="bus"]  { border-color: var(--good); background: rgba(52,211,153,0.07); }
.compare-row[data-winner="star"].open .cr-cell[data-side="star"] { border-color: var(--good); background: rgba(52,211,153,0.07); }

.cr-cell p { margin: 0; font-size: 0.95rem; color: var(--ink); line-height: 1.5; }
.cr-verdict {
  display: inline-block;
  font-size: 0.78rem;
  font-weight: 700;
  padding: 3px 10px;
  border-radius: 999px;
  letter-spacing: 0.03em;
  margin-bottom: 8px;
  text-transform: uppercase;
}
.cr-verdict.good { background: rgba(52,211,153,0.15); color: var(--good); border: 1px solid rgba(52,211,153,0.4); }
.cr-verdict.bad  { background: rgba(251,191,36,0.12); color: var(--warn); border: 1px solid rgba(251,191,36,0.4); }

/* Winner crown badge on the better cell */
.compare-row.open[data-winner="bus"]  .cr-cell[data-side="bus"]::after,
.compare-row.open[data-winner="star"] .cr-cell[data-side="star"]::after {
  content: "👑 Winner";
  position: absolute;
  top: -10px;
  right: 12px;
  background: var(--good);
  color: var(--bg);
  font-size: 0.7rem;
  font-weight: 700;
  padding: 3px 10px;
  border-radius: 999px;
  letter-spacing: 0.04em;
  box-shadow: 0 4px 12px rgba(52,211,153,0.4);
}

/* Summary cards */
.compare-summary {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
  margin-top: 1em;
}
.cs-card {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 18px 20px;
}
.cs-bus  { border-top: 3px solid var(--warn); }
.cs-star { border-top: 3px solid var(--accent-2); }
.cs-card h3 { font-size: 1.05rem; margin: 0 0 6px; color: var(--ink); }
.cs-card p { margin: 0; color: var(--ink-dim); font-size: 0.95rem; }

/* Hardware cards */
.hw-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 18px;
  margin: 1.5em 0;
}
.hw-card {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 20px;
  cursor: pointer;
  text-align: left;
  font: inherit;
  color: inherit;
  transition: border-color 0.2s, transform 0.15s;
  display: flex;
  flex-direction: column;
}
.hw-card:hover { border-color: var(--accent); transform: translateY(-2px); }
.hw-card.active { border-color: var(--accent); background: rgba(94,234,212,0.06); }
.hw-card[data-img] { position: relative; }
.hw-card[data-img]::after {
  content: "🔍 Click to see a real one";
  position: absolute;
  top: 12px; right: 12px;
  font-size: 0.7rem;
  color: var(--accent);
  background: rgba(94,234,212,0.1);
  border: 1px solid rgba(94,234,212,0.35);
  padding: 3px 8px;
  border-radius: 999px;
  pointer-events: none;
}

/* Combined router/WAP card */
.combo-card {
  display: grid;
  grid-template-columns: 1.2fr 1fr;
  gap: 22px;
  margin: 1.8em 0 1em;
  background: var(--panel);
  border: 1px solid var(--line);
  border-left: 4px solid var(--accent-2);
  border-radius: var(--radius);
  padding: 22px;
  align-items: center;
}
.combo-text h3 { color: var(--accent); font-size: 1.15rem; margin-bottom: 0.5em; }
.combo-list {
  list-style: none;
  padding: 0;
  margin: 0.6em 0 1em;
  display: grid;
  gap: 6px;
}
.combo-list li {
  background: rgba(0,0,0,0.18);
  padding: 8px 12px;
  border-radius: 8px;
  font-size: 0.95rem;
  border-left: 3px solid var(--accent);
}
.combo-img-btn {
  position: relative;
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 0;
  background: #fff;
  cursor: pointer;
  overflow: hidden;
  transition: transform 0.2s, border-color 0.2s;
}
.combo-img-btn:hover { transform: translateY(-2px); border-color: var(--accent); }
.combo-img-btn img { display: block; width: 100%; height: auto; }
.combo-img-tag {
  position: absolute;
  bottom: 8px; right: 8px;
  background: rgba(15,23,42,0.85);
  color: var(--accent);
  font-size: 0.72rem;
  padding: 4px 10px;
  border-radius: 999px;
  border: 1px solid rgba(94,234,212,0.4);
}

@media (max-width: 800px) {
  .combo-card { grid-template-columns: 1fr; }
}
.hw-svg { display: flex; justify-content: center; margin-bottom: 12px; }
.hw-svg svg { width: 100%; height: 80px; max-width: 220px; }
.hw-card h3 { color: var(--accent); font-size: 1.1rem; margin-bottom: 4px; }
.hw-short { color: var(--ink-dim); font-size: 0.9rem; margin: 0; }
.hw-info {
  font-size: 0.92rem;
  color: var(--ink-dim);
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.4s ease, margin-top 0.4s ease;
}
.hw-card.active .hw-info {
  max-height: 240px;
  margin-top: 12px;
  color: var(--ink);
}

/* Plenary matching game */
.tld-game {
  display: grid;
  grid-template-columns: 1fr 1.6fr;
  gap: 24px;
  margin: 1.5em 0;
}
.tld-col { display: flex; flex-direction: column; gap: 10px; }
.tld-btn {
  background: var(--panel);
  color: var(--ink);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 12px 16px;
  font-size: 1rem;
  cursor: pointer;
  text-align: left;
  transition: all 0.15s;
  font-family: inherit;
}
.tld-btn:hover:not(.matched):not(.selected) { border-color: var(--accent); }
.tld-btn.selected { border-color: var(--accent); background: rgba(94,234,212,0.1); }
.tld-btn.matched {
  background: rgba(52,211,153,0.1);
  border-color: var(--good);
  color: var(--good);
  cursor: default;
}
.tld-btn.wrong {
  animation: shake 0.3s;
  border-color: var(--bad);
}
@keyframes shake {
  0%, 100% { transform: translateX(0); }
  25% { transform: translateX(-8px); }
  75% { transform: translateX(8px); }
}
.tld-controls {
  display: flex; gap: 12px; align-items: center; flex-wrap: wrap;
  margin-top: 1em;
}
.score { color: var(--ink-dim); margin-right: auto; }

.term-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 16px;
  margin: 1.5em 0;
}
.end-note {
  text-align: center;
  font-size: 1.3rem;
  margin-top: 3em;
  color: var(--accent);
}

/* Responsive */
@media (max-width: 800px) {
  #side-nav { display: none; }
  .section { padding: 60px 18px; }
  .proscons { grid-template-columns: 1fr; }
  .topo-preview { grid-template-columns: 1fr; }
  .tld-game { grid-template-columns: 1fr; }
  .analogy-card { grid-template-columns: 1fr; gap: 18px; }
  .cr-toggle { grid-template-columns: 32px 1fr auto; }
  .cr-hint { display: none; }
  .cr-body { grid-template-columns: 1fr; }
  .compare-row.open .cr-body { max-height: 600px; }
  .compare-summary { grid-template-columns: 1fr; }
}