:root {
  --bg: #0f1220;
  --panel: #171b2e;
  --panel-2: #1e2340;
  --text: #e8eaf6;
  --muted: #9aa0c3;
  --accent: #4f7cff;
  --accent-2: #8fb0ff;
  --warn: #ffb547;
  --warn-bg: #2b2212;
  --border: #2a3058;
  --radius: 14px;
}

* { box-sizing: border-box; }

html, body { margin: 0; padding: 0; }

body {
  background: radial-gradient(1200px 600px at 20% -10%, #1c2552 0%, transparent 60%), var(--bg);
  color: var(--text);
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  line-height: 1.6;
  min-height: 100vh;
}

a { color: var(--accent-2); }

.hero {
  max-width: 820px;
  margin: 0 auto;
  padding: 64px 20px 28px;
}

.eyebrow {
  text-transform: uppercase;
  letter-spacing: 0.14em;
  font-size: 0.78rem;
  color: var(--accent-2);
  margin: 0 0 8px;
}

h1 {
  font-size: clamp(2rem, 5vw, 2.9rem);
  margin: 0 0 14px;
  font-family: ui-monospace, "SF Mono", Menlo, Consolas, monospace;
  letter-spacing: -0.02em;
}

.lede { font-size: 1.12rem; color: #cfd3ef; margin: 0 0 20px; }

.badges { display: flex; flex-wrap: wrap; gap: 8px; margin-bottom: 18px; }

.badge {
  font-size: 0.82rem;
  padding: 4px 10px;
  border-radius: 999px;
  background: var(--panel-2);
  border: 1px solid var(--border);
  color: var(--muted);
}

.badge-warn { color: var(--warn); border-color: #5a4518; background: var(--warn-bg); }

.repo-link {
  display: inline-block;
  font-weight: 600;
  text-decoration: none;
  padding: 10px 16px;
  border-radius: 10px;
  background: var(--accent);
  color: #fff;
}
.repo-link:hover { filter: brightness(1.1); }

main {
  max-width: 820px;
  margin: 0 auto;
  padding: 0 20px 40px;
  display: grid;
  gap: 18px;
}

.card {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 22px 24px;
}

.card h2 { margin: 0 0 10px; font-size: 1.3rem; }
.card p { margin: 0 0 10px; }
.card p:last-child { margin-bottom: 0; }

.hint, .small { color: var(--muted); font-size: 0.9rem; }

/* Steps */
.steps {
  list-style: none;
  padding: 0;
  margin: 12px 0 14px;
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 8px;
}

.step {
  width: 100%;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
  padding: 10px 4px;
  font: inherit;
  font-size: 0.9rem;
  color: var(--muted);
  background: var(--panel-2);
  border: 1px solid var(--border);
  border-radius: 10px;
  cursor: pointer;
  transition: border-color .15s, color .15s, background .15s;
}
.step:hover { color: var(--text); }
.step.active { color: #fff; border-color: var(--accent); background: #233063; }
.step .num {
  display: inline-grid;
  place-items: center;
  width: 26px; height: 26px;
  border-radius: 50%;
  background: var(--border);
  font-weight: 700;
  font-size: 0.85rem;
}
.step.active .num { background: var(--accent); }

.step-detail {
  background: var(--panel-2);
  border-left: 3px solid var(--accent);
  border-radius: 8px;
  padding: 14px 16px;
  min-height: 84px;
}
.step-detail h3 { margin: 0 0 4px; font-size: 1.05rem; }
.step-detail p { margin: 0; color: #cfd3ef; }

/* Demo */
.demo {
  background: var(--panel-2);
  border-radius: 12px;
  padding: 18px;
  margin: 12px 0;
  text-align: center;
}
.demo-word {
  font-family: ui-monospace, "SF Mono", Menlo, Consolas, monospace;
  font-size: 2rem;
  font-weight: 700;
  color: var(--accent-2);
  margin-bottom: 10px;
}
.demo-meanings {
  list-style: none;
  padding: 0;
  margin: 0 auto 14px;
  max-width: 460px;
  text-align: left;
  display: grid;
  gap: 6px;
}
.demo-meanings li {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 8px 12px;
  animation: pop .3s ease both;
}
.demo-meanings li b { color: var(--accent-2); margin-right: 6px; }

@keyframes pop {
  from { opacity: 0; transform: translateY(4px); }
  to { opacity: 1; transform: none; }
}

.btn {
  font: inherit;
  font-weight: 600;
  color: #fff;
  background: var(--accent);
  border: 0;
  border-radius: 10px;
  padding: 9px 16px;
  cursor: pointer;
}
.btn:hover { filter: brightness(1.1); }

/* Features */
.grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 12px;
}
.feature {
  background: var(--panel-2);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 14px 16px;
}
.feature h3 { margin: 0 0 4px; font-size: 1rem; }
.feature p { margin: 0; color: var(--muted); font-size: 0.93rem; }

/* Warning */
.card.warn { background: var(--warn-bg); border-color: #6a5220; }
.card.warn h2 { color: var(--warn); }
.card.warn ul { margin: 8px 0 0; padding-left: 20px; }
.card.warn li { margin-bottom: 4px; }

/* Calculator */
.calc {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
  gap: 12px;
  margin: 12px 0;
}
.calc label { display: flex; flex-direction: column; gap: 4px; font-size: 0.9rem; color: var(--muted); }
.calc input {
  font: inherit;
  color: var(--text);
  background: var(--panel-2);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 8px 10px;
}
.calc input:focus { outline: 2px solid var(--accent); outline-offset: 1px; }

.calc-out {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 10px;
  margin-bottom: 10px;
}
.calc-out > div {
  background: var(--panel-2);
  border-radius: 10px;
  padding: 12px;
  text-align: center;
}
.out-label { display: block; font-size: 0.8rem; color: var(--muted); text-transform: uppercase; letter-spacing: .06em; }
.out-val { display: block; font-size: 1.35rem; font-weight: 700; font-variant-numeric: tabular-nums; }

/* Glossary */
.glossary { margin: 0; display: grid; grid-template-columns: max-content 1fr; gap: 8px 16px; }
.glossary dt { font-weight: 700; color: var(--accent-2); }
.glossary dd { margin: 0; color: #cfd3ef; }

footer {
  max-width: 820px;
  margin: 0 auto;
  padding: 10px 20px 48px;
  color: var(--muted);
  font-size: 0.85rem;
}

@media (max-width: 560px) {
  .steps { grid-template-columns: repeat(5, minmax(0, 1fr)); gap: 4px; }
  .step { font-size: 0.75rem; }
  .calc-out { grid-template-columns: 1fr; }
  .glossary { grid-template-columns: 1fr; }
  .glossary dd { margin-bottom: 6px; }
}