:root {
  --bg: #121212;
  --panel: #1c1c1c;
  --ink: #f5f5f5;
  --muted: #b0b0b0;
  --line: #333;
  --yellow: #ffd400;
  --accent: #00b8d4;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: "Malgun Gothic", "Consolas", monospace;
  line-height: 1.65;
  display: grid;
  grid-template-columns: 200px 1fr;
  min-height: 100vh;
}

.rail {
  position: sticky;
  top: 0;
  height: 100vh;
  background: repeating-linear-gradient(
    -45deg,
    #1a1a1a,
    #1a1a1a 8px,
    #222 8px,
    #222 16px
  );
  border-right: 4px solid var(--yellow);
  padding: 24px 16px;
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.brand {
  font-weight: 800;
  letter-spacing: 0.08em;
  color: var(--yellow);
  text-decoration: none;
  font-size: 18px;
}

.rail nav { display: grid; gap: 6px; }

.rail nav a {
  color: var(--muted);
  text-decoration: none;
  padding: 8px 10px;
  border-left: 3px solid transparent;
  font-size: 14px;
}

.rail nav a:hover,
.rail nav a.active {
  color: var(--ink);
  border-left-color: var(--yellow);
  background: rgba(255, 212, 0, 0.08);
}

.content {
  padding: 20px clamp(16px, 3vw, 40px) 32px;
}

.visual {
  border: 2px solid var(--line);
  border-radius: 4px;
  overflow: hidden;
  background: var(--panel);
}

.visual img {
  width: 100%;
  display: block;
  max-height: 440px;
  object-fit: cover;
}

.cap {
  padding: 18px 20px 22px;
  border-top: 4px solid var(--yellow);
}

.line {
  margin: 0;
  font-size: 11px;
  letter-spacing: 0.2em;
  color: var(--accent);
}

.cap h1 {
  margin: 8px 0;
  font-size: clamp(26px, 4vw, 42px);
  line-height: 1.1;
}

.cap p { margin: 0; color: var(--muted); }

.sec {
  margin-top: 22px;
  padding: 18px 20px;
  background: var(--panel);
  border: 1px solid var(--line);
  border-left: 4px solid var(--accent);
}

.sec h2 { margin-top: 0; font-size: 20px; }

.tags { display: flex; gap: 8px; flex-wrap: wrap; margin-bottom: 12px; }

.tag {
  border: 1px solid var(--line);
  background: #111;
  color: var(--muted);
  padding: 7px 12px;
  cursor: pointer;
  font: inherit;
}

.tag.on {
  background: var(--yellow);
  color: #111;
  border-color: var(--yellow);
  font-weight: 700;
}

.box {
  border: 1px dashed var(--line);
  padding: 14px;
  background: #111;
}

.box h3 { margin-top: 0; color: var(--yellow); }

.hint { color: var(--muted); font-size: 14px; }

.sec a { color: var(--accent); }

#crowdRange { width: 100%; accent-color: var(--yellow); }

.steps {
  list-style: none;
  padding: 0;
  margin: 0 0 12px;
  display: grid;
  gap: 6px;
}

.step {
  width: 100%;
  text-align: left;
  border: 1px solid var(--line);
  background: #111;
  color: var(--ink);
  padding: 10px 12px;
  cursor: pointer;
  font: inherit;
}

.step.on {
  border-color: var(--yellow);
  box-shadow: inset 4px 0 0 var(--yellow);
}

.checks {
  list-style: none;
  padding: 0;
  margin: 14px 0 0;
  display: grid;
  gap: 6px;
}

.checks label {
  display: flex;
  gap: 8px;
  align-items: center;
  border: 1px solid var(--line);
  padding: 8px 10px;
  background: #111;
}

footer {
  margin-top: 24px;
  color: var(--muted);
  font-size: 13px;
}

.reveal {
  opacity: 0;
  transform: translateX(16px);
  transition: 0.4s ease;
}
.reveal.show { opacity: 1; transform: none; }

@media (max-width: 820px) {
  body { grid-template-columns: 1fr; }
  .rail {
    position: static;
    height: auto;
    flex-direction: row;
    flex-wrap: wrap;
    align-items: center;
  }
  .rail nav { display: flex; flex-wrap: wrap; }
}