/* Tetris Attack — style.css (mobile-first) */
:root {
  --bg: #0e0e1a;
  --surface: #16172a;
  --surface2: #1e2040;
  --border: #2a2d52;
  --text: #d8dae5;
  --text-dim: #8889a5;
  --accent: #6c5ce7;
  --yellow: #ffd43b;
  --green: #51cf66;
  --red: #ff6b6b;
  --blue: #339af0;
  --purple: #b197fc;
  --pink: #f06595;
  --max-w: 900px;
}

* { margin: 0; padding: 0; box-sizing: border-box; }

body {
  font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
  min-height: 100vh;
  -webkit-text-size-adjust: 100%;
}

/* Navigation — mobile: compact, wrapping */
nav {
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 100;
}

nav .nav-inner {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 1rem;
  display: flex;
  align-items: center;
  gap: 0;
  flex-wrap: wrap;
}

nav .logo {
  font-weight: 700;
  font-size: 1rem;
  color: var(--yellow);
  text-decoration: none;
  padding: 0.6rem 0;
  margin-right: auto;
  letter-spacing: -0.02em;
}

nav .logo span { color: var(--purple); }

nav a {
  color: var(--text-dim);
  text-decoration: none;
  padding: 0.5rem 0.45rem;
  font-size: 0.82rem;
  transition: color 0.15s;
  white-space: nowrap;
}

nav a:hover, nav a.active { color: var(--yellow); }

/* Layout — mobile base */
main {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 1.5rem 1rem 3rem;
}

/* Hero — mobile base */
.hero {
  text-align: center;
  padding: 1.5rem 0 1rem;
}

.hero h1 {
  font-size: 1.7rem;
  font-weight: 800;
  letter-spacing: -0.03em;
  line-height: 1.2;
  margin-bottom: 0.75rem;
}

.hero h1 .yellow { color: var(--yellow); }
.hero h1 .green { color: var(--green); }
.hero h1 .red { color: var(--red); }
.hero h1 .blue { color: var(--blue); }
.hero h1 .purple { color: var(--purple); }

.hero p {
  font-size: 1rem;
  color: var(--text-dim);
  max-width: 600px;
  margin: 0 auto;
}

/* Block grid (homepage hero) */
.block-row {
  display: flex;
  justify-content: center;
  gap: 0.4rem;
  margin: 1.5rem 0;
}

.block-row svg { width: 36px; height: 36px; }

/* Cards — mobile: single column */
.card-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1rem;
  margin: 1.5rem 0;
}

.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 1.25rem;
  text-decoration: none;
  color: var(--text);
  transition: border-color 0.2s, transform 0.15s;
}

.card:hover {
  border-color: var(--accent);
  transform: translateY(-2px);
}

.card h3 {
  font-size: 1.05rem;
  margin-bottom: 0.3rem;
  color: #fff;
}

.card p {
  font-size: 0.88rem;
  color: var(--text-dim);
  line-height: 1.5;
}

.card .card-icon {
  width: 32px;
  height: 32px;
  margin-bottom: 0.6rem;
}

/* Headings — mobile base */
h1 { font-size: 1.6rem; font-weight: 800; letter-spacing: -0.02em; margin-bottom: 0.6rem; color: #fff; }
h2 { font-size: 1.3rem; font-weight: 700; margin: 2rem 0 0.6rem; color: #fff; letter-spacing: -0.01em; }
h3 { font-size: 1.05rem; font-weight: 600; margin: 1.5rem 0 0.4rem; color: #fff; }

/* Body text */
p { margin-bottom: 1rem; }
strong { color: #fff; }

/* Lists */
ul, ol { margin: 0 0 1rem 1.5rem; }
li { margin-bottom: 0.35rem; }

/* Inline code / labels */
.tag {
  display: inline-block;
  background: var(--surface2);
  border: 1px solid var(--border);
  border-radius: 5px;
  padding: 0.15em 0.5em;
  font-size: 0.85em;
  color: var(--purple);
  font-family: 'Consolas', 'Courier New', monospace;
}

/* Technique cards (chains page) */
.technique {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 1.25rem;
  margin: 1rem 0;
}

.technique .label {
  display: inline-block;
  font-size: 0.7rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  padding: 0.2em 0.6em;
  border-radius: 4px;
  margin-bottom: 0.4rem;
}

.technique .label.easy { background: #1b3a2a; color: var(--green); }
.technique .label.medium { background: #3a3520; color: var(--yellow); }
.technique .label.hard { background: #3a1f1f; color: var(--red); }
.technique .label.extreme { background: #2e1a3a; color: var(--pink); }

.technique h3 { margin-top: 0.25rem; }

/* Code blocks (secrets page) */
.code-block {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 1rem 1.25rem;
  margin: 1rem 0;
}

.code-block .game-label {
  font-size: 0.7rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--accent);
  margin-bottom: 0.4rem;
}

.code-block h4 {
  font-size: 1rem;
  color: #fff;
  margin-bottom: 0.3rem;
}

.code-block .keys {
  font-family: 'Consolas', 'Courier New', monospace;
  color: var(--yellow);
  font-size: 0.85rem;
  margin: 0.3rem 0;
  word-break: break-word;
}

/* Timeline (history page) — mobile: stacked */
.timeline { margin: 1.5rem 0; }

.timeline-entry {
  margin-bottom: 1.75rem;
}

.timeline-year {
  font-weight: 800;
  font-size: 1.05rem;
  color: var(--yellow);
  margin-bottom: 0.25rem;
}

.timeline-body h3 { margin-top: 0; color: #fff; }

/* SVG diagrams */
.diagram {
  display: flex;
  justify-content: center;
  margin: 1.25rem 0;
  padding: 1rem;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 10px;
  overflow-x: auto;
}

.diagram svg { max-width: 100%; height: auto; }

/* Intro text */
.intro {
  font-size: 1rem;
  color: var(--text-dim);
  border-bottom: 1px solid var(--border);
  padding-bottom: 1.25rem;
  margin-bottom: 1.5rem;
}

/* Game mode boxes — mobile: single column */
.mode-grid {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 0.75rem;
  margin: 1.25rem 0;
}

.mode-box {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 1rem;
  flex: 1 1 100%;
}

.mode-box h4 {
  color: #fff;
  font-size: 1rem;
  margin-bottom: 0.25rem;
}

.mode-box p {
  font-size: 0.88rem;
  color: var(--text-dim);
  margin: 0;
}

/* Footer */
footer {
  text-align: center;
  padding: 1.5rem 1rem;
  color: var(--text-dim);
  font-size: 0.78rem;
  border-top: 1px solid var(--border);
  max-width: var(--max-w);
  margin: 0 auto;
}

/* ===================== */
/* Tablet: 600px+        */
/* ===================== */
@media (min-width: 600px) {
  nav .nav-inner { padding: 0 1.5rem; gap: 0.25rem; }
  nav .logo { font-size: 1.1rem; }
  nav a { padding: 0.75rem 0.7rem; font-size: 0.88rem; }

  main { padding: 2rem 1.5rem 4rem; }

  .hero { padding: 2rem 0 1.5rem; }
  .hero h1 { font-size: 2.2rem; }
  .hero p { font-size: 1.1rem; }

  .block-row svg { width: 44px; height: 44px; }
  .block-row { gap: 0.5rem; }

  .card-grid { grid-template-columns: repeat(2, 1fr); gap: 1.25rem; }
  .card { padding: 1.5rem; }
  .card h3 { font-size: 1.1rem; }
  .card .card-icon { width: 36px; height: 36px; }

  h1 { font-size: 1.8rem; }
  h2 { font-size: 1.4rem; }
  h3 { font-size: 1.1rem; }

  .intro { font-size: 1.05rem; }

  .technique { padding: 1.5rem; }
  .code-block { padding: 1.25rem 1.5rem; }
  .code-block .keys { font-size: 0.95rem; }

  .timeline-entry {
    display: flex;
    gap: 1.5rem;
    align-items: flex-start;
  }
  .timeline-year {
    flex-shrink: 0;
    width: 70px;
    text-align: right;
    margin-bottom: 0;
    padding-top: 0.2rem;
  }
  .timeline-body {
    border-left: 2px solid var(--border);
    padding-left: 1.5rem;
    flex: 1;
  }

  .mode-box { flex: 0 1 calc(33.333% - 0.5rem); }

  .diagram { padding: 1.5rem; }
  footer { padding: 2rem 1.5rem; }
}

/* ===================== */
/* Desktop: 900px+       */
/* ===================== */
@media (min-width: 900px) {
  .hero h1 { font-size: 2.6rem; }
  .hero p { font-size: 1.15rem; }

  .block-row svg { width: 48px; height: 48px; }

  h1 { font-size: 2rem; }
  h2 { font-size: 1.5rem; margin: 2.5rem 0 0.75rem; }
  h3 { font-size: 1.15rem; }

  .intro { font-size: 1.1rem; }
}