:root {
  --bg: #0d1117;
  --surface: #161b22;
  --surface2: #21262d;
  --border: #30363d;
  --text: #c9d1d9;
  --text2: #8b949e;
  --accent: #58a6ff;
  --accent2: #79c0ff;
  --green: #3fb950;
  --red: #f85149;
  --orange: #d2991d;
  --purple: #bc8cff;
  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  --mono: "SF Mono", "Cascadia Code", "Fira Code", monospace;
}

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

body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  overflow-x: hidden;
}

/* Top bar */
.exp-header {
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  padding: 0.75rem 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 0.75rem;
  position: sticky;
  top: 0;
  z-index: 100;
}
.exp-brand { font-weight: 700; font-size: 1.05rem; color: var(--accent); }
.exp-nav { display: flex; gap: 0.25rem; overflow-x: auto; }
.exp-nav a {
  color: var(--text2);
  text-decoration: none;
  padding: 0.4rem 0.75rem;
  border-radius: 6px;
  font-size: 0.8rem;
  white-space: nowrap;
}
.exp-nav a:hover, .exp-nav a.active { color: var(--text); background: var(--surface2); }

/* Main layout */
.exp-main { max-width: 1200px; margin: 0 auto; padding: 2rem 1.5rem; }

h1 { font-size: 1.5rem; margin-bottom: 0.5rem; }
h2 { font-size: 1.15rem; color: var(--text); margin-bottom: 0.5rem; }
.exp-subtitle { color: var(--text2); font-size: 0.9rem; margin-bottom: 1.5rem; }

/* Cards */
.exp-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 1.25rem;
  margin-bottom: 1rem;
}

/* Layout: side-by-side panels */
.exp-panels { display: grid; grid-template-columns: 300px 1fr; gap: 1rem; }
.exp-controls { }
.exp-visual { min-height: 400px; position: relative; }

/* Controls */
.control-group { margin-bottom: 1rem; }
.control-group label {
  display: block;
  font-size: 0.75rem;
  color: var(--text2);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 0.25rem;
}
.control-row { display: flex; align-items: center; gap: 0.5rem; }

input[type="range"] {
  -webkit-appearance: none;
  width: 100%;
  height: 6px;
  background: var(--surface2);
  border-radius: 3px;
  outline: none;
}
input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 16px; height: 16px;
  background: var(--accent);
  border-radius: 50%;
  cursor: pointer;
}

input[type="number"], select {
  background: var(--surface2);
  border: 1px solid var(--border);
  color: var(--text);
  padding: 0.35rem 0.5rem;
  border-radius: 4px;
  font-size: 0.85rem;
  font-family: var(--mono);
  width: 80px;
}
select { width: auto; }

.exp-btn {
  background: var(--surface2);
  color: var(--text);
  border: 1px solid var(--border);
  padding: 0.5rem 1rem;
  border-radius: 6px;
  cursor: pointer;
  font-size: 0.85rem;
  font-family: var(--font);
  transition: all 0.15s;
}
.exp-btn:hover { background: var(--border); border-color: var(--text2); }
.exp-btn.primary { background: var(--accent); color: #000; border-color: var(--accent); font-weight: 600; }
.exp-btn.primary:hover { background: var(--accent2); }

/* Value display */
.val-display {
  font-family: var(--mono);
  font-size: 0.9rem;
  color: var(--accent2);
}

/* Canvas containers */
canvas { display: block; width: 100%; border-radius: 6px; }

/* Stats display */
.stat-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(120px, 1fr)); gap: 0.5rem; }
.stat-item { background: var(--surface2); padding: 0.5rem 0.75rem; border-radius: 4px; }
.stat-label { font-size: 0.65rem; color: var(--text2); text-transform: uppercase; }
.stat-value { font-family: var(--mono); font-size: 0.95rem; font-weight: 600; }

/* Distribution legend/colorbar */
.dist-legend { display: flex; gap: 1rem; flex-wrap: wrap; margin-bottom: 0.75rem; }
.legend-item { display: flex; align-items: center; gap: 0.4rem; font-size: 0.8rem; }
.legend-dot { width: 12px; height: 12px; border-radius: 50%; }

/* Tabs */
.exp-tabs { display: flex; gap: 0.25rem; margin-bottom: 1rem; }
.exp-tab {
  padding: 0.4rem 1rem;
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--text2);
  border-radius: 6px;
  cursor: pointer;
  font-size: 0.8rem;
}
.exp-tab:hover { color: var(--text); }
.exp-tab.active { background: var(--surface2); color: var(--text); border-color: var(--text2); }

/* Quizzes / Knowledge checks */
.quiz-question {
  font-size: 1rem;
  line-height: 1.6;
  padding: 1rem;
  background: var(--surface2);
  border-radius: 6px;
  margin-bottom: 0.75rem;
}
.quiz-options { display: grid; gap: 0.4rem; }
.quiz-opt {
  display: block;
  width: 100%;
  text-align: left;
  padding: 0.6rem 1rem;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 4px;
  color: var(--text);
  cursor: pointer;
  font-size: 0.9rem;
  transition: all 0.15s;
}
.quiz-opt:hover { border-color: var(--accent); background: rgba(88,166,255,0.05); }
.quiz-opt.correct { border-color: var(--green); background: rgba(63,185,80,0.1); }
.quiz-opt.wrong { border-color: var(--red); background: rgba(248,81,73,0.1); }
.quiz-feedback { margin-top: 0.5rem; padding: 0.5rem 0.75rem; border-radius: 4px; font-size: 0.85rem; }
.quiz-feedback.good { background: rgba(63,185,80,0.15); color: var(--green); }
.quiz-feedback.bad { background: rgba(248,81,73,0.15); color: var(--red); }

/* Tooltips on hover */
[data-tip] { position: relative; cursor: help; border-bottom: 1px dotted var(--text2); }

@media (max-width: 768px) {
  .exp-panels { grid-template-columns: 1fr; }
  .exp-header { padding: 0.5rem 1rem; }
  .exp-main { padding: 1rem; }
  .exp-nav { display: none; }
}