* { margin: 0; padding: 0; box-sizing: border-box; }
body { font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', system-ui, sans-serif; background: #0d1117; color: #c9d1d9; }
header { background: #161b22; padding: 1.5rem 2rem; border-bottom: 1px solid #30363d; }
header h1 { color: #58a6ff; font-size: 1.5rem; }
header p { color: #8b949e; font-size: 0.875rem; margin-top: 0.25rem; }
nav { background: #161b22; padding: 0.5rem 2rem; border-bottom: 1px solid #30363d; }
nav a { color: #8b949e; text-decoration: none; margin-right: 1rem; padding: 0.5rem 0; display: inline-block; }
nav a.active, nav a:hover { color: #58a6ff; border-bottom: 2px solid #58a6ff; }
main { max-width: 1200px; margin: 2rem auto; padding: 0 2rem; }
h2 { color: #e6edf3; margin-bottom: 1rem; }
h3 { color: #e6edf3; margin: 1.5rem 0 0.75rem; }
.card { background: #161b22; border: 1px solid #30363d; border-radius: 6px; padding: 1.25rem; margin-bottom: 1rem; cursor: pointer; transition: border-color 0.2s; }
.card:hover { border-color: #58a6ff; }
.card h3 { margin: 0 0 0.5rem; font-size: 1.1rem; }
.card .meta { color: #8b949e; font-size: 0.875rem; }
.card .accuracy { font-size: 1.5rem; font-weight: bold; color: #3fb950; }
.metrics-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 1rem; margin-bottom: 1.5rem; }
.metric-card { background: #161b22; border: 1px solid #30363d; border-radius: 6px; padding: 1rem; text-align: center; }
.metric-card .label { color: #8b949e; font-size: 0.75rem; text-transform: uppercase; }
.metric-card .value { font-size: 1.5rem; font-weight: bold; color: #58a6ff; margin-top: 0.25rem; }
table { width: 100%; border-collapse: collapse; background: #161b22; border: 1px solid #30363d; border-radius: 6px; overflow: hidden; }
th { background: #21262d; color: #8b949e; text-align: left; padding: 0.75rem 1rem; font-size: 0.75rem; text-transform: uppercase; }
td { padding: 0.5rem 1rem; border-top: 1px solid #30363d; font-size: 0.875rem; }
tr:hover td { background: #1c2128; }
.correct { color: #3fb950; }
.incorrect { color: #f85149; }
#questions-controls { margin-bottom: 1rem; display: flex; gap: 1rem; align-items: center; }
select, input[type="checkbox"] { background: #21262d; color: #c9d1d9; border: 1px solid #30363d; padding: 0.4rem; border-radius: 4px; }
