:root {
  --bg-primary: #09090b;
  --bg-secondary: #121215;
  --bg-card: #18181b;
  --bg-card-hover: #222226;
  --border: #27272a;
  --border-focus: #3f3f46;
  --text-primary: #f4f4f5;
  --text-secondary: #a1a1aa;
  --text-muted: #71717a;
  --accent: #22c55e;
  --accent-dim: rgba(34, 197, 94, 0.12);
  --accent-cyan: #06b6d4;
  --accent-cyan-dim: rgba(6, 182, 212, 0.12);
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace;
}

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

body {
  background-color: var(--bg-primary);
  color: var(--text-primary);
  font-family: var(--font-sans);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  min-height: 100vh;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 24px;
}

/* Header */
header {
  border-bottom: 1px solid var(--border);
  background-color: rgba(9, 9, 11, 0.85);
  backdrop-filter: blur(12px);
  position: sticky;
  top: 0;
  z-index: 50;
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 72px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  text-decoration: none;
  color: var(--text-primary);
}

.brand-badge {
  background-color: var(--accent-dim);
  color: var(--accent);
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.05em;
  padding: 4px 8px;
  border-radius: 6px;
  border: 1px solid rgba(34, 197, 94, 0.3);
}

.brand-title {
  font-weight: 600;
  font-size: 16px;
  letter-spacing: -0.01em;
}

.header-links {
  display: flex;
  align-items: center;
  gap: 16px;
}

.header-btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background-color: var(--bg-card);
  color: var(--text-primary);
  border: 1px solid var(--border);
  padding: 8px 16px;
  border-radius: 8px;
  font-size: 13px;
  font-weight: 500;
  text-decoration: none;
  transition: all 0.15s ease;
}

.header-btn:hover {
  background-color: var(--bg-card-hover);
  border-color: var(--border-focus);
}

/* Hero Section */
.hero {
  padding: 64px 0 40px;
  text-align: center;
}

.hero-pill {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background-color: var(--bg-secondary);
  border: 1px solid var(--border);
  padding: 6px 14px;
  border-radius: 9999px;
  font-size: 12px;
  color: var(--text-secondary);
  margin-bottom: 24px;
}

.hero-pill .dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background-color: var(--accent);
  box-shadow: 0 0 8px var(--accent);
}

.hero h1 {
  font-size: clamp(32px, 5vw, 48px);
  font-weight: 700;
  letter-spacing: -0.03em;
  line-height: 1.15;
  margin-bottom: 16px;
}

.hero p {
  color: var(--text-secondary);
  font-size: 18px;
  max-width: 680px;
  margin: 0 auto 32px;
}

.stats-bar {
  display: flex;
  justify-content: center;
  gap: 32px;
  padding: 18px 0;
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
  margin-bottom: 48px;
}

.stat-item {
  text-align: center;
}

.stat-value {
  font-size: 22px;
  font-weight: 700;
  font-family: var(--font-mono);
  color: var(--text-primary);
}

.stat-label {
  font-size: 12px;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

/* Tab Navigation */
.tabs-nav {
  display: flex;
  gap: 8px;
  background-color: var(--bg-secondary);
  padding: 6px;
  border-radius: 10px;
  border: 1px solid var(--border);
  max-width: 460px;
  margin: 0 auto 40px;
}

.tab-btn {
  flex: 1;
  background: transparent;
  border: none;
  color: var(--text-muted);
  font-size: 14px;
  font-weight: 600;
  padding: 10px 16px;
  border-radius: 7px;
  cursor: pointer;
  transition: all 0.2s ease;
  min-height: 48px;
}

.tab-btn.active {
  background-color: var(--bg-card);
  color: var(--text-primary);
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.4);
}

/* Grid Layout */
.project-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(360px, 1fr));
  gap: 24px;
  margin-bottom: 80px;
}

.project-card {
  background-color: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 24px;
  display: flex;
  flex-direction: column;
  transition: all 0.2s ease;
}

.project-card:hover {
  border-color: var(--border-focus);
  background-color: var(--bg-card);
}

.card-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  margin-bottom: 14px;
}

.project-num {
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 700;
  color: var(--accent);
  background-color: var(--accent-dim);
  padding: 3px 8px;
  border-radius: 4px;
}

.project-badge {
  font-size: 11px;
  color: var(--text-muted);
  font-family: var(--font-mono);
}

.project-card h3 {
  font-size: 18px;
  font-weight: 600;
  margin-bottom: 8px;
  letter-spacing: -0.01em;
}

.project-card p {
  color: var(--text-secondary);
  font-size: 13.5px;
  line-height: 1.5;
  margin-bottom: 20px;
  flex-grow: 1;
}

/* Interactive Playground within cards */
.interactive-box {
  background-color: var(--bg-primary);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 14px;
  margin-bottom: 16px;
}

.input-row {
  display: flex;
  gap: 8px;
  margin-bottom: 10px;
}

.code-input {
  flex: 1;
  background-color: var(--bg-card);
  border: 1px solid var(--border);
  color: var(--text-primary);
  padding: 10px 12px;
  border-radius: 6px;
  font-family: var(--font-mono);
  font-size: 12.5px;
  outline: none;
  min-height: 44px;
}

.code-input:focus {
  border-color: var(--accent);
}

.run-btn {
  background-color: var(--accent);
  color: #000;
  font-weight: 600;
  border: none;
  border-radius: 6px;
  padding: 0 16px;
  font-size: 12.5px;
  cursor: pointer;
  transition: opacity 0.15s ease;
  min-height: 44px;
}

.run-btn:hover {
  opacity: 0.9;
}

.output-box {
  background-color: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 10px 12px;
  font-family: var(--font-mono);
  font-size: 12px;
  color: #e4e4e7;
  max-height: 180px;
  overflow-y: auto;
  white-space: pre-wrap;
  word-break: break-all;
}

/* Footer */
footer {
  border-top: 1px solid var(--border);
  padding: 36px 0;
  text-align: center;
  color: var(--text-muted);
  font-size: 13px;
}

footer a {
  color: var(--text-secondary);
  text-decoration: none;
}

footer a:hover {
  color: var(--text-primary);
}

@media (max-width: 640px) {
  .project-grid {
    grid-template-columns: 1fr;
  }
  .stats-bar {
    gap: 16px;
  }
}