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

:root {
  --bg: #0d0d0f;
  --surface: #131316;
  --border: #222228;
  --border-hover: #3a3a44;
  --text-primary: #f0f0f2;
  --text-secondary: #6b6b78;
  --text-muted: #3a3a44;
  --accent: #c8f549;
  --accent-dim: rgba(200, 245, 73, 0.08);
  --font-display: 'Syne', sans-serif;
  --font-mono: 'DM Mono', monospace;
}

html {
  background: var(--bg);
  color: var(--text-primary);
  font-family: var(--font-mono);
  min-height: 100vh;
}

body {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  position: relative;
  overflow-x: hidden;
}

/* Background grid */
.bg-grid {
  position: fixed;
  inset: 0;
  background-image:
    linear-gradient(var(--border) 1px, transparent 1px),
    linear-gradient(90deg, var(--border) 1px, transparent 1px);
  background-size: 40px 40px;
  opacity: 0.4;
  z-index: 0;
  pointer-events: none;
}

/* Header */
header {
  position: relative;
  z-index: 1;
  padding: 72px 48px 56px;
  border-bottom: 1px solid var(--border);
}

.header-inner {
  max-width: 960px;
  margin: 0 auto;
}

.badge {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 500;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--accent);
  background: var(--accent-dim);
  border: 1px solid rgba(200, 245, 73, 0.2);
  padding: 4px 12px;
  border-radius: 4px;
  margin-bottom: 24px;
}

h1 {
  font-family: var(--font-display);
  font-size: clamp(40px, 7vw, 72px);
  font-weight: 800;
  line-height: 0.95;
  letter-spacing: -0.03em;
  color: var(--text-primary);
  margin-bottom: 16px;
}

.subtitle {
  font-family: var(--font-mono);
  font-size: 13px;
  color: var(--text-secondary);
  letter-spacing: 0.02em;
}

/* Main content */
main {
  position: relative;
  z-index: 1;
  flex: 1;
  padding: 48px;
  max-width: 960px;
  margin: 0 auto;
  width: 100%;
}

/* Assignment grid */
.grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 16px;
}

/* Card */
.card {
  display: flex;
  flex-direction: column;
  gap: 12px;
  padding: 24px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 10px;
  text-decoration: none;
  color: inherit;
  transition: border-color 0.2s, background 0.2s, transform 0.2s;
  animation: fadeUp 0.4s both ease-out;
  position: relative;
  overflow: hidden;
}

.card::after {
  content: '';
  position: absolute;
  bottom: 0; left: 0; right: 0;
  height: 2px;
  background: var(--accent);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 0.25s ease;
}

.card:hover {
  border-color: var(--border-hover);
  background: #18181c;
  transform: translateY(-3px);
}

.card:hover::after {
  transform: scaleX(1);
}

.card .num {
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 500;
  color: var(--accent);
  letter-spacing: 0.1em;
}

.card .title {
  font-family: var(--font-display);
  font-size: 18px;
  font-weight: 700;
  color: var(--text-primary);
  letter-spacing: -0.01em;
}

.card .arrow {
  font-size: 18px;
  color: var(--text-muted);
  margin-top: auto;
  transition: color 0.2s, transform 0.2s;
}

.card:hover .arrow {
  color: var(--accent);
  transform: translate(3px, -3px);
}

/* Empty state */
.empty-state {
  flex-direction: column;
  align-items: center;
  gap: 16px;
  padding: 80px 24px;
  text-align: center;
  color: var(--text-secondary);
}

.empty-icon {
  font-size: 40px;
}

.empty-state p {
  font-size: 13px;
  max-width: 320px;
  line-height: 1.7;
}

.empty-state code {
  color: var(--accent);
  background: var(--accent-dim);
  padding: 2px 6px;
  border-radius: 4px;
  font-family: var(--font-mono);
}

/* Footer */
footer {
  position: relative;
  z-index: 1;
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 20px 48px;
  border-top: 1px solid var(--border);
  font-size: 12px;
  color: var(--text-muted);
  letter-spacing: 0.04em;
}

.dot {
  opacity: 0.4;
}

/* Animations */
@keyframes fadeUp {
  from {
    opacity: 0;
    transform: translateY(16px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* Responsive */
@media (max-width: 600px) {
  header { padding: 48px 24px 40px; }
  main { padding: 32px 24px; }
  footer { padding: 16px 24px; }
  .grid { grid-template-columns: 1fr; }
}

/* Back link (sub-assignment pages) */
.back-link {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--text-secondary);
  text-decoration: none;
  margin-bottom: 20px;
  letter-spacing: 0.04em;
  transition: color 0.2s;
}

.back-link:hover {
  color: var(--accent);
}

/* Parts badge on home cards */
.card .badge {
  font-family: var(--font-mono);
  font-size: 10px;
  font-weight: 500;
  letter-spacing: 0.08em;
  color: var(--accent);
  background: var(--accent-dim);
  border: 1px solid rgba(200, 245, 73, 0.2);
  padding: 2px 8px;
  border-radius: 4px;
  width: fit-content;
}

/* ── Sub-assignment additions ── */

/* "↓ 3 parts" badge on home cards */
.parts-badge {
  font-family: var(--font-mono);
  font-size: 10px;
  font-weight: 500;
  letter-spacing: 0.08em;
  color: var(--accent);
  background: var(--accent-dim);
  border: 1px solid rgba(200, 245, 73, 0.2);
  padding: 2px 8px;
  border-radius: 4px;
  width: fit-content;
}

/* Back link on sub-assignment pages */
.back-link {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--text-secondary);
  text-decoration: none;
  margin-bottom: 20px;
  letter-spacing: 0.04em;
  transition: color 0.2s;
}

.back-link:hover {
  color: var(--accent);
}