:root {
  --bg: #0f1220;
  --card: #151a2e;
  --text: #f8fafc;
  --muted: #94a3b8;
  --accent: #7c3aed;
  --accent2: #22d3ee;
  --border: rgba(148, 163, 184, 0.2);
  --green: #22c55e;
  --yellow: #eab308;
  --red: #ef4444;
  --orange: #f97316;
  --gold: #ffd700;
  --silver: #c0c0c0;
  --bronze: #cd7f32;
}

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

body {
  font-family: ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial;
  background: radial-gradient(circle at top left, #1f2440, #0b0d18 65%);
  color: var(--text);
  min-height: 100vh;
  padding: 40px 24px;
}

.container {
  max-width: 1100px;
  margin: 0 auto;
}

header { margin-bottom: 32px; }

.back {
  color: var(--muted);
  text-decoration: none;
  font-size: 0.9rem;
  display: inline-block;
  margin-bottom: 16px;
}

.back:hover { color: var(--accent2); }

h1 { font-size: 2rem; margin-bottom: 8px; }

.subtitle { color: var(--muted); font-size: 1rem; }

/* Stats Grid */
.stats-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 16px;
  margin-bottom: 24px;
}

.stat-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 20px;
  text-align: center;
}

.stat-value {
  font-size: 2rem;
  font-weight: 700;
  color: var(--text);
}

.stat-value.active { color: var(--accent2); }
.stat-value.pending { color: var(--yellow); }
.stat-value.completed { color: var(--green); }

.stat-label {
  color: var(--muted);
  font-size: 0.85rem;
  margin-top: 4px;
}

/* Tabs */
.tabs {
  display: flex;
  gap: 8px;
  margin-bottom: 24px;
  border-bottom: 1px solid var(--border);
  padding-bottom: 12px;
}

.tab {
  padding: 10px 18px;
  background: transparent;
  border: 1px solid var(--border);
  border-radius: 8px;
  color: var(--muted);
  cursor: pointer;
  font-size: 0.9rem;
  transition: all 0.2s;
}

.tab:hover { background: rgba(124, 58, 237, 0.1); color: var(--text); }
.tab.active { background: var(--accent); color: white; border-color: var(--accent); }

.tab-content { display: none; }
.tab-content.active { display: block; }

/* Two Column */
.two-col {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 24px;
}

/* Cards */
.card {
  background: rgba(21, 26, 46, 0.7);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 24px;
  margin-bottom: 24px;
}

.card h3 {
  font-size: 1.1rem;
  margin-bottom: 16px;
  color: var(--text);
}

/* Challenge List */
.challenge-list {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.challenge-card {
  background: rgba(0, 0, 0, 0.2);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 16px;
  cursor: pointer;
  transition: all 0.2s;
}

.challenge-card:hover {
  background: rgba(0, 0, 0, 0.3);
  border-color: var(--accent);
}

.challenge-card.selected {
  border-color: var(--accent2);
  box-shadow: 0 0 0 1px var(--accent2);
}

.challenge-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  margin-bottom: 8px;
}

.challenge-title {
  font-weight: 600;
  font-size: 1.05rem;
}

.challenge-category {
  font-size: 0.8rem;
  color: var(--muted);
}

.challenge-badge {
  padding: 4px 10px;
  border-radius: 20px;
  font-size: 0.7rem;
  font-weight: 600;
  text-transform: uppercase;
}

.challenge-badge.weekly { background: rgba(249, 115, 22, 0.2); color: var(--orange); }
.challenge-badge.monthly { background: rgba(124, 58, 237, 0.2); color: var(--accent); }

.challenge-description {
  font-size: 0.9rem;
  color: var(--muted);
  margin-bottom: 12px;
  line-height: 1.5;
}

.challenge-meta {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
  margin-bottom: 12px;
}

.challenge-stat {
  font-size: 0.85rem;
  color: var(--muted);
}

.challenge-stat-value {
  color: var(--text);
  font-weight: 600;
}

.challenge-actions {
  display: flex;
  gap: 8px;
}

/* Buttons */
.btn {
  padding: 10px 20px;
  background: var(--accent);
  color: white;
  border: none;
  border-radius: 8px;
  cursor: pointer;
  font-size: 0.9rem;
  font-weight: 500;
  transition: all 0.2s;
}

.btn:hover { background: #6d28d9; }
.btn:disabled { opacity: 0.5; cursor: not-allowed; }

.btn-primary { background: var(--accent2); color: #0f1220; }
.btn-primary:hover { background: #06b6d4; }

.btn-small { padding: 8px 14px; font-size: 0.85rem; }

/* Leaderboard */
.leaderboard {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.leaderboard-entry {
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 12px 16px;
  background: rgba(0, 0, 0, 0.2);
  border-radius: 8px;
}

.leaderboard-entry.gold { background: rgba(255, 215, 0, 0.1); border: 1px solid rgba(255, 215, 0, 0.3); }
.leaderboard-entry.silver { background: rgba(192, 192, 192, 0.1); border: 1px solid rgba(192, 192, 192, 0.3); }
.leaderboard-entry.bronze { background: rgba(205, 127, 50, 0.1); border: 1px solid rgba(205, 127, 50, 0.3); }

.leaderboard-rank {
  font-size: 1.5rem;
  min-width: 40px;
  text-align: center;
}

.leaderboard-user {
  flex: 1;
}

.leaderboard-name {
  font-weight: 600;
}

.leaderboard-stats {
  font-size: 0.85rem;
  color: var(--muted);
}

.leaderboard-points {
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--accent2);
}

/* Submit Form */
.submit-form {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.form-group label {
  display: block;
  color: var(--muted);
  font-size: 0.85rem;
  margin-bottom: 6px;
}

.form-group input,
.form-group select,
.form-group textarea {
  width: 100%;
  padding: 12px;
  background: rgba(0, 0, 0, 0.3);
  border: 1px solid var(--border);
  border-radius: 8px;
  color: var(--text);
  font-size: 0.95rem;
  font-family: inherit;
}

.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
  outline: none;
  border-color: var(--accent);
}

.form-group textarea { resize: vertical; }

.submit-result {
  padding: 16px;
  border-radius: 8px;
  margin-top: 8px;
}

.submit-result.success {
  background: rgba(34, 197, 94, 0.1);
  border: 1px solid rgba(34, 197, 94, 0.3);
  color: var(--green);
}

.submit-result.error {
  background: rgba(239, 68, 68, 0.1);
  border: 1px solid rgba(239, 68, 68, 0.3);
  color: var(--red);
}

.submit-result.pending {
  background: rgba(234, 179, 8, 0.1);
  border: 1px solid rgba(234, 179, 8, 0.3);
  color: var(--yellow);
}

/* Submissions List */
.submissions-list {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.submission-item {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 12px;
  background: rgba(0, 0, 0, 0.2);
  border-radius: 8px;
}

.submission-icon { font-size: 1.5rem; }

.submission-info { flex: 1; }

.submission-challenge {
  font-weight: 500;
  margin-bottom: 2px;
}

.submission-date {
  font-size: 0.8rem;
  color: var(--muted);
}

.submission-status {
  padding: 4px 10px;
  border-radius: 20px;
  font-size: 0.75rem;
  font-weight: 600;
}

.submission-status.verified { background: rgba(34, 197, 94, 0.2); color: var(--green); }
.submission-status.pending { background: rgba(234, 179, 8, 0.2); color: var(--yellow); }
.submission-status.rejected { background: rgba(239, 68, 68, 0.2); color: var(--red); }

.submission-points {
  font-weight: 700;
  color: var(--accent2);
}

/* Archive */
.archive-list {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.archive-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 16px;
  background: rgba(0, 0, 0, 0.2);
  border-radius: 8px;
}

.archive-title { font-weight: 500; }

.archive-meta {
  font-size: 0.85rem;
  color: var(--muted);
}

.archive-winner {
  display: flex;
  align-items: center;
  gap: 8px;
  color: var(--gold);
}

/* Empty State */
.empty-state {
  text-align: center;
  padding: 40px;
  color: var(--muted);
}

.empty-icon { font-size: 3rem; margin-bottom: 16px; }

/* Responsive */
@media (max-width: 768px) {
  .stats-grid { grid-template-columns: repeat(2, 1fr); }
  .two-col { grid-template-columns: 1fr; }
}

@media (max-width: 600px) {
  .tabs { flex-wrap: wrap; }
  .tab { flex: 1; min-width: 100px; text-align: center; }
}