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

:root {
  --bg: #0f0f0f;
  --surface: #1a1a1a;
  --surface2: #242424;
  --accent: #6366f1;
  --accent-hover: #4f46e5;
  --accent-light: rgba(99,102,241,.15);
  --text: #f0f0f0;
  --text-muted: #9ca3af;
  --border: #2d2d2d;
  --success: #22c55e;
  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;
  --radius: 10px;
}

body { font-family: var(--font); background: var(--bg); color: var(--text); font-size: 15px; line-height: 1.6; min-height: 100vh; }

/* Sidebar layout */
.layout { display: flex; min-height: 100vh; }
.sidebar {
  width: 220px; flex-shrink: 0;
  background: var(--surface);
  border-right: 1px solid var(--border);
  display: flex; flex-direction: column;
  padding: 24px 0;
  position: fixed; top: 0; left: 0; bottom: 0;
}
.sidebar-brand { padding: 0 20px 24px; font-weight: 700; font-size: 16px; border-bottom: 1px solid var(--border); margin-bottom: 16px; }
.sidebar-brand span { color: var(--accent); }
.sidebar-nav { flex: 1; display: flex; flex-direction: column; gap: 2px; padding: 0 10px; }
.nav-link {
  display: flex; align-items: center; gap: 10px;
  padding: 9px 12px; border-radius: 8px;
  color: var(--text-muted); text-decoration: none; font-size: 14px;
  transition: background .15s, color .15s;
}
.nav-link:hover, .nav-link.active { background: var(--accent-light); color: var(--accent); }
.sidebar-footer { padding: 16px 20px; border-top: 1px solid var(--border); margin-top: auto; }
.user-info { font-size: 13px; color: var(--text-muted); margin-bottom: 8px; }
.user-name { color: var(--text); font-weight: 500; }

/* Main content */
.content { margin-left: 220px; padding: 32px; max-width: 900px; width: 100%; }
.page-title { font-size: 22px; font-weight: 700; margin-bottom: 6px; }
.page-sub { color: var(--text-muted); font-size: 14px; margin-bottom: 28px; }

/* Cards */
.card { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 20px 24px; }
.card + .card { margin-top: 16px; }
.card-title { font-size: 13px; font-weight: 600; text-transform: uppercase; letter-spacing: 0.4px; color: var(--text-muted); margin-bottom: 8px; }
.card-value { font-size: 20px; font-weight: 700; }
.card-value.accent { color: var(--accent); }

/* Grid */
.grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px; margin-bottom: 24px; }
.grid-2 { display: grid; grid-template-columns: repeat(2, 1fr); gap: 16px; }

/* Module list */
.module-list { display: flex; flex-direction: column; gap: 12px; }
.module-card {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 18px 20px;
  display: flex; align-items: center; gap: 16px;
  text-decoration: none; color: var(--text);
  transition: border-color .15s;
}
.module-card:hover:not(.locked) { border-color: var(--accent); }
.module-card.locked { opacity: .5; cursor: not-allowed; }
.module-num {
  background: var(--accent-light); color: var(--accent);
  font-size: 13px; font-weight: 700; padding: 4px 10px; border-radius: 6px; flex-shrink: 0;
}
.module-num.locked-num { background: rgba(255,255,255,.05); color: var(--text-muted); }
.module-info { flex: 1; }
.module-title { font-weight: 600; margin-bottom: 2px; }
.module-meta { font-size: 13px; color: var(--text-muted); }
.lock-icon { font-size: 18px; color: var(--text-muted); }

/* Lesson list */
.lesson-list { display: flex; flex-direction: column; gap: 8px; margin-top: 20px; }
.lesson-item {
  background: var(--surface2); border: 1px solid var(--border);
  border-radius: 8px; padding: 14px 18px;
  cursor: pointer; transition: border-color .15s;
}
.lesson-item:hover { border-color: var(--accent); }
.lesson-item.active { border-color: var(--accent); background: var(--accent-light); }
.lesson-title { font-weight: 500; font-size: 14px; }

/* Content area */
.lesson-content {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 24px; margin-top: 20px;
  line-height: 1.8;
}
.lesson-content h1, .lesson-content h2, .lesson-content h3 { margin: 16px 0 8px; }
.lesson-content p { margin-bottom: 12px; }
.lesson-content pre { background: var(--surface2); padding: 12px; border-radius: 6px; overflow-x: auto; font-size: 13px; }
.lesson-content code { background: var(--surface2); padding: 2px 6px; border-radius: 4px; font-size: 13px; }
.lesson-content ul, .lesson-content ol { padding-left: 20px; margin-bottom: 12px; }

/* Submission form */
.submission-area { margin-top: 20px; }
.submission-area label { display: block; font-size: 13px; font-weight: 600; color: var(--text-muted); margin-bottom: 8px; text-transform: uppercase; letter-spacing: 0.4px; }
.submission-area textarea {
  width: 100%; min-height: 120px; padding: 12px;
  background: var(--surface2); border: 1px solid var(--border);
  border-radius: 8px; color: var(--text); font-size: 14px; font-family: var(--font); resize: vertical;
}
.submission-area textarea:focus { outline: none; border-color: var(--accent); }

/* Prompts */
.prompt-topic { font-size: 12px; font-weight: 700; text-transform: uppercase; letter-spacing: 0.5px; color: var(--text-muted); margin: 24px 0 10px; }
.prompt-card {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: 8px; padding: 16px 18px; margin-bottom: 10px;
  position: relative;
}
.prompt-title { font-weight: 600; font-size: 14px; margin-bottom: 8px; }
.prompt-content { font-size: 14px; color: var(--text-muted); white-space: pre-wrap; font-family: monospace; line-height: 1.5; }
.copy-btn {
  position: absolute; top: 12px; right: 12px;
  background: var(--accent-light); color: var(--accent); border: none;
  padding: 4px 10px; border-radius: 6px; font-size: 12px; cursor: pointer; font-family: var(--font);
}
.copy-btn:hover { background: var(--accent); color: #fff; }

/* Buttons */
.btn {
  display: inline-flex; align-items: center; gap: 6px;
  padding: 10px 20px; font-size: 14px; font-weight: 600;
  border-radius: 8px; border: none; cursor: pointer; font-family: var(--font);
  text-decoration: none; transition: background .15s;
}
.btn-primary { background: var(--accent); color: #fff; }
.btn-primary:hover { background: var(--accent-hover); }
.btn-secondary { background: var(--surface2); color: var(--text); border: 1px solid var(--border); }
.btn-secondary:hover { border-color: var(--accent); }
.btn:disabled { opacity: .5; cursor: not-allowed; }
.btn-sm { padding: 6px 14px; font-size: 13px; }

/* Alert */
.alert { padding: 10px 14px; border-radius: 8px; font-size: 14px; margin-bottom: 16px; }
.alert-success { background: rgba(34,197,94,.15); color: #4ade80; border: 1px solid rgba(34,197,94,.3); }
.alert-error   { background: rgba(239,68,68,.15); color: #f87171; border: 1px solid rgba(239,68,68,.3); }
.hidden { display: none !important; }

/* Login page */
.login-wrap { min-height: 100vh; display: flex; align-items: center; justify-content: center; }
.login-card { background: var(--surface); border: 1px solid var(--border); border-radius: 16px; padding: 40px; width: 100%; max-width: 400px; }
.login-card h1 { font-size: 22px; font-weight: 700; margin-bottom: 6px; }
.login-card p { color: var(--text-muted); font-size: 14px; margin-bottom: 28px; }
.form-field { margin-bottom: 16px; }
.form-field label { display: block; font-size: 13px; font-weight: 500; color: var(--text-muted); margin-bottom: 6px; }
.form-field input {
  width: 100%; padding: 12px 14px;
  background: var(--surface2); border: 1px solid var(--border);
  border-radius: 8px; color: var(--text); font-size: 15px; font-family: var(--font);
}
.form-field input:focus { outline: none; border-color: var(--accent); }
.btn-full { width: 100%; justify-content: center; }

/* Catalog page */
.catalog-promo {
  background: linear-gradient(135deg, var(--accent-light), transparent);
  border: 1px solid var(--accent);
  border-radius: 16px; padding: 40px; text-align: center; margin-top: 20px;
}
.catalog-promo h2 { font-size: 24px; font-weight: 700; margin-bottom: 10px; }
.catalog-promo p { color: var(--text-muted); margin-bottom: 24px; }
.discount-badge {
  display: inline-block; background: var(--accent); color: #fff;
  padding: 6px 16px; border-radius: 999px; font-size: 13px; font-weight: 700; margin-bottom: 20px;
}

/* Breadcrumb */
.breadcrumb { display: flex; align-items: center; gap: 8px; font-size: 13px; color: var(--text-muted); margin-bottom: 20px; }
.breadcrumb a { color: var(--accent); text-decoration: none; }
.breadcrumb a:hover { text-decoration: underline; }