@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700&family=JetBrains+Mono:wght@400;500&display=swap');

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

:root {
  --bg:       #09090f;
  --bg2:      #111118;
  --bg3:      #1a1a26;
  --bg4:      #22223a;
  --accent:   #8b5cf6;
  --accent2:  #a78bfa;
  --accent3:  #c4b5fd;
  --text1:    #f0f0ff;
  --text2:    #9090b0;
  --text3:    #55556a;
  --border:   #25254a;
  --success:  #34d399;
  --error:    #f87171;
  --warning:  #fbbf24;
  --radius:   12px;
  --radius-sm:8px;
  --shadow:   0 4px 32px rgba(0,0,0,.5);
  --shadow-lg:0 8px 64px rgba(0,0,0,.7);
  --t:        all .18s ease;
}

body {
  font-family: 'Inter', 'Segoe UI', system-ui, sans-serif;
  background: var(--bg);
  color: var(--text1);
  min-height: 100vh;
  line-height: 1.6;
}

::-webkit-scrollbar { width: 5px; height: 5px; }
::-webkit-scrollbar-track { background: var(--bg); }
::-webkit-scrollbar-thumb { background: var(--border); border-radius: 3px; }
::-webkit-scrollbar-thumb:hover { background: var(--accent); }

/* ─── Buttons ─── */
.btn {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 10px 20px; border: none; border-radius: var(--radius-sm);
  cursor: pointer; font-size: .9rem; font-weight: 500;
  transition: var(--t); text-decoration: none; font-family: inherit;
  white-space: nowrap;
}
.btn-primary  { background: var(--accent); color: #fff; }
.btn-primary:hover  { background: #7c3aed; transform: translateY(-1px); box-shadow: 0 4px 20px rgba(139,92,246,.4); }
.btn-secondary { background: var(--bg3); color: var(--text1); border: 1px solid var(--border); }
.btn-secondary:hover { background: var(--bg4); border-color: var(--accent); }
.btn-danger   { background: rgba(248,113,113,.1); color: var(--error); border: 1px solid rgba(248,113,113,.3); }
.btn-danger:hover { background: var(--error); color: #fff; border-color: var(--error); }
.btn-success  { background: var(--success); color: #fff; }
.btn-sm       { padding: 6px 12px; font-size: .8rem; }
.btn-icon     { padding: 8px; width: 34px; height: 34px; justify-content: center; }
.btn:disabled { opacity: .45; cursor: not-allowed; transform: none !important; box-shadow: none !important; }

/* ─── Inputs ─── */
input, textarea, select {
  width: 100%; padding: 11px 14px; background: var(--bg3);
  border: 1px solid var(--border); border-radius: var(--radius-sm);
  color: var(--text1); font-size: .9rem; font-family: inherit;
  transition: var(--t); outline: none;
}
input:focus, textarea:focus, select:focus {
  border-color: var(--accent); box-shadow: 0 0 0 3px rgba(139,92,246,.15);
}
input::placeholder, textarea::placeholder { color: var(--text3); }
select option { background: var(--bg3); }
textarea { resize: vertical; min-height: 90px; }

/* ─── Badges ─── */
.badge { display: inline-flex; align-items: center; padding: 3px 10px; border-radius: 20px; font-size: .72rem; font-weight: 600; }
.badge-on  { background: rgba(52,211,153,.12); color: var(--success); }
.badge-off { background: rgba(248,113,113,.12); color: var(--error); }
.badge-used { background: rgba(251,191,36,.12); color: var(--warning); }
.badge-free { background: rgba(139,92,246,.12); color: var(--accent3); }

/* ─── Alerts ─── */
.alert { padding: 11px 14px; border-radius: var(--radius-sm); font-size: .875rem; margin-top: 10px; }
.alert-error   { background: rgba(248,113,113,.1); border: 1px solid rgba(248,113,113,.3); color: var(--error); }
.alert-success { background: rgba(52,211,153,.1);  border: 1px solid rgba(52,211,153,.3);  color: var(--success); }

/* ─── Spinner ─── */
.spinner {
  display: inline-block; width: 18px; height: 18px;
  border: 2px solid rgba(255,255,255,.15);
  border-top-color: currentColor; border-radius: 50%;
  animation: spin .6s linear infinite;
}
@keyframes spin { to { transform: rotate(360deg); } }

.loading-page {
  display: flex; align-items: center; justify-content: center;
  height: 100vh; flex-direction: column; gap: 14px; color: var(--text2);
}
.loading-page .spinner { width: 36px; height: 36px; border-color: rgba(139,92,246,.2); border-top-color: var(--accent); }

/* ─── Form group ─── */
.form-group { margin-bottom: 14px; }
.form-group label { display: block; font-size: .82rem; color: var(--text2); margin-bottom: 7px; font-weight: 500; }
.form-row { display: flex; gap: 12px; }
.form-row > * { flex: 1; }

/* ─── Modal ─── */
.modal-overlay {
  position: fixed; inset: 0; background: rgba(0,0,0,.72);
  display: flex; align-items: center; justify-content: center; z-index: 1000; padding: 20px;
}
.modal {
  background: var(--bg2); border: 1px solid var(--border);
  border-radius: 16px; padding: 28px; width: 100%; max-width: 520px; box-shadow: var(--shadow-lg);
}
.modal h3 { font-size: 1.1rem; font-weight: 700; margin-bottom: 20px; }
.modal-actions { display: flex; gap: 10px; justify-content: flex-end; margin-top: 20px; }
.modal-sm { max-width: 380px; }

/* ═══════════════════════════════════════
   LOGIN PAGE
═══════════════════════════════════════ */
.login-page {
  min-height: 100vh; display: flex; align-items: center; justify-content: center;
  background:
    radial-gradient(ellipse at 50% -20%, rgba(139,92,246,.2) 0%, transparent 55%),
    radial-gradient(ellipse at 100% 110%, rgba(99,102,241,.1) 0%, transparent 45%),
    var(--bg);
  padding: 20px;
}
.login-card {
  width: 100%; max-width: 420px; background: var(--bg2);
  border: 1px solid var(--border); border-radius: 20px;
  padding: 44px 36px; box-shadow: var(--shadow-lg);
}
.login-logo { text-align: center; margin-bottom: 30px; }
.login-logo .logo-icon {
  width: 68px; height: 68px;
  background: linear-gradient(135deg, var(--accent), #4f46e5);
  border-radius: 18px; display: flex; align-items: center; justify-content: center;
  margin: 0 auto 14px; font-size: 1.9rem; box-shadow: 0 8px 24px rgba(139,92,246,.35);
}
.login-logo h1 { font-size: 1.4rem; font-weight: 700; }
.login-logo p  { color: var(--text2); font-size: .85rem; margin-top: 5px; }
.login-form    { display: flex; flex-direction: column; gap: 12px; }
.code-input input {
  font-size: 1.25rem; text-align: center; letter-spacing: 5px;
  text-transform: uppercase; font-weight: 700; padding: 16px;
  font-family: 'JetBrains Mono', monospace;
}
.code-input input::placeholder { letter-spacing: 0; font-size: .9rem; text-transform: none; font-weight: 400; font-family: 'Inter', sans-serif; }
.login-form .login-btn { width: 100%; justify-content: center; padding: 13px; font-size: .95rem; }
.admin-link { text-align: center; margin-top: 14px; }
.admin-link a { color: var(--text3); font-size: .78rem; text-decoration: none; transition: var(--t); }
.admin-link a:hover { color: var(--text2); }

/* ═══════════════════════════════════════
   COURSE PAGE
═══════════════════════════════════════ */
.course-layout { display: flex; height: 100vh; overflow: hidden; }

/* Sidebar */
.sidebar {
  width: 300px; min-width: 300px; background: var(--bg2);
  border-right: 1px solid var(--border); display: flex; flex-direction: column; overflow: hidden;
}
.sidebar-header {
  padding: 18px 20px; border-bottom: 1px solid var(--border);
  display: flex; align-items: center; justify-content: space-between;
}
.sidebar-header-info h2 { font-size: .95rem; font-weight: 700; }
.sidebar-header-info p  { font-size: .75rem; color: var(--text3); margin-top: 2px; }
.sidebar-nav { flex: 1; overflow-y: auto; padding: 8px 0; }

.chapter-item { border-bottom: 1px solid rgba(37,37,74,.5); }
.chapter-header {
  display: flex; align-items: center; gap: 10px; padding: 11px 16px;
  cursor: pointer; transition: var(--t); font-weight: 600; font-size: .83rem; color: var(--text2);
}
.chapter-header:hover { background: var(--bg3); color: var(--text1); }
.ch-num {
  width: 24px; height: 24px; border-radius: 6px; background: var(--bg3);
  border: 1px solid var(--border); display: flex; align-items: center; justify-content: center;
  font-size: .72rem; font-weight: 700; color: var(--text3); flex-shrink: 0;
}
.ch-arrow { margin-left: auto; flex-shrink: 0; transition: transform .2s; opacity: .45; }
.chapter-item.open .ch-arrow { transform: rotate(90deg); }
.chapter-lessons { display: none; }
.chapter-item.open .chapter-lessons { display: block; }

.lesson-item {
  display: flex; align-items: center; gap: 10px; padding: 9px 16px 9px 36px;
  cursor: pointer; transition: var(--t); font-size: .82rem; color: var(--text2);
  border-left: 3px solid transparent;
}
.lesson-item:hover { background: var(--bg3); color: var(--text1); }
.lesson-item.active { background: rgba(139,92,246,.08); color: var(--accent2); border-left-color: var(--accent); }
.lesson-dot { width: 7px; height: 7px; border-radius: 50%; background: var(--border); flex-shrink: 0; transition: var(--t); }
.lesson-item.active .lesson-dot { background: var(--accent); box-shadow: 0 0 8px var(--accent); }

/* Main */
.course-main { flex: 1; overflow-y: auto; display: flex; flex-direction: column; }
.course-header {
  padding: 14px 24px; border-bottom: 1px solid var(--border);
  display: flex; align-items: center; justify-content: space-between;
  background: rgba(17,17,24,.85); backdrop-filter: blur(8px);
  position: sticky; top: 0; z-index: 10;
}
.course-header h1 { font-size: 1rem; font-weight: 600; }
.course-body { padding: 32px; max-width: 920px; }

.video-wrap {
  width: 100%; aspect-ratio: 16/9; background: #000;
  border-radius: var(--radius); overflow: hidden; margin-bottom: 24px;
  border: 1px solid var(--border);
}
.video-wrap iframe { width: 100%; height: 100%; border: none; }

.lesson-title  { font-size: 1.5rem; font-weight: 700; margin-bottom: 10px; }
.lesson-desc   { color: var(--text2); margin-bottom: 28px; line-height: 1.75; }
.divider       { height: 1px; background: var(--border); margin: 24px 0; }

/* Snippets */
.snippets-title { font-size: .95rem; font-weight: 600; color: var(--text2); margin-bottom: 14px; display: flex; align-items: center; gap: 7px; }
.snippet-card { background: var(--bg3); border: 1px solid var(--border); border-radius: var(--radius); margin-bottom: 14px; overflow: hidden; }
.snippet-head {
  display: flex; align-items: center; justify-content: space-between;
  padding: 10px 14px; background: var(--bg4); border-bottom: 1px solid var(--border);
}
.snippet-name { font-size: .82rem; font-weight: 600; color: var(--text2); }
.snippet-lang-tag { font-size: .72rem; color: var(--accent3); background: rgba(139,92,246,.12); padding: 2px 9px; border-radius: 4px; font-family: 'JetBrains Mono', monospace; }
.snippet-body { position: relative; }
.snippet-body pre { margin: 0; padding: 18px; overflow-x: auto; font-size: .82rem; line-height: 1.65; font-family: 'JetBrains Mono', 'Consolas', monospace; }
.copy-btn {
  position: absolute; top: 8px; right: 8px;
  padding: 4px 10px; background: var(--bg4); border: 1px solid var(--border);
  border-radius: 5px; color: var(--text2); cursor: pointer; font-size: .72rem; transition: var(--t); font-family: inherit;
}
.copy-btn:hover { background: var(--accent); color: #fff; border-color: var(--accent); }

.no-lesson {
  display: flex; flex-direction: column; align-items: center; justify-content: center;
  height: 60vh; color: var(--text3); text-align: center; padding: 48px;
}
.no-lesson .nl-icon { font-size: 3.5rem; margin-bottom: 16px; opacity: .25; }
.no-lesson h3 { font-size: 1.1rem; color: var(--text2); margin-bottom: 8px; }

/* ═══════════════════════════════════════
   ADMIN PAGE
═══════════════════════════════════════ */
.admin-layout { display: flex; height: 100vh; overflow: hidden; }

.admin-sidebar {
  width: 230px; min-width: 230px; background: var(--bg2);
  border-right: 1px solid var(--border); display: flex; flex-direction: column; overflow: hidden;
}
.admin-logo { padding: 22px 18px; border-bottom: 1px solid var(--border); }
.admin-logo h1 { font-size: 1rem; font-weight: 700; }
.admin-logo p  { font-size: .72rem; color: var(--text3); margin-top: 3px; }
.admin-nav { flex: 1; padding: 10px 0; overflow-y: auto; }
.admin-nav-item {
  display: flex; align-items: center; gap: 10px; padding: 10px 18px;
  cursor: pointer; transition: var(--t); color: var(--text2); font-size: .88rem; text-decoration: none; border-left: 3px solid transparent;
}
.admin-nav-item:hover  { background: var(--bg3); color: var(--text1); }
.admin-nav-item.active { background: rgba(139,92,246,.08); color: var(--accent2); border-left-color: var(--accent); }
.admin-sidebar-footer { padding: 16px 18px; border-top: 1px solid var(--border); }

.admin-main { flex: 1; overflow-y: auto; padding: 28px 32px; }
.page-header { display: flex; align-items: center; justify-content: space-between; margin-bottom: 24px; }
.page-header h2 { font-size: 1.4rem; font-weight: 700; }
.page-header-actions { display: flex; gap: 8px; }
.tab-content { display: none; }
.tab-content.active { display: block; }

/* Stats */
.stats-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(160px, 1fr)); gap: 14px; margin-bottom: 28px; }
.stat-card { background: var(--bg2); border: 1px solid var(--border); border-radius: var(--radius); padding: 18px; }
.stat-val  { font-size: 1.9rem; font-weight: 700; color: var(--accent2); line-height: 1; }
.stat-lbl  { font-size: .75rem; color: var(--text3); margin-top: 6px; }

/* Table */
.table-wrap { background: var(--bg2); border: 1px solid var(--border); border-radius: var(--radius); overflow: hidden; }
table { width: 100%; border-collapse: collapse; }
th { background: var(--bg3); padding: 11px 14px; text-align: left; font-size: .75rem; color: var(--text3); font-weight: 600; text-transform: uppercase; letter-spacing: .5px; border-bottom: 1px solid var(--border); }
td { padding: 11px 14px; border-bottom: 1px solid var(--border); font-size: .87rem; vertical-align: middle; }
tr:last-child td { border-bottom: none; }
tr:hover td { background: rgba(26,26,38,.5); }
.code-mono { font-family: 'JetBrains Mono', monospace; font-weight: 700; letter-spacing: 2px; color: var(--accent3); font-size: .95rem; }
.td-actions { display: flex; gap: 6px; }

/* Course Editor */
.course-editor-wrap { display: grid; grid-template-columns: 260px 1fr; gap: 18px; }
.course-tree { background: var(--bg2); border: 1px solid var(--border); border-radius: var(--radius); overflow: hidden; }
.tree-section-header {
  padding: 11px 14px; background: var(--bg3); border-bottom: 1px solid var(--border);
  font-size: .78rem; font-weight: 600; color: var(--text3); text-transform: uppercase; letter-spacing: .5px;
  display: flex; align-items: center; justify-content: space-between;
}
.tree-item {
  padding: 10px 14px; cursor: pointer; transition: var(--t); font-size: .85rem;
  border-bottom: 1px solid var(--border); display: flex; align-items: center; justify-content: space-between;
}
.tree-item:last-child { border-bottom: none; }
.tree-item:hover  { background: var(--bg3); }
.tree-item.active { background: rgba(139,92,246,.08); color: var(--accent2); }
.tree-subitem { padding: 8px 14px 8px 28px; }
.tree-subitem:hover  { background: var(--bg3); }
.tree-subitem.active { color: var(--accent3); }
.tree-del { opacity: 0; transition: var(--t); background: none; border: none; color: var(--error); cursor: pointer; padding: 2px 4px; font-size: .8rem; }
.tree-item:hover .tree-del { opacity: 1; }

/* Editing panel */
.edit-panel { background: var(--bg2); border: 1px solid var(--border); border-radius: var(--radius); padding: 22px; }
.edit-panel-empty { display: flex; align-items: center; justify-content: center; height: 200px; color: var(--text3); font-size: .9rem; }

/* Snippet editor row */
.snip-row { background: var(--bg3); border: 1px solid var(--border); border-radius: var(--radius-sm); padding: 14px; margin-bottom: 10px; }
.snip-row-head { display: flex; gap: 10px; margin-bottom: 10px; }
.snip-row textarea { font-family: 'JetBrains Mono', monospace; font-size: .82rem; min-height: 120px; }

/* Empty state */
.empty-state { text-align: center; padding: 40px 24px; color: var(--text3); }
.empty-state .ei { font-size: 2.2rem; margin-bottom: 10px; opacity: .35; }

/* Breadcrumb */
.breadcrumb { display: flex; align-items: center; gap: 8px; font-size: .82rem; color: var(--text3); margin-bottom: 20px; }
.breadcrumb a { color: var(--accent3); text-decoration: none; cursor: pointer; }
.breadcrumb a:hover { text-decoration: underline; }
.breadcrumb .sep { opacity: .4; }

/* ─── Responsive ─── */
@media (max-width: 768px) {
  .course-layout { flex-direction: column; }
  .sidebar { width: 100%; min-width: unset; height: auto; max-height: 45vh; border-right: none; border-bottom: 1px solid var(--border); }
  .course-body { padding: 16px; }
  .admin-layout { flex-direction: column; }
  .admin-sidebar { width: 100%; min-width: unset; height: auto; }
  .course-editor-wrap { grid-template-columns: 1fr; }
  .login-card { padding: 30px 20px; }
}