/* ── Reset & base ───────────────────────────────────────── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --bg:        #0f1117;
  --bg2:       #181c27;
  --bg3:       #1e2333;
  --border:    #2a2f42;
  --text:      #e2e8f0;
  --muted:     #7c87a0;
  --primary:   #3b82f6;
  --primary-h: #2563eb;
  --accent:    #f59e0b;
  --success:   #10b981;
  --danger:    #ef4444;
  --radius:    10px;
  --shadow:    0 4px 24px rgba(0,0,0,.4);
  --font:      'Inter', system-ui, -apple-system, sans-serif;
}

[data-theme="light"] {
  --bg:        #f0f4f8;
  --bg2:       #ffffff;
  --bg3:       #e8edf5;
  --border:    #d1d9e6;
  --text:      #1a202c;
  --muted:     #5a6478;
  --shadow:    0 4px 24px rgba(0,0,0,.08);
}

html { font-size: 16px; scroll-behavior: smooth; }

body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  line-height: 1.6;
  transition: background .2s, color .2s;
}

a { color: var(--primary); text-decoration: none; }
a:hover { color: var(--primary-h); }

/* ── Layout ─────────────────────────────────────────────── */
.container { max-width: 1100px; margin: 0 auto; padding: 0 20px; }

/* ── Navbar ─────────────────────────────────────────────── */
.navbar {
  background: var(--bg2);
  border-bottom: 1px solid var(--border);
  position: sticky; top: 0; z-index: 100;
  backdrop-filter: blur(8px);
}
.navbar .container {
  display: flex; align-items: center; justify-content: space-between;
  height: 56px; gap: 16px;
}
.logo {
  font-weight: 700; font-size: 1.1rem; color: var(--text) !important;
  display: flex; align-items: center; gap: 8px;
}
.logo svg { width: 22px; height: 22px; flex-shrink: 0; }
.nav-links { display: flex; align-items: center; gap: 4px; flex-wrap: wrap; }
.nav-links a {
  color: var(--muted); padding: 6px 12px; border-radius: 6px;
  font-size: .875rem; font-weight: 500; transition: all .15s;
}
.nav-links a:hover { color: var(--text); background: var(--bg3); }
.nav-links a.active { color: var(--primary); background: rgba(59,130,246,.12); }
.nav-user {
  color: var(--muted); font-size: .8rem; padding: 4px 10px;
  background: var(--bg3); border-radius: 6px;
}
.theme-btn {
  background: var(--bg3); border: 1px solid var(--border);
  color: var(--text); border-radius: 8px; padding: 6px 10px;
  cursor: pointer; font-size: .85rem; transition: all .15s;
}
.theme-btn:hover { background: var(--border); }

/* ── Main & footer ──────────────────────────────────────── */
main { flex: 1; padding: 28px 0 48px; }
.footer {
  text-align: center; color: var(--muted); font-size: .8rem;
  padding: 20px; border-top: 1px solid var(--border);
}

/* ── Messages ───────────────────────────────────────────── */
.messages { margin-bottom: 20px; display: flex; flex-direction: column; gap: 8px; }
.msg {
  padding: 12px 16px; border-radius: var(--radius);
  font-size: .875rem; font-weight: 500; border: 1px solid transparent;
}
.msg-success { background: rgba(16,185,129,.12); border-color: var(--success); color: var(--success); }
.msg-error   { background: rgba(239,68,68,.12);  border-color: var(--danger);  color: var(--danger);  }
.msg-warning { background: rgba(245,158,11,.12); border-color: var(--accent);  color: var(--accent);  }

/* ── Page header ────────────────────────────────────────── */
.page-header { margin-bottom: 28px; }
.page-header h1 { font-size: 1.6rem; font-weight: 700; color: var(--text); }
.page-header p  { color: var(--muted); margin-top: 4px; font-size: .9rem; }
.breadcrumb { color: var(--muted); font-size: .8rem; margin-bottom: 12px; }
.breadcrumb a { color: var(--muted); }
.breadcrumb a:hover { color: var(--primary); }

/* ── Cards ──────────────────────────────────────────────── */
.card {
  background: var(--bg2); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 24px; margin-bottom: 20px;
  box-shadow: var(--shadow);
}
.card h2 { font-size: 1rem; font-weight: 600; margin-bottom: 16px; color: var(--text); }

/* ── Search ─────────────────────────────────────────────── */
.search-box { margin-bottom: 14px; }
.search-box input {
  width: 100%; max-width: 380px; padding: 10px 14px;
  background: var(--bg3); border: 1px solid var(--border);
  border-radius: 8px; color: var(--text); font-size: .875rem;
  outline: none; transition: border-color .15s;
}
.search-box input:focus { border-color: var(--primary); }
.search-box input::placeholder { color: var(--muted); }

/* ── Entity grid (groups/teachers) ─────────────────────── */
.entity-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
  gap: 8px;
}
.entity-grid a {
  display: block; text-align: center; padding: 10px 8px;
  background: var(--bg3); border: 1px solid var(--border);
  border-radius: 8px; font-size: .85rem; font-weight: 500;
  color: var(--text); transition: all .15s;
}
.entity-grid a:hover {
  border-color: var(--primary); background: rgba(59,130,246,.08);
  color: var(--primary); transform: translateY(-1px);
}

/* ── Date selector ──────────────────────────────────────── */
.date-form {
  display: flex; align-items: center; gap: 10px;
  margin-bottom: 20px; flex-wrap: wrap;
}
.date-form label { color: var(--muted); font-size: .85rem; font-weight: 500; }
.date-form select {
  background: var(--bg3); border: 1px solid var(--border);
  color: var(--text); padding: 8px 12px; border-radius: 8px;
  font-size: .875rem; cursor: pointer; outline: none;
  transition: border-color .15s;
}
.date-form select:focus { border-color: var(--primary); }

/* ── Schedule table ─────────────────────────────────────── */
.table-wrap { overflow-x: auto; }
table { width: 100%; border-collapse: collapse; }
th {
  background: var(--bg3); color: var(--muted); font-size: .75rem;
  font-weight: 600; text-transform: uppercase; letter-spacing: .05em;
  padding: 10px 14px; text-align: left; border-bottom: 1px solid var(--border);
}
td {
  padding: 12px 14px; border-bottom: 1px solid var(--border);
  vertical-align: middle; font-size: .875rem;
}
tr:last-child td { border-bottom: none; }
tr:hover td { background: rgba(255,255,255,.025); }

/* ── Badges ─────────────────────────────────────────────── */
.badge {
  display: inline-flex; align-items: center; justify-content: center;
  border-radius: 6px; font-size: .75rem; font-weight: 600; padding: 2px 8px;
}
.badge-pair {
  background: rgba(59,130,246,.15); color: var(--primary);
  width: 28px; height: 28px; border-radius: 50%;
  display: inline-flex; align-items: center; justify-content: center;
  font-weight: 700; font-size: .85rem;
}
.badge-sub {
  background: rgba(245,158,11,.12); color: var(--accent);
  border-radius: 4px; padding: 1px 6px; font-size: .7rem;
  font-weight: 600; margin-left: 4px;
}
.badge-room {
  background: var(--bg3); color: var(--muted);
  padding: 2px 8px; border-radius: 4px; font-size: .8rem;
}
.badge-room.remote { color: var(--accent); background: rgba(245,158,11,.1); }
.pair-cell { display: flex; align-items: center; gap: 6px; }
.pair-time { color: var(--muted); font-size: .7rem; white-space: nowrap; }

/* ── Stats grid ─────────────────────────────────────────── */
.stats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(120px, 1fr));
  gap: 12px;
}
.stat-card {
  background: var(--bg3); border: 1px solid var(--border);
  border-radius: 8px; padding: 16px; text-align: center;
}
.stat-card .num { font-size: 1.8rem; font-weight: 700; color: var(--primary); }
.stat-card .lbl { color: var(--muted); font-size: .8rem; margin-top: 4px; }

/* ── Upload form ────────────────────────────────────────── */
.upload-zone {
  border: 2px dashed var(--border); border-radius: var(--radius);
  padding: 32px 24px; text-align: center; cursor: pointer;
  transition: border-color .15s;
}
.upload-zone:hover { border-color: var(--primary); }
.upload-zone input[type="file"] { display: none; }
.upload-zone label { cursor: pointer; }
.upload-zone p { color: var(--muted); font-size: .875rem; margin-top: 8px; }
.upload-zone .upload-icon { font-size: 2.5rem; margin-bottom: 8px; }

/* ── Buttons ────────────────────────────────────────────── */
.btn {
  display: inline-flex; align-items: center; gap: 6px;
  padding: 9px 18px; border-radius: 8px; font-size: .875rem;
  font-weight: 600; border: none; cursor: pointer; transition: all .15s;
}
.btn-primary  { background: var(--primary); color: #fff; }
.btn-primary:hover  { background: var(--primary-h); }
.btn-danger   { background: rgba(239,68,68,.12); color: var(--danger); border: 1px solid rgba(239,68,68,.3); }
.btn-danger:hover   { background: var(--danger); color: #fff; }
.btn-ghost    { background: var(--bg3); color: var(--text); border: 1px solid var(--border); }
.btn-ghost:hover    { border-color: var(--primary); color: var(--primary); }
.btn-sm { padding: 5px 12px; font-size: .8rem; }

/* ── Login page ─────────────────────────────────────────── */
.login-wrap {
  min-height: calc(100vh - 120px); display: flex;
  align-items: center; justify-content: center;
}
.login-card { width: 100%; max-width: 380px; }
.login-card h1 { font-size: 1.4rem; margin-bottom: 4px; }
.login-card .sub { color: var(--muted); font-size: .875rem; margin-bottom: 24px; }
.field { margin-bottom: 16px; }
.field label { display: block; font-size: .85rem; font-weight: 500; margin-bottom: 6px; color: var(--muted); }
.field input {
  width: 100%; padding: 10px 14px; background: var(--bg3);
  border: 1px solid var(--border); border-radius: 8px;
  color: var(--text); font-size: .875rem; outline: none; transition: border-color .15s;
}
.field input:focus { border-color: var(--primary); }

/* ── Empty state ────────────────────────────────────────── */
.empty {
  text-align: center; padding: 48px 20px; color: var(--muted);
}
.empty-icon { font-size: 3rem; margin-bottom: 12px; }
.empty p { font-size: .9rem; }

/* ── Responsive ─────────────────────────────────────────── */
@media (max-width: 640px) {
  .page-header h1 { font-size: 1.3rem; }
  .entity-grid { grid-template-columns: repeat(auto-fill, minmax(110px, 1fr)); }
  td, th { padding: 10px 10px; }
  .nav-links a { padding: 5px 8px; font-size: .8rem; }
}