:root {
  color-scheme: light;
  --bg: #f4f7fb;
  --panel: #ffffff;
  --text: #16202a;
  --muted: #667788;
  --line: #d8e0ea;
  --accent: #0f9d58;
  --accent-soft: #def7e8;
  --danger: #c0392b;
  --danger-soft: #fde8e5;
  --dark: #1f3b57;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: Inter, Arial, sans-serif;
  color: var(--text);
  background: linear-gradient(180deg, #eff5fb 0%, #f9fbfd 100%);
}

button,
input,
select {
  font: inherit;
}

.app-shell {
  max-width: 1440px;
  margin: 0 auto;
  padding: 20px;
}

.topbar,
.panel-head,
.grid-two,
.inline-grid {
  display: grid;
  gap: 16px;
}

.topbar {
  grid-template-columns: 1fr auto;
  align-items: start;
  margin-bottom: 20px;
}

.eyebrow {
  margin: 0 0 6px;
  color: var(--muted);
  font-size: 13px;
  text-transform: uppercase;
}

h1,
h2,
p {
  margin: 0;
}

.user-chip,
.status-pill {
  padding: 10px 14px;
  border-radius: 8px;
  background: var(--panel);
  border: 1px solid var(--line);
  font-weight: 600;
}

.panel {
  background: rgba(255, 255, 255, 0.92);
  border: 1px solid rgba(216, 224, 234, 0.8);
  border-radius: 8px;
  padding: 18px;
  margin-bottom: 18px;
  box-shadow: 0 12px 30px rgba(24, 40, 60, 0.06);
}

.panel-head {
  grid-template-columns: 1fr auto;
  align-items: center;
  margin-bottom: 16px;
}

.muted {
  color: var(--muted);
  font-size: 14px;
}

.session-list,
.stats-grid,
.stack {
  display: grid;
  gap: 12px;
}

.session-card,
.stat-card,
.group-stat-card {
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fbfdff;
  padding: 14px;
}

.session-card {
  cursor: pointer;
}

.user-row {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  padding: 10px 12px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fff;
}

.user-row span {
  color: var(--muted);
}

.session-card.active {
  border-color: #83b6ff;
  background: #eaf3ff;
}

.badge {
  display: inline-flex;
  align-items: center;
  padding: 6px 10px;
  border-radius: 999px;
  background: #eef4ff;
  color: #315ea8;
  font-size: 12px;
  font-weight: 700;
}

.table-wrap {
  overflow-x: auto;
}

table {
  width: 100%;
  min-width: 950px;
  border-collapse: collapse;
}

th,
td {
  padding: 10px 8px;
  border-bottom: 1px solid var(--line);
  text-align: left;
  vertical-align: middle;
}

th {
  font-size: 13px;
  color: var(--muted);
  font-weight: 700;
}

.empty {
  text-align: center;
  color: var(--muted);
  padding: 24px;
}

.action-btn,
.ghost-btn,
button[type="submit"],
.danger-btn {
  border: 0;
  border-radius: 8px;
  padding: 10px 12px;
  cursor: pointer;
  font-weight: 700;
}

.action-btn.present {
  background: var(--accent-soft);
  color: var(--accent);
}

.action-btn.absent {
  background: var(--danger-soft);
  color: var(--danger);
}

.action-btn.active.present {
  background: var(--accent);
  color: #fff;
}

.action-btn.active.absent {
  background: var(--danger);
  color: #fff;
}

.ghost-btn {
  background: #edf3f9;
  color: var(--dark);
}

.danger-btn {
  background: var(--danger-soft);
  color: var(--danger);
}

button[type="submit"] {
  background: var(--dark);
  color: #fff;
}

.stack input,
.stack select {
  width: 100%;
  padding: 12px;
  border-radius: 8px;
  border: 1px solid var(--line);
  background: #fff;
}

.grid-two {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.inline-grid {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.stats-grid {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.stat-card strong {
  display: block;
  font-size: 28px;
  margin-top: 10px;
}

.micro {
  margin-top: 6px;
  color: var(--muted);
  font-size: 13px;
}

.group-manage-row {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 16px;
  align-items: center;
  padding: 14px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fbfdff;
}

.student-manage-list {
  display: grid;
  gap: 10px;
}

.student-manage-row {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 12px;
  align-items: center;
  padding: 12px 14px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fbfdff;
}

.manage-actions {
  display: flex;
  gap: 10px;
}

.footer-note {
  text-align: center;
  margin-top: 2rem;
  color: var(--muted);
  font-size: 0.875rem;
}

@media (max-width: 920px) {
  .topbar,
  .panel-head,
  .grid-two,
  .inline-grid,
  .stats-grid {
    grid-template-columns: 1fr;
  }

  .app-shell {
    padding: 14px;
  }

  .group-manage-row,
  .student-manage-row {
    grid-template-columns: 1fr;
  }

  .manage-actions {
    flex-direction: column;
  }
}