* { box-sizing: border-box; }
body {
  margin: 0;
  background: #090b10;
  color: #eef1f7;
  font: 14px Inter, system-ui, sans-serif;
}
.app { display: flex; min-height: 100vh; }
.sidebar {
  width: 250px;
  background: #0e1118;
  border-right: 1px solid #202632;
  padding: 24px 18px;
  position: sticky;
  top: 0;
  height: 100vh;
}
.sidebar h1 { margin: 0; font-size: 25px; }
.sidebar h1 span, .eyebrow { color: #8b5cf6; }
.muted { color: #8993a7; }
.sidebar nav { display: grid; gap: 7px; margin: 25px 0; }
.nav, .ghost, .primary, .danger, .btn-import, .file-button {
  border-radius: 8px;
  cursor: pointer;
  transition: background 0.2s ease, border-color 0.2s ease, transform 0.2s ease;
}
.nav,.ghost { background: transparent; color: #b9c1d1; border: 1px solid transparent; padding: 10px 12px; text-align: left; }
.nav:hover, .nav.active, .ghost:hover { background: #171b25; border-color: #293140; color: #fff; }
.sidebox { border-top: 1px solid #242a36; padding-top: 15px; display: grid; gap: 8px; }
.sidebox label, .session-grid label, .toolbar label { display: grid; gap: 5px; color: #8993a7; font-size: 12px; }
.primary {
  background: #8b5cf6;
  color: #fff;
  border: 0;
  padding: 10px 14px;
  font-weight: 600;
}
.danger {
  background: #7f1d1d;
  border: 1px solid #ef4444;
  color: #fff;
  padding: 10px 12px;
  font-weight: 600;
}
.danger:hover { filter: brightness(1.08); }
.btn-import {
  background: #16a34a;
  color: #fff;
  border: 1px solid #22c55e;
  padding: 10px 12px;
  font-weight: 600;
  display: inline-flex;
  align-items: center;
  justify-content: center;
}
.btn-import:hover { background: #15803d; }
.file-button {
  background: #171b25;
  padding: 10px;
  border: 1px solid #293140;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  color: #eef1f7;
}
.file-button input { display: none; }
input, select {
  width: 100%;
  background: #11151e;
  color: #eef1f7;
  border: 1px solid #293140;
  border-radius: 8px;
  padding: 10px;
}
.main { flex: 1; max-width: 1500px; margin: auto; padding: 28px; }
.topbar { margin-bottom: 20px; }
.topbar h2 { margin: 5px 0; font-size: 27px; }
.page { display: none; }
.page.active { display: block; }
.panel, .card {
  background: #10141c;
  border: 1px solid #222936;
  border-radius: 12px;
  padding: 18px;
  margin-bottom: 16px;
}
.cards { display: grid; grid-template-columns: repeat(6, minmax(0, 1fr)); gap: 12px; }
.card span { color: #8993a7; }
.card strong { font-size: 28px; display: block; margin-top: 8px; }
.grid2 { display: grid; grid-template-columns: 2fr 1fr; gap: 16px; }
.panel h3{ margin-top: 0; }
.formgrid, .session-grid { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 10px; margin: 14px 0; }
.session-grid label { display: grid; gap: 5px; color: #8993a7; font-size: 12px; }
.formgrid.five{ grid-template-columns: repeat(4, minmax(0, 1fr)); }
.toolbar { display: flex; gap: 10px; align-items: end; flex-wrap: wrap; margin: 14px 0; }
.toolbar label { min-width: 180px; }
.panelhead { display: flex; justify-content: space-between; align-items: center; gap: 12px; }
.tablewrap { overflow: auto; }
table { width: 100%; border-collapse: collapse; margin-top: 8px; }
th, td { padding: 10px 8px; border-bottom: 1px solid #2a3344; text-align: left; }
th { color: #c7d0dd; }
tr:hover td { background: rgba(255,255,255,0.02); }
.good { color: #4ade80; }
.bad { color: #f87171; }
.small { font-size: 12px; color: #8993a7; }
.empty { padding: 20px; color: #8993a7; }
#toast {
  position: fixed;
  bottom: 22px;
  right: 22px;
  background: rgba(17,21,30,0.96);
  border: 1px solid #39445a;
  color: white;
  padding: 10px 14px;
  border-radius: 10px;
  box-shadow: 0 8px 20px rgba(0,0,0,0.25);
  display: none;
  z-index: 999;
}
#studentList, #historyList, #timetableList, #subjectList, #attendanceList { margin-top: 12px; }
.student-row, .attendance-row, .subject-row, .timetable-row { display: grid; grid-template-columns: repeat(auto-fit, minmax(100px, 1fr)); gap: 8px; align-items: center; }
.student-row { background: rgba(255,255,255,0.02); border: 1px solid rgba(255,255,255,0.06); border-radius: 8px; padding: 10px; }
.student-actions, .attendance-actions, .row-actions { display: flex; gap: 6px; flex-wrap: wrap; justify-content: flex-end; }
.attendance-counters { display: flex; flex-wrap: wrap; gap: 18px; margin: 12px 0; color: #aeb9cc; }
.attendance-counters strong { color: #fff; }
.mini-btn.selected { background: #8b5cf6; border-color: #a78bfa; color: #fff; }
.attendance-empty { border: 1px dashed #39445a; border-radius: 8px; }
.attendance-empty .toolbar { margin-bottom: 0; }
.row-btn, .mini-btn {
  border: 1px solid #334155;
  background: #171b25;
  color: #e5ecff;
  border-radius: 6px;
  padding: 6px 8px;
  cursor: pointer;
}
.row-btn.danger { background: rgba(239,68,68,0.12); border-color: rgba(239,68,68,0.5); }
.section-label { color: #c7d0dd; font-size: 12px; letter-spacing: 0.08em; text-transform: uppercase; margin-top: 6px; }
.backup-info { margin-top: 10px; padding: 10px; border: 1px solid #293140; background: rgba(255,255,255,0.02); border-radius: 8px; color: #dbe7ff; font-size: 12px; line-height: 1.6; }
.status-row { margin-top: 8px; }
.data-status { font-size: 12px; font-weight: 600; }
.data-status.saved { color: #4ade80; }
.data-status.error { color: #fca5a5; }
.modal {
  position: fixed; inset: 0; display: none; align-items: center; justify-content: center; background: rgba(3, 6, 12, 0.7); z-index: 9999; padding: 18px;
}
.modal.open { display: flex; }
.modal-card {
  width: min(560px, 100%);
  background: #0f172a;
  border: 1px solid #334155;
  border-radius: 12px;
  padding: 20px;
  box-shadow: 0 18px 40px rgba(0,0,0,0.32);
}
.modal-card h3 { margin-top: 0; margin-bottom: 12px; }
.modal-card p { margin: 8px 0; line-height: 1.6; color: #dfe8ff; }
.modal-actions { display: flex; justify-content: flex-end; gap: 10px; margin-top: 16px; flex-wrap: wrap; }
.modal-actions .ghost { color: #dfe8ff; }
.danger-button { background: rgba(127,29,29,0.12); border-color: rgba(239,68,68,0.5); }
.calendar { display: grid; grid-template-columns: repeat(7, minmax(0, 1fr)); gap: 8px; }
.calendar-day {
  min-height: 110px;
  border-radius: 8px;
  border: 1px solid #2b3644;
  background: #101a28;
  padding: 8px;
  position: relative;
}
.calendar-day.header { min-height: auto; background: transparent; border: none; text-align: center; color: #99a7c2; padding: 2px; }
.calendar-day.other-month { opacity: 0.35; }
.calendar-day.today { border-color: #8b5cf6; box-shadow: inset 0 0 0 1px #8b5cf6; }
.calendar-date { font-weight: 700; }
.calendar-badge { position: absolute; bottom: 8px; right: 8px; font-size: 11px; color: #a5b4fc; }
@media (max-width: 900px) {
  .app { display: block; }
  .sidebar { width: 100%; height: auto; position: static; border-right: none; border-bottom: 1px solid #202632; }
  .cards { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .grid2 { grid-template-columns: 1fr; }
  .formgrid, .session-grid { grid-template-columns: 1fr 1fr; }
}
@media (max-width: 600px) {
  .main { padding: 16px; }
  .cards, .formgrid, .session-grid { grid-template-columns: 1fr; }
  .toolbar { flex-direction: column; align-items: stretch; }
  .attendance-counters { gap: 10px; }
}