:root {
  --color-primary: #0E3A56;
  --color-primary-hover: #0A2C42;
  --color-secondary: #4C6A7D;
  --color-accent: #1A7A72;
  --color-success: #1F7A4D;
  --color-warning: #9A6700;
  --color-danger: #9B2C2C;
  --color-info: #1D4E89;
  --bg-body: #E7EEF2;
  --bg-surface: #FFFFFF;
  --bg-muted: #F4F7F9;
  --bg-sidebar: #0B2C42;
  --text-primary: #1C2430;
  --text-secondary: #5C6B7A;
  --text-on-primary: #FFFFFF;
  --border-color: #D5E0E8;
  --badge-success-bg: #E5F4EC;
  --badge-warning-bg: #FBF3DE;
  --badge-danger-bg: #F8E8E8;
  --badge-info-bg: #E7F0FA;
  --badge-neutral-bg: #EEF2F5;
  --color-danger-hover: #7E2424;
  --border-strong: #C5D3DE;
  --border-hover: #B7C8D4;
  --border-focus: #7AA0B8;
  --row-hover: #F7FBFC;
  --alert-success-border: #C9E6D6;
  --alert-danger-border: #E7C8C8;
  --alert-warning-border: #EAD9A8;
  --alert-info-border: #C9D9EE;
  --sidebar-top: #143E5C;
  --sidebar-bottom: #092433;
  --mark-light: #3DCFC3;
  --mark-mid: #147A86;
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --space-1: 4px;
  --space-2: 8px;
  --space-3: 12px;
  --space-4: 16px;
  --space-5: 24px;
  --space-6: 32px;
  --shadow-sm: 0 1px 2px rgba(14, 36, 54, .05), 0 1px 1px rgba(14, 36, 54, .04);
  --shadow-md: 0 16px 40px rgba(11, 32, 48, .14);
  --font: "Segoe UI Variable Text", "Segoe UI", system-ui, sans-serif;
  --text-sm: 13px;
  --text-md: 15px;
  --text-lg: 22px;
  --header-h: 60px;
  --sidebar-w: 248px;
  --focus: 0 0 0 3px rgba(14, 58, 86, .16);
}

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

body {
  margin: 0;
  font-family: var(--font);
  font-size: var(--text-md);
  color: var(--text-primary);
  background:
    radial-gradient(1100px 420px at 100% -8%, rgba(26, 122, 114, .09), transparent 58%),
    radial-gradient(820px 380px at -8% -4%, rgba(14, 58, 86, .07), transparent 52%),
    var(--bg-body);
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
}

a { color: var(--color-primary); }
a:hover { color: var(--color-primary-hover); }

h1 {
  font-size: var(--text-lg);
  font-weight: 650;
  letter-spacing: -.02em;
  line-height: 1.25;
  margin: 0 0 var(--space-4);
}

:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 2px;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  min-height: 40px;
  padding: var(--space-2) var(--space-4);
  border-radius: var(--radius-sm);
  border: 1px solid transparent;
  font: inherit;
  font-weight: 650;
  letter-spacing: .01em;
  cursor: pointer;
  text-decoration: none;
  transition: background .15s ease, border-color .15s ease, box-shadow .15s ease, color .15s ease;
}
.btn-primary {
  background: var(--color-primary);
  color: var(--text-on-primary);
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, .14), 0 1px 2px rgba(10, 32, 48, .18);
}
.btn-primary:hover { background: var(--color-primary-hover); color: var(--text-on-primary); }
.btn-secondary {
  background: var(--bg-surface);
  color: var(--color-secondary);
  border-color: var(--border-strong);
}
.btn-secondary:hover { background: var(--bg-muted); color: var(--color-primary); border-color: var(--border-hover); }
.btn-danger { background: var(--color-danger); color: var(--text-on-primary); }
.btn-danger:hover { background: var(--color-danger-hover); color: var(--text-on-primary); }
.btn-ghost { background: transparent; color: var(--text-primary); }
.btn-ghost:hover { background: var(--bg-muted); }

.form-field { margin-bottom: var(--space-4); }
.label {
  display: block;
  margin-bottom: var(--space-1);
  font-size: var(--text-sm);
  font-weight: 650;
  color: var(--text-primary);
}
.req { color: var(--color-danger); }
.input, .select, .textarea {
  width: 100%;
  min-height: 42px;
  padding: var(--space-2) var(--space-3);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  font: inherit;
  color: var(--text-primary);
  background: var(--bg-surface);
  transition: border-color .15s ease, box-shadow .15s ease;
}
.textarea { min-height: 96px; resize: vertical; }
.input:hover, .select:hover, .textarea:hover { border-color: var(--border-hover); }
.input:focus, .select:focus, .textarea:focus {
  outline: none;
  border-color: var(--border-focus);
  box-shadow: var(--focus);
}
.help { color: var(--text-secondary); font-size: var(--text-sm); margin: 0 0 var(--space-4); }
.field-error { color: var(--color-danger); font-size: var(--text-sm); margin-top: var(--space-1); }

.card {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-sm);
  padding: var(--space-5);
}
.stat {
  position: relative;
  overflow: hidden;
  min-width: 0;
  min-height: 104px;
  padding: var(--space-4) var(--space-4) var(--space-4) var(--space-5);
}
.stat::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: 3px;
  background: var(--color-accent);
}
.stat-label {
  color: var(--text-secondary);
  font-size: var(--text-sm);
  font-weight: 650;
  letter-spacing: .02em;
}
.stat-value {
  font-size: 28px;
  font-weight: 680;
  letter-spacing: -.03em;
  line-height: 1.15;
  margin-top: var(--space-2);
  font-variant-numeric: tabular-nums;
}

.table-wrap { overflow-x: auto; }
.table {
  width: 100%;
  border-collapse: collapse;
  background: var(--bg-surface);
}
.table th, .table td {
  padding: 12px var(--space-4);
  border-bottom: 1px solid var(--border-color);
  text-align: left;
  vertical-align: middle;
}
.table th {
  font-size: 12px;
  font-weight: 700;
  letter-spacing: .04em;
  text-transform: uppercase;
  color: var(--text-secondary);
  background: var(--bg-muted);
}
.table tbody tr:last-child td { border-bottom: 0; }
.table tbody tr:hover td { background: var(--row-hover); }
.table a { font-weight: 650; text-decoration: none; }
.table a:hover { text-decoration: underline; }

.badge {
  display: inline-block;
  padding: 3px 9px;
  border-radius: 999px;
  font-size: 12px;
  font-weight: 700;
  letter-spacing: .01em;
  line-height: 1.4;
  white-space: nowrap;
}
.badge-success { background: var(--badge-success-bg); color: var(--color-success); }
.badge-warning { background: var(--badge-warning-bg); color: var(--color-warning); }
.badge-danger { background: var(--badge-danger-bg); color: var(--color-danger); }
.badge-neutral { background: var(--badge-neutral-bg); color: var(--text-secondary); }
.badge-info { background: var(--badge-info-bg); color: var(--color-info); }

.alert {
  padding: var(--space-3) var(--space-4);
  border-radius: var(--radius-sm);
  margin-bottom: var(--space-4);
  border: 1px solid transparent;
  border-left-width: 3px;
}
.alert-success { background: var(--badge-success-bg); color: var(--color-success); border-color: var(--alert-success-border); }
.alert-danger { background: var(--badge-danger-bg); color: var(--color-danger); border-color: var(--alert-danger-border); }
.alert-warning { background: var(--badge-warning-bg); color: var(--color-warning); border-color: var(--alert-warning-border); }
.alert-info { background: var(--badge-info-bg); color: var(--color-info); border-color: var(--alert-info-border); }

.empty, .error-state {
  padding: var(--space-6);
  text-align: center;
  color: var(--text-secondary);
}
td.empty { background: transparent; }

.shell { min-height: 100vh; }

.sidebar {
  position: fixed;
  top: 0;
  left: 0;
  width: var(--sidebar-w);
  height: 100vh;
  background: linear-gradient(180deg, var(--sidebar-top) 0%, var(--bg-sidebar) 38%, var(--sidebar-bottom) 100%);
  color: var(--text-on-primary);
  padding: var(--space-5) var(--space-3) var(--space-4);
  overflow: auto;
  z-index: 20;
  box-shadow: 8px 0 28px rgba(8, 24, 36, .08);
}
.sidebar .brand {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  font-weight: 700;
  letter-spacing: -.02em;
  margin: 0 var(--space-2) var(--space-4);
  padding-bottom: var(--space-4);
  border-bottom: 1px solid rgba(255, 255, 255, .1);
}
.brand-mark {
  width: 36px;
  height: 36px;
  flex: 0 0 36px;
  border-radius: 11px;
  background:
    radial-gradient(circle at 30% 30%, rgba(255, 255, 255, .45), transparent 36%),
    linear-gradient(155deg, var(--mark-light) 0%, var(--mark-mid) 46%, var(--color-primary) 100%);
  box-shadow: inset 0 0 0 1px rgba(255, 255, 255, .22);
}
.nav { display: flex; flex-direction: column; gap: 2px; }
.sidebar a {
  color: rgba(255, 255, 255, .82);
  text-decoration: none;
  display: block;
  min-height: 40px;
  padding: 9px var(--space-3);
  border-radius: var(--radius-sm);
  font-weight: 550;
}
.sidebar a:hover { background: rgba(255, 255, 255, .08); color: var(--text-on-primary); }
.sidebar a.is-active {
  background: rgba(255, 255, 255, .12);
  color: var(--text-on-primary);
  box-shadow: inset 3px 0 0 var(--mark-light);
}

.header {
  position: fixed;
  top: 0;
  left: var(--sidebar-w);
  right: 0;
  height: var(--header-h);
  background: rgba(255, 255, 255, .9);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border-color);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-3);
  padding: 0 var(--space-5);
  z-index: 10;
}
.header-start { display: flex; align-items: center; gap: var(--space-3); min-width: 0; }
.page-title {
  font-size: 16px;
  font-weight: 680;
  letter-spacing: -.015em;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}
.header-actions { display: flex; align-items: center; gap: var(--space-3); }
.user-chip {
  max-width: 180px;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  font-size: var(--text-sm);
  font-weight: 650;
  color: var(--text-secondary);
  background: var(--bg-muted);
  border: 1px solid var(--border-color);
  border-radius: 999px;
  padding: 6px 10px;
}
.header-link {
  color: var(--text-secondary);
  text-decoration: none;
  font-size: var(--text-sm);
  font-weight: 700;
}
.header-link:hover { color: var(--color-primary); }
.menu-btn {
  display: none;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  padding: 0;
  background: transparent;
  border: 1px solid transparent;
  border-radius: var(--radius-sm);
  color: var(--text-primary);
  cursor: pointer;
}
.menu-btn:hover { background: var(--bg-muted); }
.menu-btn span,
.menu-btn span::before,
.menu-btn span::after {
  display: block;
  width: 16px;
  height: 2px;
  border-radius: 2px;
  background: currentColor;
  position: relative;
}
.menu-btn span::before,
.menu-btn span::after {
  content: "";
  position: absolute;
  left: 0;
}
.menu-btn span::before { top: -5px; }
.menu-btn span::after { top: 5px; }

.backdrop {
  position: fixed;
  inset: 0;
  background: rgba(8, 24, 36, .46);
  z-index: 19;
}
.backdrop[hidden] { display: none; }

.content {
  margin-left: var(--sidebar-w);
  padding: calc(var(--header-h) + var(--space-5)) var(--space-5) var(--space-6);
}

.login-wrap {
  min-height: 100vh;
  display: grid;
  place-items: center;
  padding: var(--space-5) var(--space-4);
}
.login-panel { width: min(420px, 100%); }
.login-brand {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  margin-bottom: var(--space-4);
  color: var(--color-primary);
  font-weight: 750;
  letter-spacing: -.02em;
  font-size: 18px;
}
.login-card { width: 100%; }
.login-card h1 { margin-bottom: var(--space-4); }
.login-card .btn { width: 100%; margin-top: var(--space-1); }
.login-demos { margin-top: var(--space-3); }
.login-demos p { margin: 0 0 var(--space-2); }
.login-demos form + form { margin-top: var(--space-2); }

.checkbox, .radio {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  min-height: 44px;
}
.toolbar {
  display: flex;
  gap: var(--space-3);
  align-items: center;
  justify-content: space-between;
  margin-bottom: var(--space-4);
  flex-wrap: wrap;
}
.toolbar h1 { margin: 0; }
.filters {
  display: flex;
  gap: var(--space-3);
  flex-wrap: wrap;
  align-items: flex-end;
  margin-bottom: var(--space-4);
  padding: var(--space-3);
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-sm);
}
.filters .input, .filters .select { width: auto; min-width: 160px; }
.breadcrumb { font-size: var(--text-sm); color: var(--text-secondary); margin-bottom: var(--space-3); }
.breadcrumb a { color: var(--text-secondary); text-decoration: none; }
.breadcrumb a:hover { color: var(--color-primary); }
.pagination { display: flex; gap: var(--space-2); margin-top: var(--space-4); flex-wrap: wrap; }
.tabs {
  display: flex;
  gap: var(--space-1);
  border-bottom: 1px solid var(--border-color);
  margin-bottom: var(--space-4);
  overflow-x: auto;
}
.tabs a {
  padding: var(--space-2) var(--space-3);
  text-decoration: none;
  color: var(--text-secondary);
  font-weight: 650;
  border-bottom: 2px solid transparent;
  white-space: nowrap;
}
.tabs a:hover { color: var(--color-primary); }
.tabs a.is-active { color: var(--color-primary); border-bottom-color: var(--color-accent); }
.modal {
  position: fixed;
  inset: 0;
  background: rgba(8, 24, 36, .46);
  display: grid;
  place-items: center;
  z-index: 30;
  padding: var(--space-4);
}
.modal[hidden] { display: none; }
.modal-card {
  width: min(480px, 100%);
  background: var(--bg-surface);
  border-radius: var(--radius-lg);
  padding: var(--space-5);
  box-shadow: var(--shadow-md);
}
.dropdown { position: relative; display: inline-block; }
.row-actions { display: flex; gap: var(--space-2); flex-wrap: wrap; align-items: center; }
.lesson-meta { color: var(--text-secondary); margin: calc(var(--space-2) * -1) 0 var(--space-4); }
.attendance-row {
  display: flex;
  justify-content: space-between;
  gap: var(--space-3);
  align-items: center;
  min-height: 44px;
  padding: var(--space-3) 0;
  border-bottom: 1px solid var(--border-color);
}
.attendance-row .person { font-weight: 650; }
.attendance-row .choices { display: flex; gap: var(--space-2); flex-wrap: wrap; justify-content: flex-end; }
.attendance-row .radio {
  margin: 0;
  min-height: 44px;
  padding: 0 var(--space-3);
  border: 1px solid var(--border-color);
  border-radius: 999px;
  background: var(--bg-surface);
  font-weight: 650;
}
.attendance-row .radio:hover { border-color: var(--border-hover); background: var(--bg-muted); }
.attendance-row .radio:has(:checked) {
  background: var(--color-primary);
  border-color: var(--color-primary);
  color: var(--text-on-primary);
}
.attendance-row .radio:has(:checked) input { accent-color: var(--text-on-primary); }
.action-bar { display: flex; justify-content: flex-end; margin-top: var(--space-4); }
.form-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: var(--space-4); }
.stack { display: flex; flex-direction: column; gap: var(--space-4); }
form.card { max-width: 960px; }
.card + .card,
form.card + form.card,
form.card + .card,
.card + form.card { margin-top: var(--space-4); }
.stats { display: grid; grid-template-columns: repeat(auto-fill, minmax(200px, 1fr)); gap: var(--space-4); }

@media (min-width: 768px) {
  .table-wrap {
    background: var(--bg-surface);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-sm);
  }
  .table-wrap .table th:first-child { border-top-left-radius: var(--radius-md); }
  .table-wrap .table th:last-child { border-top-right-radius: var(--radius-md); }
}

@media (max-width: 1023px) {
  .sidebar { transform: translateX(-105%); transition: transform .2s ease; }
  .sidebar.is-open { transform: none; }
  .header { left: 0; padding: 0 var(--space-3); }
  .content { margin-left: 0; }
  .menu-btn { display: inline-flex; }
}

@media (min-width: 1024px) {
  .backdrop { display: none; }
}

@media (max-width: 767px) {
  .content { padding: calc(var(--header-h) + var(--space-4)) var(--space-3) calc(var(--space-6) + 72px); }
  .user-chip { display: none; }
  .card { padding: var(--space-4); }
  .stat-value { font-size: 24px; }
  .table-cards thead { display: none; }
  .table-cards,
  .table-cards tbody { display: block; }
  .table-cards tr {
    display: block;
    background: var(--bg-surface);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    margin-bottom: var(--space-3);
    padding: var(--space-3) var(--space-4);
    box-shadow: var(--shadow-sm);
  }
  .table-cards td {
    display: block;
    border: 0;
    padding: var(--space-1) 0;
  }
  .table-cards tbody tr:hover td { background: transparent; }
  .attendance-row { align-items: stretch; flex-direction: column; }
  .attendance-row .choices { display: grid; grid-template-columns: repeat(auto-fit, minmax(120px, 1fr)); }
  .attendance-row .radio { justify-content: center; }
  .action-bar {
    position: fixed;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(255, 255, 255, .96);
    backdrop-filter: blur(10px);
    border-top: 1px solid var(--border-color);
    padding: var(--space-3);
    margin: 0;
    z-index: 15;
    box-shadow: 0 -8px 24px rgba(11, 32, 48, .08);
  }
  .action-bar .btn { width: 100%; }
}