/* === Material Design 3 风格 === */

/* Google Material Symbols 字体 */
@import url('https://fonts.googleapis.com/css2?family=Noto+Sans+SC:wght@400;500;600;700&display=swap');

:root {
  /* M3 色彩系统 */
  --md-primary: #1a73e8;
  --md-primary-container: #d3e3fd;
  --md-on-primary: #ffffff;
  --md-on-primary-container: #041e49;
  --md-secondary: #5f6368;
  --md-secondary-container: #e8eaed;
  --md-tertiary: #1e8e3e;
  --md-error: #d93025;
  --md-warning: #f9ab00;

  /* M3 表面 - Light */
  --md-surface: #ffffff;
  --md-surface-dim: #f8f9fa;
  --md-surface-container-lowest: #ffffff;
  --md-surface-container-low: #f1f3f4;
  --md-surface-container: #e8eaed;
  --md-surface-container-high: #dadce0;
  --md-surface-variant: #e8eaed;
  --md-on-surface: #202124;
  --md-on-surface-variant: #5f6368;
  --md-outline: #dadce0;
  --md-outline-variant: #e8eaed;
  --md-background: #f8f9fa;

  /* M3 状态层 */
  --md-state-hover: rgba(26, 115, 232, 0.08);
  --md-state-focus: rgba(26, 115, 232, 0.12);
  --md-state-pressed: rgba(26, 115, 232, 0.16);

  /* M3 海拔阴影 */
  --md-elevation-1: 0 1px 2px rgba(0,0,0,0.3), 0 1px 3px 1px rgba(0,0,0,0.15);
  --md-elevation-2: 0 1px 2px rgba(0,0,0,0.3), 0 2px 6px 2px rgba(0,0,0,0.15);
  --md-elevation-3: 0 4px 8px 3px rgba(0,0,0,0.15), 0 1px 3px rgba(0,0,0,0.3);

  /* M3 形状 */
  --md-shape-xs: 4px;
  --md-shape-sm: 8px;
  --md-shape-md: 12px;
  --md-shape-lg: 16px;
  --md-shape-xl: 28px;
  --md-shape-full: 9999px;

  /* M3 动效 */
  --md-motion-standard: 300ms cubic-bezier(0.2, 0, 0, 1);
  --md-motion-emphasized: 500ms cubic-bezier(0.2, 0, 0, 1);

  /* 字体 */
  --md-font: 'Noto Sans SC', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
}

[data-theme="dark"] {
  --md-primary: #8ab4f8;
  --md-primary-container: #004a77;
  --md-on-primary: #003258;
  --md-on-primary-container: #d3e3fd;
  --md-secondary: #9aa0a6;
  --md-secondary-container: #3c4043;
  --md-tertiary: #81c995;
  --md-error: #f28b82;
  --md-warning: #fdd663;

  --md-surface: #1f1f1f;
  --md-surface-dim: #141414;
  --md-surface-container-lowest: #0e0e0e;
  --md-surface-container-low: #1c1c1c;
  --md-surface-container: #252525;
  --md-surface-container-high: #2f2f2f;
  --md-surface-variant: #3c4043;
  --md-on-surface: #e8eaed;
  --md-on-surface-variant: #9aa0a6;
  --md-outline: #5f6368;
  --md-outline-variant: #3c4043;
  --md-background: #141414;

  --md-state-hover: rgba(138, 180, 248, 0.08);
  --md-state-focus: rgba(138, 180, 248, 0.12);
  --md-state-pressed: rgba(138, 180, 248, 0.16);

  --md-elevation-1: 0 1px 3px 1px rgba(0,0,0,0.4), 0 1px 2px rgba(0,0,0,0.6);
  --md-elevation-2: 0 2px 6px 2px rgba(0,0,0,0.4), 0 1px 2px rgba(0,0,0,0.6);
  --md-elevation-3: 0 4px 8px 3px rgba(0,0,0,0.4), 0 1px 3px rgba(0,0,0,0.6);
}

/* === Base === */
*, *::before, *::after { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }

body {
  font-family: var(--md-font);
  color: var(--md-on-surface);
  background: var(--md-background);
  font-size: 14px;
  line-height: 1.5;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  -webkit-font-smoothing: antialiased;
  transition: background-color var(--md-motion-standard), color var(--md-motion-standard);
}

::selection { background: var(--md-primary); color: var(--md-on-primary); }

/* === App Bar (Header) === */
.app-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: var(--md-surface);
  border-bottom: 1px solid var(--md-outline-variant);
  transition: background-color var(--md-motion-standard);
}

.app-header-inner {
  max-width: 1200px;
  margin: 0 auto;
  padding: 12px 16px;
  display: flex;
  align-items: center;
  gap: 12px;
  flex-wrap: wrap;
}

.app-title {
  margin: 0;
  font-size: 18px;
  font-weight: 500;
  letter-spacing: 0;
  display: flex;
  align-items: center;
  gap: 12px;
  color: var(--md-on-surface);
}

.app-title-icon {
  width: 36px;
  height: 36px;
  border-radius: var(--md-shape-full);
  background: var(--md-primary);
  color: var(--md-on-primary);
  display: grid;
  place-items: center;
}

.header-spacer { flex: 1; }

.header-controls {
  display: flex;
  align-items: center;
  gap: 4px;
}

/* Theme toggle */
[data-theme="light"] .icon-moon { display: none; }
[data-theme="dark"] .icon-sun { display: none; }

/* === M3 Buttons === */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 10px 16px;
  font-size: 14px;
  font-weight: 500;
  font-family: inherit;
  color: var(--md-primary);
  background: transparent;
  border: none;
  border-radius: var(--md-shape-full);
  cursor: pointer;
  transition: background-color var(--md-motion-standard), box-shadow var(--md-motion-standard);
  user-select: none;
  white-space: nowrap;
  line-height: 1;
  position: relative;
  overflow: hidden;
  min-height: 40px;
}

.btn::after {
  content: '';
  position: absolute;
  inset: 0;
  border-radius: inherit;
  transition: background-color var(--md-motion-standard);
}

.btn:hover::after { background: var(--md-state-hover); }
.btn:focus-visible::after { background: var(--md-state-focus); }
.btn:active::after { background: var(--md-state-pressed); }

.btn:focus-visible {
  outline: 2px solid var(--md-primary);
  outline-offset: 2px;
}

.btn-primary {
  background: var(--md-primary);
  color: var(--md-on-primary);
  box-shadow: var(--md-elevation-1);
}

.btn-primary:hover { box-shadow: var(--md-elevation-2); }
.btn-primary:hover::after { background: rgba(255,255,255,0.08); }
.btn-primary:active::after { background: rgba(255,255,255,0.16); }

.btn-ghost {
  color: var(--md-on-surface-variant);
}

.btn-ghost:hover::after { background: rgba(0,0,0,0.04); }
[data-theme="dark"] .btn-ghost:hover::after { background: rgba(255,255,255,0.04); }

.btn-danger { color: var(--md-error); }
.btn-danger:hover::after { background: rgba(217, 48, 37, 0.08); }

.btn-icon-only {
  padding: 8px;
  width: 40px;
  height: 40px;
  border-radius: var(--md-shape-full);
}

.btn-sm {
  padding: 6px 12px;
  font-size: 13px;
  min-height: 32px;
}

/* === M3 Cards === */
.student-info-card {
  background: var(--md-surface-container-low);
  border: none;
  border-radius: var(--md-shape-lg);
  padding: 20px 24px;
  margin-bottom: 16px;
  transition: background-color var(--md-motion-standard);
}

.info-row {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 16px;
}

.info-field {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.info-field label {
  font-size: 12px;
  font-weight: 500;
  color: var(--md-on-surface-variant);
  letter-spacing: 0.5px;
  text-transform: uppercase;
}

.info-field input {
  font: inherit;
  font-size: 14px;
  padding: 12px 16px;
  border: 1px solid var(--md-outline);
  border-radius: var(--md-shape-xs);
  background: transparent;
  color: var(--md-on-surface);
  transition: border-color var(--md-motion-standard), box-shadow var(--md-motion-standard);
  outline: none;
}

.info-field input:focus {
  border-color: var(--md-primary);
  border-width: 2px;
  padding: 11px 15px;
  box-shadow: none;
}

.info-field input::placeholder {
  color: var(--md-on-surface-variant);
}

/* === Stats cards === */
.stats-cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 12px;
  margin-bottom: 16px;
}

.stat-card {
  background: var(--md-surface-container-low);
  border: none;
  border-radius: var(--md-shape-lg);
  padding: 16px 20px;
  display: flex;
  align-items: center;
  gap: 16px;
  transition: box-shadow var(--md-motion-standard), background-color var(--md-motion-standard);
}

.stat-card:hover {
  box-shadow: var(--md-elevation-1);
}

.stat-icon {
  width: 40px;
  height: 40px;
  border-radius: var(--md-shape-full);
  display: grid;
  place-items: center;
  flex-shrink: 0;
}

.stat-icon-total { background: var(--md-primary-container); color: var(--md-on-primary-container); }
.stat-icon-avg { background: rgba(30, 142, 62, 0.12); color: var(--md-tertiary); }
.stat-icon-best { background: rgba(249, 171, 0, 0.12); color: var(--md-warning); }
.stat-icon-trend { background: var(--md-secondary-container); color: var(--md-secondary); }

.stat-content { min-width: 0; }

.stat-label {
  font-size: 12px;
  color: var(--md-on-surface-variant);
  font-weight: 500;
  margin-bottom: 4px;
  letter-spacing: 0.4px;
}

.stat-value {
  font-size: 22px;
  font-weight: 600;
  color: var(--md-on-surface);
  line-height: 1.2;
  font-variant-numeric: tabular-nums;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

/* === M3 Section (Surface) === */
.section {
  background: var(--md-surface);
  border: none;
  border-radius: var(--md-shape-lg);
  padding: 20px 24px;
  margin-bottom: 16px;
  box-shadow: var(--md-elevation-1);
  transition: background-color var(--md-motion-standard);
}

.section-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 16px;
  gap: 12px;
  flex-wrap: wrap;
}

.section-title {
  margin: 0;
  font-size: 16px;
  font-weight: 500;
  display: flex;
  align-items: center;
  gap: 8px;
  color: var(--md-on-surface);
}

.section-title-dot {
  width: 8px;
  height: 8px;
  border-radius: var(--md-shape-full);
  background: var(--md-primary);
}

.section-hint {
  font-size: 12px;
  color: var(--md-on-surface-variant);
}

/* === M3 Tabs (Grade Tabs) === */
.grade-tabs-wrap {
  margin-bottom: 12px;
}

.grade-tabs {
  display: flex;
  gap: 0;
  background: transparent;
  border-bottom: 1px solid var(--md-outline-variant);
  overflow-x: auto;
  scrollbar-width: none;
  padding: 0;
  border-radius: 0;
}

.grade-tabs::-webkit-scrollbar { display: none; }

.grade-tab {
  padding: 12px 16px;
  font: inherit;
  font-size: 14px;
  font-weight: 500;
  color: var(--md-on-surface-variant);
  background: transparent;
  border: none;
  border-bottom: 3px solid transparent;
  cursor: pointer;
  transition: all var(--md-motion-standard);
  text-align: center;
  white-space: nowrap;
  flex-shrink: 0;
  position: relative;
}

.grade-tab:hover {
  color: var(--md-on-surface);
  background: var(--md-state-hover);
}

.grade-tab.active {
  color: var(--md-primary);
  border-bottom-color: var(--md-primary);
  font-weight: 600;
  background: transparent;
  box-shadow: none;
}

/* === M3 Chips (Semester Tabs) === */
.semester-tabs {
  display: flex;
  gap: 8px;
  margin-bottom: 16px;
  overflow-x: auto;
  padding-bottom: 4px;
  scrollbar-width: none;
}

.semester-tabs::-webkit-scrollbar { display: none; }

.semester-btn {
  padding: 8px 16px;
  font: inherit;
  font-size: 14px;
  font-weight: 500;
  color: var(--md-on-surface-variant);
  background: var(--md-surface-container-low);
  border: 1px solid var(--md-outline);
  border-radius: var(--md-shape-sm);
  cursor: pointer;
  white-space: nowrap;
  transition: all var(--md-motion-standard);
}

.semester-btn:hover {
  background: var(--md-state-hover);
  border-color: var(--md-on-surface-variant);
}

.semester-btn.active {
  background: var(--md-primary-container);
  color: var(--md-on-primary-container);
  border-color: transparent;
  font-weight: 600;
}

.semester-btn.has-data { position: relative; }

.semester-btn.has-data::after {
  content: '';
  position: absolute;
  top: 6px;
  right: 6px;
  width: 6px;
  height: 6px;
  border-radius: var(--md-shape-full);
  background: var(--md-tertiary);
}

.semester-btn.active.has-data::after {
  background: var(--md-on-primary-container);
}

/* === Student Switcher === */
.student-switcher {
  margin-bottom: 12px;
}

.student-switcher-inner {
  display: flex;
  align-items: center;
  gap: 12px;
  flex-wrap: wrap;
}

.student-list {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  flex: 1;
  min-width: 0;
}

.student-chip {
  padding: 8px 16px;
  font: inherit;
  font-size: 14px;
  font-weight: 500;
  color: var(--md-on-surface-variant);
  background: var(--md-surface-container-low);
  border: 1px solid var(--md-outline);
  border-radius: var(--md-shape-sm);
  cursor: pointer;
  transition: all var(--md-motion-standard);
  white-space: nowrap;
  max-width: 140px;
  overflow: hidden;
  text-overflow: ellipsis;
}

.student-chip:hover {
  background: var(--md-state-hover);
  border-color: var(--md-primary);
}

.student-chip.active {
  background: var(--md-primary-container);
  color: var(--md-on-primary-container);
  border-color: transparent;
  font-weight: 600;
}

.student-actions {
  display: flex;
  gap: 8px;
  align-items: center;
  flex-shrink: 0;
}

/* === M3 Data Table === */
.grade-table-wrap {
  overflow-x: auto;
  margin: 0 -8px;
  padding: 0 8px 4px;
}

.grade-grid {
  width: 100%;
  border-collapse: separate;
  border-spacing: 0;
  font-size: 14px;
  min-width: 720px;
}

.grade-grid th,
.grade-grid td {
  text-align: center;
  padding: 12px 16px;
  border-bottom: 1px solid var(--md-outline-variant);
  vertical-align: middle;
}

.grade-grid thead th {
  background: var(--md-surface-container-low);
  color: var(--md-on-surface-variant);
  font-weight: 500;
  font-size: 12px;
  letter-spacing: 0.5px;
  white-space: nowrap;
  text-transform: uppercase;
}

.grade-grid thead th:first-child {
  border-top-left-radius: var(--md-shape-sm);
  text-align: left;
  padding-left: 16px;
}

.grade-grid thead th:last-child {
  border-top-right-radius: var(--md-shape-sm);
}

.grade-grid tbody tr {
  transition: background-color var(--md-motion-standard);
}

.grade-grid tbody tr:hover {
  background: var(--md-state-hover);
}

.grade-grid tbody tr:last-child td {
  border-bottom: none;
}

.grade-grid .subject-cell {
  text-align: left;
  padding-left: 16px;
  font-weight: 500;
  color: var(--md-on-surface);
  white-space: nowrap;
}

.grade-grid .subject-cap {
  margin-left: 6px;
  color: var(--md-on-surface-variant);
  font-weight: 400;
  font-size: 12px;
}

.grade-grid .subject-max-btn {
  cursor: pointer;
  padding: 2px 6px;
  border-radius: var(--md-shape-xs);
  transition: all var(--md-motion-standard);
}

.grade-grid .subject-max-btn:hover {
  background: var(--md-state-focus);
  color: var(--md-primary);
}

.grade-grid td.editable {
  cursor: pointer;
  font-variant-numeric: tabular-nums;
  font-weight: 500;
  position: relative;
  border-radius: var(--md-shape-xs);
  transition: all var(--md-motion-standard);
}

.grade-grid td.editable:hover {
  background: var(--md-primary);
  color: var(--md-on-primary);
}

.grade-grid td.editable.empty {
  color: var(--md-on-surface-variant);
  font-weight: 400;
}

.grade-grid td.editable.empty:hover { color: var(--md-on-primary); }

/* M3 Score colors */
.grade-grid td.g-excellent { color: var(--md-primary); font-weight: 600; }
.grade-grid td.g-good { color: var(--md-tertiary); }
.grade-grid td.g-mid { color: var(--md-warning); }
.grade-grid td.g-low { color: var(--md-error); }

.grade-grid td.editable.g-excellent:hover,
.grade-grid td.editable.g-good:hover,
.grade-grid td.editable.g-mid:hover,
.grade-grid td.editable.g-low:hover { color: var(--md-on-primary); }

.grade-grid td.aggregate {
  background: var(--md-surface-container-low);
  font-weight: 600;
  color: var(--md-on-surface);
  font-variant-numeric: tabular-nums;
}

.grade-grid tfoot td,
.grade-grid tfoot th {
  background: var(--md-surface-container-low);
  font-weight: 600;
  border-bottom: none;
  border-top: 2px solid var(--md-outline);
}

.grade-grid tfoot th {
  text-align: left;
  padding-left: 16px;
}

/* Cell input - M3 text field */
.cell-input {
  width: 100%;
  max-width: 70px;
  padding: 8px 12px;
  font: inherit;
  font-weight: 500;
  text-align: center;
  border: 2px solid var(--md-primary);
  border-radius: var(--md-shape-xs);
  background: var(--md-surface);
  color: var(--md-on-surface);
  outline: none;
  font-variant-numeric: tabular-nums;
  -moz-appearance: textfield;
}

.cell-input::-webkit-outer-spin-button,
.cell-input::-webkit-inner-spin-button { -webkit-appearance: none; margin: 0; }

/* === M3 Select === */
.select-inline-wrap { display: inline-flex; align-items: center; }

.select-inline {
  appearance: none;
  font: inherit;
  font-size: 14px;
  font-weight: 500;
  color: var(--md-on-surface);
  background: var(--md-surface-container-low);
  border: 1px solid var(--md-outline);
  border-radius: var(--md-shape-sm);
  padding: 8px 32px 8px 12px;
  cursor: pointer;
  transition: border-color var(--md-motion-standard);
  background-image: url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' width='10' height='6' viewBox='0 0 10 6'><path fill='none' stroke='%235f6368' stroke-width='1.5' stroke-linecap='round' stroke-linejoin='round' d='M1 1l4 4 4-4'/></svg>");
  background-repeat: no-repeat;
  background-position: right 10px center;
}

.select-inline:hover { border-color: var(--md-on-surface); }
.select-inline:focus { outline: 2px solid var(--md-primary); outline-offset: -1px; border-color: var(--md-primary); }

/* === Chart === */
.chart-section { }

.chart-filters {
  display: flex;
  gap: 8px;
  align-items: center;
  flex-wrap: wrap;
}

.chart-container {
  width: 100%;
  height: 280px;
  position: relative;
}

#trendChart {
  width: 100%;
  height: 100%;
  display: block;
  border-radius: var(--md-shape-sm);
}

.chart-hint {
  margin: 12px 0 0;
  color: var(--md-on-surface-variant);
  font-size: 12px;
}

/* === M3 Snackbar (Toast) === */
#toastRoot {
  position: fixed;
  bottom: 24px;
  left: 50%;
  transform: translateX(-50%);
  z-index: 300;
  display: flex;
  flex-direction: column;
  gap: 8px;
  pointer-events: none;
  max-width: calc(100vw - 48px);
}

.toast {
  padding: 14px 24px;
  background: var(--md-on-surface);
  color: var(--md-surface);
  border-radius: var(--md-shape-xs);
  font-size: 14px;
  font-weight: 500;
  box-shadow: var(--md-elevation-3);
  opacity: 0;
  transform: translateY(16px);
  transition: opacity 200ms ease, transform 200ms ease;
  pointer-events: auto;
  max-width: 400px;
  text-align: center;
}

.toast.show { opacity: 1; transform: translateY(0); }
.toast-success { background: var(--md-tertiary); color: white; }
.toast-error { background: var(--md-error); color: white; }

/* === Main === */
main {
  flex: 1;
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 24px 16px 64px;
}

/* === Responsive === */
@media (max-width: 768px) {
  .app-header-inner { padding: 8px 12px; }
  .app-title { font-size: 16px; }
  .app-title-icon { width: 32px; height: 32px; }
  .app-title-icon svg { width: 16px; height: 16px; }

  main { padding: 16px 12px 48px; }

  .student-info-card { padding: 16px; border-radius: var(--md-shape-md); }
  .info-row { grid-template-columns: 1fr; gap: 12px; }

  .stats-cards { grid-template-columns: repeat(2, 1fr); gap: 8px; }
  .stat-card { padding: 12px 14px; border-radius: var(--md-shape-md); }
  .stat-value { font-size: 18px; }
  .stat-icon { width: 36px; height: 36px; }

  .section { padding: 16px; border-radius: var(--md-shape-md); }

  .grade-tab { padding: 10px 12px; font-size: 13px; }

  .chart-container { height: 220px; }

  .header-controls .btn-label { display: none; }
}

@media (max-width: 480px) {
  .stats-cards { grid-template-columns: 1fr 1fr; gap: 8px; }
  .stat-card { gap: 10px; padding: 10px 12px; }
  .stat-icon { width: 32px; height: 32px; }
  .stat-icon svg { width: 15px; height: 15px; }
  .stat-value { font-size: 16px; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    transition-duration: 0.01ms !important;
    animation-duration: 0.01ms !important;
  }
}