:root {
  --board-font-sans: "Inter", "PingFang SC", "Microsoft YaHei", "Segoe UI",
    system-ui, -apple-system, sans-serif;
  --board-font-mono: "JetBrains Mono", "SF Mono", "Cascadia Code", "Consolas",
    ui-monospace, monospace;

  --board-radius-sm: 6px;
  --board-radius-md: 10px;
  --board-radius-lg: 14px;
  --board-radius-xl: 20px;

  --board-background: #f7f7fb;
  --board-foreground: #18181b;
  --board-card: #ffffff;
  --board-card-foreground: #18181b;
  --board-popover: #ffffff;
  --board-popover-foreground: #18181b;

  --board-primary: #4f46e5;
  --board-primary-foreground: #ffffff;
  --board-primary-soft: #eef2ff;
  --board-primary-soft-foreground: #4338ca;

  --board-muted: #f3f4f6;
  --board-muted-foreground: #71717a;

  --board-border: #e7e7ee;
  --board-input: #e7e7ee;
  --board-ring: #4f46e5;

  --board-surface-2: #f0f1f6;
  --board-surface-3: #e9eaf2;

  --board-state-success: #16a34a;
  --board-state-success-soft: #ecfdf5;
  --board-state-warning: #d97706;
  --board-state-warning-soft: #fffbeb;
  --board-state-error: #dc2626;
  --board-state-error-soft: #fef2f2;
  --board-state-info: #2563eb;
  --board-state-info-soft: #eff6ff;

  --board-shadow-sm: 0 1px 2px 0 rgba(15, 17, 38, 0.04);
  --board-shadow-md: 0 4px 14px -3px rgba(15, 17, 38, 0.08);
  --board-shadow-lg: 0 18px 40px -12px rgba(15, 17, 38, 0.18);
}

.dark {
  --board-background: #0b0b0f;
  --board-foreground: #f4f4f6;
  --board-card: #15151b;
  --board-card-foreground: #f4f4f6;
  --board-popover: #16161d;
  --board-popover-foreground: #f4f4f6;

  --board-primary: #6366f1;
  --board-primary-foreground: #ffffff;
  --board-primary-soft: #1e1b3a;
  --board-primary-soft-foreground: #c7d2fe;

  --board-muted: #1c1c24;
  --board-muted-foreground: #a1a1aa;

  --board-border: #26262f;
  --board-input: #2a2a34;
  --board-ring: #6366f1;

  --board-surface-2: #1a1a22;
  --board-surface-3: #20202a;

  --board-state-success: #22c55e;
  --board-state-success-soft: #0f2e1c;
  --board-state-warning: #f59e0b;
  --board-state-warning-soft: #2e2410;
  --board-state-error: #ef4444;
  --board-state-error-soft: #2e1414;
  --board-state-info: #3b82f6;
  --board-state-info-soft: #11203a;

  --board-shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.4);
  --board-shadow-md: 0 4px 14px -3px rgba(0, 0, 0, 0.5);
  --board-shadow-lg: 0 18px 40px -12px rgba(0, 0, 0, 0.65);
}

* {
  box-sizing: border-box;
}

html, body {
  height: 100%;
  margin: 0;
}

html {
  font-family: var(--board-font-sans);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--board-font-sans);
  background: var(--board-background);
  color: var(--board-foreground);
  line-height: 1.5;
}

[data-viewport-mode="app-shell"] {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.board-topbar {
  position: sticky;
  top: 0;
  z-index: 30;
  flex-shrink: 0;
  height: 64px;
  background: var(--board-card);
  border-bottom: 1px solid var(--board-border);
  display: flex;
  align-items: center;
}

[data-scroll-region="primary"] {
  flex: 1 1 auto;
  min-height: 0;
  overflow-y: auto;
  overflow-x: hidden;
}

.board-search {
  background: var(--board-muted);
  border: 1px solid transparent;
  border-radius: var(--board-radius-md);
  height: 38px;
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 0 12px;
  transition: border-color .15s ease, box-shadow .15s ease, background .15s ease;
}

.board-search:focus-within {
  background: var(--board-card);
  border-color: var(--board-primary);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--board-primary) 20%, transparent);
}

.board-search input {
  background: transparent;
  border: none;
  outline: none;
  flex: 1;
  min-width: 0;
  font-size: 14px;
  color: var(--board-foreground);
  font-family: inherit;
}

.board-search input::placeholder { color: var(--board-muted-foreground); }

.btn-primary {
  background: var(--board-primary);
  color: var(--board-primary-foreground);
  border-radius: var(--board-radius-md);
  height: 38px;
  padding: 0 16px;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 14px;
  font-weight: 500;
  border: none;
  cursor: pointer;
  transition: opacity .15s ease, transform .1s ease;
  font-family: inherit;
}

.btn-primary:hover { opacity: .92; }
.btn-primary:active { transform: scale(.98); }

.btn-ghost {
  background: transparent;
  color: var(--board-muted-foreground);
  border: 1px solid var(--board-border);
  border-radius: var(--board-radius-md);
  height: 38px;
  padding: 0 14px;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 14px;
  cursor: pointer;
  transition: background .15s ease, color .15s ease;
  font-family: inherit;
}

.btn-ghost:hover {
  background: var(--board-muted);
  color: var(--board-foreground);
}

.icon-btn {
  width: 36px;
  height: 36px;
  border-radius: var(--board-radius-md);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  background: transparent;
  border: 1px solid transparent;
  color: var(--board-muted-foreground);
  cursor: pointer;
  transition: all .15s ease;
}

.icon-btn:hover {
  background: var(--board-muted);
  color: var(--board-foreground);
  border-color: var(--board-border);
}

.filter-pill {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 12px;
  border-radius: 999px;
  font-size: 13px;
  font-weight: 500;
  white-space: nowrap;
  cursor: pointer;
  border: 1px solid transparent;
  transition: all .15s ease;
  background: var(--board-muted);
  color: var(--board-muted-foreground);
  font-family: inherit;
}

.filter-pill:hover { background: var(--board-surface-3); color: var(--board-foreground); }
.filter-pill.active {
  background: var(--board-primary);
  color: var(--board-primary-foreground);
}

.filter-pill .dot {
  width: 6px;
  height: 6px;
  border-radius: 999px;
  background: var(--board-state-warning);
}

.modal-overlay {
  position: fixed;
  inset: 0;
  z-index: 50;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(0,0,0,.4);
  backdrop-filter: blur(4px);
  -webkit-backdrop-filter: blur(4px);
}

.modal-overlay.hidden { display: none; }

.modal-card {
  background: var(--board-card);
  border: 1px solid var(--board-border);
  border-radius: var(--board-radius-lg);
  padding: 24px;
  width: 100%;
  max-width: 440px;
  box-shadow: var(--board-shadow-lg);
  margin: 16px;
}

.form-label {
  display: block;
  font-size: 13px;
  font-weight: 500;
  color: var(--board-foreground);
  margin-bottom: 6px;
}

.form-input, .form-textarea {
  width: 100%;
  background: var(--board-background);
  border: 1px solid var(--board-border);
  border-radius: var(--board-radius-md);
  padding: 9px 12px;
  font-size: 14px;
  color: var(--board-foreground);
  outline: none;
  transition: border-color .15s ease, box-shadow .15s ease;
  font-family: inherit;
}

.form-input:focus, .form-textarea:focus {
  border-color: var(--board-primary);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--board-primary) 20%, transparent);
}

.form-input.error {
  border-color: var(--board-state-error);
  animation: shake 0.5s ease-in-out;
}

@keyframes shake {
  0%, 100% { transform: translateX(0); }
  20%, 60% { transform: translateX(-4px); }
  40%, 80% { transform: translateX(4px); }
}

.form-textarea { resize: vertical; min-height: 60px; }

.icon-pick {
  width: 36px;
  height: 36px;
  border-radius: var(--board-radius-md);
  border: 1px solid var(--board-border);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  background: var(--board-background);
  color: var(--board-muted-foreground);
  cursor: pointer;
  transition: all .15s ease;
}

.icon-pick:hover {
  border-color: var(--board-primary);
  background: color-mix(in srgb, var(--board-primary) 5%, transparent);
  color: var(--board-primary);
}

.icon-pick.selected {
  border-color: var(--board-primary);
  background: color-mix(in srgb, var(--board-primary) 10%, transparent);
  color: var(--board-primary);
}

.category-grid {
  display: grid;
  gap: 16px;
  grid-template-columns: 1fr;
}

@media (min-width: 640px) { .category-grid { grid-template-columns: repeat(2, minmax(0,1fr)); gap: 20px; } }
@media (min-width: 1024px) { .category-grid { grid-template-columns: repeat(3, minmax(0,1fr)); } }
@media (min-width: 1280px) { .category-grid { grid-template-columns: repeat(4, minmax(0,1fr)); } }

.category-card {
  background: var(--board-card);
  border: 1px solid var(--board-border);
  border-radius: var(--board-radius-lg);
  position: relative;
  overflow: hidden;
  transition: border-color .18s ease, box-shadow .18s ease, transform .18s ease;
  cursor: pointer;
}

.category-card:hover {
  border-color: color-mix(in srgb, var(--board-primary) 50%, var(--board-border));
  box-shadow: 0 4px 14px -3px rgba(15,17,38,.06);
}

.dark .category-card:hover {
  box-shadow: 0 4px 14px -3px rgba(0,0,0,.35);
}

.add-category-card {
  background: transparent;
  border: 1px dashed var(--board-border);
  border-radius: var(--board-radius-lg);
  transition: all .18s ease;
  cursor: pointer;
}

.add-category-card:hover {
  border-color: var(--board-primary);
  background: color-mix(in srgb, var(--board-primary) 5%, transparent);
}

.stat-card {
  background: var(--board-card);
  border: 1px solid var(--board-border);
  border-radius: var(--board-radius-md);
  padding: 10px 14px;
  min-width: 110px;
  display: flex;
  align-items: center;
  gap: 10px;
  flex-shrink: 0;
}

.tag {
  display: inline-flex;
  align-items: center;
  font-size: 11px;
  padding: 2px 8px;
  border-radius: 999px;
  line-height: 1.6;
}

.tag-primary { background: color-mix(in srgb, var(--board-primary) 10%, transparent); color: var(--board-primary); }
.tag-warning { background: var(--board-state-warning-soft); color: var(--board-state-warning); }
.tag-advanced { background: color-mix(in srgb, #8b5cf6 12%, transparent); color: #7c3aed; }

.accent-strip {
  position: absolute;
  left: 0;
  top: 16px;
  bottom: 16px;
  width: 3px;
  background: var(--board-primary);
  border-radius: 0 999px 999px 0;
}

.logo-block {
  width: 32px;
  height: 32px;
  border-radius: var(--board-radius-md);
  background: var(--board-primary);
  color: var(--board-primary-foreground);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.icon-tile {
  width: 40px;
  height: 40px;
  border-radius: var(--board-radius-md);
  background: var(--board-primary-soft);
  color: var(--board-primary);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.dark .icon-tile { color: var(--board-primary-soft-foreground); }

.line-clamp-2 {
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

kbd {
  font-family: var(--board-font-mono);
  font-size: 11px;
  padding: 2px 6px;
  border-radius: 4px;
  background: var(--board-background);
  color: var(--board-muted-foreground);
  border: 1px solid var(--board-border);
  line-height: 1.4;
}

@media (max-width: 639px) {
  kbd.hidden-sm { display: none; }
}

.no-scrollbar::-webkit-scrollbar { display: none; }
.no-scrollbar { -ms-overflow-style: none; scrollbar-width: none; }



code {
  font-family: var(--board-font-mono);
  font-size: 0.875em;
  background: var(--board-muted);
  color: var(--board-primary);
  padding: 2px 6px;
  border-radius: 4px;
}

.toast {
  position: fixed;
  bottom: 24px;
  right: 24px;
  z-index: 100;
  padding: 12px 20px;
  border-radius: var(--board-radius-md);
  font-size: 14px;
  font-weight: 500;
  color: white;
  box-shadow: var(--board-shadow-lg);
  display: flex;
  align-items: center;
  gap: 8px;
  animation: toast-in 0.3s ease-out;
  max-width: calc(100vw - 48px);
}

.toast.success {
  background: var(--board-state-success);
}

.toast.error {
  background: var(--board-state-error);
}

.toast.info {
  background: var(--board-foreground);
}

@keyframes toast-in {
  from {
    opacity: 0;
    transform: translateY(16px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

::-webkit-scrollbar {
  width: 8px;
  height: 8px;
}

::-webkit-scrollbar-track {
  background: transparent;
}

::-webkit-scrollbar-thumb {
  background: var(--board-border);
  border-radius: 999px;
}

::-webkit-scrollbar-thumb:hover {
  background: var(--board-muted-foreground);
}

button, a, input, textarea {
  transition: all .15s ease;
}

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

a:hover {
  text-decoration: underline;
}

.note-card {
  background: var(--board-card);
  border: 1px solid var(--board-border);
  border-radius: var(--board-radius-xl);
  overflow: hidden;
  transition: border-color .15s ease, box-shadow .15s ease;
}

.note-card:hover {
  border-color: color-mix(in srgb, var(--board-primary) 30%, var(--board-border));
}

.mastery-dots {
  display: inline-flex;
  align-items: center;
  gap: 3px;
}

.mastery-dots:hover .mastery-dot {
  opacity: 0.8;
}

.mastery-dot {
  width: 8px;
  height: 8px;
  border-radius: 9999px;
  transition: all 0.15s ease;
  cursor: pointer;
}

.mastery-dot.filled {
  background: var(--board-primary);
}

.mastery-dot.empty {
  border: 1px solid color-mix(in srgb, var(--board-muted-foreground) 30%, transparent);
  background: transparent;
}

.mastery-dot:hover {
  transform: scale(1.2);
}

.action-btn {
  width: 28px;
  height: 28px;
  border-radius: var(--board-radius-md);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  background: transparent;
  border: none;
  color: var(--board-muted-foreground);
  cursor: pointer;
  transition: all .15s ease;
}

.action-btn:hover {
  background: var(--board-muted);
  color: var(--board-foreground);
}

.delete-note-btn:hover {
  color: var(--board-state-error) !important;
  background: var(--board-state-error-soft) !important;
}

.add-row {
  width: 100%;
  border: 2px dashed var(--board-border);
  border-radius: var(--board-radius-xl);
  padding: 14px 16px;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  color: var(--board-muted-foreground);
  cursor: pointer;
  transition: all .15s ease;
  font-size: 14px;
  background: transparent;
  font-family: inherit;
}

.add-row:hover {
  border-color: var(--board-primary);
  color: var(--board-primary);
  background: color-mix(in srgb, var(--board-primary) 5%, transparent);
}

.tag-pill {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  font-size: 11px;
  font-weight: 500;
  padding: 3px 10px;
  border-radius: 9999px;
  background: var(--board-muted);
  color: var(--board-muted-foreground);
}

.tag-pill.tag-primary {
  background: color-mix(in srgb, var(--board-primary) 10%, transparent);
  color: var(--board-primary);
}

.tag-pill.tag-warning {
  background: var(--board-state-warning-soft);
  color: var(--board-state-warning);
}

.tag-pill.tag-hot {
  background: var(--board-state-error-soft);
  color: var(--board-state-error);
}

.tag-pill.tag-hand {
  background: var(--board-state-success-soft);
  color: var(--board-state-success);
}

.tag-pill.tag-basic {
  background: var(--board-state-info-soft);
  color: var(--board-state-info);
}

.sort-dropdown {
  background: var(--board-card);
  border: 1px solid var(--board-border);
  border-radius: var(--board-radius-md);
  box-shadow: var(--board-shadow-lg);
  padding: 4px 0;
  min-width: 140px;
}

.category-more-dropdown {
  background: var(--board-card);
  border: 1px solid var(--board-border);
  border-radius: var(--board-radius-md);
  box-shadow: var(--board-shadow-lg);
  padding: 4px 0;
  min-width: 120px;
}

.dropdown-item {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 8px 14px;
  font-size: 13px;
  color: var(--board-foreground);
  cursor: pointer;
  transition: background .15s ease;
  width: 100%;
  text-align: left;
  border: none;
  background: transparent;
  font-family: inherit;
}

.dropdown-item:hover {
  background: var(--board-muted);
}

.dropdown-item.active {
  color: var(--board-primary);
  background: color-mix(in srgb, var(--board-primary) 5%, transparent);
}

.dropdown-item.text-danger {
  color: var(--board-state-error);
}

.dropdown-item.text-danger:hover {
  background: var(--board-state-error-soft);
}

.tag-toggle {
  display: inline-flex;
  align-items: center;
  padding: 5px 12px;
  border-radius: 9999px;
  font-size: 12px;
  border: 1px solid var(--board-border);
  background: transparent;
  color: var(--board-muted-foreground);
  cursor: pointer;
  transition: all .15s ease;
  font-family: inherit;
}

.tag-toggle:hover {
  border-color: var(--board-primary);
  color: var(--board-primary);
}

.tag-toggle.selected {
  background: color-mix(in srgb, var(--board-primary) 10%, transparent);
  border-color: var(--board-primary);
  color: var(--board-primary);
}

.tag-remove {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 14px;
  height: 14px;
  border-radius: 50%;
  margin-left: 4px;
  font-size: 12px;
  line-height: 1;
  opacity: 0;
  transition: opacity .15s ease, background .15s ease;
  cursor: pointer;
}

.tag-toggle:hover .tag-remove {
  opacity: 0.7;
}

.tag-remove:hover {
  opacity: 1 !important;
  background: color-mix(in srgb, var(--board-foreground) 15%, transparent);
}

.tag-add-btn {
  padding: 5px 8px !important;
  gap: 0;
}

.tag-add-btn:hover {
  background: color-mix(in srgb, var(--board-primary) 8%, transparent);
  border-color: var(--board-primary);
  color: var(--board-primary);
}

.tag-add-input {
  display: inline-flex;
  align-items: center;
  padding: 4px 10px;
  border-radius: 9999px;
  font-size: 12px;
  border: 1px dashed var(--board-primary);
  background: color-mix(in srgb, var(--board-primary) 5%, transparent);
  color: var(--board-foreground);
  outline: none;
  width: 90px;
  height: 26px;
}

.tag-add-input::placeholder {
  color: var(--board-muted-foreground);
}

.tag-add-input:focus {
  border-style: solid;
}

.confirm-modal {
  max-width: 380px;
}

.btn-danger {
  background: var(--board-state-error);
}

.btn-danger:hover {
  background: color-mix(in srgb, var(--board-state-error) 85%, black);
}

.view-mode, .edit-mode {
  width: 100%;
}

.note-edit-textarea {
  font-family: inherit;
  font-size: 14px;
  line-height: 1.6;
}

.category-more-btn {
  display: flex !important;
}

.empty-state {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 60px 20px;
  text-align: center;
  grid-column: 1 / -1;
}

.empty-state-icon {
  opacity: 0.6;
}

.hidden {
  display: none !important;
}

@media (max-width: 639px) {
  .board-topbar {
    padding: 0 12px !important;
    height: 56px;
  }

  .board-topbar .logo-block {
    width: 28px;
    height: 28px;
  }

  .board-search {
    margin: 0 8px !important;
  }

  .category-card {
    padding: 16px !important;
  }

  .note-card > div > div:last-child {
    padding: 16px !important;
  }

  .action-btn-visible {
    opacity: 1 !important;
    display: inline-flex !important;
  }

  .category-more-btn {
    opacity: 1 !important;
  }

  .stat-card {
    padding: 8px 12px;
    min-width: 100px;
  }

  .stat-card .text-lg {
    font-size: 16px;
  }

  main > div {
    padding-left: 12px !important;
    padding-right: 12px !important;
    padding-top: 16px !important;
  }

  h1 {
    font-size: 22px !important;
  }

  .detail-category-header {
    gap: 12px !important;
  }

  .detail-category-icon {
    width: 48px !important;
    height: 48px !important;
  }

  .detail-category-icon i {
    width: 22px !important;
    height: 22px !important;
  }

  .detail-category-title {
    font-size: 20px !important;
  }

  .detail-category-meta {
    gap: 12px !important;
    margin-top: 12px !important;
  }

  .note-card-content {
    padding: 16px !important;
  }
}

@media (min-width: 640px) {
  .hidden-sm {
    display: block;
  }
}