:root {
  --sidebar-bg: #0f1b2d;
  --sidebar-bg-hover: #16243a;
  --sidebar-fg: #c5cbd6;
  --sidebar-fg-strong: #ffffff;
  --sidebar-fg-muted: #8a94a6;
  --sidebar-w: 260px;
  --sidebar-w-collapsed: 64px;
  --brand: #f5a623;
  --accent: #4f7cff;
  --accent-contrast: #ffffff;
  --accent-soft: #e8eeff;
  --badge: #ff4d6d;
  --content-bg: #f3f4f7;
  --surface: #ffffff;
  --border: #e6e8ee;
  --text: #1f2633;
  --text-muted: #6b7385;
  --overlay: rgba(15, 27, 45, 0.5);
  --topbar-h: 64px;
  --radius: 8px;
  --space-1: 4px;
  --space-2: 8px;
  --space-3: 12px;
  --space-4: 16px;
  --space-5: 24px;
  --space-6: 32px;
  --shadow-card: 0 1px 2px rgba(16, 24, 40, 0.06);
  --shadow-flyout: 4px 4px 16px rgba(0, 0, 0, 0.25);
  --transition: 200ms ease;
  --z-topbar: 10;
  --z-overlay: 20;
  --z-sidebar: 30;
  --z-flyout: 40;
  --font-sans: system-ui, -apple-system, "Segoe UI", "Noto Sans TC", "Microsoft JhengHei", sans-serif;
}

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

body {
  margin: 0;
  font-family: var(--font-sans);
  color: var(--text);
  background: var(--content-bg);
  -webkit-font-smoothing: antialiased;
}

a {
  color: inherit;
}

.app-shell__main {
  margin-left: var(--sidebar-w);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  transition: margin-left var(--transition);
}

.app-shell--collapsed .app-shell__main {
  margin-left: var(--sidebar-w-collapsed);
}

.app-shell__content {
  flex: 1;
  padding: var(--space-5);
}

.app-shell__overlay {
  display: none;
}

@media (max-width: 767px) {
  .app-shell__main,
  .app-shell--collapsed .app-shell__main {
    margin-left: 0;
  }
  .app-shell__content {
    padding: var(--space-4);
  }
  .app-shell--drawer-open .app-shell__overlay {
    display: block;
    position: fixed;
    inset: 0;
    background: var(--overlay);
    z-index: var(--z-overlay);
  }
}
.sidebar {
  position: fixed;
  inset: 0 auto 0 0;
  width: var(--sidebar-w);
  display: flex;
  flex-direction: column;
  background: var(--sidebar-bg);
  color: var(--sidebar-fg);
  z-index: var(--z-sidebar);
  transition: width var(--transition), transform var(--transition);
}

.sidebar__brand {
  height: var(--topbar-h);
  flex-shrink: 0;
  display: flex;
  align-items: center;
  gap: var(--space-3);
  padding: 0 var(--space-5);
  color: var(--sidebar-fg-strong);
  font-size: 18px;
  font-weight: 700;
  white-space: nowrap;
  overflow: hidden;
}

.sidebar__logo {
  display: flex;
  flex-shrink: 0;
  font-size: 28px;
  color: var(--brand);
}

.sidebar__nav {
  flex: 1;
  padding: var(--space-3) 0;
  overflow-x: hidden;
  overflow-y: auto;
}

.app-shell--collapsed .sidebar {
  width: var(--sidebar-w-collapsed);
}
.app-shell--collapsed .sidebar__brand {
  justify-content: center;
  padding: 0;
}
.app-shell--collapsed .sidebar__title {
  display: none;
}
.app-shell--collapsed .sidebar__nav {
  overflow: visible;
}

@media (max-width: 767px) {
  .sidebar {
    transform: translateX(-100%);
  }
  .app-shell--drawer-open .sidebar {
    transform: none;
  }
}
.topbar {
  position: sticky;
  top: 0;
  height: var(--topbar-h);
  display: flex;
  align-items: center;
  gap: var(--space-4);
  padding: 0 var(--space-5);
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  z-index: var(--z-topbar);
}

.topbar__title {
  margin: 0;
  font-size: 18px;
  font-weight: 600;
}

.topbar__actions {
  margin-left: auto;
  display: flex;
  gap: var(--space-2);
  font-size: 28px;
  color: var(--text-muted);
}

@media (max-width: 767px) {
  .topbar {
    padding: 0 var(--space-4);
  }
}
.nav-item {
  position: relative;
  width: 100%;
  height: 44px;
  display: flex;
  align-items: center;
  gap: var(--space-3);
  padding: 0 var(--space-4) 0 var(--space-5);
  border: 0;
  background: none;
  color: var(--sidebar-fg);
  font: inherit;
  font-size: 14px;
  font-weight: 600;
  text-align: left;
  text-decoration: none;
  cursor: pointer;
  transition: background var(--transition), color var(--transition);
}
.nav-item:hover {
  background: var(--sidebar-bg-hover);
  color: var(--sidebar-fg-strong);
}
.nav-item:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: -2px;
}

.nav-item--active,
.nav-item--active:hover {
  color: var(--accent);
}

.nav-item--nested {
  height: 38px;
  padding-left: calc(var(--space-5) + 32px);
  font-weight: 500;
}

.nav-item__icon {
  display: flex;
  flex-shrink: 0;
  font-size: 20px;
}

.nav-item--nested .nav-item__icon {
  font-size: 16px;
}

.nav-item__label {
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.nav-item__badge {
  align-self: flex-start;
  margin-top: 12px;
  margin-left: calc(var(--space-1) * -1);
  width: 6px;
  height: 6px;
  flex-shrink: 0;
  border-radius: 50%;
  background: var(--badge);
}

.app-shell--collapsed .nav-item {
  justify-content: center;
  padding: 0;
}
.app-shell--collapsed .nav-item__label {
  display: none;
}
.app-shell--collapsed .nav-item__badge {
  position: absolute;
  top: 10px;
  right: 18px;
  margin: 0;
}

.nav-item__chevron {
  display: flex;
  margin-left: auto;
  font-size: 14px;
  transition: transform var(--transition);
}

.nav-group--open .nav-item__chevron {
  transform: rotate(90deg);
}

.nav-group__children,
.nav-group__flyout-title {
  display: none;
}

.nav-group--open .nav-group__children {
  display: block;
}

.app-shell--collapsed .nav-group {
  position: relative;
}
.app-shell--collapsed .nav-item__chevron {
  display: none;
}
.app-shell--collapsed .nav-group__children {
  display: none;
  position: absolute;
  top: 0;
  left: 100%;
  min-width: 200px;
  padding: var(--space-2) 0;
  background: var(--sidebar-bg);
  border-radius: 0 var(--radius) var(--radius) 0;
  box-shadow: var(--shadow-flyout);
  z-index: var(--z-flyout);
}
.app-shell--collapsed .nav-group:hover .nav-group__children,
.app-shell--collapsed .nav-group:focus-within .nav-group__children {
  display: block;
}
.app-shell--collapsed .nav-group__flyout-title {
  display: block;
  padding: var(--space-2) var(--space-4);
  color: var(--sidebar-fg-muted);
  font-size: 12px;
  font-weight: 700;
}
.app-shell--collapsed .nav-group__children .nav-item {
  justify-content: flex-start;
  padding: 0 var(--space-4);
}
.app-shell--collapsed .nav-group__children .nav-item__label {
  display: block;
}

.icon-button {
  width: 40px;
  height: 40px;
  flex-shrink: 0;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border: 0;
  border-radius: var(--radius);
  background: var(--accent-soft);
  color: var(--accent);
  font-size: 20px;
  cursor: pointer;
  transition: filter var(--transition);
}
.icon-button:hover {
  filter: brightness(0.95);
}
.icon-button:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

.icon-button--primary {
  background: var(--accent);
  color: var(--accent-contrast);
}

.card {
  background: var(--surface);
  border-radius: var(--radius);
  box-shadow: var(--shadow-card);
}

.card__header {
  margin: 0;
  padding: var(--space-4) var(--space-5);
  border-bottom: 1px solid var(--border);
  font-size: 18px;
  font-weight: 500;
}

.card__body {
  padding: var(--space-5);
}

.stat-card__title {
  margin: 0 0 var(--space-2);
  color: var(--text-muted);
  font-size: 13px;
}

.stat-card__value {
  margin: 0;
  font-size: 22px;
  font-weight: 600;
}

.stat-card__hint {
  margin: var(--space-2) 0 0;
  color: var(--text-muted);
  font-size: 12px;
}

.dashboard {
  display: flex;
  flex-direction: column;
  gap: var(--space-5);
}

.dashboard__stats {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: var(--space-5);
}

.dashboard__chart-placeholder {
  height: 320px;
  display: flex;
  align-items: center;
  justify-content: center;
  border: 2px dashed var(--border);
  border-radius: var(--radius);
  color: var(--text-muted);
}

.placeholder-page {
  padding: var(--space-6) 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
}

.placeholder-page__icon {
  display: flex;
  font-size: 48px;
  color: var(--brand);
}

.placeholder-page__title {
  margin: var(--space-4) 0 var(--space-2);
  font-size: 20px;
}

.placeholder-page__message {
  margin: 0;
  color: var(--text-muted);
}