*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html, body {
  height: 100%;
  background-color: var(--bg-main);
  color: var(--text-primary);
  font-family: var(--font-sans);
  font-size: 14px;
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
  overflow: hidden;
}

/* Scrollbar Customization */
::-webkit-scrollbar {
  width: 6px;
  height: 6px;
}

::-webkit-scrollbar-track {
  background: var(--bg-main);
}

::-webkit-scrollbar-thumb {
  background: var(--border-color);
  border-radius: var(--radius-full);
}

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

/* App Shell Layout */
#app-root {
  display: flex;
  height: 100dvh;
  width: 100vw;
  overflow: hidden;
}

/* Sidebar */
.sidebar {
  width: 240px;
  background-color: var(--bg-surface);
  border-right: 1px solid var(--border-color);
  display: flex;
  flex-direction: column;
  flex-shrink: 0;
  user-select: none;
}

.sidebar-header {
  padding: 20px;
  display: flex;
  align-items: center;
  gap: 12px;
  border-bottom: 1px solid var(--border-subtle);
}

.brand-icon {
  width: 32px;
  height: 32px;
  background: linear-gradient(135deg, #3b82f6, #1d4ed8);
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  color: #ffffff;
  box-shadow: var(--glow-accent);
}

.brand-title {
  font-size: 16px;
  font-weight: 700;
  letter-spacing: -0.3px;
  color: var(--text-primary);
}

.brand-subtitle {
  font-size: 11px;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.nav-list {
  list-style: none;
  padding: 16px 12px;
  display: flex;
  flex-direction: column;
  gap: 4px;
  flex: 1;
}

.nav-item {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 10px 14px;
  border-radius: var(--radius-md);
  color: var(--text-secondary);
  font-weight: 500;
  cursor: pointer;
  transition: background-color var(--transition-fast), color var(--transition-fast);
}

.nav-item:hover {
  background-color: var(--bg-raised);
  color: var(--text-primary);
}

.nav-item:focus-visible {
  outline: 2px solid var(--accent-primary);
  outline-offset: 2px;
}

.nav-item.active {
  background-color: rgba(59, 130, 246, 0.12);
  color: var(--accent-primary);
  font-weight: 600;
}

.nav-item svg {
  width: 18px;
  height: 18px;
  stroke-width: 2;
}

.sidebar-footer {
  padding: 16px;
  border-top: 1px solid var(--border-subtle);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.user-badge {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 13px;
  font-weight: 500;
  color: var(--text-secondary);
}

/* Main Content Area */
.main-wrapper {
  flex: 1;
  min-width: 0;
  display: flex;
  flex-direction: column;
  height: 100dvh;
  overflow: hidden;
}

.top-bar {
  height: 64px;
  background-color: var(--bg-surface);
  border-bottom: 1px solid var(--border-color);
  padding: 0 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-shrink: 0;
}

.page-title {
  font-size: 18px;
  font-weight: 700;
  color: var(--text-primary);
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 16px;
}

.content-area {
  flex: 1;
  min-width: 0;
  min-height: 0;
  padding: 24px;
  overflow-y: auto;
}

@media (max-width: 640px) {
  #app-root {
    flex-direction: column;
  }

  .sidebar {
    width: 100%;
    border-right: 0;
    border-bottom: 1px solid var(--border-color);
    flex-shrink: 0;
  }

  .sidebar-header {
    padding: 12px 16px;
  }

  .brand-icon {
    width: 28px;
    height: 28px;
  }

  .brand-subtitle,
  .sidebar-footer {
    display: none;
  }

  .nav-list {
    display: grid;
    grid-template-columns: repeat(4, minmax(0, 1fr));
    padding: 8px;
    flex: none;
  }

  .nav-item {
    min-width: 0;
    flex-direction: column;
    justify-content: center;
    gap: 4px;
    padding: 6px 4px;
    font-size: 12px;
    line-height: 1.2;
    text-align: center;
  }

  .nav-item svg {
    width: 16px;
    height: 16px;
  }

  .main-wrapper {
    width: 100%;
    height: auto;
    min-height: 0;
  }

  .top-bar {
    height: 52px;
    padding: 0 16px;
  }

  .content-area {
    padding: 16px;
  }
}