theme.css

/* theme.css - Portable UI Engine Global Design Tokens */
:root {
  /* Color Palette - Neutrals */
  --color-bg-app: #f8fafc;
  --color-bg-surface: #ffffff;
  --color-bg-surface-elevated: #ffffff;
  --color-bg-hover: #f1f5f9;
  --color-bg-active: #e2e8f0;
  --color-bg-stripe: #f8fafc;
  
  --color-text-primary: #0f172a;
  --color-text-secondary: #475569;
  --color-text-muted: #94a3b8;
  --color-text-inverse: #ffffff;

  --color-border: #e2e8f0;
  --color-border-strong: #cbd5e1;

  /* Color Palette - Brand & Accents */
  --color-primary: #2563eb;
  --color-primary-hover: #1d4ed8;
  --color-primary-light: #eff6ff;
  --color-accent: #0d9488;

  /* Color Palette - Statuses */
  --color-success: #16a34a;
  --color-success-bg: #f0fdf4;
  --color-warning: #d97706;
  --color-warning-bg: #fffbeb;
  --color-danger: #dc2626;
  --color-danger-bg: #fef2f2;

  /* Typography Scale */
  --font-sans: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, 'Liberation Mono', monospace;
  
  --font-size-xs: 0.75rem;    /* 12px */
  --font-size-sm: 0.875rem;   /* 14px */
  --font-size-base: 1rem;     /* 16px */
  --font-size-lg: 1.125rem;   /* 18px */
  --font-size-xl: 1.25rem;    /* 20px */
  --font-size-2xl: 1.5rem;    /* 24px */
  --font-size-3xl: 1.875rem;  /* 30px */

  --font-weight-normal: 400;
  --font-weight-medium: 500;
  --font-weight-semibold: 600;
  --font-weight-bold: 700;

  --line-height-tight: 1.25;
  --line-height-normal: 1.5;
  --line-height-relaxed: 1.75;

  /* Spacing Scale */
  --spacing-0: 0px;
  --spacing-1: 0.25rem;  /* 4px */
  --spacing-2: 0.5rem;   /* 8px */
  --spacing-3: 0.75rem;  /* 12px */
  --spacing-4: 1rem;     /* 16px */
  --spacing-5: 1.25rem;  /* 20px */
  --spacing-6: 1.5rem;   /* 24px */
  --spacing-8: 2rem;     /* 32px */
  --spacing-10: 2.5rem;  /* 40px */
  --spacing-12: 3rem;    /* 48px */
  --spacing-16: 4rem;    /* 64px */

  /* Border Radii */
  --radius-none: 0px;
  --radius-sm: 0.25rem;  /* 4px */
  --radius-md: 0.375rem; /* 6px */
  --radius-lg: 0.5rem;   /* 8px */
  --radius-xl: 0.75rem;  /* 12px */
  --radius-2xl: 1rem;    /* 16px */
  --radius-full: 9999px;

  /* Layout Dimensions */
  --header-height: 64px;
  --drawer-width: 260px;

  /* Elevation & Shadows */
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -2px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -4px rgba(0, 0, 0, 0.1);

  /* Animation & Transitions */
  --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-normal: 250ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: 350ms cubic-bezier(0.4, 0, 0.2, 1);
}

/* Preset Theme Overrides via data-theme attribute */
[data-theme="dark"] {
  --color-bg-app: #0f172a;
  --color-bg-surface: #1e293b;
  --color-bg-surface-elevated: #334155;
  --color-bg-hover: #334155;
  --color-bg-active: #475569;
  --color-bg-stripe: #182234;

  --color-text-primary: #f8fafc;
  --color-text-secondary: #cbd5e1;
  --color-text-muted: #64748b;
  --color-text-inverse: #0f172a;

  --color-border: #334155;
  --color-border-strong: #475569;

  --color-primary: #3b82f6;
  --color-primary-hover: #60a5fa;
  --color-primary-light: #1e3a8a;
  --color-accent: #14b8a6;
}

[data-theme="corporate"] {
  --color-bg-app: #f3f4f6;
  --color-bg-surface: #ffffff;
  --color-bg-surface-elevated: #f9fafb;
  --color-bg-hover: #f3f4f6;
  --color-bg-active: #e5e7eb;
  --color-bg-stripe: #f9fafb;

  --color-text-primary: #111827;
  --color-text-secondary: #4b5563;
  --color-text-muted: #9ca3af;
  --color-text-inverse: #ffffff;

  --color-border: #e5e7eb;
  --color-border-strong: #d1d5db;

  --color-primary: #1e40af;
  --color-primary-hover: #1e3a8a;
  --color-primary-light: #dbeafe;
  --color-accent: #0369a1;

  --radius-sm: 2px;
  --radius-md: 4px;
  --radius-lg: 6px;
  --radius-xl: 8px;
}

[data-theme="cyberpunk"] {
  --color-bg-app: #0d0221;
  --color-bg-surface: #150534;
  --color-bg-surface-elevated: #220b4f;
  --color-bg-hover: #2a0e5f;
  --color-bg-active: #39137d;
  --color-bg-stripe: #12042c;

  --color-text-primary: #00f5d4;
  --color-text-secondary: #f72585;
  --color-text-muted: #7209b7;
  --color-text-inverse: #0d0221;

  --color-border: #39137d;
  --color-border-strong: #7209b7;

  --color-primary: #f72585;
  --color-primary-hover: #b5179e;
  --color-primary-light: #3a0ca3;
  --color-accent: #4cc9f0;

  --radius-sm: 0px;
  --radius-md: 0px;
  --radius-lg: 0px;
  --radius-xl: 0px;
}

[data-theme="midnight"] {
  --color-bg-app: #030712;
  --color-bg-surface: #111827;
  --color-bg-surface-elevated: #1f2937;
  --color-bg-hover: #1f2937;
  --color-bg-active: #374151;
  --color-bg-stripe: #0b0f19;

  --color-text-primary: #f9fafb;
  --color-text-secondary: #9ca3af;
  --color-text-muted: #6b7280;
  --color-text-inverse: #111827;

  --color-border: #1f2937;
  --color-border-strong: #374151;

  --color-primary: #6366f1;
  --color-primary-hover: #4f46e5;
  --color-primary-light: #312e81;
  --color-accent: #8b5cf6;

  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
}

[data-theme="emerald"] {
  --color-bg-app: #f0fdf4;
  --color-bg-surface: #ffffff;
  --color-bg-surface-elevated: #ffffff;
  --color-bg-hover: #dcfce7;
  --color-bg-active: #bbf7d0;
  --color-bg-stripe: #f6fef9;

  --color-text-primary: #064e3b;
  --color-text-secondary: #047857;
  --color-text-muted: #34d399;
  --color-text-inverse: #ffffff;

  --color-border: #a7f3d0;
  --color-border-strong: #6ee7b7;

  --color-primary: #059669;
  --color-primary-hover: #047857;
  --color-primary-light: #ecfdf5;
  --color-accent: #10b981;

  --radius-sm: 0.25rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
}

/* Base Body Styles */
*, *::before, *::after {
  box-sizing: border-box;
}

/* Low-Latency Hydration Baseline for Custom Elements (Eliminating FOUC) */
universal-app-shell:not(:defined),
universal-form:not(:defined),
universal-metric-grid:not(:defined),
universal-data-table:not(:defined),
universal-saas-dashboard:not(:defined),
universal-billing-funnel:not(:defined),
universal-ai-bridge:not(:defined),
:not(:defined) {
  opacity: 0.3;
  min-height: 80px;
  background: linear-gradient(90deg, var(--color-bg-surface, #ffffff) 25%, var(--color-bg-hover, #f1f5f9) 50%, var(--color-bg-surface, #ffffff) 75%);
  background-size: 200% 100%;
  animation: engine-skeleton-pulse 1.5s infinite ease-in-out;
  border-radius: var(--radius-lg, 8px);
  transition: opacity var(--transition-fast, 150ms ease);
}

@keyframes engine-skeleton-pulse {
  0% { background-position: 200% 0; }
  100% { background-position: -200% 0; }
}

body {
  margin: 0;
  padding: 0;
  font-family: var(--font-sans);
  background-color: var(--color-bg-app);
  color: var(--color-text-primary);
  line-height: var(--line-height-normal);
  -webkit-font-smoothing: antialiased;
  transition: background-color var(--transition-normal), color var(--transition-normal);
}