:root {
    /* Design System Colors */
    --color-primary: #007AFF;
    --color-secondary: #5856D6;
    --color-success: #34C759;
    --color-warning: #FF9500;
    --color-error: #FF3B30;
    --color-background: #F3F6FA;
    --color-surface: #FFFFFF;
    --color-text-primary: #000000;
    --color-text-secondary: #3C3C43;
    --color-text-tertiary: #6B7280;
    --color-text-disabled: #C7C7CC;
    --color-primary-rgb: 0, 122, 255;
    --color-primary-dark: #0062CC;

    /* Neural Scale (50-950) - Design System */
    --neutral-50: #F9FAFB;
    --neutral-100: #F3F4F6;
    --neutral-200: #E5E7EB;
    --neutral-300: #D1D5DB;
    --neutral-400: #9CA3AF;
    --neutral-500: #6B7280;
    --neutral-600: #4B5563;
    --neutral-700: #374151;
    --neutral-800: #1F2937;
    --neutral-900: #111827;
    --neutral-950: #030712;

    /* Typography */
    --font-family: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Arial, sans-serif;
    --font-size-xs: 12px;
    --font-size-sm: 14px;
    --font-size-base: 16px;
    --font-size-lg: 18px;
    --font-size-xl: 20px;
    --font-size-2xl: 24px;
    --font-size-3xl: 30px;

    /* Font weights */
    --font-weight-normal: 400;
    --font-weight-medium: 500;
    --font-weight-semibold: 600;
    --font-weight-bold: 700;

    /* Spacing */
    --spacing-xs: 4px;
    --spacing-sm: 8px;
    --spacing-md: 16px;
    --spacing-lg: 24px;
    --spacing-xl: 32px;
    --spacing-2xl: 48px;

    /* Breakpoints */
    --breakpoint-mobile: 320px;
    --breakpoint-tablet: 768px;
    --breakpoint-desktop: 1024px;
    --breakpoint-wide: 1440px;

    /* Legacy brand colors for backward compatibility */
    --brand-primary: var(--color-primary);
    --brand-primary-hover: #0056ad;
    --brand-accent: var(--color-success);
    --brand-deal: var(--color-error);

    /* Backgrounds */
    --bg-main: var(--color-background);
    --bg-alt: var(--color-surface);
    --bg-card: var(--color-background);
    --bg-surface: var(--color-surface);
    --bg-inverse: #0f172a;

    /* Text */
    --text-main: var(--color-text-primary);
    --text-muted: var(--color-text-secondary);
    --text-inverse: #ffffff;
    --text-link: var(--color-primary);

    /* Borders */
    --border-subtle: #e5e7eb;
    --border-default: var(--color-text-disabled);
    --border-focus: var(--color-primary);

    /* UI Tokens */
    --radius-sm: var(--spacing-xs);
    --radius-md: 8px;
    --radius-lg: var(--spacing-md);
    --radius-xl: 16px;
    --radius-round: 9999px;

    /* Elevation / Shadows (Tiered System) */
    --shadow-elevate-1: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-elevate-2: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-elevate-3: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --shadow-elevate-4: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
    --shadow-elevate-5: 0 25px 50px -12px rgba(0, 0, 0, 0.25);

    /* Legacy Mapping */
    --shadow-sm: var(--shadow-elevate-1);
    --shadow-card: 0 4px 12px rgba(0, 0, 0, 0.06);
    --shadow-card-hover: 0 20px 40px -12px rgba(0, 0, 0, 0.15);
    --shadow-lg: var(--shadow-elevate-3);

    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-medium: 200ms cubic-bezier(0.4, 0, 0.2, 1);

    /* Spacing */
    --space-xs: 4px;
    --space-sm: 8px;
    --space-md: 16px;
    --space-lg: 24px;
    --space-xl: 32px;
    --space-xxl: 48px;

    /* Typography */
    --font-base: "Inter", system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Arial, sans-serif;
    --font-mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;

    /* Premium semantic aliases */
    --surface-shell: #f8fafc;
    --surface-canvas: #ffffff;
    --surface-card: #ffffff;
    --surface-muted: #f3f4f6;
    --text-strong: #0f172a;
    --text-body: #334155;
    --text-subtle: #64748b;
    --border-soft: #e2e8f0;
    --focus-ring: rgba(2, 132, 199, 0.42);
    --elevation-1: 0 1px 2px rgba(2, 6, 23, 0.04);
    --elevation-2: 0 8px 20px rgba(15, 23, 42, 0.08);
    --elevation-3: 0 16px 36px rgba(15, 23, 42, 0.11);
}

[data-theme="dark"] {
    --bg-main: #0f172a;
    --bg-alt: #020617;
    --bg-card: #1e293b;
    --bg-surface: #334155;
    --bg-inverse: #ffffff;

    --text-main: #e5e7eb;
    --text-muted: #94a3b8;
    --text-inverse: #0f172a;

    --border-subtle: #1e293b;
    --border-default: #334155;

    --shadow-card: 0 4px 12px rgba(0, 0, 0, 0.4);

    /* Dark Mode Neutral Swaps */
    --neutral-50: #020617;
    --neutral-100: #0f172a;
    --neutral-200: #1e293b;
    --neutral-300: #334155;
    --neutral-400: #475569;
    --neutral-500: #64748b;
    --neutral-600: #94a3b8;
    --neutral-700: #cbd5e1;
    --neutral-800: #e2e8f0;
    --neutral-900: #f1f5f9;
    --neutral-950: #f8fafc;

    --surface-shell: var(--neutral-50);
    --surface-canvas: var(--neutral-100);
    --surface-card: #111827;
    --surface-muted: #1f2937;
    --text-strong: #f8fafc;
    --text-body: #d1d5db;
    --text-subtle: #9ca3af;
    --border-soft: #374151;
    --focus-ring: rgba(96, 165, 250, 0.35);
    --elevation-1: 0 1px 2px rgba(0, 0, 0, 0.45);
    --elevation-2: 0 10px 30px rgba(0, 0, 0, 0.5);
    --elevation-3: 0 24px 54px rgba(0, 0, 0, 0.6);
}

@layer base {
    :root {
        --spacing-1: 0.25rem;
        --spacing-2: 0.5rem;
        --spacing-3: 0.75rem;
        --spacing-4: 1rem;
        --spacing-6: 1.5rem;
        --spacing-8: 2rem;

        --type-step--1: 0.875rem;
        --type-step-0: 1rem;
        --type-step-1: 1.125rem;
        --type-step-2: 1.375rem;
        --type-step-3: 1.75rem;

        --status-success-bg: #d1fae5;
        --status-success-fg: #065f46;
        --status-warning-bg: #fef3c7;
        --status-warning-fg: #92400e;
        --status-danger-bg: #fee2e2;
        --status-danger-fg: #991b1b;
    }
}