/* ==========================================
   Design System — Premium 2026
   Inspired by Stripe, Linear, Vercel
   ============================================ */

:root {
  /* ---------- Dark theme (default) ---------- */
  --color-bg-primary: #09090b;
  --color-bg-secondary: #111113;
  --color-bg-tertiary: #18181b;
  --color-bg-elevated: #1c1c20;
  --color-bg-glass: rgba(24, 24, 27, 0.7);

  /* Primary Brand — Indigo */
  --color-primary: #818cf8;
  --color-primary-light: rgba(129, 140, 248, 0.12);
  --color-primary-dark: #6366f1;
  --color-primary-glow: rgba(129, 140, 248, 0.25);

  /* Secondary — Emerald */
  --color-secondary: #34d399;
  --color-secondary-light: rgba(52, 211, 153, 0.1);

  /* Accent — used for premium highlights */
  --color-accent: linear-gradient(135deg, #818cf8, #34d399);

  /* Neutrals */
  --color-text-primary: #fafafa;
  --color-text-secondary: #a1a1aa;
  --color-text-muted: #52525b;
  --color-border-subtle: rgba(255, 255, 255, 0.06);
  --color-border-hover: rgba(255, 255, 255, 0.12);
  --color-border-active: rgba(129, 140, 248, 0.4);

  /* Status */
  --color-success: #34d399;
  --color-warning: #fbbf24;
  --color-error: #f87171;

  /* Typography */
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;

  --text-xs: 0.75rem;
  --text-sm: 0.8125rem;
  --text-base: 0.9375rem;
  --text-lg: 1.0625rem;
  --text-xl: 1.25rem;
  --text-2xl: 1.5rem;
  --text-3xl: 2rem;
  --text-4xl: 2.75rem;
  --text-5xl: 3.5rem;

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

  --leading-tight: 1.15;
  --leading-normal: 1.6;
  --leading-relaxed: 1.75;

  /* Spacing (4px base) */
  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-5: 1.25rem;
  --space-6: 1.5rem;
  --space-8: 2rem;
  --space-10: 2.5rem;
  --space-12: 3rem;
  --space-16: 4rem;
  --space-20: 5rem;
  --space-24: 6rem;

  /* Border Radius */
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-xl: 24px;
  --radius-2xl: 32px;
  --radius-full: 9999px;

  /* Shadows — layered for depth */
  --shadow-xs: 0 1px 2px rgba(0,0,0,0.4);
  --shadow-sm: 0 2px 4px rgba(0,0,0,0.3), 0 1px 2px rgba(0,0,0,0.2);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.4), 0 2px 4px rgba(0,0,0,0.2);
  --shadow-lg: 0 8px 24px rgba(0,0,0,0.5), 0 4px 8px rgba(0,0,0,0.3);
  --shadow-xl: 0 16px 48px rgba(0,0,0,0.5), 0 8px 16px rgba(0,0,0,0.3);
  --shadow-glow: 0 0 40px var(--color-primary-glow);
  --shadow-glow-sm: 0 0 20px var(--color-primary-glow);

  /* Transitions */
  --ease-out: cubic-bezier(0.16, 1, 0.3, 1);
  --ease-in-out: cubic-bezier(0.4, 0, 0.2, 1);
  --transition-fast: 150ms var(--ease-in-out);
  --transition-base: 250ms var(--ease-out);
  --transition-slow: 400ms var(--ease-out);

  /* Layout */
  --container-max: 1200px;
  --header-height: 72px;
}

/* ---------- Light theme ---------- */
[data-theme="light"] {
  --color-bg-primary: #ffffff;
  --color-bg-secondary: #f8fafc;
  --color-bg-tertiary: #f1f5f9;
  --color-bg-elevated: #ffffff;
  --color-bg-glass: rgba(255, 255, 255, 0.8);

  --color-primary: #6366f1;
  --color-primary-light: rgba(99, 102, 241, 0.08);
  --color-primary-dark: #4f46e5;
  --color-primary-glow: rgba(99, 102, 241, 0.15);

  --color-secondary: #10b981;
  --color-secondary-light: rgba(16, 185, 129, 0.08);

  --color-text-primary: #0f172a;
  --color-text-secondary: #475569;
  --color-text-muted: #94a3b8;
  --color-border-subtle: rgba(0, 0, 0, 0.06);
  --color-border-hover: rgba(0, 0, 0, 0.12);
  --color-border-active: rgba(99, 102, 241, 0.4);

  --shadow-xs: 0 1px 2px rgba(0,0,0,0.04);
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.06), 0 1px 2px rgba(0,0,0,0.04);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.08), 0 2px 4px rgba(0,0,0,0.04);
  --shadow-lg: 0 8px 24px rgba(0,0,0,0.1), 0 4px 8px rgba(0,0,0,0.06);
  --shadow-xl: 0 16px 48px rgba(0,0,0,0.12), 0 8px 16px rgba(0,0,0,0.06);
  --shadow-glow: 0 0 40px rgba(99, 102, 241, 0.08);
  --shadow-glow-sm: 0 0 20px rgba(99, 102, 241, 0.06);
}

/* ---------- Reset & Base ---------- */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html {
  scroll-behavior: smooth;
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-sans);
  font-size: var(--text-base);
  background-color: var(--color-bg-primary);
  color: var(--color-text-primary);
  line-height: var(--leading-normal);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
  min-height: 100vh;
}

h1, h2, h3, h4, h5, h6 {
  font-weight: var(--font-semibold);
  line-height: var(--leading-tight);
  letter-spacing: -0.025em;
  color: var(--color-text-primary);
}

h1 { font-size: clamp(var(--text-3xl), 5vw, var(--text-5xl)); font-weight: var(--font-bold); }
h2 { font-size: clamp(var(--text-2xl), 4vw, var(--text-4xl)); }
h3 { font-size: clamp(var(--text-xl), 3vw, var(--text-2xl)); }

p {
  color: var(--color-text-secondary);
  margin-bottom: var(--space-4);
  line-height: var(--leading-relaxed);
}

a {
  color: var(--color-primary);
  text-decoration: none;
  transition: color var(--transition-fast);
}
a:hover { color: var(--color-primary-dark); }

img { max-width: 100%; height: auto; display: block; }
ul, ol { list-style: none; }

.container {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--space-6);
}

@media (min-width: 768px) {
  .container { padding: 0 var(--space-8); }
}

/* ---------- Utility: sr-only ---------- */
.sr-only {
  position: absolute;
  width: 1px; height: 1px;
  padding: 0; margin: -1px;
  overflow: hidden;
  clip: rect(0,0,0,0);
  white-space: nowrap;
  border: 0;
}

/* ---------- Focus ---------- */
*:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
  border-radius: var(--radius-sm);
}