/* ==========================================================================
   CSS Custom Properties (Design Tokens)
   ========================================================================== */

:root {
  /* Colors (with fallbacks for older browsers) */
  --color-bg: #1a1a1a;
  --color-bg: oklch(10% 0 0);
  --color-bg-light: #262626;
  --color-bg-light: oklch(15% 0 0);
  --color-text: #f0f0f0;
  --color-text: oklch(95% 0 0);
  --color-text-muted: #a3a3a3;
  --color-text-muted: oklch(70% 0 0);
  --color-accent: #8c8c8c;
  --color-accent: oklch(60% 0 0);
  --color-accent-dark: #595959;
  --color-accent-dark: oklch(40% 0 0);
  --color-card-bg: rgba(51, 51, 51, 0.8);
  --color-card-bg: oklch(20% 0 0 / 0.8);
  --color-card-border: #737373;
  --color-card-border: oklch(50% 0 0);

  /* Typography */
  --font-mono: ui-monospace, 'Cascadia Code', 'Source Code Pro', Menlo, Consolas, 'DejaVu Sans Mono', monospace;
  --font-math: 'Cambria Math', 'STIX Two Math', 'Latin Modern Math', 'Noto Sans Math', 'Segoe UI Symbol', system-ui, sans-serif;

  /* Spacing */
  --space-xs: 0.25rem;
  --space-sm: 0.5rem;
  --space-md: 1rem;
  --space-lg: 1.5rem;
  --space-xl: 2rem;
  --space-2xl: 3rem;

  /* Animation */
  --transition-fast: 0.2s ease;
  --transition-normal: 0.3s ease;
  --transition-slow: 0.4s ease-out;
}

/* ==========================================================================
   Keyframes
   ========================================================================== */

@keyframes fade-in-down {
  from {
    opacity: 0;
    transform: translateY(-20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes fade-in-up {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* ==========================================================================
   Reset & Base
   ========================================================================== */

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

html {
  background-color: var(--color-bg);
}

body {
  font-family: var(--font-mono);
  background: transparent;
  color: var(--color-text);
  line-height: 1.6;
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

/* ==========================================================================
   Canvas Background
   ========================================================================== */

#background-canvas {
  position: fixed;
  inset: 0;
  z-index: -1;
  pointer-events: none;
}

/* Decorative geometric shapes */
body::before,
body::after {
  content: '';
  position: fixed;
  opacity: 0.07;
  z-index: -1;
  pointer-events: none;
  background: var(--color-accent);
  transition: transform var(--transition-fast);
}

body::before {
  top: 10vh;
  left: 10vw;
  width: 150px;
  height: 150px;
  clip-path: polygon(50% 0%, 0% 100%, 100% 100%);
  transform: rotate(-15deg);
}

body::after {
  bottom: 15vh;
  right: 15vw;
  width: 200px;
  height: 200px;
  background: var(--color-accent-dark);
  clip-path: polygon(50% 0%, 100% 50%, 50% 100%, 0% 50%);
  transform: rotate(45deg);
}

/* ==========================================================================
   Layout
   ========================================================================== */

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: var(--space-xl);
  width: 100%;
  position: relative;
  z-index: 1;
}

.main-content {
  flex-grow: 1;
}

/* ==========================================================================
   Header
   ========================================================================== */

.header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: var(--space-2xl);
  padding-bottom: var(--space-lg);
  border-bottom: 1px solid var(--color-card-border);
  animation: fade-in-down 0.8s 0.2s ease-out forwards;
  opacity: 0;
}

/* ==========================================================================
   Language Switcher
   ========================================================================== */

.lang-switcher button {
  background-color: var(--color-card-bg);
  color: var(--color-text-muted);
  border: 1px solid var(--color-card-border);
  padding: var(--space-sm) var(--space-md);
  font-family: inherit;
  font-size: 0.9rem;
  cursor: pointer;
  margin-left: var(--space-sm);
  transition:
    background-color var(--transition-fast),
    color var(--transition-fast),
    border-color var(--transition-fast),
    transform var(--transition-fast);
}

.lang-switcher button.active {
  background-color: var(--color-accent-dark);
  color: var(--color-bg);
  border-color: var(--color-accent-dark);
}

.lang-switcher button:not(.active):hover {
  background-color: oklch(25% 0.07 270);
  color: var(--color-text);
  transform: skewX(-10deg);
}

/* ==========================================================================
   Links Section (Cards Grid)
   ========================================================================== */

.links-section {
  display: none;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: var(--space-xl);
  justify-content: center;
}

.links-section.active {
  display: grid;
}

/* ==========================================================================
   Responsive Design
   ========================================================================== */

@media (max-width: 768px) {
  .links-section {
    grid-template-columns: 1fr;
  }

  .header {
    flex-direction: column;
    align-items: flex-start;
  }

  site-logo {
    margin-bottom: var(--space-lg);
  }

  .lang-switcher {
    width: 100%;
    display: flex;
    justify-content: space-around;
  }

  .lang-switcher button {
    flex-grow: 1;
    margin: 0 var(--space-xs);
  }

  .container {
    padding: var(--space-md);
  }

  body::before,
  body::after {
    display: none;
  }
}

@media (max-width: 480px) {
  site-logo {
    --logo-font-size: 2rem;
  }
}