:root {
  /* Light Mode Variables */
  --background: 0 0% 100%;
  --foreground: 222.2 84% 4.9%;
  --card: 0 0% 100%;
  --card-foreground: 222.2 84% 4.9%;
  --popover: 0 0% 100%;
  --popover-foreground: 222.2 84% 4.9%;
  --primary: 222.2 47.4% 11.2%;
  --primary-foreground: 210 40% 98%;
  --secondary: 210 40% 96.1%;
  --secondary-foreground: 222.2 47.4% 11.2%;
  --muted: 210 40% 96.1%;
  --muted-foreground: 215.1 16.3% 46.9%;
  --accent: 210 40% 96.1%;
  --accent-foreground: 222.2 47.4% 11.2%;
  --destructive: 0 84.2% 60.2%;
  --destructive-foreground: 210 40% 98%;
  --border: 214.3 31.8% 91.4%;
  --input: 214.3 31.8% 91.4%;
  --ring: 222.2 84% 4.9%;
  --radius: 0.5rem;

  --font-sans: ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
}

.dark {
  /* Dark Mode Variables */
  --background: 222.2 84% 4.9%;
  --foreground: 210 40% 98%;
  --card: 222.2 84% 4.9%;
  --card-foreground: 210 40% 98%;
  --popover: 222.2 84% 4.9%;
  --popover-foreground: 210 40% 98%;
  --primary: 210 40% 98%;
  --primary-foreground: 222.2 47.4% 11.2%;
  --secondary: 217.2 32.6% 17.5%;
  --secondary-foreground: 210 40% 98%;
  --muted: 217.2 32.6% 17.5%;
  --muted-foreground: 215 20.2% 65.1%;
  --accent: 217.2 32.6% 17.5%;
  --accent-foreground: 210 40% 98%;
  --destructive: 0 62.8% 30.6%;
  --destructive-foreground: 210 40% 98%;
  --border: 217.2 32.6% 17.5%;
  --input: 217.2 32.6% 17.5%;
  --ring: 212.7 26.8% 83.9%;
}

* {
  box-sizing: border-box;
  border-color: hsl(var(--border));
}

body {
  margin: 0;
  font-family: var(--font-sans);
  background-color: hsl(var(--background));
  color: hsl(var(--foreground));
  line-height: 1.6;
  transition: background-color 0.3s, color 0.3s;
}

.container {
  max-width: 800px;
  margin: 0 auto;
  padding: 2rem;
}

header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 3rem;
  padding-bottom: 1rem;
  border-bottom: 1px solid hsl(var(--border));
}

.brand {
  font-size: 1.5rem;
  font-weight: 700;
  color: hsl(var(--foreground));
  text-decoration: none;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.controls {
  display: flex;
  gap: 1rem;
  align-items: center;
}

select {
  padding: 0.5rem;
  border-radius: var(--radius);
  border: 1px solid hsl(var(--border));
  background-color: hsl(var(--background));
  color: hsl(var(--foreground));
  cursor: pointer;
}

button.theme-toggle {
  background: none;
  border: 1px solid hsl(var(--border));
  border-radius: var(--radius);
  padding: 0.5rem;
  cursor: pointer;
  color: hsl(var(--foreground));
  display: flex;
  align-items: center;
  justify-content: center;
}

button.theme-toggle:hover {
  background-color: hsl(var(--accent));
}

h1 {
  font-size: 2.5rem;
  font-weight: 800;
  margin-bottom: 1.5rem;
  letter-spacing: -0.025em;
}

h2 {
  font-size: 1.5rem;
  font-weight: 700;
  margin-top: 2.5rem;
  margin-bottom: 1rem;
  letter-spacing: -0.025em;
}

h3 {
  font-size: 1.25rem;
  font-weight: 600;
  margin-top: 2rem;
  margin-bottom: 0.75rem;
}

p, ul, ol {
  margin-bottom: 1.25rem;
  color: hsl(var(--muted-foreground));
}

ul, ol {
  padding-left: 1.5rem;
}

li {
  margin-bottom: 0.5rem;
}

a {
  color: hsl(var(--primary));
  text-decoration: underline;
  text-underline-offset: 4px;
}

a:hover {
  color: hsl(var(--primary) / 0.8);
}

.card {
  border: 1px solid hsl(var(--border));
  border-radius: var(--radius);
  padding: 1.5rem;
  margin-bottom: 1.5rem;
  background-color: hsl(var(--card));
  color: hsl(var(--card-foreground));
  transition: transform 0.2s;
}

.card:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
}

.card h2 {
  margin-top: 0;
}

footer {
  margin-top: 4rem;
  padding-top: 2rem;
  border-top: 1px solid hsl(var(--border));
  text-align: center;
  font-size: 0.875rem;
  color: hsl(var(--muted-foreground));
}

/* Language Visibility */
[data-lang-content] {
  display: none;
}

[data-lang-content].active {
  display: block;
}

/* Utility */
.text-sm {
  font-size: 0.875rem;
}
.font-bold {
  font-weight: 700;
}
.mb-4 {
  margin-bottom: 1rem;
}
.mt-8 {
  margin-top: 2rem;
}