:root {
  /* Colors - Modern OKLCH */
  --bg-color: oklch(0.98 0.01 250);
  --primary-color: oklch(0.55 0.18 250);
  --secondary-color: oklch(0.75 0.12 210);
  --accent-color: oklch(0.85 0.15 190);
  --text-color: oklch(0.25 0.02 250);
  --card-bg: oklch(1 0 0);
  --shadow-color: oklch(0 0 0 / 0.1);
  
  /* Spacing */
  --spacing-xs: 0.5rem;
  --spacing-sm: 1rem;
  --spacing-md: 2rem;
  --spacing-lg: 3rem;

  /* Typography */
  --font-main: 'Nanum Gothic', sans-serif;
  --font-display: 'Gaegu', cursive;
}

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

body {
  font-family: var(--font-main);
  background-color: var(--bg-color);
  color: var(--text-color);
  line-height: 1.6;
  background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 200 200' xmlns='http://www.w3.org/2000/svg'%3%3Ffilter id='noiseFilter'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.65' numOctaves='3' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23noiseFilter)'/%3E%3C/svg%3E");
  background-blend-mode: soft-light;
}

#app-container {
  max-width: 800px;
  margin: 0 auto;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

header {
  padding: var(--spacing-md) var(--spacing-sm);
  text-align: center;
  background: var(--card-bg);
  box-shadow: 0 4px 20px var(--shadow-color);
  border-radius: 0 0 24px 24px;
  margin-bottom: var(--spacing-md);
  position: sticky;
  top: 0;
  z-index: 100;
}

header h1 {
  font-family: var(--font-display);
  font-size: 2.5rem;
  color: var(--primary-color);
  margin-bottom: var(--spacing-sm);
}

nav {
  display: flex;
  justify-content: center;
  gap: var(--spacing-sm);
  overflow-x: auto;
  padding-bottom: var(--spacing-xs);
}

.nav-btn {
  padding: 0.6rem 1.2rem;
  border: none;
  background: transparent;
  color: var(--text-color);
  font-weight: 700;
  cursor: pointer;
  border-radius: 12px;
  transition: all 0.3s ease;
  white-space: nowrap;
}

.nav-btn.active {
  background: var(--primary-color);
  color: white;
  box-shadow: 0 4px 12px oklch(0.55 0.18 250 / 0.3);
}

.nav-btn:hover:not(.active) {
  background: oklch(0.92 0.04 250);
}

main {
  flex: 1;
  padding: 0 var(--spacing-sm);
}

.view {
  animation: fadeIn 0.4s ease-out;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(10px); }
  to { opacity: 1; transform: translateY(0); }
}

footer {
  padding: var(--spacing-md);
  text-align: center;
  font-size: 0.9rem;
  color: oklch(0.5 0.01 250);
}

/* Common Card Style */
.card {
  background: var(--card-bg);
  border-radius: 20px;
  padding: var(--spacing-md);
  box-shadow: 0 10px 30px var(--shadow-color);
  margin-bottom: var(--spacing-md);
}

/* Button glow effect */
.btn-primary {
  background: var(--primary-color);
  color: white;
  border: none;
  padding: 0.8rem 1.5rem;
  border-radius: 12px;
  font-weight: 700;
  cursor: pointer;
  transition: all 0.3s ease;
  box-shadow: 0 4px 15px oklch(0.55 0.18 250 / 0.4);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px oklch(0.55 0.18 250 / 0.6);
}

@media (max-width: 600px) {
  header {
    padding: var(--spacing-sm);
    margin-bottom: var(--spacing-sm);
    border-radius: 0 0 16px 16px;
  }
  header h1 { 
    font-size: 1.4rem; 
    margin-bottom: var(--spacing-xs);
  }
  .nav-btn { 
    padding: 0.4rem 0.7rem; 
    font-size: 0.85rem; 
  }
  nav {
    gap: 0.4rem;
  }
  .card {
    padding: var(--spacing-sm);
  }
}