/* 
 * 요알남 Design System
 * Based on Linear.app design principles
 * Version: 1.0.0
 */

/* ============================================
   CSS Variables - Design Tokens
   ============================================ */
:root {
  /* Primary Colors - Black Theme */
  --color-bg-primary: #0a0a0a;
  --color-bg-secondary: #141414;
  --color-bg-tertiary: #1f1f1f;
  --color-bg-elevated: #1a1a1a;
  
  /* Text Colors */
  --color-text-primary: #ffffff;
  --color-text-secondary: #b3b3b3;
  --color-text-tertiary: #808080;
  --color-text-quaternary: #666666;
  
  /* Accent Colors - Orange Theme */
  --color-accent-primary: #ff6b35;
  --color-accent-hover: #ff5722;
  --color-accent-active: #e64a19;
  --color-accent-light: #ff8c42;
  --color-accent-dark: #cc5528;
  --color-success: #22c55e;
  --color-warning: #f97316;
  --color-error: #ef4444;
  
  /* Border Colors */
  --color-border-primary: #2a2a2a;
  --color-border-secondary: #404040;
  --color-border-hover: #595959;
  
  /* Typography */
  --font-family-primary: 'Inter var', -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', sans-serif;
  --font-family-mono: 'SF Mono', 'Monaco', 'Inconsolata', 'Fira Code', monospace;
  
  /* Font Sizes */
  --font-size-xs: 0.75rem;
  --font-size-sm: 0.875rem;
  --font-size-base: 1rem;
  --font-size-lg: 1.125rem;
  --font-size-xl: 1.25rem;
  --font-size-2xl: 1.5rem;
  --font-size-3xl: 1.875rem;
  --font-size-4xl: 2.25rem;
  --font-size-5xl: 3rem;
  
  /* Font Weights */
  --font-weight-normal: 400;
  --font-weight-medium: 500;
  --font-weight-semibold: 600;
  --font-weight-bold: 700;
  
  /* Line Heights */
  --line-height-tight: 1.25;
  --line-height-normal: 1.5;
  --line-height-relaxed: 1.75;
  
  /* Letter Spacing */
  --letter-spacing-tight: -0.025em;
  --letter-spacing-normal: 0;
  --letter-spacing-wide: 0.025em;
  
  /* Spacing */
  --spacing-0: 0;
  --spacing-1: 0.25rem;
  --spacing-2: 0.5rem;
  --spacing-3: 0.75rem;
  --spacing-4: 1rem;
  --spacing-5: 1.25rem;
  --spacing-6: 1.5rem;
  --spacing-7: 1.75rem;
  --spacing-8: 2rem;
  --spacing-10: 2.5rem;
  --spacing-12: 3rem;
  --spacing-16: 4rem;
  --spacing-20: 5rem;
  --spacing-24: 6rem;
  
  /* Border Radius */
  --radius-sm: 0.25rem;
  --radius-md: 0.375rem;
  --radius-lg: 0.5rem;
  --radius-xl: 0.75rem;
  --radius-2xl: 1rem;
  --radius-full: 9999px;
  
  /* Shadows */
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
  
  /* Transitions */
  --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-base: 200ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: 300ms cubic-bezier(0.4, 0, 0.2, 1);
  
  /* Z-index */
  --z-base: 0;
  --z-dropdown: 10;
  --z-sticky: 20;
  --z-overlay: 30;
  --z-modal: 40;
  --z-popover: 50;
  --z-tooltip: 60;
}

/* ============================================
   Base Styles
   ============================================ */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
}

body {
  font-family: var(--font-family-primary);
  font-size: var(--font-size-base);
  font-weight: var(--font-weight-normal);
  line-height: var(--line-height-normal);
  color: var(--color-text-primary);
  background-color: var(--color-bg-primary);
  overflow-x: hidden;
}

/* ============================================
   Typography
   ============================================ */
h1, h2, h3, h4, h5, h6 {
  font-weight: var(--font-weight-semibold);
  line-height: var(--line-height-tight);
  letter-spacing: var(--letter-spacing-tight);
  color: var(--color-text-primary);
}

h1 { font-size: var(--font-size-5xl); }
h2 { font-size: var(--font-size-4xl); }
h3 { font-size: var(--font-size-3xl); }
h4 { font-size: var(--font-size-2xl); }
h5 { font-size: var(--font-size-xl); }
h6 { font-size: var(--font-size-lg); }

p {
  color: var(--color-text-secondary);
  line-height: var(--line-height-relaxed);
}

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

a:hover {
  color: var(--color-accent-hover);
}

/* ============================================
   Layout Components
   ============================================ */
.container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--spacing-6);
}

.section {
  padding: var(--spacing-16) 0;
}

.grid {
  display: grid;
  gap: var(--spacing-6);
}

.grid-cols-1 { grid-template-columns: repeat(1, 1fr); }
.grid-cols-2 { grid-template-columns: repeat(2, 1fr); }
.grid-cols-3 { grid-template-columns: repeat(3, 1fr); }
.grid-cols-4 { grid-template-columns: repeat(4, 1fr); }

/* ============================================
   Components
   ============================================ */

/* Navigation */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: 64px;
  background: rgba(9, 9, 11, 0.8);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--color-border-primary);
  z-index: var(--z-sticky);
  transition: all var(--transition-base);
}

.navbar-container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
}

.navbar-brand {
  display: flex;
  align-items: center;
  gap: var(--spacing-2);
  font-size: var(--font-size-lg);
  font-weight: var(--font-weight-semibold);
  color: var(--color-text-primary);
}

.navbar-menu {
  display: flex;
  align-items: center;
  gap: var(--spacing-1);
  list-style: none;
}

.navbar-link {
  display: flex;
  align-items: center;
  gap: var(--spacing-2);
  padding: var(--spacing-2) var(--spacing-3);
  font-size: var(--font-size-sm);
  font-weight: var(--font-weight-medium);
  color: var(--color-text-secondary);
  border-radius: var(--radius-md);
  transition: all var(--transition-fast);
}

.navbar-link:hover {
  color: var(--color-text-primary);
  background: var(--color-bg-secondary);
}

.navbar-link.active {
  color: var(--color-text-primary);
  background: var(--color-bg-tertiary);
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-2);
  padding: var(--spacing-2) var(--spacing-4);
  font-size: var(--font-size-sm);
  font-weight: var(--font-weight-medium);
  line-height: var(--line-height-normal);
  border-radius: var(--radius-md);
  border: 1px solid transparent;
  cursor: pointer;
  transition: all var(--transition-fast);
  white-space: nowrap;
  user-select: none;
}

.btn-primary {
  color: white;
  background: var(--color-accent-primary);
  border-color: var(--color-accent-primary);
}

.btn-primary:hover {
  background: var(--color-accent-hover);
  border-color: var(--color-accent-hover);
}

.btn-secondary {
  color: var(--color-text-primary);
  background: var(--color-bg-secondary);
  border-color: var(--color-border-primary);
}

.btn-secondary:hover {
  background: var(--color-bg-tertiary);
  border-color: var(--color-border-secondary);
}

.btn-ghost {
  color: var(--color-text-secondary);
  background: transparent;
  border-color: transparent;
}

.btn-ghost:hover {
  color: var(--color-text-primary);
  background: var(--color-bg-secondary);
}

.btn-lg {
  padding: var(--spacing-3) var(--spacing-6);
  font-size: var(--font-size-base);
}

.btn-sm {
  padding: var(--spacing-1) var(--spacing-3);
  font-size: var(--font-size-xs);
}

/* Cards */
.card {
  background: var(--color-bg-secondary);
  border: 1px solid var(--color-border-primary);
  border-radius: var(--radius-lg);
  padding: var(--spacing-6);
  transition: all var(--transition-base);
}

.card:hover {
  background: var(--color-bg-elevated);
  border-color: var(--color-border-secondary);
}

.card-header {
  margin-bottom: var(--spacing-4);
}

.card-title {
  font-size: var(--font-size-lg);
  font-weight: var(--font-weight-semibold);
  color: var(--color-text-primary);
  margin-bottom: var(--spacing-2);
}

.card-description {
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
  line-height: var(--line-height-relaxed);
}

/* Hero Section */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding-top: 64px;
  position: relative;
}

.hero-content {
  text-align: center;
  max-width: 800px;
}

.hero-title {
  font-size: clamp(2rem, 5vw, 3.5rem);
  font-weight: var(--font-weight-bold);
  letter-spacing: -0.03em;
  margin-bottom: var(--spacing-6);
  background: linear-gradient(135deg, var(--color-text-primary) 0%, var(--color-text-secondary) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-subtitle {
  font-size: var(--font-size-lg);
  color: var(--color-text-secondary);
  margin-bottom: var(--spacing-8);
  line-height: var(--line-height-relaxed);
}

.hero-actions {
  display: flex;
  gap: var(--spacing-4);
  justify-content: center;
  flex-wrap: wrap;
}

/* Features Grid */
.features {
  padding: var(--spacing-20) 0;
  background: var(--color-bg-primary);
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: var(--spacing-6);
}

.feature-card {
  position: relative;
  padding: var(--spacing-8);
  background: var(--color-bg-secondary);
  border: 1px solid var(--color-border-primary);
  border-radius: var(--radius-lg);
  transition: all var(--transition-base);
}

.feature-card:hover {
  transform: translateY(-2px);
  border-color: var(--color-border-secondary);
  box-shadow: 0 10px 40px rgba(0, 0, 0, 0.3);
}

.feature-icon {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 48px;
  height: 48px;
  margin-bottom: var(--spacing-4);
  background: var(--color-bg-tertiary);
  border-radius: var(--radius-lg);
  font-size: var(--font-size-xl);
  color: var(--color-accent-primary);
}

.feature-title {
  font-size: var(--font-size-lg);
  font-weight: var(--font-weight-semibold);
  margin-bottom: var(--spacing-2);
  color: var(--color-text-primary);
}

.feature-description {
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
  line-height: var(--line-height-relaxed);
}

/* Footer */
.footer {
  padding: var(--spacing-12) 0;
  background: var(--color-bg-primary);
  border-top: 1px solid var(--color-border-primary);
}

.footer-content {
  text-align: center;
  color: var(--color-text-tertiary);
  font-size: var(--font-size-sm);
}

.footer-links {
  display: flex;
  gap: var(--spacing-6);
  justify-content: center;
  margin-top: var(--spacing-4);
}

/* ============================================
   Utilities
   ============================================ */
.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }

.flex { display: flex; }
.flex-col { flex-direction: column; }
.items-center { align-items: center; }
.justify-center { justify-content: center; }
.justify-between { justify-content: space-between; }
.gap-1 { gap: var(--spacing-1); }
.gap-2 { gap: var(--spacing-2); }
.gap-3 { gap: var(--spacing-3); }
.gap-4 { gap: var(--spacing-4); }

.mt-4 { margin-top: var(--spacing-4); }
.mb-4 { margin-bottom: var(--spacing-4); }
.mt-8 { margin-top: var(--spacing-8); }
.mb-8 { margin-bottom: var(--spacing-8); }

.opacity-0 { opacity: 0; }
.opacity-50 { opacity: 0.5; }
.opacity-100 { opacity: 1; }

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

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

.animate-fadeIn {
  animation: fadeIn var(--transition-slow) ease-out forwards;
}

.animate-slideDown {
  animation: slideDown var(--transition-base) ease-out forwards;
}

/* ============================================
   Responsive Design
   ============================================ */
@media (max-width: 768px) {
  .container {
    padding: 0 var(--spacing-4);
  }
  
  .grid-cols-2,
  .grid-cols-3,
  .grid-cols-4 {
    grid-template-columns: 1fr;
  }
  
  .navbar-menu {
    display: none;
  }
  
  .hero-title {
    font-size: clamp(1.75rem, 4vw, 2.5rem);
  }
  
  .hero-actions {
    flex-direction: column;
    align-items: center;
  }
  
  .btn {
    width: 100%;
    max-width: 300px;
  }
}

@media (max-width: 480px) {
  :root {
    font-size: 14px;
  }
  
  .container {
    padding: 0 var(--spacing-3);
  }
}

/* ============================================
   Custom Scrollbar
   ============================================ */
::-webkit-scrollbar {
  width: 8px;
  height: 8px;
}

::-webkit-scrollbar-track {
  background: var(--color-bg-primary);
}

::-webkit-scrollbar-thumb {
  background: var(--color-bg-tertiary);
  border-radius: var(--radius-full);
}

::-webkit-scrollbar-thumb:hover {
  background: var(--color-border-primary);
}

/* ============================================
   Focus Styles
   ============================================ */
:focus {
  outline: none;
}

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

button:focus-visible,
a:focus-visible {
  outline-offset: 4px;
}

/* ============================================
   Selection Styles
   ============================================ */
::selection {
  background: var(--color-accent-primary);
  color: white;
}

::-moz-selection {
  background: var(--color-accent-primary);
  color: white;
}