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

:root {
  --color-bg: #ffffff;
  --color-bg-subtle: #f8f9fa;
  --color-text: #212529;
  --color-text-muted: #6c757d;
  --color-accent: #2563eb;
  --color-accent-hover: #1d4ed8;
  --color-border: #e5e7eb;
  --color-border-light: #f3f4f6;
  
  --font-sans: 'Pretendard', 'Noto Sans KR', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  
  --space-xs: 0.25rem;
  --space-sm: 0.5rem;
  --space-md: 1rem;
  --space-lg: 1.5rem;
  --space-xl: 2rem;
  --space-2xl: 3rem;
  
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;
  
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.07);
  --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.1);
  
  --container-max: 900px;
  --header-height: 64px;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
}

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

a {
  color: var(--color-accent);
  text-decoration: none;
  transition: color 0.2s ease;
}

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

img {
  max-width: 100%;
  height: auto;
  display: block;
}

h1, h2, h3, h4, h5, h6 {
  font-weight: 600;
  line-height: 1.3;
  color: var(--color-text);
}

h1 { font-size: 1.75rem; margin-bottom: var(--space-lg); }
h2 { font-size: 1.375rem; margin-top: var(--space-xl); margin-bottom: var(--space-md); color: var(--color-text-muted); }
h2:first-child { margin-top: 0; }

p {
  margin-bottom: var(--space-md);
}

ul, ol {
  padding-left: var(--space-lg);
  margin-bottom: var(--space-md);
}

li {
  margin-bottom: var(--space-sm);
}

.container {
  width: 100%;
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--space-md);
}

/* Header */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--color-bg);
  border-bottom: 1px solid var(--color-border);
  height: var(--header-height);
  display: flex;
  align-items: center;
}

.site-header .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
}

.logo img {
  height: 40px;
  width: auto;
}

.logo-text {
  font-size: 1.125rem;
  font-weight: 600;
  color: var(--color-text);
}

/* Navigation */
.nav {
  display: flex;
  align-items: center;
  gap: var(--space-lg);
}

.nav-link {
  color: var(--color-text-muted);
  font-weight: 500;
  font-size: 0.9375rem;
  padding: var(--space-sm) 0;
  position: relative;
  transition: color 0.2s ease;
}

.nav-link:hover,
.nav-link.active {
  color: var(--color-text);
  text-decoration: none;
}

.nav-link.active::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  height: 2px;
  background: var(--color-accent);
  border-radius: 1px;
}

/* Mobile menu button */
.mobile-menu-toggle {
  display: none;
  background: none;
  border: none;
  padding: var(--space-sm);
  cursor: pointer;
}

.mobile-menu-toggle span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--color-text);
  margin: 5px 0;
  transition: 0.3s;
}

/* Main content */
.main {
  flex: 1;
  padding: var(--space-xl) 0;
}

.page-header {
  margin-bottom: var(--space-xl);
  padding-bottom: var(--space-lg);
  border-bottom: 1px solid var(--color-border-light);
}

.page-title {
  font-size: 1.5rem;
  margin-bottom: var(--space-xs);
}

.page-subtitle {
  color: var(--color-text-muted);
  font-size: 0.9375rem;
}

/* Article / Content */
.content {
  line-height: 1.7;
}

.content img {
  margin: var(--space-lg) 0;
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-sm);
}

.content p + h2 {
  margin-top: var(--space-xl);
}

.feature-list {
  list-style: none;
  padding: 0;
}

.feature-list li {
  padding: var(--space-md);
  background: var(--color-bg-subtle);
  border-radius: var(--radius-md);
  margin-bottom: var(--space-md);
  display: flex;
  align-items: center;
  gap: var(--space-md);
}

.feature-list li::before {
  content: '';
  width: 8px;
  height: 8px;
  background: var(--color-accent);
  border-radius: 50%;
  flex-shrink: 0;
}

/* Download section */
.download-section {
  background: var(--color-bg-subtle);
  border-radius: var(--radius-lg);
  padding: var(--space-xl);
  margin: var(--space-lg) 0;
}

.download-btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  padding: var(--space-md) var(--space-lg);
  background: var(--color-accent);
  color: white;
  font-weight: 600;
  font-size: 1rem;
  border-radius: var(--radius-md);
  text-decoration: none;
  transition: all 0.2s ease;
}

.download-btn:hover {
  background: var(--color-accent-hover);
  color: white;
  text-decoration: none;
  transform: translateY(-1px);
  box-shadow: var(--shadow-md);
}

.download-note {
  font-size: 0.875rem;
  color: var(--color-text-muted);
  margin-top: var(--space-md);
}

/* News list */
.news-list {
  list-style: none;
  padding: 0;
}

.news-item {
  padding: var(--space-lg) 0;
  border-bottom: 1px solid var(--color-border-light);
}

.news-item:first-child {
  padding-top: 0;
}

.news-item:last-child {
  border-bottom: none;
}

.news-date {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--color-accent);
  margin-bottom: var(--space-sm);
}

.news-content {
  color: var(--color-text-muted);
  font-size: 0.9375rem;
}

.news-content ul {
  margin-top: var(--space-md);
  margin-bottom: 0;
}

/* Requirements list */
.requirements {
  background: var(--color-bg-subtle);
  border-radius: var(--radius-md);
  padding: var(--space-lg);
  margin-bottom: var(--space-xl);
}

.requirements h3 {
  font-size: 1rem;
  margin-bottom: var(--space-md);
}

.requirements ul {
  margin-bottom: 0;
}

/* Installation steps */
.install-steps {
  counter-reset: step;
  list-style: none;
  padding: 0;
}

.install-steps li {
  counter-increment: step;
  position: relative;
  padding-left: var(--space-2xl);
  margin-bottom: var(--space-lg);
}

.install-steps li::before {
  content: counter(step);
  position: absolute;
  left: 0;
  top: 2px;
  width: 24px;
  height: 24px;
  background: var(--color-accent);
  color: white;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.875rem;
  font-weight: 600;
}

.install-steps img {
  margin: var(--space-md) 0;
}

/* Footer */
.site-footer {
  background: var(--color-bg-subtle);
  border-top: 1px solid var(--color-border);
  padding: var(--space-lg) 0;
  margin-top: auto;
}

.footer-content {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.copyright {
  font-size: 0.875rem;
  color: var(--color-text-muted);
}

/* Error page */
.error-page {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  min-height: 100vh;
  text-align: center;
  padding: var(--space-xl);
}

.error-page img {
  max-width: 400px;
  margin-bottom: var(--space-lg);
}

.error-page h1 {
  font-size: 1.5rem;
  color: var(--color-text-muted);
  margin-bottom: var(--space-md);
}

.error-page a {
  color: var(--color-accent);
}

/* Responsive */
@media (max-width: 768px) {
  :root {
    --space-xl: 1.5rem;
    --space-2xl: 2rem;
  }
}

@media (max-width: 640px) {
  .nav {
    position: fixed;
    top: var(--header-height);
    left: 0;
    right: 0;
    background: var(--color-bg);
    flex-direction: column;
    padding: var(--space-lg);
    gap: 0;
    border-bottom: 1px solid var(--color-border);
    transform: translateY(-100%);
    opacity: 0;
    visibility: hidden;
    transition: all 0.3s ease;
    z-index: 99;
  }
  
  .nav.open {
    transform: translateY(0);
    opacity: 1;
    visibility: visible;
  }
  
  .nav-link {
    padding: var(--space-md) 0;
    width: 100%;
    border-bottom: 1px solid var(--color-border-light);
  }
  
  .nav-link:last-child {
    border-bottom: none;
  }
  
  .mobile-menu-toggle {
    display: block;
  }
  
  .mobile-menu-toggle.open span:nth-child(1) {
    transform: rotate(45deg) translate(5px, 5px);
  }
  
  .mobile-menu-toggle.open span:nth-child(2) {
    opacity: 0;
  }
  
  .mobile-menu-toggle.open span:nth-child(3) {
    transform: rotate(-45deg) translate(5px, -5px);
  }
  
  .download-section {
    padding: var(--space-lg);
  }
  
  .footer-content {
    flex-direction: column;
    gap: var(--space-md);
    text-align: center;
  }
}

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

.text-muted {
  color: var(--color-text-muted);
}

.mt-0 { margin-top: 0; }
.mb-0 { margin-bottom: 0; }