:root {
  --primary: #e94560;
  --primary-dark: #c23854;
  --secondary: #0f3460;
  --bg: #1a1a2e;
  --bg-card: #16213e;
  --text: #f8fafc;
  --text-muted: #94a3b8;
  --border: #2d3748;
  --accent: #16e7cf;
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Noto Sans KR', sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.8;
  padding: 20px;
  max-width: 900px;
  margin: 0 auto;
}

header {
  text-align: center;
  padding: 40px 20px;
  border-bottom: 2px solid var(--border);
  margin-bottom: 40px;
}

.standard-badge {
  display: inline-block;
  background: var(--primary);
  color: white;
  padding: 8px 16px;
  border-radius: 20px;
  font-size: 0.9rem;
  font-weight: 600;
  margin-bottom: 15px;
}

h1 {
  font-size: 2.5rem;
  margin-bottom: 10px;
  background: linear-gradient(90deg, var(--primary), var(--accent));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.subtitle {
  font-size: 1.2rem;
  color: var(--text-muted);
  margin-bottom: 8px;
}

.version {
  font-size: 0.95rem;
  color: var(--text-muted);
  margin-top: 15px;
}

nav {
  background: var(--bg-card);
  padding: 30px;
  border-radius: 12px;
  margin-bottom: 40px;
  border: 1px solid var(--border);
}

nav h2 {
  font-size: 1.5rem;
  margin-bottom: 20px;
  color: var(--primary);
}

nav ol {
  list-style-position: inside;
  padding-left: 10px;
}

nav li {
  margin-bottom: 12px;
  line-height: 1.6;
}

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

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

main {
  padding: 20px 0;
}

section {
  margin-bottom: 40px;
}

h2 {
  font-size: 2rem;
  margin: 40px 0 20px;
  color: var(--primary);
  border-left: 4px solid var(--primary);
  padding-left: 15px;
}

h3 {
  font-size: 1.5rem;
  margin: 30px 0 15px;
  color: var(--accent);
}

h4 {
  font-size: 1.2rem;
  margin: 20px 0 10px;
  color: var(--text);
}

p {
  margin-bottom: 15px;
  line-height: 1.8;
}

ul, ol {
  margin-left: 25px;
  margin-bottom: 20px;
}

li {
  margin-bottom: 10px;
  line-height: 1.7;
}

.info-box {
  background: var(--bg-card);
  border-left: 4px solid var(--primary);
  padding: 20px;
  margin: 25px 0;
  border-radius: 8px;
  border: 1px solid var(--border);
}

.info-box h4 {
  color: var(--primary);
  margin-bottom: 12px;
}

.warning-box {
  background: rgba(233, 69, 96, 0.1);
  border-left: 4px solid var(--primary);
  padding: 20px;
  margin: 25px 0;
  border-radius: 8px;
  border: 1px solid rgba(233, 69, 96, 0.3);
}

.warning-box h4 {
  color: var(--primary);
  margin-bottom: 12px;
}

.code-box {
  background: #0d1117;
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 20px;
  margin: 20px 0;
  overflow-x: auto;
  font-family: 'Courier New', monospace;
  font-size: 0.9rem;
  line-height: 1.6;
  color: #e6edf3;
}

code {
  background: rgba(233, 69, 96, 0.1);
  padding: 2px 6px;
  border-radius: 4px;
  font-family: 'Courier New', monospace;
  font-size: 0.9em;
  color: var(--primary);
}

pre code {
  background: transparent;
  padding: 0;
  color: #e6edf3;
}

table {
  width: 100%;
  border-collapse: collapse;
  margin: 25px 0;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 8px;
  overflow: hidden;
}

th {
  background: var(--primary);
  color: white;
  padding: 12px;
  text-align: left;
  font-weight: 600;
}

td {
  padding: 12px;
  border-bottom: 1px solid var(--border);
}

tr:last-child td {
  border-bottom: none;
}

tr:hover {
  background: rgba(233, 69, 96, 0.05);
}

.navigation {
  display: flex;
  justify-content: space-between;
  margin-top: 50px;
  padding-top: 30px;
  border-top: 2px solid var(--border);
  gap: 15px;
}

.nav-button {
  display: inline-block;
  padding: 12px 24px;
  background: var(--bg-card);
  color: var(--text);
  text-decoration: none;
  border-radius: 8px;
  transition: all 0.2s;
  border: 1px solid var(--border);
  font-weight: 500;
}

.nav-button:hover {
  background: var(--primary);
  color: white;
  border-color: var(--primary);
  transform: translateY(-2px);
}

.nav-button.next {
  background: var(--primary);
  color: white;
  border-color: var(--primary);
}

.nav-button.next:hover {
  background: var(--primary-dark);
}

footer {
  margin-top: 60px;
  padding: 30px 0;
  border-top: 2px solid var(--border);
  text-align: center;
  color: var(--text-muted);
}

.footer-motto {
  color: #ffd700;
  font-weight: 600;
  margin-top: 10px;
}

.shield-layers {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 20px;
  margin: 30px 0;
}

.shield-card {
  background: var(--bg-card);
  padding: 25px;
  border-radius: 12px;
  text-align: center;
  border: 1px solid var(--border);
  transition: all 0.2s;
}

.shield-card:hover {
  transform: translateY(-3px);
  border-color: var(--primary);
}

.shield-icon {
  font-size: 3rem;
  margin-bottom: 15px;
}

@media (max-width: 768px) {
  body {
    padding: 15px;
  }

  h1 {
    font-size: 2rem;
  }

  h2 {
    font-size: 1.6rem;
  }

  h3 {
    font-size: 1.3rem;
  }

  .navigation {
    flex-direction: column;
  }

  .nav-button {
    text-align: center;
  }
}