:root {
  --primary-color: #4a90e2;
  --secondary-color: #61afef;
  --bg-color: #f8f9fa;
  --text-color: #2d3436;
  --card-bg: #ffffff;
  --nav-bg: #ffffff;
  --footer-bg: #f1f3f5;
  --border-color: #dee2e6;
}

body.dark-mode {
  --bg-color: #1a1a1b;
  --text-color: #e9ecef;
  --card-bg: #2d2d2e;
  --nav-bg: #2d2d2e;
  --footer-bg: #121212;
  --border-color: #444;
}

body {
  background-color: var(--bg-color);
  color: var(--text-color);
  font-family: 'Apple SD Gothic Neo', 'Malgun Gothic', sans-serif;
  margin: 0;
  line-height: 1.6;
  transition: background-color 0.3s;
}

/* Navbar */
header {
  position: sticky;
  top: 0;
  z-index: 1000;
  background-color: var(--nav-bg);
  box-shadow: 0 2px 10px rgba(0,0,0,0.1);
}

.navbar {
  max-width: 1100px;
  margin: 0 auto;
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 10px 20px;
}

.logo {
  font-size: 1.5rem;
  font-weight: 800;
  color: var(--primary-color);
}

.nav-links {
  list-style: none;
  display: flex;
  gap: 20px;
  margin: 0;
  padding: 0;
}

.nav-links a {
  text-decoration: none;
  color: var(--text-color);
  font-weight: 600;
  transition: color 0.2s;
}

.nav-links a:hover { color: var(--primary-color); }

.nav-right { display: flex; align-items: center; gap: 15px; }

.icon-btn {
  background: none;
  border: none;
  font-size: 1.2rem;
  cursor: pointer;
  padding: 5px;
}

/* Main Content */
main {
  max-width: 1100px;
  margin: 0 auto;
  padding: 20px;
}

.hero {
  text-align: center;
  padding: 60px 0;
}

.content-block {
  background: var(--card-bg);
  padding: 40px;
  border-radius: 20px;
  margin-bottom: 40px;
  box-shadow: 0 4px 20px rgba(0,0,0,0.05);
}

.grid-container {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 20px;
  margin-bottom: 40px;
}

.info-card {
  background: var(--card-bg);
  padding: 30px;
  border-radius: 20px;
  box-shadow: 0 4px 15px rgba(0,0,0,0.05);
}

/* Test Container */
.test-container {
  max-width: 500px;
  margin: 0 auto;
  background: var(--card-bg);
  padding: 30px;
  border-radius: 20px;
  box-shadow: 0 10px 30px rgba(0,0,0,0.1);
}

#image-container {
  min-height: 200px;
  display: flex;
  align-items: center;
  justify-content: center;
  border: 2px dashed var(--border-color);
  border-radius: 15px;
  margin-bottom: 20px;
  overflow: hidden;
}

/* Buttons */
.primary-btn {
  background-color: var(--primary-color);
  color: white;
  border: none;
  padding: 15px 30px;
  border-radius: 10px;
  font-size: 1.1rem;
  font-weight: bold;
  cursor: pointer;
  width: 100%;
  transition: transform 0.2s;
}

.primary-btn:hover { transform: translateY(-2px); }

.secondary-btn {
  background-color: var(--text-color);
  color: var(--bg-color);
  border: none;
  padding: 12px 25px;
  border-radius: 8px;
  font-weight: bold;
  cursor: pointer;
}

.privacy-note {
  font-size: 0.8rem;
  color: #888;
  margin-top: 10px;
}

/* Footer */
footer {
  background-color: var(--footer-bg);
  padding: 40px 20px;
  text-align: center;
  border-top: 1px solid var(--border-color);
}

.footer-links {
  list-style: none;
  padding: 0;
  display: flex;
  justify-content: center;
  gap: 20px;
  margin-top: 15px;
}

.footer-links a {
  text-decoration: none;
  color: #666;
  font-size: 0.9rem;
}

/* Ad Slot Placeholder */
.ad-slot {
  margin: 30px 0;
  text-align: center;
  min-height: 90px;
}

@media (max-width: 768px) {
  .nav-links { display: none; }
  .content-block { padding: 25px; }
}