:root {
  --primary-color: #2c3e50;
  --secondary-color: #3498db;
  --accent-color: #e74c3c;
  --text-color: #333;
  --background-color: #f8f9fa;
  --card-bg: #ffffff;
  --footer-bg: #1a252f;
  --footer-text: #e0e0e0;
  --transition: all 0.3s ease;
}

.dark-mode {
  --primary-color: #1a252f;
  --secondary-color: #1f3a5f;
  --accent-color: #c0392b;
  --text-color: #e0e0e0;
  --background-color: #121212;
  --card-bg: #1e1e1e;
  --footer-bg: #0d1117;
  --footer-text: #e0e0e0;
}

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

body {
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  line-height: 1.6;
  color: var(--text-color);
  background-color: var(--background-color);
  transition: var(--transition);
}

.container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
}

header {
  position: sticky;
  top: 0;
  z-index: 1000;
  background-color: var(--primary-color);
  color: white;
  padding: 1rem 0;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
  transition: var(--transition);
}

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

header h1 a {
  color: white;
  text-decoration: none;
  font-size: 1.8rem;
  font-weight: 600;
}

header nav ul {
  display: flex;
  list-style: none;
  gap: 20px;
}

header nav a {
  color: white;
  text-decoration: none;
  transition: var(--transition);
}

header nav a:hover {
  color: var(--secondary-color);
}

header button {
  background: var(--secondary-color);
  color: white;
  border: none;
  padding: 8px 16px;
  border-radius: 4px;
  cursor: pointer;
  font-weight: 500;
  transition: var(--transition);
}

header button:hover {
  background: #2980b9;
}

main {
  padding: 2rem 0;
  min-height: calc(100vh - 150px);
}

section, article {
  padding: 2rem 0;
  background: var(--background-color);
}

article#about .about-content {
  display: grid;
  grid-template-columns: 2fr 1fr;
  gap: 20px;
  margin-top: 1rem;
}

article#about .about-text {
  background: var(--card-bg);
  padding: 1.5rem;
  border-radius: 8px;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.05);
}

article#about aside.profile {
  background: var(--card-bg);
  padding: 1.5rem;
  border-radius: 8px;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.05);
}

article#about aside.profile img {
  width: 100%;
  border-radius: 8px;
  margin-bottom: 1rem;
}

.certificates-grid,
.projects-grid,
.gallery-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 20px;
  margin-top: 1.5rem;
}

.certificate-item,
.project-item,
.gallery-item {
  background: var(--card-bg);
  border-radius: 8px;
  overflow: hidden;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
  transition: var(--transition);
}

.certificate-item:hover,
.project-item:hover,
.gallery-item:hover {
  transform: translateY(-5px);
  box-shadow: 0 5px 15px rgba(0, 0, 0, 0.1);
}

.certificate-item img,
.project-item img,
.gallery-item img {
  width: 100%;
  height: 200px;
  object-fit: cover;
}

.certificate-item h3,
.project-item h3 {
  padding: 10px 15px;
  color: var(--primary-color);
}

.certificate-item p,
.project-item p {
  padding: 0 15px 15px;
  font-size: 0.9rem;
}

footer {
  background: var(--footer-bg);
  color: var(--footer-text);
  padding: 2rem 0;
  margin-top: auto;
}

footer .container {
  display: flex;
  justify-content: center;
  flex-direction: column;
  align-items: center;
}

footer h3 {
  margin-bottom: 1rem;
}

.social-links {
  display: flex;
  list-style: none;
  gap: 20px;
  flex-wrap: wrap;
  justify-content: center;
}

.social-links a {
  color: var(--footer-text);
  text-decoration: none;
  padding: 8px 15px;
  border-radius: 4px;
  transition: var(--transition);
  background: rgba(255, 255, 255, 0.1);
}

.social-links a:hover {
  background: var(--secondary-color);
  transform: scale(1.05);
}

/* Responsive design */
@media (max-width: 1024px) {
  article#about .about-content {
    grid-template-columns: 1fr;
  }

  .projects-grid {
    grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
  }
}

@media (max-width: 768px) {
  header .container {
    flex-direction: column;
    gap: 10px;
    text-align: center;
  }

  header nav ul {
    justify-content: center;
  }

  section, article {
    padding: 1.5rem 0;
  }

  .certificates-grid,
  .projects-grid,
  .gallery-grid {
    grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  }
}

@media (max-width: 480px) {
  header h1 a {
    font-size: 1.5rem;
  }

  .social-links {
    flex-direction: column;
    gap: 10px;
  }

  .certificates-grid,
  .projects-grid,
  .gallery-grid {
    grid-template-columns: 1fr;
  }
}