:root {
  --bg-color: #ffffff;
  --text-color: #333333;
  --accent-color: #007bff;
  --card-bg: #f8f9fa;
  --border-color: #e9ecef;
  --shadow: rgba(0, 0, 0, 0.1);
}

[data-theme="dark"] {
  --bg-color: #1a1a1a;
  --text-color: #ffffff;
  --accent-color: #4dabf7;
  --card-bg: #2d2d2d;
  --border-color: #404040;
  --shadow: rgba(0, 0, 0, 0.3);
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  line-height: 1.6;
  color: var(--text-color);
  background-color: var(--bg-color);
  transition: background-color 0.3s, color 0.3s;
}

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

.header {
  background-color: var(--accent-color);
  color: white;
  padding: 2rem 0;
}

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

.profile h1 {
  font-size: 2.5rem;
  margin-bottom: 0.5rem;
}

.profile p {
  font-size: 1.1rem;
  opacity: 0.9;
}

.theme-toggle {
  background: rgba(255, 255, 255, 0.2);
  border: none;
  color: white;
  padding: 0.5rem 1rem;
  border-radius: 5px;
  cursor: pointer;
  transition: background 0.3s;
}

.theme-toggle:hover {
  background: rgba(255, 255, 255, 0.3);
}

.main {
  padding: 2rem 0;
}

.section {
  margin-bottom: 3rem;
}

.section h2 {
  font-size: 2rem;
  margin-bottom: 1.5rem;
  text-align: center;
  color: var(--accent-color);
}

.skills-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
  gap: 1rem;
}

.skill-card {
  background-color: var(--card-bg);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 1rem;
  text-align: center;
  font-weight: bold;
  transition: transform 0.3s, box-shadow 0.3s;
}

.skill-card:hover {
  transform: translateY(-5px);
  box-shadow: 0 4px 8px var(--shadow);
}

.projects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 1.5rem;
}

.project-card {
  background-color: var(--card-bg);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 1.5rem;
  transition: transform 0.3s, box-shadow 0.3s;
  animation: fadeInUp 0.6s ease-out;
}

.project-card:hover {
  transform: translateY(-5px);
  box-shadow: 0 6px 12px var(--shadow);
}

.project-card h3 {
  margin-bottom: 0.5rem;
  color: var(--accent-color);
}

.footer {
  background-color: var(--card-bg);
  text-align: center;
  padding: 1rem 0;
  margin-top: 2rem;
}

@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

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

  .profile h1 {
    font-size: 2rem;
  }

  .skills-grid {
    grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
  }

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

@media (max-width: 640px) {
  .site-header {
    padding: 56px 16px;
  }

  .container {
    padding: 16px;
  }
}