:root {
  --bg: #f9f9f9;
  --text: #111;
  --primary: #3b82f6;
  --secondary: #e5e7eb;
  --card-bg: #fff;
  --transition: 0.3s ease;
  --focus-color: #2563eb;
}

body.dark {
  --bg: #111827;
  --text: #f9f9f9;
  --primary: #60a5fa;
  --secondary: #1f2937;
  --card-bg: #1e293b;
  --focus-color: #93c5fd;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
  background: var(--bg);
  color: var(--text);
  transition: background var(--transition), color var(--transition);
}

.container {
  width: 90%;
  max-width: 960px;
  margin: auto;
}

.skills {
  max-width: 600px;
  margin: 2rem auto;
  text-align: center;
}

.hero {
  background: var(--primary);
  color: white;
  text-align: center;
  padding: 3rem 1rem;
  position: relative;
  user-select: none;
}

#toggle-theme {
  position: absolute;
  top: 1rem;
  right: 1rem;
  background: transparent;
  border: none;
  font-size: 1.8rem;
  cursor: pointer;
  color: white;
  transition: transform 0.2s ease;
}

#toggle-theme:hover,
#toggle-theme:focus {
  transform: scale(1.2);
  outline: 2px solid var(--focus-color);
  outline-offset: 2px;
}

.navbar {
  background: var(--secondary);
  box-shadow: inset 0 -1px 0 rgba(0, 0, 0, 0.1);
}

.navbar ul {
  display: flex;
  justify-content: center;
  list-style: none;
  padding: 1rem 0;
  margin: 0;
  gap: 2.5rem;
}

.navbar a {
  text-decoration: none;
  color: var(--text);
  font-weight: 600;
  font-size: 1.1rem;
  transition: color var(--transition);
  cursor: pointer;
}

.navbar a:hover,
.navbar a:focus {
  color: var(--primary);
  outline: none;
  text-decoration: underline;
}

h2 {
  color: var(--primary);
  margin-top: 2rem;
  margin-bottom: 1rem;
  font-size: 2.25rem;
  font-weight: 700;
  user-select: none;
}

.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1.75rem;
  margin-top: 1.5rem;
}

.card {
  background: var(--card-bg);
  border-radius: 12px;
  padding: 1.75rem;
  box-shadow: 0 4px 16px rgba(0, 0, 0, 0.07);
  transition: transform var(--transition), box-shadow var(--transition);
  cursor: pointer;
  user-select: none;
}

.card:hover,
.card:focus {
  transform: translateY(-6px);
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.15);
  outline: none;
}

.card:focus-visible {
  outline: 3px solid var(--focus-color);
  outline-offset: 4px;
}

footer {
  text-align: center;
  padding: 2rem 1rem;
  background: var(--secondary);
  margin-top: 4rem;
  color: var(--text);
  font-size: 0.9rem;
  user-select: none;
}

a {
  color: var(--primary);
  transition: color var(--transition);
  cursor: pointer;
}

a:hover,
a:focus {
  color: #2563eb;
  outline: none;
  text-decoration: underline;
}

.fade-in {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 1s ease, transform 1s ease;
}

.fade-in.visible {
  opacity: 1;
  transform: translateY(0);
}