:root {
  --bg-light: #ffffff;
  --text-light: #111111;
  --accent-light: #0056b3;
  --bg-dark: #111111;
  --text-dark: #f2f2f2;
  --accent-dark: #4da3ff;
}

/* Skip link for accessibility */
.skip-link {
  position: absolute;
  top: -40px;
  left: 0;
  background: var(--accent-light);
  color: white;
  padding: 8px;
  text-decoration: none;
  z-index: 100;
  border-radius: 4px;
}

.skip-link:focus {
  top: 0;
}

body {
  font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
  margin: 0;
  padding: 0;
  background-color: var(--bg-light);
  color: var(--text-light);
  transition: background-color 0.3s, color 0.3s;
  scroll-behavior: smooth;
}

body.dark {
  background-color: var(--bg-dark);
  color: var(--text-dark);
}

/* Header */
header {
  text-align: center;
  padding: 2rem 1rem;
  background: linear-gradient(135deg, #0078ff, #00c6ff);
  color: white;
  position: relative;
}

.logo {
  width: 120px;
  height: auto;
  display: block;
  margin: 0 auto 1rem auto;
  border-radius: 10px;
  background-color: white;
  padding: 5px;
}

h1 {
  margin: 0.2em 0;
}

.toggle-theme {
  position: absolute;
  top: 1rem;
  right: 1rem;
  padding: 0.5rem 1rem;
  border: none;
  border-radius: 20px;
  cursor: pointer;
  background: rgba(255, 255, 255, 0.2);
  color: white;
  font-size: 0.9em;
  transition: 0.3s;
}

.toggle-theme:hover {
  background: rgba(255, 255, 255, 0.4);
}

/* Content */
main {
  min-height: calc(100vh - 200px);
}

section {
  max-width: 800px;
  margin: 2rem auto;
  padding: 0 1rem;
  line-height: 1.8;
}

ul {
  margin-left: 1.2rem;
}

.register-btn {
  display: inline-block;
  margin-top: 1.5rem;
  padding: 0.8rem 1.5rem;
  font-size: 1rem;
  text-decoration: none;
  color: white;
  background-color: #0078ff;
  border-radius: 8px;
  transition: background-color 0.3s;
}

.register-btn:hover,
.register-btn:focus {
  background-color: #0056b3;
  outline: 2px solid rgba(255, 255, 255, 0.5);
  outline-offset: 2px;
}

.register-btn:active {
  transform: scale(0.98);
}

footer {
  text-align: center;
  padding: 1rem;
  font-size: 0.9em;
  opacity: 0.8;
  border-top: 1px solid rgba(0, 0, 0, 0.1);
}

body.dark .register-btn {
  background-color: #4da3ff;
}

body.dark .register-btn:hover,
body.dark .register-btn:focus {
  background-color: #66b3ff;
}

body.dark footer {
  border-top: 1px solid rgba(255, 255, 255, 0.1);
}

/* Responsive */
@media (max-width: 600px) {
  h1 {
    font-size: 1.4rem;
  }
  .logo {
    width: 100px;
  }
  .toggle-theme {
    font-size: 0.8em;
    padding: 0.4rem 0.8rem;
  }
  header {
    padding: 1.5rem 1rem;
  }
  .nav-link {
    display: block;
    margin: 0.5rem 0;
    text-align: center;
  }
  section {
    margin: 1.5rem auto;
    padding: 0 1rem;
  }
  .register-btn {
    display: block;
    margin: 0.5rem auto;
    text-align: center;
  }
}
nav {
  margin-top: 1rem;
}

.nav-link {
  color: white;
  text-decoration: none;
  background: rgba(255, 255, 255, 0.2);
  padding: 0.4rem 1rem;
  border-radius: 15px;
  font-size: 0.9em;
  transition: background 0.3s;
  margin: 0 0.25rem;
  display: inline-block;
}

.nav-link:hover,
.nav-link:focus {
  background: rgba(255, 255, 255, 0.4);
  outline: 2px solid rgba(255, 255, 255, 0.6);
  outline-offset: 2px;
}

.nav-link.active {
  background: rgba(255, 255, 255, 0.3);
  font-weight: 600;
}

/* Tutors grid */
.tutors-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(230px, 1fr));
  gap: 1.5rem;
  margin-top: 2rem;
}

.tutor-card {
  text-align: center;
  background: rgba(0, 0, 0, 0.03);
  padding: 1.5rem;
  border-radius: 15px;
  transition: transform 0.2s;
}

.tutor-card:hover {
  transform: scale(1.03);
}

body.dark .tutor-card {
  background: rgba(255, 255, 255, 0.05);
}

.tutor-card img {
  width: 100px;
  height: 100px;
  object-fit: cover;
  border-radius: 50%;
  margin-bottom: 1rem;
}
.btn {
  background: var(--accent-color);
  color: white;
  padding: 10px 20px;
  border-radius: 8px;
  text-decoration: none;
  font-weight: bold;
  transition: 0.3s;
}
.btn:hover {
  opacity: 0.85;
}