:root {
    --white: #ffffff;
    --light-blue: #e3f2fd;
    --black: #212121;
    --error-red: #ff3333;
    --success-green: #4CAF50;
}

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

body {
    font-family: 'Arial', sans-serif;
    background-color: var(--light-blue);
    color: var(--black);
    line-height: 1.6;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

.header {
  background-color: var(--white);
  box-shadow: 0 2px 5px rgba(0, 0, 0, 0.1);
  padding: 1rem 0;
  position: fixed;
  width: 100%;
  top: 0;
  z-index: 1000;
}

.header-content {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

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

.nav {
  display: flex;
  gap: 1.5rem;
}

.nav a {
  color: var(--black);
  text-decoration: none;
  padding: 0.5rem 1rem;
  border-radius: 4px;
  transition: background-color 0.3s, transform 0.2s;
}

.nav a:hover,
.nav a.active {
  background-color: var(--light-blue);
  transform: translateY(-2px);
}

.main-content {
    flex: 1;
    padding: 100px 20px 40px;
    max-width: 1200px;
    margin: 0 auto;
    width: 100%;
}

.schedule-container {
    background-color: var(--white);
    padding: 2rem;
    border-radius: 10px;
    box-shadow: 0 0 20px rgba(0, 0, 0, 0.1);
}

.schedule-container h2 {
    margin-bottom: 1.5rem;
    color: var(--black);
}

.class-list {
    display: grid;
    gap: 1rem;
}

.error-message {
    color: var(--error-red);
    text-align: center;
    padding: 1rem;
    background-color: #ffe6e6;
    border-radius: 8px;
    margin-top: 1rem;
}

.class-card {
    background-color: var(--light-blue);
    padding: 1.5rem;
    border-radius: 8px;
    transition: transform 0.3s ease;
    display: grid;
    grid-template-columns: 1fr auto;
    gap: 1rem;
    align-items: center;
}

.class-card:hover {
    transform: translateY(-2px);
}

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

.class-info {
    display: grid;
    gap: 0.5rem;
    font-size: 0.9rem;
}

.class-time {
    color: var(--black);
    font-weight: 500;
}

.class-instructor {
    color: #666;
}

.footer {
  background-color: var(--white);
  padding: 3rem 0 1rem;
  margin-top: auto;
}

.footer-content {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 2rem;
}

.footer-section {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.footer-section h3 {
  color: var(--black);
  margin-bottom: 1rem;
}

.footer-section a {
  color: var(--black);
  text-decoration: none;
  transition: color 0.3s;
}

.footer-section a:hover {
  color: var(--blue-400);
}

.social-links {
  display: flex;
  gap: 1rem;
}

.footer-bottom {
  text-align: center;
  margin-top: 2rem;
  padding-top: 1rem;
  border-top: 1px solid var(--grey-200);
}

.loading-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-color: rgba(255, 255, 255, 0.95);
  display: flex;
  justify-content: center;
  align-items: center;
  z-index: 1000;
  opacity: 1;
  transition: opacity 0.3s ease;
}

.loading-overlay.hidden {
  opacity: 0;
  pointer-events: none;
}

.loading-content {
  text-align: center;
  padding: 2rem;
}

.spinner {
  width: 48px;
  height: 48px;
  border: 4px solid var(--blue-200);
  border-top-color: var(--blue-500);
  border-radius: 50%;
  margin: 0 auto 1rem;
  animation: spin 1s linear infinite;
}

@keyframes spin {
  to {
    transform: rotate(360deg);
  }
}

.loading-text {
  font-size: 1.5rem;
  color: var(--black);
  margin-bottom: 0.5rem;
}

.loading-subtext {
  color: var(--grey-500);
}

@media (max-width: 768px) {
    .header-content {
        flex-direction: column;
        gap: 1rem;
    }

    .nav {
        flex-wrap: wrap;
        justify-content: center;
    }

    .class-card {
        grid-template-columns: 1fr;
    }
}