/* styles.css */
:root {
  --primary-color: #4a90e2;
  --secondary-color: #6c5ce7;
  --accent-color: #ff4757;
  --group-color: #2ecc71;
  --text-dark: #2d3436;
  --text-light: #f8f9fa;
  --transition-speed: 0.3s;
}

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

body {
  font-family: 'LXGW WenKai', sans-serif;
  line-height: 1.8;
  background-image: url('https://s21.ax1x.com/2024/12/27/pAv7481.jpg');
  background-size: cover;
  background-position: center;
  background-attachment: fixed;
  min-height: 100vh;
  color: var(--text-dark);
  display: flex;
  flex-direction: column;
}

body::after {
  content: '';
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(255, 255, 255, 0.88);
  z-index: -1;
}

a {
  color: inherit;
  text-decoration: none;
  transition: all var(--transition-speed) ease;
}

a:hover {
  text-decoration: none;
}

.navbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 1rem 2rem;
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(12px);
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
  position: sticky;
  top: 0;
  z-index: 1000;
}

.logo {
  display: flex;
  align-items: center;
  gap: 12px;
}

.logo-icon {
  width: 40px;
  height: 40px;
  transition: transform 0.3s ease;
  border-radius: 8px;
}

.logo h1 {
  margin: 0;
  font-size: 1.8rem;
  white-space: nowrap;
  background: linear-gradient(
    135deg,
    #FF6B6B 0%,
    #4ECDC4 25%,
    #45B7D1 50%,
    #96F2D7 75%,
    #FFE66D 100%
  );
  background-size: 300% 300%;
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  animation: gradient-flow 8s ease infinite;
}

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

.nav-button {
  padding: 0.6rem 1.2rem;
  border-radius: 8px;
  font-weight: 500;
  transition: all var(--transition-speed) ease;
  text-decoration: none;
  display: inline-flex;
  align-items: center;
}

.cloud-link {
  background: rgba(108, 92, 231, 0.1);
  border: 2px solid var(--secondary-color);
  color: var(--secondary-color);
}

.cloud-link:hover {
  background: var(--secondary-color);
  color: white;
  transform: translateY(-2px);
}

.card-container {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 2rem;
  padding: 2rem;
  max-width: 1200px;
  margin: 2rem auto;
  background: rgba(255, 255, 255, 0.75);
  backdrop-filter: blur(8px);
  border-radius: 16px;
}

.tutorial-card {
  background: white;
  border-radius: 16px;
  padding: 1.5rem;
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.06);
  transition: transform var(--transition-speed) ease;
}

.tutorial-card:hover {
  transform: translateY(-5px);
}

.button-group {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 0.8rem;
  width: 100%;
}

.card-button {
  padding: 0.8rem;
  border-radius: 8px;
  text-align: center;
  font-weight: 500;
  transition: all var(--transition-speed) ease;
  display: flex;
  align-items: center;
  justify-content: center;
  border: 2px solid transparent;
}

.tutorial-btn {
  background: var(--primary-color);
  color: white;
  border-color: var(--primary-color);
}

.purchase-btn {
  background: var(--secondary-color);
  color: white;
  border-color: var(--secondary-color);
}

.cloud-btn {
  background: rgba(255, 71, 87, 0.1);
  border-color: var(--accent-color);
  color: var(--accent-color);
}

.group-btn {
  background: rgba(46, 204, 113, 0.1);
  border-color: var(--group-color);
  color: var(--group-color);
}

.card-button:hover {
  filter: brightness(1.1);
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
}

.site-footer {
  text-align: center;
  padding: 2rem;
  background: transparent !important;
  margin-top: auto;
}

@keyframes gradient-flow {
  0% { background-position: 0% 50%; }
  50% { background-position: 100% 50%; }
  100% { background-position: 0% 50%; }
}

@media (max-width: 1024px) {
  .button-group {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 768px) {
  .navbar {
    padding: 0.8rem;
  }
  .logo-icon {
    width: 35px;
    height: 35px;
  }
  .logo h1 {
    font-size: 1.5rem;
  }
  .card-container {
    padding: 1rem;
  }
}

@media (max-width: 480px) {
  .button-group {
    grid-template-columns: 1fr;
  }
  .card-button {
    font-size: 0.9rem;
  }
}