:root {
  --color-primary: #6366f1;
  --color-primary-dark: #4f46e5;
  --color-secondary: #0ea5e9;
  --color-accent: #10b981;
  --color-danger: #ef4444;
  --color-bg: #f8fafc;
  --color-card-bg: #ffffff;
  --color-text: #1e293b;
  --color-muted: #64748b;
  --color-border: #e2e8f0;
  --shadow-card: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
  --shadow-card-hover: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  min-height: 100vh;
  color: var(--color-text);
}

.hub-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 40px 20px;
}

.hub-header {
  text-align: center;
  margin-bottom: 60px;
  color: white;
}

.hub-title {
  font-size: 4rem;
  font-weight: 800;
  letter-spacing: -2px;
  margin-bottom: 10px;
  text-shadow: 0 4px 8px rgba(0, 0, 0, 0.2);
}

.ai-logo {
  background: linear-gradient(135deg, #fbbf24, #f59e0b);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hub-subtitle {
  font-size: 1.5rem;
  opacity: 0.9;
  font-weight: 300;
}

.hub-modules {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 30px;
  margin-bottom: 40px;
}

.module-card {
  background: var(--color-card-bg);
  border-radius: 20px;
  padding: 40px 30px;
  box-shadow: var(--shadow-card);
  cursor: pointer;
  transition: all 0.3s ease;
  border: 2px solid transparent;
}

.module-card:hover {
  transform: translateY(-8px);
  box-shadow: var(--shadow-card-hover);
  border-color: var(--color-primary);
}

.module-card-disabled {
  opacity: 0.6;
  cursor: not-allowed;
}

.module-card-disabled:hover {
  transform: none;
  border-color: transparent;
  box-shadow: var(--shadow-card);
}

.module-icon {
  font-size: 4rem;
  margin-bottom: 20px;
  display: block;
}

.module-icon-translate {
  background: linear-gradient(135deg, #6366f1, #8b5cf6);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.module-icon-document {
  background: linear-gradient(135deg, #0ea5e9, #06b6d4);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.module-icon-ppt {
  background: linear-gradient(135deg, #10b981, #34d399);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.module-title {
  font-size: 1.75rem;
  font-weight: 700;
  margin-bottom: 15px;
  color: var(--color-text);
}

.module-description {
  font-size: 1rem;
  line-height: 1.6;
  color: var(--color-muted);
  margin-bottom: 20px;
}

.module-tags {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
}

.tag {
  display: inline-block;
  padding: 6px 14px;
  border-radius: 20px;
  font-size: 0.875rem;
  font-weight: 500;
}

.tag:nth-child(1) {
  background: #dbeafe;
  color: #1e40af;
}

.tag:nth-child(2) {
  background: #fce7f3;
  color: #be185d;
}

.tag:nth-child(3) {
  background: #d1fae5;
  color: #065f46;
}

.hub-footer {
  text-align: center;
  padding: 30px;
  color: white;
  opacity: 0.8;
}

.topbar .back-to-hub {
  display: inline-flex;
  align-items: center;
  padding: 8px 16px;
  background: rgba(255, 255, 255, 0.1);
  border-radius: 10px;
  color: white;
  text-decoration: none;
  font-weight: 600;
  margin-right: 20px;
  transition: all 0.2s ease;
}

.topbar .back-to-hub:hover {
  background: rgba(255, 255, 255, 0.2);
  transform: translateX(-4px);
}

@media (max-width: 768px) {
  .hub-title {
    font-size: 3rem;
  }
  
  .hub-modules {
    grid-template-columns: 1fr;
  }
  
  .module-card {
    padding: 30px 20px;
  }
}