/* ========================================================================= */
/* SHARED HUB SYSTEM (AI, Tools, Learning, Gaming)                           */
/* ========================================================================= */

:root {
  --hub-bg: #000000;
  --hub-surface: #0a0a0a;
  --hub-card-bg: #111111;
  --hub-card-hover: #1a1a1a;
  --hub-border: rgba(255, 255, 255, 0.1);
  --hub-border-hover: rgba(59, 130, 246, 0.4);
  --hub-text-primary: #ffffff;
  --hub-text-secondary: #a1a1aa;
  --hub-accent: #3b82f6;
  --hub-accent-hover: #2563eb;
  --hub-radius: 12px;
  --hub-shadow: 0 4px 20px rgba(0, 0, 0, 0.5);
  --hub-shadow-hover: 0 8px 30px rgba(59, 130, 246, 0.15);
  --hub-transition: all 0.25s cubic-bezier(0.4, 0, 0.2, 1);
}

body.hub-page {
  background-color: var(--hub-bg);
  color: var(--hub-text-primary);
  font-family: 'Inter', system-ui, sans-serif;
  margin: 0;
  min-height: 100vh;
}


.hub-container {
  max-width: 1280px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

/* --- Hero Section --- */
.hub-hero {
  text-align: center;
  padding: 4rem 1rem 3rem;
  background: radial-gradient(circle at top, rgba(59, 130, 246, 0.1) 0%, transparent 60%);
}

.hub-title {
  font-family: 'Space Grotesk', sans-serif;
  font-size: clamp(2.5rem, 5vw, 4rem);
  font-weight: 800;
  margin-bottom: 1rem;
  background: linear-gradient(135deg, #ffffff, #a1a1aa);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hub-subtitle {
  color: var(--hub-text-secondary);
  font-size: clamp(1rem, 2vw, 1.25rem);
  max-width: 600px;
  margin: 0 auto;
}

/* --- Search & Filters --- */
.hub-search-section {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1.5rem;
  margin-bottom: 3rem;
}

.hub-search-bar {
  position: relative;
  width: 100%;
  max-width: 600px;
}

.hub-search-icon {
  position: absolute;
  left: 1rem;
  top: 50%;
  transform: translateY(-50%);
  color: var(--hub-text-secondary);
  pointer-events: none;
}

.hub-search-input {
  width: 100%;
  padding: 1rem 3rem;
  background: var(--hub-surface);
  border: 1px solid var(--hub-border);
  border-radius: 50px;
  color: var(--hub-text-primary);
  font-size: 1rem;
  transition: var(--hub-transition);
}

.hub-search-input:focus {
  outline: none;
  border-color: var(--hub-accent);
  box-shadow: 0 0 0 4px rgba(59, 130, 246, 0.1);
}

.hub-clear-btn {
  position: absolute;
  right: 1rem;
  top: 50%;
  transform: translateY(-50%);
  background: none;
  border: none;
  color: var(--hub-text-secondary);
  cursor: pointer;
  display: none;
  padding: 4px;
}

.hub-clear-btn:hover {
  color: var(--hub-text-primary);
}

.hub-filters {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  justify-content: center;
}

.hub-filter-btn {
  background: var(--hub-surface);
  border: 1px solid var(--hub-border);
  color: var(--hub-text-secondary);
  padding: 0.5rem 1rem;
  border-radius: 50px;
  font-size: 0.9rem;
  cursor: pointer;
  transition: var(--hub-transition);
}

.hub-filter-btn:hover {
  background: var(--hub-card-hover);
  color: var(--hub-text-primary);
}

.hub-filter-btn.active {
  background: var(--hub-accent);
  color: #fff;
  border-color: var(--hub-accent);
}

/* --- Grids & Layouts --- */
.hub-section {
  margin-bottom: 4rem;
}

.hub-section-title {
  font-family: 'Space Grotesk', sans-serif;
  font-size: 1.75rem;
  margin-bottom: 1.5rem;
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.hub-grid {
  display: grid;
  grid-template-columns: repeat(1, 1fr);
  gap: 1.5rem;
}

@media (min-width: 640px) {
  .hub-grid { grid-template-columns: repeat(2, 1fr); }
}

@media (min-width: 1024px) {
  .hub-grid { grid-template-columns: repeat(3, 1fr); }
}

@media (min-width: 1280px) {
  .hub-grid { grid-template-columns: repeat(4, 1fr); }
}

/* --- Generic Hub Card --- */
.hub-card {
  background: var(--hub-card-bg);
  border: 1px solid var(--hub-border);
  border-radius: var(--hub-radius);
  overflow: hidden;
  display: flex;
  flex-direction: column;
  transition: var(--hub-transition);
  box-shadow: var(--hub-shadow);
  text-decoration: none;
  color: inherit;
}

.hub-card:hover {
  transform: translateY(-4px);
  border-color: var(--hub-border-hover);
  box-shadow: var(--hub-shadow-hover);
}

.hub-card-image {
  width: 100%;
  aspect-ratio: 16/9;
  object-fit: cover;
  background: var(--hub-surface);
}

.hub-card-icon {
  font-size: 2.5rem;
  padding: 1.5rem 1.5rem 0;
  display: flex;
  align-items: center;
}

.hub-card-icon img {
  width: 48px;
  height: 48px;
  border-radius: 8px;
}

.hub-card-content {
  padding: 1.5rem;
  flex: 1;
  display: flex;
  flex-direction: column;
}

.hub-card-badge {
  display: inline-block;
  background: rgba(255, 255, 255, 0.1);
  color: var(--hub-text-secondary);
  font-size: 0.75rem;
  font-weight: 600;
  padding: 4px 8px;
  border-radius: 4px;
  margin-bottom: 0.75rem;
  text-transform: uppercase;
}

.hub-card-title {
  font-size: 1.25rem;
  font-weight: 700;
  margin: 0 0 0.5rem;
  color: var(--hub-text-primary);
}

.hub-card-desc {
  font-size: 0.95rem;
  color: var(--hub-text-secondary);
  line-height: 1.5;
  margin: 0 0 1.5rem;
  flex: 1;
}

.hub-card-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-top: auto;
  border-top: 1px solid var(--hub-border);
  padding-top: 1rem;
}

.hub-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.5rem 1rem;
  background: transparent;
  border: 1px solid var(--hub-border);
  color: var(--hub-text-primary);
  border-radius: 6px;
  font-weight: 500;
  font-size: 0.9rem;
  cursor: pointer;
  transition: var(--hub-transition);
  text-decoration: none;
}

.hub-btn:hover {
  background: var(--hub-surface);
  border-color: var(--hub-text-primary);
}

.hub-btn.primary {
  background: var(--hub-accent);
  border-color: var(--hub-accent);
  color: #fff;
}

.hub-btn.primary:hover {
  background: var(--hub-accent-hover);
  border-color: var(--hub-accent-hover);
}

/* --- Loading Skeletons --- */
.hub-skeleton {
  background: linear-gradient(90deg, var(--hub-surface) 25%, var(--hub-card-bg) 50%, var(--hub-surface) 75%);
  background-size: 200% 100%;
  animation: shimmer 1.5s infinite;
  border-radius: 4px;
}

@keyframes shimmer {
  0% { background-position: 200% 0; }
  100% { background-position: -200% 0; }
}

.skeleton-card {
  height: 350px;
  border-radius: var(--hub-radius);
}

/* --- Empty / Error States --- */
.hub-empty-state {
  text-align: center;
  padding: 4rem 1rem;
  color: var(--hub-text-secondary);
  grid-column: 1 / -1;
}

.hub-empty-icon {
  font-size: 3rem;
  margin-bottom: 1rem;
  opacity: 0.5;
}

/* --- Functional Tools Modals/Containers --- */
.tool-interface {
  background: var(--hub-card-bg);
  border: 1px solid var(--hub-border);
  border-radius: var(--hub-radius);
  padding: 2rem;
  margin-bottom: 2rem;
  display: none; /* Hidden by default */
}

.tool-interface.active {
  display: block;
}

.tool-textarea {
  width: 100%;
  min-height: 150px;
  background: var(--hub-surface);
  border: 1px solid var(--hub-border);
  border-radius: 8px;
  color: var(--hub-text-primary);
  padding: 1rem;
  font-family: inherit;
  font-size: 1rem;
  resize: vertical;
  margin-bottom: 1rem;
  transition: border-color 0.2s;
}

.tool-textarea:focus {
  outline: none;
  border-color: var(--hub-accent);
}

.tool-actions {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
}

@media (prefers-reduced-motion: reduce) {
  * {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}

/* Global UI Components for Learning & Quizzes */
.hub-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  background: var(--hub-surface);
  color: var(--hub-text-primary);
  text-decoration: none;
  padding: 0.75rem 1.5rem;
  border-radius: 8px;
  font-weight: 600;
  transition: var(--hub-transition);
  border: 1px solid var(--hub-border);
  cursor: pointer;
}
.hub-btn:hover {
  background: var(--hub-card-hover);
  border-color: var(--hub-accent);
  transform: translateY(-2px);
}
.hub-btn.primary {
  background: rgba(59,130,246,0.1);
  color: var(--hub-accent);
  border-color: transparent;
}
.hub-btn.primary:hover {
  background: var(--hub-accent);
  color: #fff;
}

.topic-card {
  background: var(--hub-surface);
  border: 1px solid var(--hub-border);
  border-radius: var(--hub-radius);
  padding: 1.5rem;
  text-align: left;
  cursor: pointer;
  transition: var(--hub-transition);
  display: flex;
  align-items: center;
  gap: 1rem;
  text-decoration: none;
}
.topic-card:hover {
  background: var(--hub-card-hover);
  border-color: var(--hub-accent);
  transform: translateY(-2px);
}