/* ----------------------------------------
   Concept Hub Page Styles
---------------------------------------- */

/* Concept Hub Page Section Spacing */
section {
  padding: 100px 20px;
}

/* Main hub container */
.concepts-hub {
  max-width: 1200px;
  margin: 0 auto;
  padding: 100px 20px;
}

/* Page header */
.concepts-hub > h1 {
  font-size: 2.75rem;
  margin-bottom: 12px;
  position: relative;
  text-align: center;
}

/* Subheading / description */
.concepts-hub > p {
  font-size: 1.125rem;
  color: #666666;
  margin-bottom: 40px;
  text-align: center;
}

/* Horizontal line under page header */
.concepts-hub > p::after {
  content: "";
  display: block;
  width: 60px;
  height: 2px;
  background-color: #e0e0e0;
  margin: 12px auto 0 auto;
  border-radius: 1px;
}

/* Two-column layout for desktop */
.concept-columns {
  display: flex;
  gap: 40px;
}

/* Categories column */
.concept-categories {
  flex: 1;
}

/* Category title */
.concept-category h2 {
  font-size: 1.5rem;
  margin-bottom: 16px;
  border-bottom: 1px solid #e0e0e0;
  padding-bottom: 6px;
}

/* Concept list under each category */
.concept-list {
  list-style: none;
  padding-left: 0;
  margin-top: 16px;
}

.concept-item {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  padding: 12px 16px;
  margin-bottom: 12px;
  background-color: #fafafa;
  border-radius: 8px;
  transition: background-color 0.2s ease, transform 0.2s ease;
  cursor: pointer;
}

/* Hover effect for concept items */
.concept-item:hover {
  background-color: #f0f4f8;
  transform: translateY(-2px);
}

/* Concept title and summary */
.concept-item a {
  font-weight: 600;
  font-size: 1rem;
  color: #2c79c0;
  text-decoration: none;
}

.concept-summary {
  font-size: 0.95rem;
  color: #555555;
  margin-top: 4px;
}

/* Minimalist arrow on right side of concept */
.concept-arrow {
  font-size: 1.25rem;
  color: #999999;
  margin-left: 12px;
  transition: color 0.2s ease;
}

.concept-item:hover .concept-arrow {
  color: #2c79c0;
}

/* Responsive: stack columns vertically for mobile */
@media (max-width: 768px) {
  .concept-columns {
    flex-direction: column;
  }

  .concept-item {
    flex-direction: column;
    align-items: flex-start;
  }

  .concept-arrow {
    margin-left: 0;
    margin-top: 6px;
  }
}