:root {
  /* Color Variables */
  --primary-dark: #2c3e50;
  --primary-medium: #34495e;
  --accent-blue: #3498db;
  --accent-blue-dark: #2980b9;
  --accent-green: #2ecc71;
  --text-light: #ecf0f1;
  --text-dark: #333;
  --text-medium: #7f8c8d;
  --background-light: #f5f5f5;
  --white: #fff;

  /* Shadow Variables */
  --shadow-small: 0 4px 6px rgba(0, 0, 0, 0.1);
  --shadow-medium: 0 10px 15px rgba(0, 0, 0, 0.1);
  --shadow-large: 0 15px 30px rgba(0, 0, 0, 0.15);

  /* Transition Variables */
  --transition-fast: all 0.2s ease;
  --transition-medium: all 0.3s ease;
  --transition-slow: all 0.4s ease;

  /* Size and Spacing */
  --container-width: 90%;
  --container-max: 1200px;
  --border-radius-small: 5px;
  --border-radius-medium: 10px;
  --border-radius-large: 15px;
  --border-radius-full: 50%;

  /* Gradients */
  --gradient-primary: linear-gradient(90deg, #3498db, #2ecc71);
  --gradient-header: linear-gradient(90deg, #2c3e50, #34495e);
  --gradient-button: linear-gradient(90deg, #3498db, #2980b9);
  --gradient-hover: linear-gradient(90deg, #2980b9, #3498db);
}

.activities-header {
  text-align: center;
  margin-bottom: 3rem;
  position: relative;
}

.activities-header h1 {
  font-size: 2.5rem;
  color: var(--primary-dark);
  margin-bottom: 1rem;
  position: relative;
  display: inline-block;
}

.activities-header h1::after {
  content: '';
  position: absolute;
  bottom: -10px;
  left: 10%;
  width: 80%;
  height: 4px;
  background: var(--gradient-primary);
  border-radius: var(--border-radius-small);
}

.activities-header p {
  color: var(--text-medium);
  font-size: 1.1rem;
  max-width: 700px;
  margin: 0 auto;
}

.filter-buttons {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  margin-bottom: 2.5rem;
  gap: 1rem;
}

.filter-btn {
  padding: 0.6rem 1.5rem;
  background: var(--white);
  color: var(--primary-dark);
  font-weight: 600;
  border: 2px solid var(--accent-blue);
  border-radius: var(--border-radius-medium);
  cursor: pointer;
  transition: var(--transition-medium);
}

.filter-btn:hover, .filter-btn.active {
  background: var(--gradient-button);
  color: var(--white);
  box-shadow: var(--shadow-small);
}

.filter-btn.active {
  position: relative;
}

.filter-btn.active::after {
  content: '';
  position: absolute;
  bottom: -5px;
  left: 25%;
  width: 50%;
  height: 3px;
  background: var(--accent-green);
  border-radius: var(--border-radius-small);
}

.activities-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 2rem;
  margin-bottom: 3rem;
}

.activity-card {
  background: var(--white);
  border-radius: var(--border-radius-medium);
  overflow: hidden;
  box-shadow: var(--shadow-small);
  transition: var(--transition-medium);
}

.activity-card:hover {
  transform: translateY(-10px);
  box-shadow: var(--shadow-large);
}

.activity-image {
  height: 200px;
  overflow: hidden;
  position: relative;
}

.activity-image img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: var(--transition-medium);
}

.activity-card:hover .activity-image img {
  transform: scale(1.1);
}

.activity-badge {
  position: absolute;
  top: 15px;
  right: 15px;
  background: var(--accent-blue);
  color: var(--white);
  padding: 0.3rem 0.8rem;
  border-radius: var(--border-radius-small);
  font-size: 0.8rem;
  font-weight: 600;
}

.activity-content {
  padding: 1.5rem;
}

.activity-title {
  font-size: 1.3rem;
  color: var(--primary-dark);
  margin-bottom: 0.5rem;
}

.activity-info {
  display: flex;
  align-items: center;
  margin-bottom: 0.8rem;
  font-size: 0.9rem;
  color: var(--text-medium);
}

.activity-info i {
  margin-right: 5px;
  color: var(--accent-blue);
}

.activity-info span {
  margin-right: 15px;
  display: flex;
  align-items: center;
}

.activity-description {
  color: var(--text-medium);
  margin-bottom: 1rem;
  font-size: 0.95rem;
  line-height: 1.5;
}

.activity-footer {
  display: flex;
  justify-content: space-between;
  align-items: center;
  border-top: 1px solid rgba(0,0,0,0.05);
  padding-top: 1rem;
}

.join-btn {
  padding: 0.4rem 1.2rem;
  background: var(--gradient-button);
  color: var(--white);
  border: none;
  border-radius: var(--border-radius-small);
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition-fast);
}

.join-btn:hover {
  background: var(--gradient-hover);
  box-shadow: var(--shadow-small);
}

.activity-classes {
  display: flex;
  gap: 5px;
}

.class-tag {
  font-size: 0.8rem;
  padding: 0.2rem 0.5rem;
  background: rgba(52, 152, 219, 0.1);
  color: var(--accent-blue);
  border-radius: var(--border-radius-small);
}

.calendar-section {
  background: var(--white);
  padding: 2rem;
  border-radius: var(--border-radius-medium);
  box-shadow: var(--shadow-medium);
  margin-bottom: 3rem;
}

.calendar-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 1.5rem;
}

.calendar-title {
  font-size: 1.5rem;
  color: var(--primary-dark);
}

.calendar-controls {
  display: flex;
  gap: 1rem;
}

.calendar-btn {
  background: var(--accent-blue-dark);
  color: var(--white);
  border: none;
  width: 35px;
  height: 35px;
  border-radius: var(--border-radius-full);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: var(--transition-fast);
}

.calendar-btn:hover {
  background: var(--accent-blue);
  transform: scale(1.1);
}

.calendar-month {
  font-weight: 600;
  color: var(--primary-dark);
}

.calendar-grid {
  display: grid;
  grid-template-columns: repeat(7, 1fr);
  gap: 10px;
}

.calendar-day {
  text-align: center;
  font-weight: 600;
  color: var(--text-medium);
  padding: 0.5rem;
}

.calendar-date {
  text-align: center;
  padding: 0.75rem 0;
  border-radius: var(--border-radius-small);
  cursor: pointer;
  transition: var(--transition-fast);
}

.calendar-date:hover {
  background: rgba(52, 152, 219, 0.1);
}

.calendar-date.has-event {
  background: rgba(46, 204, 113, 0.1);
  position: relative;
}

.calendar-date.has-event::after {
  content: '';
  position: absolute;
  bottom: 5px;
  left: 50%;
  transform: translateX(-50%);
  width: 5px;
  height: 5px;
  background: var(--accent-green);
  border-radius: var(--border-radius-full);
}

.calendar-date.active {
  background: var(--accent-blue);
  color: var(--white);
}

.upcoming-events {
  background: var(--white);
  padding: 2rem;
  margin-bottom: 12rem;
  border-radius: var(--border-radius-medium);
  box-shadow: var(--shadow-medium);
}

.upcoming-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 1.5rem;
}

.upcoming-title {
  font-size: 1.5rem;
  color: var(--primary-dark);
}

.view-all {
  color: var(--accent-blue);
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition-fast);
}

.view-all:hover {
  color: var(--accent-blue-dark);
  text-decoration: underline;
}

.event-list {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.event-item {
  display: flex;
  gap: 1rem;
  padding: 1rem;
  border-radius: var(--border-radius-small);
  transition: var(--transition-fast);
}

.event-item:hover {
  background: rgba(0,0,0,0.02);
}

.event-date {
  min-width: 60px;
  height: 60px;
  background: var(--accent-blue);
  color: var(--white);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  border-radius: var(--border-radius-small);
}

.event-day {
  font-size: 1.2rem;
  font-weight: 700;
  line-height: 1;
}

.event-month {
  font-size: 0.8rem;
  text-transform: uppercase;
}

.event-details {
  flex: 1;
}

.event-name {
  font-weight: 600;
  color: var(--primary-dark);
  margin-bottom: 0.3rem;
}

.event-meta {
  font-size: 0.85rem;
  color: var(--text-medium);
  display: flex;
  gap: 1rem;
}

.event-meta span {
  display: flex;
  align-items: center;
  gap: 5px;
}

/* Responsive */
@media (max-width: 768px) {
  .activities-header h1 {
      font-size: 2rem;
  }

  .activities-grid {
      grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
  }

  .calendar-grid {
      gap: 5px;
  }

  .calendar-date {
      padding: 0.5rem 0;
  }
}

@media (max-width: 576px) {
  .container {
      width: 95%;
  }

  .activities-header h1 {
      font-size: 1.8rem;
  }

  .activities-grid {
      grid-template-columns: 1fr;
  }

  .filter-buttons {
      flex-direction: column;
      align-items: center;
  }

  .filter-btn {
      width: 100%;
      max-width: 250px;
      text-align: center;
  }
}

/* Special highlights and animations */
@keyframes pulse {
  0% { transform: scale(1); }
  50% { transform: scale(1.05); }
  100% { transform: scale(1); }
}

.highlight {
  position: relative;
  overflow: hidden;
}

.highlight::before {
  content: '';
  position: absolute;
  top: -50%;
  left: -50%;
  width: 200%;
  height: 200%;
  background: radial-gradient(circle, rgba(52, 152, 219, 0.2) 0%, rgba(255,255,255,0) 70%);
  animation: pulse 2s infinite;
  z-index: -1;
}