body {
  font-family: 'Lato', sans-serif;
  margin: 0;
  background: #f4f4f4;
  color: #333;
}

.primary-header {
  background: #2c3e50;
  color: white;
  text-align: center;
  padding: 2rem 1rem;
}

.logo {
  margin: 0;
  font-size: 2rem;
}

.tagline {
  margin-top: 0.5rem;
  font-weight: 300;
}

.tab-container {
  max-width: 800px;
  margin: 2rem auto;
  background: white;
  border-radius: 10px;
  overflow: hidden;
  box-shadow: 0 8px 20px rgba(0,0,0,0.1);
}

.tabs {
  display: flex;
  background: #ecf0f1;
}

.tab {
  flex: 1;
  font-size:1rem;
  padding: 1rem;
  cursor: pointer;
  background: transparent;
  border: none;
  font-weight: bold;
  transition: background 0.3s;
}

.tab:hover,
.tab.active {
  background: #3498db;
  color: white;
  font-size:1.1rem;
}

.tab-content {
  display: none;
  padding: 1.5rem;
  animation: fadeIn 0.5s ease-in-out;
}

.tab-content.active {
  display: block;
}

.schedule {
  list-style: none;
  padding: 0;
}

.schedule li {
  padding: 0.8rem 0;
  border-bottom: 1px solid #ddd;
}

.schedule li span {
  display: block;
  font-weight: bold;
  color: #2980b9;
  margin-bottom: 0.3rem;
}

.primary-footer {
  text-align: center;
  padding: 1rem;
  background: #2c3e50;
  color: white;
  font-size: 0.9rem;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(20px); }
  to { opacity: 1; transform: translateY(0); }
}

@media (max-width: 600px) {
  .tab {
    font-size: 0.9rem;
    padding: 0.8rem;
  }

  .schedule li span {
    font-size: 0.9rem;
  }

}
  
  .parallel-sessions {
    display: flex;
    gap: 2rem;
    flex-wrap: wrap;
  }
  
  .session-column {
    flex: 1;
    min-width: 280px;
  }
  
  .session-column h3 {
    margin-bottom: 1rem;
    color: #2c3e50;
    border-bottom: 2px solid #3498db;
    padding-bottom: 0.5rem;
  }
  
  @media (max-width: 768px) {
    .parallel-sessions {
      flex-direction: column;
    }
  }
  .inner-tab-content {
    display: none;
    transition: all 0.3s ease-in-out;
  }
  .inner-tab-content.active {
    display: block;
  }
  .inner-tabs {
    display: flex;
    gap: 10px;
    margin-bottom: 1rem;
  }
  .inner-tab-button.active {
    font-weight: bold;
    border-bottom: 2px solid #000;
  }
  .inner-tab-button {
    font-size: 1.1rem;       /* Yazı boyutu */
 
    cursor: pointer;
    background: none;
    border: none;
    border-bottom: 2px solid transparent;
    transition: all 0.2s ease;
  }