* {
    box-sizing: border-box;
    font-family: Arial, sans-serif;
  }
  body {
    margin: 0;
  }
  header {
    background-color: #8fcbe7;
    padding: 20px;
    border-bottom: 1px solid black;
  }

  nav ul {
    list-style: none;
    margin: 0;
    padding: 0;
    display: flex;
  }
  nav li {
    margin-right: 20px;
    font-size: large;
    padding-right: 10px;
  }
  nav li:last-child {
    margin-right: 0;
  }

  nav .aktiv a {
    color: #2c829c;
    text-decoration:none;
  }
  nav  .inaktiv a{
    color: #333;
    text-decoration: none;
  }
  main {
    display: grid;
    grid-template-columns: 1fr 1100px 1fr;
    justify-items: center;
    align-items: stretch;
    height: 100%;
}

.tartalom {
  padding-top: 20px;
  padding-left: 2mm;
  border-right: 1px solid blue;
  border-left: 1px solid blue;
}
.jobb_oszlop {
  width: 100%;
  height: 100%;
  background-image: url(bg.jpg);
  background-repeat: repeat;
  background-size: cover;
  overflow: hidden;
}

.bal_oszlop {
  width: 100%;
  height: 100%;
  background-image: url(bg.jpg);
  background-repeat: repeat;
  background-size: cover;
  background-position:center ;
  overflow: hidden;
}
  section {
    margin-bottom: 20px;
  }
  h1, h2 {
    text-align: center;
  }
  footer {
    background-color: #333;
    color: #fff;
    padding: 10px;
    text-align: center;
  }