body {
    background-color: lightgray;
}
.main {
    text-align: center;
    margin: 5%;
    font-size: 2em;
}
.obraz {
    width: 30%;
    height: 30%;
    margin: auto;
}
hr { 
    display: block;
    margin-top: 0.5em;
    margin-bottom: 0.5em;
    margin-left: auto;
    margin-right: auto;
    border-style: inset;
    border-width: 1px;
  }