.cam-image-main {
    width: 100%;
    height: auto;
}
.main-preview {
    background-color: #CCCCCC;
    min-height: 78vw; /* 78% zo sirky - podla pomeru stran obrazka */
}
.cam-preview {
    background-color: #ffffff;
    color: #343434;
    width: calc(33% - 20px);
    margin: 10px;
    float: left;
}
.cam-preview img {
    width: 100%;
    height: auto;
}
.cam-preview h3 {
    font-size: 1.1em;
    line-height: 1.5em;
    padding: 0;
    margin: 0;
    text-align: center;
}