.block-modal-test > * {
     box-sizing: border-box;
 }

.block-modal-test {
    width: 250px;
    height: 340px;
    border: 1px solid black;
    /*padding: 10px;*/
    margin: 100px auto;
    position: relative;
    overflow: hidden;
}

.form-slider {
    width: 500px;
    height: 340px;
    background: bisque;
    margin-left: 0;
    transition: all ease 1s;
}

.read-rules, .read-rules-back {
    background: rgba(50, 50, 50, .1);
    font-synthesis: weight;
    font-style: oblique;
    padding: 10px;
}

.left-50 {
    position:relative;
    width: 50%;
    float: left;
    min-height: 50px;
    background: rgba(155, 176, 234, .3);
}

.right-50 {
    position: relative;
    width: 50%;
    float: left;
    min-height: 50px;
    max-height: 340px;
    overflow-y: scroll;
    background: lightgreen;
}

.left-50>p , .right-50>p {
    margin: 8px 0;
    padding: 5px 10px;
    text-align: justify;
}

.read-rules-back {
    position: static;
    bottom: 0;
    vertical-align:bottom;
    display:inline-block;
}