fieldset width 100% of parent [duplicate]

Answer 1

from your jsfiddle, perhaps you forget to add a fieldset to the second section

this is a quick fix

.section {
    width: 100%;
    border: 10px double;
    box-sizing: border-box;
    overflow-x: auto;
}

td {
    padding: 0 100px;
    border: 1px solid;
}

http://jsfiddle.net/oussamaelgoumri/meqvbjf1/