.Category
{
    border: 1px solid Blue;
    margin: -1px;
}

.SectionGroup
{
    display: inline-block;
    vertical-align: top;
    height: 100%;
    border: 1px solid Green;
    margin: -1px;
    overflow: hidden;
}

.Section
{
    border: 1px solid Aqua;
    vertical-align: top;
    height: 100%;
}