test

HTML

<div class="main">
    <div class="mmm">
    </div>
    <!-- <div class="clear"></div> -->
    <div class="bbb">
    </div>
</div>

CSS

.main {
    padding: 10px;
}
.main:after {
    clear: both;
    content: "";
    display: block;
}

.mmm, .bbb {
    position: relative;
    padding: 0 15px; min-width: 70px; max-width: 75%; min-height: 36px;
    -webkit-border-radius: 3px; border-radius: 3px;    
}
.mmm {
    margin-left: 20px; float: left;
    background-color: #f28980;
    border: solid 1px #ed7165;        
}

.bbb {
    float: right; margin-right: 20px;
    background-color: #e3e3e3;
    border: solid 1px #c5c5c5;
    clear: left;
}