Putting 2 divs next to each other with same class

I have 2 divs which i cannot give different class names, due to them being the same but in a repeatable php code, which doesen't allow me to give them different class names. So i basically want to display them side by side. I have tried giving them a float left and relative position and a master div surrounding them with absolute position and other things like that, but to no avail.

HTML:

<div class="master"> 
<div class="second">1st</div>
<div class="second">2nd</div>
</div>

CSS currently applied:

.second{
    color:#FFF;
    width:300px;
    height: 10%;
    background-color:#69F;
    border-radius:25px;
    opacity: 0.7;
    filter: alpha(opacity=40);
    float:left;
}
.master{
width:960px;
padding-top:12%;
margin: 0 auto;
font-size:50px;
}