Div inside Div Alignment and auto width

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CSS

HTML

HI friends,
I'm developing android application, in my application I want to create 3 buttons for

1. Add task<br />
2. Delete Task<br />
3. Save Task

I'm making use of Div instead of buttons as following

<div id="actions" class="divActions topMargin">
            <div id="divAdd" class="button floatLeft">
                Add Task
            </div>
            <div id="divDelete" class="button floatLeft">
                Delete Task
            </div>
            <div id="divSave" class="button floatLeft">
                Save Tasks
            </div>
    </div>

I have Given following style

.divActions{height:5em;}
#divAdd, #divDelete, #divSave, #prev, #taskno, #next{width:32%;}
.button
{
    border: 1px solid #C7C7C7;
    height: 3em;
    background: #FCFCFC;
    vertical-align: middle;
    text-align: center;
    width: 10%;
    cursor: pointer;
    color: #2489CE;
}

My problem is it if working fine in some mobiles, but as resolution changes the 3 div are not in straight line one of the div goes in next line.

Can anyone give idea how the width of my 3 div can automatically takes the 1/3 of the screen width?

Thanks in advance