$("#ui-1").css({'position':'absolute','left':'27.0px','top':'51.0px','width':'120.0px','height':'30.0px',});
$("#ui-1 .ui-btn-text").css({'font-family':'"Calibri","Arial","Sans Serif"','font-size':'0.75em','color':'black','text-align':'left','wordwrap':'normal','text-shadow':'1px 1px 1px #FFFFFF'});

// For all buttons use something like this
$('.ui-btn').css('width','50%');

// For individual buttons use something like this
$('#theButton1').parent().css('width', '75%');

// Or this for HREF data-role buttons
$('#hrefButton4').css('width', '45%');

// this changes the height for all buttons
$('.ui-btn-text').css('font-size','50px');

// This changes the height for a single element
$('#hrefButton3').children().children().css('font-size','30px');

<div data-role="page" id="home">
    <div data-role="content">
        <input type="button" id="theButton1" value="Press Me 1" />
        <input type="button" id="theButton2" value="Press Me 2" />
        <input type="button" id="theButton3" value="Press Me 3" />
        <input type="button" id="theButton4" value="Press Me 4" />
        <br />
        <a href="#" data-role="button" id="hrefButton1">HREF Me 1</a>
        <a href="#" data-role="button" id="hrefButton2">HREF Me 2</a>
        <a href="#" data-role="button" id="hrefButton3">HREF Me 3</a>
        <a href="#" data-role="button" id="hrefButton4">HREF Me 4</a>
    </div>
</div>

display: inline-block;