transform-origin

значения свойства:

css/style.css

* {
margin: 0;
padding: 0;
}
.main {
height: 600px;
width: 900px;
position: absolute;
top: 50%;
left: 50%;
margin-top: -300px;
margin-left: -450px;
}
.wrapper {
width: 33.3%;
height: 100%;
float: left;
}
#div1, #div2, #div3 {
height: 200px;
width: 200px;
float: left;
position: relative;
top: 50%;
left: 50%;
margin-top: -100px;
margin-left: -100px;
border: 1px solid #F00;
}
#d1, #d2, #d3 {
height: 100px;
width: 100px;
float: left;
position: relative;
top: 50%;
left: 50%;
margin-top: -50px;
margin-left: -50px;
background-color: #3BA9DE;
text-align: center;
line-height: 100px;
transform: rotate(45deg);
-moz-transform: rotate(45deg);
-o-transform: rotate(45deg);
-webkit-transform: rotate(45deg);
-ms-transform: rotate(45deg);
}
#d1 {
transform-origin: 20% 0;
-moz-transform-origin: 20% 0;
-o-transform-origin: 20% 0;
-webkit-transform-origin: 20% 0;
-ms-transform-origin: 20% 0;
}
#d2 {
-moz-transform-origin: 0 20%;
-o-transform-origin: 0 20%;
-webkit-transform-origin: 0 20%;
}

* {
 margin: 0;
 padding: 0;
}

.main {
 height: 600px;
 width: 900px;
 position: absolute;
 top: 50%;
 left: 50%;
 margin-top: -300px;
 margin-left: -450px;
}

.wrapper {
 width: 33.3%;
 height: 100%;
 float: left;
}

#div1, #div2, #div3 {
 height: 200px;
 width: 200px;
 float: left;
 position: relative;
 top: 50%;
 left: 50%;
 margin-top: -100px;
 margin-left: -100px;
 border: 1px solid #F00;

} 

#d1, #d2, #d3 {
 height: 100px;
 width: 100px;
 float: left;
 position: relative;
 top: 50%;
 left: 50%;
 margin-top: -50px;
 margin-left: -50px;
 background-color: #3BA9DE;
 text-align: center;
 line-height: 100px;
 transform: rotate(45deg);
 -moz-transform: rotate(45deg);
 -o-transform: rotate(45deg);
 -webkit-transform: rotate(45deg);
 -ms-transform: rotate(45deg);
}

#d1 {
 transform-origin: 20% 0;
 -moz-transform-origin: 20% 0;
 -o-transform-origin: 20% 0;
 -webkit-transform-origin: 20% 0;
 -ms-transform-origin: 20% 0;
}

#d2 {
 -moz-transform-origin: 0 20%;
 -o-transform-origin: 0 20%;
 -webkit-transform-origin: 0 20%;
}

index.html

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>New Page</title>
<link href="css/style.css" rel="stylesheet" />
<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js"></script>
</head>
<body>
<div class="main">
<div class="wrapper">
<div id="div1">
<div id="d1">B</div>
</div>
</div>
<div class="wrapper">
<div id="div2">
<div id="d2">S</div>
</div>
</div>
<div class="wrapper">
<div id="div3">
<div id="d3">M</div>
</div>
</div>
</div>
<script>
/*JavaScript*/
document.getElementById("d2").style.transformOrigin="0 20%";
document.getElementById("d2").style.msTransformOrigin="0 20%";
/*jQuery*/
$(document).ready(function() {
$("#d3").css({ "transform-origin": "20% 20%" });
$("#d3").css({ "-moz-transform-origin": "20% 20%" });
$("#d3").css({ "-o-transform-origin": "20% 20%" });
$("#d3").css({ "-webkit-transform-origin": "20% 20%" });
$("#d3").css({ "-ms-transform-origin": "20% 20%" });
});
</script>
</body>
</html>

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>New Page</title>
<link href="css/style.css" rel="stylesheet" />
<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js"></script>
</head>
<body>
<div class="main">
<div class="wrapper">
<div id="div1">
<div id="d1">B</div>
</div>
</div>
<div class="wrapper">
<div id="div2">
<div id="d2">S</div>
</div>
</div>
<div class="wrapper">
<div id="div3">
<div id="d3">M</div>
</div>
</div>
</div>
<script>
/*JavaScript*/
document.getElementById("d2").style.transformOrigin="0 20%";
document.getElementById("d2").style.msTransformOrigin="0 20%";
/*jQuery*/
$(document).ready(function() {
$("#d3").css({ "transform-origin": "20% 20%" });
$("#d3").css({ "-moz-transform-origin": "20% 20%" });
$("#d3").css({ "-o-transform-origin": "20% 20%" });
$("#d3").css({ "-webkit-transform-origin": "20% 20%" });
$("#d3").css({ "-ms-transform-origin": "20% 20%" });
});
</script>
</body>
</html>