Can you post the css you are using? Or modify this test app to show the problem you are experiencing:
<!DOCTYPE html>
<html>
<head>
<title>Create a Web Map</title>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<meta name="viewport" content="initial-scale=1, maximum-scale=1,user-scalable=no">
<link rel="stylesheet" type="text/css" href="http://js.arcgis.com/3.11/esri/css/esri.css">
<style>
html,body,#mapDiv,.map.container{
padding:0;
margin:0;
height:100%;
}
#LocateButton {
position: absolute;
top: 95px;
left: 20px;
z-index: 30;
}
#HomeButton {
position: absolute;
top: 155px;
left: 20px;
z-index: 30;
}
#HomeButton .home, #LocateButton .zoomLocateButton{
width:42px;
height:42px;
}
</style>
<script>var dojoConfig = { parseOnLoad: true };</script>
<script src="http://js.arcgis.com/3.11compact/"></script>
<script>
var map,
webmapId = "1a40fa5cc1ab4569b79f45444d728067";
require([
"esri/map",
"esri/arcgis/utils",
"esri/dijit/HomeButton",
"esri/dijit/LocateButton",
"dojo/domReady!"
], function (Map, arcgisUtils, HomeButton, LocateButton) {
arcgisUtils.createMap(webmapId, "mapDiv").then(function (response) {
map = response.map;
geoLocate = new LocateButton({
map: map
}, "LocateButton");
geoLocate.startup();
//set up geolocator and home buttons
var home = new HomeButton({
map: map
}, "HomeButton");
home.startup();
});
});
</script>
</head>
<body>
<div id="mapDiv">
<div id="HomeButton"></div>
<div id="LocateButton"></div>
</div>
</body>
</html>