Souci de novice CSS

<img src="url_img"/>

<div id="global">
    <div id="droite">200px</div>
    <div id="centre">400px</div>
    <div id="gauche">400px</div>
</div>

<style>
#global{
border:solid red 1px;
width:1010px;
overflow:hidden;
}
#droite{
border:solid green 1px;
width:200px;
float:left;
}
#centre{
border:solid blue 1px;
width:400px;
float:left;
}
#gauche{
border:solid orange 1px;
width:400px;
float:left;
}
</style>