Breite eines Textfeldes

[theCSSbeginnerer]

div#MiddleRow {  
	margin-left: 30px;  
	margin-right: 30px;  
	max-width: 900px;  
}  
	  
div#MiddleRow div#ChatBox {  
	background: #A8D28F;  
	width: auto;  
	min-height: 45px;  
	margin: 0 auto;  
	padding: 2px 2px 0px 2px;  
	border: dotted 2px #7DBC57;  
	margin-bottom: 5px;  
}  
  
	div#MiddleRow div#ChatBox div#From {  
		padding: 4px 0px 0px 0px;  
		float: left;  
		width: 120px;  
		height: 100%;  
		min-height: 43px;  
		text-align: center;  
	}  
	  
		div#MiddleRow div#ChatBox div#From div#Name {  
			font: bold 14px Verdana, Arial, Helvetica, sans-serif;  
		}  
  
		div#MiddleRow div#ChatBox div#From div#Date {  
			font: bold 9px Verdana, Arial, Helvetica, sans-serif;  
		}  
		  
	div#MiddleRow div#ChatBox div#Message {  
		margin-left: 125px;  
		padding: 0px 0px 0px 2px;  
		width: auto;  
		min-height: 43px;  
		height: auto;  
		left: 125px;  
		font: 12px Verdana, Arial, Helvetica, sans-serif;  
		border-left: dotted 2px #7DBC57  
	}  
  
	div#MiddleRow div#ChatBox div#Message form#sbform  {  
		width: 100%;  
		position: relative;  
	}  
	  
	div#MiddleRow div#ChatBox div#Message form#sbform input#addtext {  
		background: #EDF7E7;  
		border: solid 2px #7DBC57;  
		width: 100%;  
		margin: 11px 52px 0px 5px;  
		display: block;  
		position: absolute;  
	}  
	  
	div#MiddleRow div#ChatBox div#Message form#sbform input#submit {  
		font: bold 12px Verdana, Arial, Helvetica, sans-serif;  
		background: #EDF7E7;  
		border: solid 2px #7DBC57;  
		width: 42px;  
		height: 42px;  
		position: absolute;  
		right: 5px;  
		top: 0px;  
	}

So siehts zur Zeit aus. Trotz margin: 11px 52px 0px 5px; nimmt das Textfeld 100% der Formbreite ein (und ist um 5px nach Rechts verschoben).

Ich schaffs nicht.

MfG