I am using the <apex:messages/> tag to display messages on a visualforce page that is overriding the New button on a custom object. When the messages present their font color is black, and the message is way to the left of the page.  How do I get the messages to display in red and be centered on the page rather than left justified?

 Here is my visualforce code.

<apex:page standardController="Salesforce_Issue__c"  >

 <style type="text/css">
  .exceptionText{font-style:italic; 
                 font-size:16px; 
                 font-weight:bold; 
                 text-align:center;
                 color:red;}
 </style>

   <apex:form>
    <apex:pageBlock mode="edit">
        <apex:pageBlockButtons  >
            <apex:commandButton value="Save" action="{!Save}"/>
            <apex:commandButton value="Cancel" action="{!Cancel}"/>
        </apex:pageBlockButtons>
        
        <apex:messages layout="table" styleClass="exceptionText"/>

 It seems that the css is not working fully. Font-weight,  font-size, font-style all work but text-align and color don't seem to be recognized.

Any help would be appreciated.