così?

<html>
<head>
<title>Untitled</title>
<style>
.messaggio1 {
width: 558px;
height: 40px;
border: 1px solid gray;
background-color: #EBEBEB;
font-family: Arial;
font-size: 1em;
text-align : left;
display:inline;
}
.utenteInfo1 {
width: 140px;
height: 40px;
background-color: #D5DBE1;
border: 1px solid gray;
font-family: Arial;
font-size: 1em;
text-align: left;
display:inline;
}
</style>

</head>

<body>
<div class="utenteinfo1">2
prova</div>

<div class="messaggio1">1
prova</div>