How to Customize the Text Area Box?

To do this follow the steps below,

1. Go to Blogger > Layout > Edit HTML
2. Search for </b:skin>
3. And just above it paste the code below,

.mbt-textarea {
padding:0;
margin:0;
background: #fff;
width:400px;
height:40px; 
color:#666;
font:12px arial;
border:1px dotted #289728; }

.mbt-textarea:hover {
color:#289728;
border:2px solid #666; 
}

4.  Finally save your template!