You need to add the style sheet file in project after that add this style in it. Drag and Drop the css file in your master page so that it gets applied to all the Textboxes in your website.
input[type=text]
{
border: 1px solid #36BEC4;
outline: none;
}
Complete sample
HTML
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
<style type="text/css">
input[type=text], textarea
{
border: 1px solid #36BEC4;
outline: none;
}
</style>
</head>
<body>
<form id="form1" runat="server">
<div>
TextBox
<br />
<input type="text" name="name" value=" " />
<br />
TextArea
<br />
<textarea></textarea>
</div>
</form>
</body>
</html>
Demo