JSFiddle - React, Tailwind, and code Playground
HTML
<form name="foo" action="#">
<div class="bb">div</div>
<input class="bb" size="20" name="bar" value="field">
</form>
CSS
form {display:block; margin:0; padding:0; width:50%; border:1px solid green; overflow:visible}
div, input {display:block; border:1px solid red; padding:5px; width:auto; font:normal 12px Arial}
/* The voodoo starts here */
.bb {
box-sizing: border-box; /* css3 rec */
behavior: url("boxsizing.htc"); /* ie6/7 */
-ms-box-sizing: border-box; /* ie8 */
-moz-box-sizing: border-box; /* ff2+ */
-webkit-box-sizing: border-box; /* safari3+ */
-khtml-box-sizing: border-box; /* konqueror */
}