Ah, I get it.
There are two problems at once.
First, there can be no spaces between the end of input 1 and the beginning of input 2.
Known IE bug.
And then, for buttons the same size as the text box, you need to apply the window size property
-moz-box-sizing: content-box; -webkit-box-sizing: content-box; box-sizing: content-box;
Like this:
label, input { margin: 0.1em 0.2em; padding: 0.3em 0.4em; border: 1px solid #f90; background-color: #fff; display: block; height: 50px; float: left; -moz-box-sizing: content-box; -webkit-box-sizing: content-box; box-sizing: content-box; } input[type=text] { margin-right: 0; border-radius: 0.6em 0 0 0.6em; } input[type=text]:focus { outline: none; background-color: #ffa; background-color: rgba(255,255,210,0.5); } input[type=submit] { margin-left: 0; border-radius: 0 0.6em 0.6em 0; background-color: #aef; } input[type=submit]:active, input[type=submit]:focus { background-color: #acf; outline: none; } <form action="#" method="post"> <input type="text" name="something" id="something" /><input type="submit" value="It a button!" /> </form>
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