<p>Use <code>box-sizing: border-box;</code> instead of default <code>box-sizing: content-box;</code> </p>

<p>Background: <a href="http://www.paulirish.com/2012/box-sizing-border-box-ftw/">http://www.paulirish.com/2012/box-sizing-border-box-ftw/</a></p>

<p style="font-size:small;-webkit-text-size-adjust:none;color:#666;">—<br>Reply to this email directly or <a href='https://github.com/openstreetmap/openstreetmap-website/issues/301'>view it on GitHub</a>.<img src='https://github.com/notifications/beacon/uTRSc6ihLa7Shf84BpiOpnW3CjVVvl_F70GbpXaNNIhGcOCSHXFGi2oc2AK-id-J.gif' height='1' width='1'></p>