I have an anchor link with padding:
<a href="http://my.cris.dev:3008/services/3/viewer" style="text-decoration:none; background-color:#137191; color:#fff; display:block; padding:16px 16px 16px; font:100 16px/16px "Cabin",Arial, Helvetica, sans-serif; letter-spacing:0.025em; border-radius:4px;">Discover your 3D</a>
But outlook doesn't respect this padding, it's just removed, what's the best solution to not mess up the design in other clients.
Outlook's support for the box model is... sketchy. Try this code:
<table width="100%" border="0" cellspacing="0" cellpadding="0">
<tr>
<td>
<table border="0" cellspacing="0" cellpadding="0">
<tr>
<td bgcolor="#137191" style="padding: 16px; border-radius:4px">
<a href="http://my.cris.dev:3008/services/3/viewer" target="_blank" style="font-size: 16px; mso-line-height-rule:exactly; line-height: 16px; font-family: 'Cabin',Arial, Helvetica, sans-serif; font-weight: 100; letter-spacing:0.025em; color: #ffffff; text-decoration: none; display: inline-block;">Discover your 3D</a>
</td>
</tr>
</table>
</td>
</tr>
</table>
This will solve your collapsing padding issue in Outlook. Outlook will still display squared-off corners instead of border-radius, but at least you'll get a padded button that is clickable.
(I added/edited a few other properties to help cross-client display)
There are a few way to achieve bulletproof buttons in email if you prefer another method.