!important styles are ignored by Outlook when they are inlined. There
are no other rules that would override the width of the expanded
buttons, so it is not necessary to have it declared as !important.
Removing !important means that the style will be inlined as
style="width: 100%" instead of style="width: 100% !important". The
latter is ignored by Outlook, while the first one works and makes the
button expand. Ref:
https://www.campaignmonitor.com/blog/email-marketing/2010/05/outlook-2007-and-the-inline-important-declaration/
table.button.expand,
table.button.expanded {
- width: 100% !important;
+ width: 100%;
table {
width: 100%;