I couldn't find this documented anywhere else on the internet, so I thought I'd post it here. Jetpack includes sharing icons on each individual post that look like:

However, I'm finding that they look like this by default:

There are various ways to fix this in the Jetpack CSS, but short of an upstream fix (I'm looking at you, Jetpack devs), the best way I've found to fix this is to:

  1. Log into your Wordpress site as an admin
  2. Navigate to https://yourdomain.tld/wp-admin/themes.php?page=editcss
  3. Add the following to the input field:
    #sharing_email .sharing_send, .sd-content ul li .option a.share-ustom, .sd-content ul li a.sd-button, .sd-content ul li.advanced a.share-more, .sd-content ul li.preview-item div.option.option-smart-off a, .sd-social-icon .sd-content ul li a.sd-button, .sd-social-icon-text .sd-content ul li a.sd-button, .sd-social-official .sd-content > ul > li .digg_button > a, .sd-social-official .sd-content > ul > li > a.sd-button, .sd-social-text .sd-content ul li a.sd-button {
    padding: 1px 20px 0 35px;
  4. Save your changes

If this doesn't work, you may need to tweak the padding values. I found it easiest to modify the CSS values in Firebird, then use the final code to override Jetpack.