Remove space between pictures

If you look at the CSS, you’ll see there’s 40px of padding above and below each image, making for 80px between them.

View post on imgur.com

You may want to reduce that — something like

.blog .post img {
   padding-top:10px;
   padding-bottom: 10px;
}

To add CSS: If you are using WordPress 4.7, use the “Custom CSS” option in the customizer. If your theme has a custom CSS option, use that to add the CSS shown above. If not, install the plugin Simple Custom CSS. Or, if you have Jetpack installed, enable its Custom CSS module.

Learn the Chrome Developer Tools to help you see and test changes to your CSS.