Now that your theme is available in Liferay, it’s time to dress it up for a
stylistic appeal. Currently in the Look and Feel settings, your theme’s
thumbnail is a broken image. To remedy this, create a 1080 pixels wide by 864
pixels high image to use as your theme’s thumbnail. You may want to take a
snapshot of your theme and resize it to these dimension. It is very important to
abide by these exact dimensions or your image will not display properly as a
thumbnail. Save the image as a .png file named screenshot.png and place it
in your theme’s docroot/_diffs/images directory (create this directory if it
doesn’t already exist). On redeployment, your screenshot.png file
automatically displays as your theme’s thumbnail.
Now go to the Look and Feel settings. Your theme’s thumbnail should appear there, along with the Classic theme’s thumbnail.
Let’s talk about Liferay’s JavaScript library next.