To adapt the height of your image gallery block in a custom page feature, and thus eliminate the scroll, you can use this CSS snippet in the Advanced Customization section of the Colors menu:
1) Log into your App Manager and select your app.
2) Click Colors from the left-hand-side of the screen (or the middle of the screen).
3) Scroll down to the Advanced SCSS box. If there is already code in the advanced SCSS box, do not remove it. Start a new line “after” the last character in the box, then paste the code below.
/** Begin gallery height edit*/
/** End gallery height edit*/
4) Click Save.