Remove white margin by adjusting context box height

Hi all,

I am building the homepage of my website ” bazenhebbenazen.nl ” . I am using page builder from site origin. I have created 3 content boxes.

For some reason there is a huge white margin below the content boxes. When I inspect the element I can only decrease this by reducing the height of the element: div class= t4p-one-third one_third t4p-column. But how do I go from here? Where do I actually add the ‘style’ height=650px for example?

The shortcode I used for one of these boxes is as follows:

[one_third last=”no”]
[content_boxes layout=”icon-on-top” iconcolor=”#333333″ circlecolor=”#ffffff” circlebordercolor=”#5bc0de” backgroundcolor=”#ffffff”]
[content_box title=”Nieuwe spelers” icon=”” image=”” image_width=”35″ image_height=”35″ link=”#” linktarget=”_self” linktext=”” animation_type=”slide” animation_direction=”left” animation_speed=”1″]

CONTENT
[/content_box]

Thank you, I’m at a loss. I have been trying for days now to get this fixed. But more importantly, to understand how I go from inspecting an element to actually finding a place to permanently change it.