I want to preface the below with a reminder that Custom CSS is an advanced feature akin to custom programming (for styles) and is not something we can provide official support for.
Keep in mind that the Hero Attribute tile has some <div> tags that are used for positioning content which is slightly different than most normal tiles. The main purpose of this is to allow for content that might span multiple lines while allowing the content to appear to scroll ‘under’ the title while still being visually centered for regular short content.
As with any Custom CSS, it’s really helpful to understand HTML + CSS and have the ability to use your browser’s developer tools to inspect things.
From a brief review, it looks like the .main-content div shifts things down and then the nested .content-holder within that offsets things at the bottom to help with the centering. Depending on your goals, you would likely need to override those if you didn’t want the offsetting for the title space.