Last posts boxes on homepage having different sizes

Hello
I have customizr on a website, and in the homepage I have 3 boxes containing the last 3 posts and they have the grid layout, the problem is that their sizes are different depending on the post title size, the longer is the title, the longer is the box containing the post. I want them to have the same size so I tried this in my child theme style.css

.tc-grid {
   max-height:270px;
}

But nothing changed,Thank you in advance for the help.