Bootstrap 3 - Aligning column height

Question

create a site for educational purposes but I\'m stuck with grid/column height issue.

Here\'s an image of site I\'m trying to replicate: Click me

Here\'s what I\'

Answer 1

Here is a snippet, but I can't realize why are so huge gaps between columns.

Although look at https://jsfiddle.net/xeen9s7y/ - it works well.

I've added border: solid 1px red; to images for better visual control.

img {
    width: 100%;
    height: 100%;
    border: solid 1px red;
}
.imgcont {
    height: 25vw;
    padding: 1px;
}
.imgcont2 {
    height: 50vw;
    padding: 1px;
}