Floated columns not aligning correctly on certain screen sizes - responsive-design

Question

I have a problem with a CSS grid I built. The relevant site is this: http://dr-brauchle.de/
The wall of photos underneath the content is constructed with a grid of floated boxes. This works fine as long as all the boxes have fixed width and height values.
To make the site responsive I use percentages on the width of the boxes and "auto" on their height and the same applies to the images that are loaded into these boxes. The media query jumps in at 1199px and converts the static box sizes to fluid box sizes.
This produces problems at certain resolutions where the second large image box jumps from the left margin of the page to the right and thus destroys the order of the grid. Making the browser window bigger makes the box jump in to place again. This is very annoying since the resolution on an iPad 3 for example produces this error as well.
On the boxes (sse code below) I had to use a "line-height: 0" to eliminate gaps of a few pixel between the boxes. This seems to be part of the strange float-problem.
.box-1 {
width: 25% !important;
height: auto;
display: block;
overflow: hidden;
float: left;
background-size: cover !important;
line-height: 0;
}
.box-2 {
width: 50% !important;
height: auto;
display: block;
overflow: hidden;
float: left;
background-size: cover !important;
line-height: 0;
}
Thanks a lot for ANY help!
Arne

Answer 1

So what I found is that you need to force an aspect ratio.
Try modifying the following styles:
.box-1 {
width: 25% !important;
height: 0;
display: block;
overflow: hidden;
float: left;
background-size: cover !important;
line-height: 0;
position: relative;
padding: 13.75% 0 0 0;
}
.box-1 img {
width: 100% !important;
height: auto !important;
position: absolute;
display: block;
max-width: 100%;
max-height: 100%;
left: 0;
right: 0;
top: 0;
bottom: 0;
margin: auto;
}
Basically the modification above set up the box-1 to have a fixed aspect ratio then positionsw the img in in absolutely. To calculate the 13.75%, I took one of your images and got 165/300=.55 --> .55*.25=.1375 --> 13.75%
Hope this solves your issue.
Reference