Tiled Mosaic Not Responsive

Hi everyone,
I’ve been creating my own adaptive theme, which has several breakpoints to adjust the layout based on the browser size.
I have just enabled Jetpack’s tiled mosaic image gallery. However I noticed that when the browser is resized, the tiled mosaic doesn’t resize correctly.
I have defined in functions.php
‘if ( ! isset( $content_width ) ) $content_width = 900;’
This is the maximum content width of my theme.

When the browser size is reduced, I find the tiled mosaic gallery does reduce, but its more common for parts of the gallery images to overflow the content area and cover the sidebar. I.e. before automatically resizing part of the gallery is cut off. Its best understood by viewing an example on my site: .

Any advice on how to fix this would be very much appreciated.
Thanks in advance,
Kat