Image resizing in Internet Explorer

Hi, just updated my blog from Graphene theme to Adventurous. Great theme design really impressed so far apart from an image scaling issue in Internet Explorer and to a lesser extent Edge. Images within posts scale as expected on Chrome however in IE they don't leading to the r-h menu to disappear behind the image on lower resolution screens. In Edge the images scale reasonably well but not to the same extent as Chrome. Blog is naturalbornblogger.co.uk. Easy to replicate issue by adjusting window size on the relevant browsers. I'll be really grateful for any advice. Many thanks.