set aspect ratio to be consistent when changing browser size

[davidbonnaud]

• [x ] Code builds clean without any erros or warnings
• [ x] Merged recent default branch -- main and I've no conflicts
• [ x] Didn't break any original functionality

PR type

• [x ] Bugfix

What's new? (may be part of changelog)

• closes Keep right ratio on full-screen view #445 - Changed the width to 100% and set the height to auto to keep the aspect ratio of the original image.

Small window:

Medium window:

Large window (1920x1080):

[yangwao]

WFM

[yangwao]

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