fix: Blogpost thumbnail aspect ratio, remove horizontal scroll on mobile devices (#129)

Description

Related issue

#129 (closed)

Examples

Thumbnail before the changes:

Thumbnail after the changes:

Checklist

• the MR description has been reviewed
• this MR contains text changes and they have been reviewed OR there are no texts changes
• this MR contains GUI/CLI changes and they have been reviewed OR there are no GUI/CLI changes
• this MR contains API changes and they have been reviewed OR there are no API changes

Closes #129 (closed)