Blog post banner/image not responsive on mobile

[ig-imanish]

Context

Some blog posts render an image/banner (e.g. homepage screenshot in "Ossium vs GitHub Explore") that breaks or overflows on mobile viewports.

Problem

The embedded image does not scale properly on smaller screens. It either overflows horizontally, gets cropped awkwardly, or forces horizontal scroll.

Expected

• Image should be fully responsive (max-width: 100%, proper aspect-ratio handling)
• No horizontal overflow on mobile
• Maintain visual quality without looking stretched or pixelated

Acceptance Criteria

• Banner/image scales cleanly on mobile (≤ 640px)
• No horizontal scroll introduced by the image
• Works across existing blog posts that use similar banners
• Desktop appearance remains unchanged

Notes

Affects posts that include product screenshots / hero images.

Low priority polish item.