Add explicit white background to #inbox-html-wrapper and
#inbox-plain-wrapper in the email iframe styles. Previously, the iframe
body had `background-color: transparent`, which caused the dark theme's
parent background to bleed through un-inverted, resulting in illegible
text in emails without explicit background colors.
With a white background on the content wrappers, the dark theme's
CSS filter inversion (`filter: invert(100%) hue-rotate(180deg)`)
correctly inverts white to dark, producing clean dark-on-light rendering.
Themes can still override this in their own email-frame.less.
Fixes https://community.getmailspring.com/t/poor-text-rendering-in-dark-theme/886
https://claude.ai/code/session_0122psQodPbcN8Zh2AtFNi1N
Summary
This change adds explicit white background colors to email frame styling to ensure consistent visual appearance across different contexts.
Key Changes
background-color: white;to#inbox-html-wrapperselectorbackground-color: white;to the monospace/pre-formatted text block within the email frameImplementation Details
These background color declarations ensure that the email content wrapper and pre-formatted text areas have a consistent white background, preventing potential transparency or inherited background color issues that could affect readability or visual consistency of email content display.
https://claude.ai/code/session_0122psQodPbcN8Zh2AtFNi1N