Added DarkMode version and simplified Modal functionality

Changes since last Release

• Added DarkMode of every page
• Simplified modal functionality in order to make it equally on every page that currently uses it
• Added various favicons for different browser vendors
• [build/post.html] added "place"-strings where needed in order to match the currently used design
• [build/blackboard.html] tiny tweaks in the jobs-list styling (corners of top and last item rounded)

Changed files since last Release

• [build/*.html] got changed due to DarkMode and diversified favicon-support implementation
• [dev/tailwind.css] styling implementation
• [build/styles.css] compiled file changed because of changes in [dev/tailwind.css]

Full Changelog: v0.5.0-beta...v0.5.1-beta

• Merge: Dev by @M00nD3v in #13