More CSS cleanup and (hopefully) final tweaks. * Further adjusted `--border-radius-*` vars to reduce egregious curvature. * Adjusted `post-text` padding and max width in `card` view to reduce text overflow on smaller screens. * Left `details` collapsed in `card` view when there is no media to preview. * Corrected `.image-viewer` margins when `details` is collapsed in `card` view. * Added `isPostMedia` function to `postUtils` to consolidate some `if` statements. * Fixed links not showing in `card` view if there was no other media.