TYPO3 Core

this also applies to most icons in the core. As we have css sprites, we could use either conditional css:

@media all and (-webkit-min-device-pixel-ratio: 2) {
  /*Code follows here*/
}

Or webkit specific css:

.header {
   background-image: url(img/image-set-fallback-for-all-browsers-except-webkit.png);
   background-image: -webkit-image-set(
                              url(img/image-1to1.png) 1x,
                              url(img/image-1to2.png) 2x);

Now, not yet :(

To me it looks like there is no problem anymore.

Still no SVG/high-dpi logo in the backend.