Shift + click always adds · Alt + click removes
Vector borders and labels are redrawn at the target size. Raster street tiles may be less sharp and need attribution.
Auto tries H.264 MP4 first and falls back to a lossless MOV if your browser can't encode that resolution, so quality is never lowered. For glowing borders, transparent MOV avoids chroma-key halos. MOV files can be very large at 4K.