Branding
The banner is cropped differently on every device — TV gets the whole 2560 × 1440, mobile gets only the centre 1546 × 423. So every word and mark lives inside that box, and everything outside it is texture that has to be able to disappear. Turn on Guides in the header to see both crops.
channel banner — everything readable sits in the centre box; the grid field and corner brackets exist only for the TV crop and are safe to lose.
.mark-dot — 800 × 800 · the channel avatar. At 48px only the dot survives, so the dot is the logo.
.mark-s — holds down to about 64px
.mark-frame — the viewfinder mark, for merch and the watermark
.avatar-yt-light — inverted, for light backgrounds and print
.watermark — 150 × 150 transparent PNG, bottom-right in the player