Three long answers behind the number keys
Every control on the canvas hides an argument. A page of settings can state the figure it uses; it has no room to say where the figure came from or what happens when you ignore it.
These three pages carry the parts that did not fit: the dimensions the size field defaults to, the reason a smooth ramp arrives in stripes, and what the weight estimate beside the download control is actually measuring. Each one was written against this renderer rather than against the subject in general, so the numbers in them are the numbers the canvas uses. None of them is a tutorial — the tool has seven keystrokes and explains itself. They are here for the moment a result is not what you expected and you want to know whether the fault is the design, the format or the panel you are reading it on.
- 01 · Nine minutesPixel sizes that actually matterWhere each of the six preset figures comes from, why a link card is 1200 by 630 and not something rounder, and the single multiplication that turns a size in millimetres into a size in pixels.
- 02 · Eight minutesWhy gradients band, and what to do about itA ramp across 1920 pixels has 256 levels to spend and repeats each one about seven times, which the eye reads as stripes. What the dither switch buys, what it costs, and when the stripes are your screen rather than your file.
- 03 · Seven minutesWhich format to save a background inMeasured weights for the same design written three ways, why adding grain can multiply a PNG by twenty, and the case for copying the declaration instead of downloading anything.
What none of them covers
Nothing written here touches a photograph. There is no page on separating a person from what is behind them, none on retouching, none on colour grading a picture you already own, and there will not be: this site has no code that opens an image file, so a guide about one would be advice from a program that has never seen one.
The three pieces also stop short of taste. Which two colours belong in a ramp, whether grain suits the thing you are making, how dark a wallpaper should be behind white icons — those are judgements, and the library of forty starting points is a better answer to them than a thousand words would be.
Nothing here is sent anywhere. The file is drawn by your browser and written to your disk.