Prompt

Make an emoji mosaic maker with a 12 by 12 grid painted with coloured squares. Make it a single HTML file that opens in a browser with nothing to install and no other files. Put the CSS and JavaScript inside it. Do not use image files or any external address; use emoji or letters if you need a symbol.

Pick an emoji from the palette, then click or drag over the grid to place it. Right-click clears a square.

The point is that the result is text: add a copy button that copies the whole grid as lines of emoji, ready to paste into a message. Show what that text looks like in a box underneath.

Put about a dozen starter patterns in the code — a heart, a smiley, a simple flower — that fill the grid when picked, so there is something to change rather than an empty square.

When you are done, copy the result and check the lines still line up when pasted somewhere with a different font.