CSS 网格涂鸦

Create a custom element that reads its text content as a template, parses a grid size, and renders that many child divs in a shadow root using CSS grid. Before injecting styles, expand placeholder functions per cell: index, row, column, a seeded random range, and pick-one-of-list. Emit one :nth-child rule per cell (or inline custom properties) so each cell gets its own values. Re-seed and re-render on click for instant variations.