Create a single HTML file containing a Tetris game. Use 7 standard tetrominoes, SRS-lite rotation with wall kicks (simple: try offsets 0, -1, +1, -2, +2). Score: 40/100/300/1200 × level. Level up every 10 lines, speed goes up. Preview canvas. Game over overlay, restart with R/Enter. Dark style.

Write clean code.