| <!DOCTYPE html> | |
| <canvas id = 'c' width='100' height='100' style='background-color:red;'></canvas> | |
| <script> | |
| var ctx = document.getElementById('c').getContext('2d', { alpha: true }); | |
| ctx.fillStyle = 'rgba(0, 255, 0, 0.5)'; | |
| ctx.fillRect(0, 0, 100, 100); | |
| </script> |