.ba { position: relative; overflow: hidden; border-radius: 16px; touch-action: none; user-select: none; } .ba canvas { display: block; width: 100%; height: auto; } .ba #ca { position: absolute; inset: 0; } .ba i { position: absolute; top: 0; bottom: 0; width: 3px; background: #fff; box-shadow: 0 0 6px #0008; } .ba i::after { content: "⇔"; position: absolute; top: 50%; left: 50%; transform: translate(-50%, -50%); background: #fff; border-radius: 50%; width: 36px; height: 36px; display: grid; place-items: center; font-size: 18px; }