.am-arena{position:relative;overflow:hidden;block-size:min(62vh,460px);border-radius:18px;border:1px solid var(--line);background:var(--panel);display:grid;place-items:center;touch-action:manipulation;user-select:none;-webkit-user-select:none;-webkit-tap-highlight-color:transparent}.am-arena.live{cursor:crosshair;background:var(--panel2)}.am-arena.shake{border-color:var(--err)}.am-intro{display:flex;flex-direction:column;align-items:center;gap:14px;padding:20px;text-align:center}.am-intro .btn{min-inline-size:160px}.am-target{position:absolute;border-radius:50%;border:3px solid #fff;background:radial-gradient(circle at 50% 40%,var(--err),#b23a3a);padding:0;cursor:pointer;box-shadow:0 0 0 4px #ff6b6b2e}