#captchaStage {
        width: 320px;
        height: 180px;
        max-width: 100%;
    }

    #captchaCanvas {
        width: 320px;
        height: 180px;
        display: block;
    }

    #pieceWrapper {
        position: absolute;
        left: 0;
        top: 0;
        pointer-events: none;
    }

    #pieceCanvas {
        display: block;

        filter:
            drop-shadow(0 3px 5px rgba(0, 0, 0, .35)) drop-shadow(0 8px 15px rgba(0, 0, 0, .25));
    }

    #pieceCanvas {
        filter: drop-shadow(0 3px 5px rgba(0, 0, 0, .35));
    }

    .captcha-shake {
        animation: captchaShake .35s ease;
    }

    @keyframes captchaShake {

        0%,
        100% {
            transform: translateX(0);
        }

        20% {
            transform: translateX(-8px);
        }

        40% {
            transform: translateX(8px);
        }

        60% {
            transform: translateX(-6px);
        }

        80% {
            transform: translateX(6px);
        }
    }

    .captcha-success #sliderBtn {
        background: #16a34a;
        color: #fff;
        border-color: #16a34a;
    }