.content-box {
    background: #000;
    height: 38.91vw;
    box-sizing: border-box;
    position: relative;
    /* 运动长度 */
    --move-far: 1.04vw;
    --step-time: 3000;
    --step-time-final: 10000;
    --step-num: 4;
}

.index__content {
    font-size: 5.21vw;
    font-family: Montserrat-Black;
    border-bottom: .5vw solid black;
    display: inline-block;
    color: white;
    position: absolute;
    left: 50%;
    top: 13.59vw;
    transform: translateX(-50%);
    white-space: nowrap;
    width: 75.94vw;
}

.index__content--detail {
    top: 7.6vw;
}

.index__content i {
    font-style: normal;
    position: absolute;
}

.index__content i::before {
    content: '';
    display: block;
    width: 100%;
    left: 0;
    height: 0.78vw;
    background: #38ffa3;
    position: absolute;
    top: 57%;
    transform: translateY(-50%);
}

.index__content--detail i::before {
    top: 113%;
}

.step,
.step-box {
    opacity: 0;
}

.step1 {
    opacity: 1;
}

.index__img {
    width: 34.32vw;
    height: 40.05vw;
    position: absolute;
    right: 10.78vw;
    bottom: 0;
}

.index__content--m {
    display: none;
}

.line--hide::before {
    opacity: 0;
    transition: all .3s linear;
}

/* 最后屏下划线 */
.step6 i::before {
    width: 0;
}

.underline--show i::before {
    transition: all .3s linear;
    width: 100%;
}