/* Homepage business challenges: compact four-card presentation. */
.index .difficulty {
    position: relative;
    height: auto;
    padding: 62px 0 68px;
    overflow: hidden;
    background: #f3f7fd;
}

.index .difficulty::before {
    content: "";
    position: absolute;
    top: -190px;
    right: -150px;
    width: 430px;
    height: 430px;
    border: 1px solid rgba(40, 120, 245, .09);
    border-radius: 50%;
    box-shadow: 0 0 0 70px rgba(40, 120, 245, .025);
    pointer-events: none;
}

.index .difficulty .content {
    position: relative;
    z-index: 1;
}

.index .difficulty .content-title .remark {
    max-width: 720px;
    margin: 14px auto 0 !important;
}

.index .difficulty ul {
    display: grid;
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: 18px;
    width: 100%;
    height: auto;
    margin: 34px 0 0;
}

.index .difficulty ul li {
    --challenge-color: #2878f5;
    --challenge-border: #c9dcfa;
    --challenge-soft: #f2f7ff;
    position: relative;
    float: none;
    width: auto;
    min-height: 238px;
    margin: 0;
    padding: 27px 24px 80px;
    overflow: hidden;
    border: 1px solid var(--challenge-border);
    border-top: 4px solid var(--challenge-color);
    border-radius: 16px;
    background: var(--challenge-soft);
    box-shadow: 0 14px 34px rgba(40, 120, 245, .08);
    transition: transform .25s ease, border-color .25s ease, box-shadow .25s ease;
}

.index .difficulty ul li::before {
    content: "01";
    position: absolute;
    top: 24px;
    right: 22px;
    display: flex;
    align-items: center;
    justify-content: center;
    width: 36px;
    height: 25px;
    border: 1px solid #c8dcfb;
    border-radius: 7px;
    color: var(--challenge-color);
    background: #e7f0ff;
    font-size: 12px;
    font-weight: 800;
    letter-spacing: .12em;
    opacity: 1;
}

.index .difficulty ul li:nth-child(2)::before { content: "02"; }
.index .difficulty ul li:nth-child(3)::before { content: "03"; }
.index .difficulty ul li:nth-child(4)::before { content: "04"; }

.index .difficulty ul li:hover {
    border-color: var(--challenge-color);
    background: var(--challenge-soft);
    box-shadow: 0 20px 44px rgba(40, 120, 245, .16);
    transform: translateY(-5px);
}

.index .difficulty ul li .d_title,
.index .difficulty ul li:hover .d_title {
    display: flex;
    align-items: center;
    gap: 10px;
    padding-right: 44px;
    color: #17243b !important;
    font-size: 21px;
    font-weight: 700;
}

.index .difficulty ul li .d_title::before {
    content: "";
    flex: 0 0 auto;
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background: #2878f5;
    box-shadow: 0 0 0 5px #dceaff;
}

.index .difficulty ul li .remark1,
.index .difficulty ul li .remark2,
.index .difficulty ul li:hover .remark1,
.index .difficulty ul li:hover .remark2 {
    color: #718099 !important;
    font-size: 14px;
    line-height: 1.75;
}

.index .difficulty ul li .remark1 { margin-top: 15px; }

.index .difficulty ul li .remark2,
.index .difficulty ul li:hover .remark2 {
    display: inline-block;
    margin-top: 10px;
    padding: 5px 10px;
    border-radius: 6px;
    color: var(--challenge-color) !important;
    background: #e4efff;
    font-weight: 600;
}

.index .difficulty ul li .d_img,
.index .difficulty ul li:hover .d_img {
    position: absolute;
    right: 20px;
    bottom: 17px;
    left: auto;
    width: 58px;
    height: 58px;
    margin: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 14px;
    background: #2878f5 !important;
    background-image: none !important;
    box-shadow: 0 9px 20px rgba(40, 120, 245, .22);
    filter: none;
    opacity: 1;
    transform: none;
}

.index .difficulty ul li .d_img .iconfont,
.index .difficulty ul li:hover .d_img .iconfont {
    color: #fff;
    font-size: 29px;
    line-height: 1;
}

@media (max-width: 980px) {
    .index .difficulty ul { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (max-width: 640px) {
    .index .difficulty { padding: 52px 0 56px; }
    .index .difficulty ul { grid-template-columns: 1fr; gap: 14px; margin-top: 28px; }
    .index .difficulty ul li { min-height: 220px; padding: 24px 20px 74px; }
}