.about {
    background: url(../images/about-bg.jpg) no-repeat;
    background-position: center;
    background-size: cover;
}
.field {
    background: url(../images/field-bg.jpg) no-repeat;
    background-size: cover;
}
.case {
    background: url(../images/case-bg.jpg) no-repeat;
    background-size: cover;
}
.info {
    background: url(../images/info-bg.jpg) no-repeat;
    background-size: cover;
}
.contact {
    background: url(../images/contact-bg.jpg) no-repeat;
    background-size: cover;
}

.sub-promotion {
    position: relative;
    width: 100%;
    height: 480rem;
    display: flex;
    justify-content: center;
    align-items: flex-end;
    background: #111;
    background: url(../images/about-bg.jpg) no-repeat;
    background-position: center !important;
    background-size: cover;
}

.sub-promotion::before {
    content: '';
    position: absolute;
    top: 0;
    width: 100%;
    height: 100px;
    background: linear-gradient(to bottom, rgba(0, 0, 0, .2) 0%, transparent 100%);
    z-index: 1;
}

.sub-promotion-wrapper {
    height: 100%;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
}

.sub-p-text {
    position: relative;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    text-align: center;
    margin-top: 110rem;
}
.sub-p-text::before {
    content: '';
    position: absolute;
    top: -40rem;
    width: 50rem;
    height: 2px;
    background-color: #fff;
}

.sub-p-text h5 {
    color: #fff;
    font-size: 50rem;
    font-weight: 600;
}

.sub-p-text p {
    color: #fff;
    font-size: 18rem;
    margin-top: 20rem;
    display: flex;
    flex-wrap: wrap;
    gap: 7px;
}

.sub-p-text .hashtag {
    padding: 10rem 20rem;
    border-radius: 50rem;
    background-color: #ffffff30;
    letter-spacing: 0;
    margin-top: 10px;
    cursor: default;
}
.sub-p-text .hashtag:hover {
    background-color: #ffffff40;
}


.sub-nav-wrapper {
    position: absolute;
    bottom: 30rem;
    width: 1400rem;
    height: 75rem;
    display: flex;
    justify-content: center;
    align-items: center;
    border-radius: 10rem;
    background-color: #121212;
    display: none;
}

.sub-nav-container {
    width: 100%;
    display: flex;
    align-items: center;
    padding: 0 20px;
}

.nav-home {
    color: #f5f5f5;
    padding: 0 20rem;
    padding-right: 30rem;
    border-right: 1px solid #ffffff44;
}

.nav-item {
    position: relative;
    height: 100%;
    border-right: 1px solid #ffffff44;
}
.nav-item:last-child {
    border-right: none;
}

.nav-selected {
    color: #f5f5f5;
    padding: 0 30rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-weight: 500;
    cursor: pointer;
}

.nav-dropdown {
    display: none;
    position: absolute;
    top: 49rem;
    left: 0;
    background-color: #fff;
    box-shadow: 0 4px 10px rgba(0, 0, 0, 0.1);
    z-index: 100;
}

.nav-home,
.nav-selected {
    font-size: 18rem;
}

.nav-selected,
.nav-dropdown {
    min-width: 300rem;
}

.nav-dropdown li {
    border-bottom: 1px solid #f0f0f0;
}

.nav-dropdown li:last-child {
    border-bottom: none;
}

.nav-dropdown li a {
    display: block;
    padding: 17rem 20rem;
    color: #555;
    font-size: 17rem;
    transition: background 0.3s;
}

.nav-dropdown li a:hover {
    color: var(--main-color);
    background-color: #f8f8f8;
}




/*==================================================*/
@media (max-width: 550px) {
    .sub-promotion {
        height: 330px;
    }
    
    .sub-p-text {
        margin-top: 75px;
    }
    
    .sub-p-text h5 {
        font-size: 36px;
    }
    
    .sub-p-text p {
        font-size: 16px;
    }
}


@media (max-width: 450px) {
    .sub-promotion {
        height: 300px;
    }
    
    .sub-p-text h5 {
        font-size: 32px;
    }

    .sub-p-text p {
        font-size: 14px;
    }
}