header{
    border-bottom: 1px solid #dddddd;
    position: relative;
    z-index: 99;
    background-color: #fff;
}
header .flex_box{
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 79px;
}

header .flex_box h1{
    width: 101px;
}
header .flex_box h1 a{}

header .flex_box nav{}
header .flex_box nav ul{
    display: flex;
    gap: 3rem;
}
header .flex_box nav ul li{}
header .flex_box nav ul li a{
    display: inline-block;
    padding: 0.5rem 1rem;
    font-size: 1.6rem;
    letter-spacing: -0.05em;
    font-weight: 500;
    color: #353535;
}
header .flex_box nav ul li a.on{
    font-weight: 700;
    color: #de1e10;
    text-decoration: underline;
    text-underline-offset: 0.4rem;
    text-decoration-thickness: 0.2rem;
}

header .flex_box .go_main{
    padding: 0.5rem 0;
    font-size: 1.6rem;
    letter-spacing: -0.05em;
    font-weight: 500;
    color: #353535;
}

header .side_menu{
    position: absolute;
    top: 85.3rem;
    left: calc(50% + 68rem);
}
header .side_menu ul{
    display: flex;
    flex-direction: column;
    gap: 1.4rem;
    position: relative;
    padding-left: 2.5rem;
}
header .side_menu ul::after{
    content: "";
    position: absolute;
    left: 1rem;
    top: 1.1rem;
    width: 0.1rem;
    height: 8.1rem;
    background-image: url("../images/side_bar.png");
}
header .side_menu ul li{
    position: relative;
}
header .side_menu ul li::after{
    content: "";
    position: absolute;
    top: 50%;
    left: -2.1rem;
    transform: translateY(-50%);
    width: 1.3rem;
    height: 1.3rem;
    background-image: url("../images/side_off.png");
    background-color: transparent;
    z-index: 1;
    border-radius: 50%;
}
header .side_menu ul li.on::after{
    background-image: url("../images/side_on.png");
}
header .side_menu ul li a{
    font-size: 1.6rem;
    letter-spacing: -0.05em;
    color: #909090;
    font-weight: 500;
}
header .side_menu ul .on a{
    color: #000;
    font-weight: 700;
    text-decoration: underline;
    text-underline-offset: 3px;
    text-decoration-thickness: 2px;
}