header {
    position: fixed;
    top: 0;
    left: 0;

    height: var(--header-height);
    width: 100%;

    background: black;
    /* background: lightgray; */
    color: white;

    display: flex;
    align-items: center;
    justify-content: space-between;
}

header .logo-container {
    padding-left: 1rem;
}

header .logo {
    font-size: 40px;
    font-weight: bold;

    cursor: pointer;
}

header .logo:active {
    filter: brightness(0.8);
}

header .menu-container {
    padding-right: 1rem;
    padding-bottom: 4px;
}

header #language-button {
    font-size: 35px;
    margin: 0 0.8rem;

    background: transparent;
    border: none;
    color: white;

    cursor: pointer;

    opacity: 1;
    visibility: visible;
}

header #language-button.is-active {
    opacity: 0;
    visibility: hidden;

    transition:
        opacity 0.3s ease,
        visibility 0.3s ease;
}

header #menu-button {
    font-size: 40px;
    margin: 0 0.4rem;

    background: transparent;
    border: none;
    color: white;

    cursor: pointer;
}

header #menu-button:active {
    filter: brightness(0.8);
}


/* ここからハンバーガーメニューのスタイル設定 */
.menu-overlay {
    position: fixed;

    top: var(--header-height);
    left: 0;

    width: 100%;
    height: calc(100vh - var(--header-height));

    background: #000;

    opacity: 0;
    visibility: hidden;

    transition:
        opacity 0.3s ease,
        visibility 0.3s ease;

    z-index: 100;
}

.menu-overlay.is-active {
    opacity: 1;
    visibility: visible;
}

body.menu-open {
    overflow: hidden;
}

.menu-content {
    height: 100%;

    display: flex;
    flex-direction: column;
    margin: 0 3rem;
}

#menu-auth-area {
    display: flex;
    flex-direction: column;

    gap: 2.5rem;
    margin: 25px 0;
}

#menu-auth-area span {
    color: white;
    text-decoration: none;
    font-size: 1.7rem;
}

#menu-auth-area a {
    color: white;
    text-decoration: underline;
    font-size: 1.7rem;
}

#menu-auth-area a:active {
    filter: brightness(0.8);
}

.menu-divider {
    width: 100%;
    margin: 0;

    border: 1px solid #202020;
}

.menu-nav {
    display: flex;
    flex-direction: column;
    
    gap: 2.5rem;
    margin: 20px 0 0 0;
}

.menu-nav a {
    color: white;
    text-decoration: underline;
    font-size: 1.7rem;
}

.menu-nav a:active {
    filter: brightness(0.8);
}



@media(max-width: 768px){
header .logo {
    font-size: 25px;
}

header .language-button {
    font-size: 25px;
}
}