.site-header {
    position: sticky;
    top: 0;
    z-index: 100;
    width: 100%;
    background: rgba(255, 255, 255, .97);
    border-bottom: 1px solid rgba(3, 52, 107, .10);
    box-shadow: 0 4px 18px rgba(3, 52, 107, .05);
    backdrop-filter: blur(12px);
    transition: background 220ms ease, border-color 220ms ease, box-shadow 220ms ease;
}

.site-header--overlay {
    position: fixed;
    background: transparent;
    border-bottom-color: transparent;
    box-shadow: none;
    backdrop-filter: none;
}

.site-header--overlay.is-scrolled,
.site-header--overlay.is-menu-open {
    background: rgba(255, 255, 255, .97);
    border-bottom-color: rgba(3, 52, 107, .10);
    box-shadow: 0 8px 28px rgba(3, 52, 107, .09);
    backdrop-filter: blur(14px);
}

.header-inner {
    min-height: 76px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 28px;
}

.brand {
    display: inline-flex;
    align-items: center;
    gap: 0;
    color: var(--color-navy);
    text-decoration: none;
    flex: 0 0 auto;
}
.brand:hover { color: var(--color-navy); }
.site-logo {
    display: inline-block;
    width: min(273px, 100%);
    line-height: 0;
}
.site-logo__image {
    display: block;
    width: 100%;
    height: auto;
}
.site-logo__image--light {
    display: none;
}

.main-nav {
    display: flex;
    align-items: center;
    justify-content: flex-end;
    gap: 6px;
    margin-left: auto;
}
.nav-link {
    display: inline-flex;
    align-items: center;
    min-height: 40px;
    padding: 8px 11px;
    border-radius: 8px;
    color: #3e5066;
    text-decoration: none;
    font-size: 14px;
    font-weight: 650;
    white-space: nowrap;
}
.nav-link:hover { background: var(--color-primary-pale); color: var(--color-primary); }
.nav-button {
    border: 0;
    background: transparent;
    cursor: pointer;
}
.logout-form { margin: 0; }
.header-cta {
    position: relative;
    min-height: 40px;
    padding: 8px 18px;
    margin-left: 6px;
    border: 1px solid rgba(3, 52, 107, .42);
    border-radius: 999px;
    background: transparent;
    color: #03346b;
    font-size: 13px;
    font-weight: 750;
    letter-spacing: .015em;
    box-shadow: none;
    transition: color 180ms ease, background 180ms ease, border-color 180ms ease, transform 180ms ease;
}
.header-cta::after {
    content: '';
    width: 5px;
    height: 5px;
    margin-left: 9px;
    border-radius: 50%;
    background: #c9a45d;
    box-shadow: 0 0 0 3px rgba(201, 164, 93, .12);
}
.header-cta:hover {
    border-color: #03346b;
    background: #03346b;
    color: #fff;
    transform: translateY(-1px);
}
.header-cta:hover::after {
    background: #e2c47f;
}
.dev-nav {
    display: flex;
    align-items: center;
    gap: 8px;
    margin-left: 8px;
    padding-left: 12px;
    border-left: 1px solid var(--color-border);
}
.dev-nav a { color: #8793a3; font-size: 11px; text-decoration: none; }
.dev-nav a:hover { color: var(--color-primary); }
.nav-toggle { display: none; }
.nav-overlay { display: none; }

/* Hero上ではヘッダーを透明にし、文字を白で重ねる。 */
.site-header--overlay:not(.is-scrolled):not(.is-menu-open) .site-logo__image--dark { display: none; }
.site-header--overlay:not(.is-scrolled):not(.is-menu-open) .site-logo__image--light { display: block; }
.site-header--overlay:not(.is-scrolled):not(.is-menu-open) .nav-link {
    color: #fff;
    text-shadow: 0 1px 12px rgba(0, 19, 43, .28);
}
.site-header--overlay:not(.is-scrolled):not(.is-menu-open) .nav-link:hover {
    background: rgba(255, 255, 255, .11);
    color: #fff;
}
.site-header--overlay:not(.is-scrolled):not(.is-menu-open) .dev-nav {
    border-left-color: rgba(255, 255, 255, .25);
}
.site-header--overlay:not(.is-scrolled):not(.is-menu-open) .dev-nav a { color: rgba(255, 255, 255, .72); }
.site-header--overlay:not(.is-scrolled):not(.is-menu-open) .header-cta {
    border-color: rgba(255, 255, 255, .64);
    background: rgba(3, 52, 107, .12);
    color: #fff;
    backdrop-filter: blur(8px);
}
.site-header--overlay:not(.is-scrolled):not(.is-menu-open) .header-cta::after {
    background: #e1c27c;
    box-shadow: 0 0 0 3px rgba(225, 194, 124, .16);
}
.site-header--overlay:not(.is-scrolled):not(.is-menu-open) .header-cta:hover {
    border-color: rgba(225, 194, 124, .95);
    background: rgba(255, 255, 255, .12);
    color: #fff;
}

@media (max-width: 900px) {
    body.nav-open { overflow: hidden; }
    .header-inner { min-height: 68px; position: relative; }
    /* The source logo is wider than its displayed size. Keep its flex item
       at the intended 226px so it cannot push the hamburger off-screen. */
    .header-inner > .brand { flex: 0 1 226px; min-width: 0; }
    .site-logo { width: min(226px, 100%); }
    .nav-toggle {
        flex: 0 0 42px;
        position: relative;
        z-index: 112;
        width: 42px;
        height: 42px;
        display: inline-flex;
        flex-direction: column;
        align-items: center;
        justify-content: center;
        gap: 5px;
        margin-left: auto;
        border: 1px solid var(--color-border);
        border-radius: 10px;
        background: #fff;
        cursor: pointer;
    }
    .nav-toggle span {
        width: 18px;
        height: 2px;
        border-radius: 99px;
        background: var(--color-navy);
        transition: transform var(--transition), opacity var(--transition), background var(--transition);
    }
    .site-header--overlay:not(.is-scrolled):not(.is-menu-open) .nav-toggle {
        border-color: rgba(255, 255, 255, .48);
        background: rgba(3, 52, 107, .22);
        backdrop-filter: blur(8px);
    }
    .site-header--overlay:not(.is-scrolled):not(.is-menu-open) .nav-toggle span { background: #fff; }
    .nav-toggle[aria-expanded="true"] span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
    .nav-toggle[aria-expanded="true"] span:nth-child(2) { opacity: 0; }
    .nav-toggle[aria-expanded="true"] span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }
    .main-nav {
        position: absolute;
        z-index: 111;
        top: calc(100% + 1px);
        left: 0;
        right: 0;
        display: none;
        align-items: stretch;
        flex-direction: column;
        gap: 4px;
        padding: 12px 14px 16px;
        background: #fff;
        border-bottom: 1px solid var(--color-border);
        box-shadow: 0 18px 40px rgba(3, 31, 67, .20);
    }
    .main-nav.is-open { display: flex; }
    .main-nav .nav-link { color: #3e5066 !important; text-shadow: none !important; }
    .main-nav .nav-link:hover { background: var(--color-primary-pale) !important; color: var(--color-primary) !important; }
    .nav-link, .header-cta { width: 100%; justify-content: flex-start; margin: 0; padding: 10px 12px; }
    .main-nav .header-cta {
        width: auto;
        min-height: 42px;
        margin-top: 4px;
        padding: 9px 14px;
        border-color: rgba(3, 52, 107, .24);
        border-radius: 10px;
        background: #f5f8fc;
        color: #03346b !important;
    }
    .main-nav .header-cta:hover {
        border-color: #03346b;
        background: #03346b !important;
        color: #fff !important;
    }
    .logout-form { width: 100%; }
    .dev-nav {
        align-items: flex-start;
        flex-direction: column;
        margin: 6px 0 0;
        padding: 10px 12px 0;
        border-left: 0;
        border-top: 1px solid var(--color-border);
    }
    .dev-nav a { color: #8793a3 !important; }
    .nav-overlay {
        position: fixed;
        z-index: 90;
        inset: 0;
        display: block;
        background: rgba(3, 27, 57, .58);
        opacity: 0;
        visibility: hidden;
        pointer-events: none;
        transition: opacity 180ms ease, visibility 180ms ease;
        backdrop-filter: blur(2px);
    }
    .nav-overlay.is-visible {
        opacity: 1;
        visibility: visible;
        pointer-events: auto;
    }
}

/* Keep the same single-row header and 68px height on narrow phones. */
@media (max-width: 640px) {
    .header-inner { gap: 12px; }
}