.header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 5rem;
    margin: 0;
    padding: 0;
    z-index: 998;
    transition: all 1s ease;
}
.header-scrolled {
    height: 3.75rem;
    background-color: var(--header-scrolled-bg-color);
    border-bottom: 1px solid var(--light-grey-color);
}
.header-content {
    display: flex;
    margin: 0 auto;
    padding: 0;
    align-items: center;
    justify-content: space-between;
    flex-direction: row;
    background-color: transparent;
    width: 100%;
    height: 100%;
    max-width: var(--max-width);
    border-bottom: 1px solid var(--header-border-color);
}
.header-scrolled .content {
    border: 0; 
}
.logo {
    flex: 0 0 auto;
}
.logo-drawing-container {
    float: left;
}
.logo-drawing {
    width: 2.7rem;
    height: 2.7rem;
    color: black;
}
.logo-text {
    display: block;
    float: left;
    padding: 0 0.5rem;
    font-size: 1.1rem;
    line-height: 1.2em;
    font-weight: bold;
    color: var(--white-color);
    transition: color 1s ease;
}
.header-scrolled .logo-text {
    color: var(--text-color);
}
.logo-image {
    height: 2.5rem;
    width: auto;
}
.header-menu {
    flex: 1 1 auto;
    display: flex;
    align-items: center;
    justify-content: flex-end;
}
.header-menu-item {
    padding: 1rem 1rem;
    text-decoration: none;
    color: var(--header-text-color);
    font-size: 0.8rem;
    font-weight: bold;
    text-transform: uppercase;
    letter-spacing: 1px;
    transition: color 1s ease;
}
.header-scrolled .header-menu-item {
    color: var(--grey-color);
}
.header-menu-item:hover {
    color: var(--header-text-highlight-color);
}
.header-scrolled .header-menu-item:hover {
    color: var(--text-color);
}

/* Mobile menu toggle (hamburger) — hidden on desktop, shown under 48rem */
.header-toggle {
    display: none;
    flex-direction: column;
    justify-content: center;
    gap: 5px;
    width: 2.5rem;
    height: 2.5rem;
    padding: 0;
    background: transparent;
    border: none;
    cursor: pointer;
}
.header-toggle span {
    display: block;
    width: 1.5rem;
    height: 2px;
    border-radius: 2px;
    background-color: var(--white-color);
    transition: transform 0.3s ease, opacity 0.2s ease, background-color 1s ease;
}
.header-scrolled .header-toggle span {
    background-color: var(--text-color);
}
.header.nav-open .header-toggle span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.header.nav-open .header-toggle span:nth-child(2) { opacity: 0; }
.header.nav-open .header-toggle span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* Two-level (dropdown) menu */
.header-dropdown {
    position: relative;
    display: inline-flex;
    align-items: center;
}
.header-dropdown-label {
    cursor: pointer;
}
.header-dropdown-caret {
    font-size: 0.6rem;
    letter-spacing: 0;
}
.header-submenu {
    position: absolute;
    top: 100%;
    left: 0;
    display: none;
    flex-direction: column;
    min-width: 11rem;
    padding: 0.25rem 0;
    background-color: var(--white-color);
    border: 1px solid var(--light-grey-color);
    box-shadow: 0 6px 18px rgba(0, 0, 0, 0.14);
    border-radius: 4px;
    z-index: 999;
}
.header-dropdown:hover .header-submenu,
.header-dropdown:focus-within .header-submenu,
.header-dropdown.open .header-submenu {
    display: flex;
}
.header-submenu-item {
    padding: 0.6rem 1.1rem;
    text-decoration: none;
    color: var(--text-color);
    font-size: 0.75rem;
    font-weight: bold;
    text-transform: uppercase;
    letter-spacing: 1px;
    white-space: nowrap;
    transition: background-color 0.2s ease, color 0.2s ease;
}
.header-submenu-item:hover {
    background-color: var(--light-grey-color);
    color: var(--link-color);
}

@media screen and (max-width: 48rem) {
    .header {
        height: 3.75rem;
    }
    .header-scrolled {
        height: 3.75rem;
        background-color: var(--header-scrolled-bg-color);
        border-bottom: 1px solid var(--light-grey-color);
    }
    .header-content {
        flex-direction: row;
        justify-content: space-between;
        align-items: center;
        padding: 0 0.75rem;
        border-bottom: none;
        position: relative;
    }
    .header-toggle {
        display: flex;
    }
    /* While the panel is open, give the top bar a solid look. */
    .header.nav-open {
        background-color: var(--white-color);
    }
    .header.nav-open .logo-text {
        color: var(--text-color);
    }
    .header.nav-open .header-toggle span {
        background-color: var(--text-color);
    }
    /* The menu becomes a dropdown panel below the bar. */
    .header-menu {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        flex-direction: column;
        align-items: stretch;
        justify-content: flex-start;
        padding: 0.25rem 0;
        background-color: var(--white-color);
        border-bottom: 1px solid var(--light-grey-color);
        box-shadow: 0 10px 22px rgba(0, 0, 0, 0.14);
        max-height: calc(100vh - 3.75rem);
        overflow-y: auto;
    }
    .header.nav-open .header-menu {
        display: flex;
    }
    .header-menu-item {
        display: block;
        padding: 0.85rem 1.25rem;
        color: var(--text-color);
        font-size: 0.8rem;
        letter-spacing: 1px;
    }
    .header-scrolled .header-menu-item {
        color: var(--text-color);
    }
    .header-menu-item:hover {
        color: var(--link-color);
    }
    /* Dropdowns become inline accordions (tap to expand). */
    .header-dropdown {
        display: block;
        position: static;
    }
    .header-menu-item.header-dropdown-label {
        display: flex;
        justify-content: space-between;
        align-items: center;
    }
    .header-submenu {
        display: none;
        position: static;
        min-width: 0;
        padding: 0;
        border: none;
        border-radius: 0;
        box-shadow: none;
        background-color: var(--light-grey-color);
    }
    .header-dropdown:hover .header-submenu,
    .header-dropdown:focus-within .header-submenu {
        display: none;
    }
    .header-dropdown.open .header-submenu {
        display: block;
    }
    .header-submenu-item {
        display: block;
        padding: 0.75rem 1.25rem 0.75rem 2.25rem;
        font-size: 0.75rem;
    }
}