/* ヘッダー共通スタイル */
header {
    position: fixed;
    top: 0;
    width: 100%;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-color);
    z-index: 1000;
    transition: all 0.3s ease;
}

header.scrolled {
    background: rgba(255, 255, 255, 0.98);
    box-shadow: 0 2px 20px rgba(0, 0, 0, 0.1);
}

nav {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.5rem;
    font-weight: bold;
    color: var(--primary-color);
    text-decoration: none;
    transition: color 0.3s ease;
}

.logo:hover {
    color: var(--accent-blue);
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 2rem;
}

.nav-menu a {
    text-decoration: none;
    color: var(--text-dark);
    font-weight: 500;
    transition: color 0.3s ease;
    position: relative;
}

.nav-menu a:hover {
    color: var(--accent-blue);
}

.nav-menu a::after {
    content: '';
    position: absolute;
    bottom: -5px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--accent-blue);
    transition: width 0.3s ease;
}

.nav-menu a:hover::after {
    width: 100%;
}

.mobile-menu-toggle {
    display: none;
    flex-direction: column;
    cursor: pointer;
    gap: 4px;
}

.mobile-menu-toggle span {
    width: 25px;
    height: 3px;
    background: var(--primary-color);
    transition: all 0.3s ease;
}

/* レスポンシブデザイン */
@media (max-width: 768px) {
    nav {
        padding: 1rem;
    }

    .nav-menu {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        width: 100%;
        background: white;
        flex-direction: column;
        padding: 1rem;
        box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
        gap: 1rem;
    }

    .nav-menu.active {
        display: flex;
    }

    .mobile-menu-toggle {
        display: flex;
    }

    .nav-menu a {
        padding: 0.5rem 0;
        border-bottom: 1px solid var(--border-color);
    }

    .nav-menu a:last-child {
        border-bottom: none;
    }
}