body {
    margin: 0;
    font-family: 'Segoe UI', 'Meiryo', sans-serif;
    background: #0a1833;
    color: #fff;
}

header {
    position: relative;
}

.hamburger-menu {
    display: none;
    font-size: 2rem;
    cursor: pointer;
    padding: 1rem;
    color: #fff;
    z-index: 1001;
    position: fixed;
    top: 0;
    left: 0;
    background: rgba(10, 24, 51, 0.9);
    border-radius: 0 0 8px 0;
}

.sidebar {
    position: fixed;
    top: 0;
    left: 0;
    width: 260px;
    height: 100vh;
    background: linear-gradient(160deg, #0a1833 0%, #233d6d 100%);
    box-shadow: 2px 0 10px rgba(0,0,0,0.2);
    overflow-y: auto;
    transition: transform 0.3s cubic-bezier(.4,0,.2,1);
    transform: translateX(0);
    z-index: 1000;
    scrollbar-width: none;         /* Firefox */
    -ms-overflow-style: none;      /* IE/Edge */
}

.sidebar::-webkit-scrollbar {
    display: none;                 /* Chrome/Safari */
}

.sidebar ul {
    list-style: none;
    padding: 0;
    margin: 0;
}

.sidebar ul li {

    padding: 2px 0;
    margin: 1px 0;

    margin: 1px 0;
    border-bottom: 1px solid rgba(255,255,255,0.08);
}

.sidebar ul li a {
        padding: 2px 0;
    margin: 1px 0;

    display: block;
    color: #fff;
    text-decoration: none;
    padding: 1rem 0.2rem;
    font-weight: 500;
    transition: background 0.2s;
}

.sidebar ul li a:hover {
    background: rgba(255,255,255,0.08);
}

.sidebar ul li ul {
        padding: 3px 9px;
    margin: 1px 0;

    background: rgba(10,24,51,0.7);
    
}

.sidebar ul li ul li a {
        padding: 3px 9px;
    margin: 1px 0;

    font-size: 0.95rem;
    
}

.breadcrumb {
    margin: 0.2rem 0 0.2rem 0.2rem;
    font-size: 0.95rem;
    color: #b0c4de;
}

.breadcrumb a {
    color: #b0c4de;
    text-decoration: none;
}

.breadcrumb a:hover {
    text-decoration: underline;
}

main {
    margin-left: 260px;
    padding: 2rem;
    transition: margin-left 0.3s cubic-bezier(.4,0,.2,1);
}

/* レスポンシブ対応 */
@media (max-width: 900px) {
    .sidebar {
        transform: translateX(-100%);
    }
    
    .sidebar.active {
        transform: translateX(0);
    }
    
    .hamburger-menu {
        display: block;
    }
    
    main {
        margin-left: 0;
        padding: 1rem;
        padding-top: 4rem; /* ハンバーガーメニューの分の余白 */
    }
}

/* デスクトップ用のサイドバー切り替えボタン（オプション） */
@media (min-width: 901px) {
    .sidebar-toggle-desktop {
        display: block;
        position: fixed;
        top: 1rem;
        left: 270px;
        background: rgba(35, 61, 109, 0.9);
        color: #fff;
        border: none;
        padding: 0.5rem;
        cursor: pointer;
        border-radius: 4px;
        z-index: 999;
        transition: left 0.3s cubic-bezier(.4,0,.2,1);
    }
    
    .sidebar-toggle-desktop:hover {
        background: rgba(35, 61, 109, 1);
    }
    
    main.sidebar-hidden {
        margin-left: 0;
    }
    
    .sidebar.hidden {
        transform: translateX(-100%);
    }
    
    .sidebar.hidden + .sidebar-toggle-desktop {
        left: 1rem;
    }
}