:root {
    color-scheme: light;
    /* ベースカラー */
    --bg-main: #f8fafc;
    --surface: #ffffff;
    --line: #e2e8f0;
    
    /* テキストカラー */
    --text-main: #001122;
    --text-heading: #0f172a;
    --muted: #64748b;
    
    /* アクセントカラー */
    --accent-blue: #2563eb;       /* 知的なブルー */
    --accent-fire: #f97316;       /* カガリの丁火（温かいオレンジ） */
    
    /* シャドウ（影）の設定 */
    --shadow-sm: 0 4px 6px -1px rgb(0 0 0 / 0.05), 0 2px 4px -2px rgb(0 0 0 / 0.05);
    --shadow-lg: 0 20px 25px -5px rgb(0 0 0 / 0.05), 0 8px 10px -6px rgb(0 0 0 / 0.05);
}

*,
*::before,
*::after {
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    margin: 0;
    min-height: 100vh;
    background-color: var(--bg-main);
    /* ほんのり温かみのあるグラデーションを背景に */
    background-image:
        radial-gradient(at 0% 0%, hsla(217,100%,76%,0.12) 0px, transparent 50%),
        radial-gradient(at 100% 0%, hsla(28,100%,74%,0.12) 0px, transparent 50%);
    color: var(--text-main);
    font-family: "Yu Gothic", "Meiryo", sans-serif;
    line-height: 1.6;
}

/* --- レイアウト --- */
.page-shell {
    width: min(100% - 32px, 860px);
    margin: 0 auto;
    padding: 40px 0 80px;
}

/* --- ヘッダー（すりガラス風・グラスモーフィズム） --- */
.page-site-header {
    position: sticky;
    top: 20px;
    z-index: 100;
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    justify-content: space-between;
    gap: 14px 20px;
    margin-bottom: 40px;
    padding: 12px 24px;
    background: rgba(255, 255, 255, 0.7);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border: 1px solid rgba(255, 255, 255, 0.4);
    border-radius: 999px;
    box-shadow: var(--shadow-sm);
}

.page-site-header.is-compact {
    top: 10px;
    gap: 8px 14px;
    margin-bottom: 24px;
    padding: 8px 16px;
    box-shadow: 0 10px 20px rgb(0 0 0 / 0.08);
}

.page-site-link {
    color: var(--text-heading);
    font-size: 1.5rem;
    font-weight: 700;
    letter-spacing: 0.04em;
    text-decoration: none;
    transition: color 0.3s ease;
    margin-left: 20px;
}

.page-site-header.is-compact .page-site-link {
    margin-left: 8px;
    font-size: 1.18rem;
}

.page-site-link:hover {
    color: var(--accent-blue);
}

/* --- ナビゲーション --- */
.page-site-nav {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
}

.page-site-header.is-compact .page-site-nav {
    gap: 6px;
}

.page-site-nav-link {
    display: inline-flex;
    align-items: center;
    padding: 8px 16px;
    border-radius: 999px;
    color: var(--muted);
    font-size: 0.95rem;
    font-weight: 500;
    text-decoration: none;
    transition: all 0.3s ease;
}

.page-site-header.is-compact .page-site-nav-link {
    padding: 6px 12px;
    font-size: 0.86rem;
}

.page-site-nav-link:hover {
    background: rgba(37, 99, 235, 0.08);
    color: var(--accent-blue);
}

.page-site-nav-link.current {
    background: var(--accent-blue);
    color: #fff;
    box-shadow: 0 4px 12px rgba(37, 99, 235, 0.25);
}

/* --- メインコンテンツ（カード風） --- */
.page-content {
    padding: 56px 64px;
    border: 1px solid rgba(255, 255, 255, 0.6);
    border-radius: 32px;
    background: rgba(255, 255, 255, 0.85);
    box-shadow: var(--shadow-lg);
}

.page-content > :first-child {
    margin-top: 0;
}

.page-content > :last-child {
    margin-bottom: 0;
}

/* --- タイポグラフィ --- */
h1 {
    font-size: clamp(2rem, 4vw, 2.6rem);
    color: var(--text-heading);
    text-align: center;
    margin: 0 0 1.2em;
    letter-spacing: -0.03em;
    line-height: 1.3;
}

h2 {
    position: relative;
    margin: 2em 0 1em;
    padding-bottom: 0.5em;
    border-bottom: 2px solid var(--line);
    font-size: clamp(1.4rem, 3vw, 1.75rem);
    color: var(--text-heading);
    letter-spacing: -0.02em;
}

/* カガリの丁火（ていか）アクセント！ */
h2::after {
    content: '';
    position: absolute;
    bottom: -2px;
    left: 0;
    width: 60px;
    height: 2px;
    background: var(--accent-fire);
}

p {
    margin: 0 0 1.4em;
    font-size: 1.05rem;
}

/* 強調表示をモダンなマーカー風に */
strong {
    color: var(--text-heading);
    font-weight: 700;
    background: linear-gradient(transparent 50%, rgba(245, 163, 36, 0.28) 60%);
}

/* --- リスト --- */
ul {
    margin: 0 0 1.8em 0.5em;
    padding: 0;
    list-style: none;
}

ul ul {
    margin-top: 0.35em;
    margin-bottom: 0.35em;
    margin-left: 0.2em;
}

ul li {
    position: relative;
    margin: 0.6em 0;
    padding-left: 1.6em;
    font-size: 1.05rem;
    line-height: 1.6;
}

/* リストのマーカーを優しいドットに */
ul li::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0.6em;
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background: var(--accent-blue);
    opacity: 0.8;
}

ul ul li::before {
    width: 7px;
    height: 7px;
    background: #f59e0b;
    opacity: 0.78;
}

ul ul ul li::before {
    top: 0.58em;
    width: 6px;
    height: 6px;
    border: 2px solid #c97712;
    background: transparent;
    opacity: 0.9;
}

ul ul ul ul li::before {
    width: 5px;
    height: 5px;
    border: 0;
    background: #7b8798;
    opacity: 0.7;
}

/* --- リンク --- */
.page-content a {
    color: var(--accent-blue);
    text-decoration: underline;
    text-decoration-color: rgba(37, 99, 235, 0.3);
    text-decoration-thickness: 2px;
    text-underline-offset: 4px;
    transition: all 0.3s ease;
}

.page-content a:hover {
    color: var(--accent-fire);
    text-decoration-color: var(--accent-fire);
}

/* --- フッター --- */
.page-footer {
    margin-top: 40px;
    color: var(--muted);
    text-align: center;
    font-size: 0.9rem;
}

/* --- レスポンシブ対応（スマホ向け） --- */
@media (max-width: 720px) {
    .page-shell {
        width: min(100% - 24px, 860px);
        padding: 24px 0 40px;
    }

    .page-site-header {
        flex-direction: column;
        align-items: flex-start;
        border-radius: 24px;
        gap: 10px 12px;
        padding: 10px 14px;
    }

    .page-site-header.is-compact {
        top: 6px;
        gap: 6px 10px;
        padding: 6px 10px;
        border-radius: 18px;
    }

    .page-site-link {
        margin-left: 6px;
        font-size: 1.18rem;
    }

    .page-site-header.is-compact .page-site-link {
        margin-left: 4px;
        font-size: 1rem;
    }

    .page-site-nav {
        gap: 6px;
    }

    .page-site-nav-link {
        padding: 6px 11px;
        font-size: 0.84rem;
    }

    .page-site-header.is-compact .page-site-nav {
        gap: 4px;
    }

    .page-site-header.is-compact .page-site-nav-link {
        padding: 4px 8px;
        font-size: 0.76rem;
    }

    .page-content {
        padding: 32px 24px;
        border-radius: 24px;
    }
}