/* ========================================
           GAKU-HUB Official Stylesheet
           Theme: The Gallery
        ======================================== */

        /* ========================================
           CSS変数定義 (Color Palette)
        ======================================== */
        :root {
            --canvas-white: #FAFAFA;
            --ink-black: #111111;
            --iron-navy: #141d58;
            --ink-gray: #444444;
            --transition-smooth: all 0.6s cubic-bezier(0.4, 0, 0.2, 1);
            --didot: Didot, "Didot LT STD", "Hoefler Text", Garamond, serif;
        }

        /* ========================================
           基本リセット & タイポグラフィ
        ======================================== */
        * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }

        body {
            font-family: 'Yu Gothic', '游ゴシック', 'Hiragino Sans', sans-serif;
            background-color: var(--canvas-white);
            color: var(--ink-black);
            line-height: 1.8;
            overflow-x: hidden;
        }

        h1, h2, h3, h4 {
            font-family: 'Yu Mincho', '游明朝', 'Hiragino Mincho ProN', serif;
            font-weight: 400;
            letter-spacing: 0.1em;
        }

        /* ========================================
           Header / Navigation
        ======================================== */
        header {
            position: fixed;
            top: 0;
            left: 0;
            width: 100%;
            
            padding: 1.5rem 5%; 
            
            display: flex;
            justify-content: space-between;
            align-items: center;
            z-index: 1000;
            background-color: transparent; 
            transition: padding 0.3s ease, background-color 0.3s ease, box-shadow 0.3s ease;
        }

        /* スクロール時はさらに少しコンパクトに */
        header.scrolled {
            padding: 1.5rem 5%;
            background-color: rgba(250, 250, 250, 0.85);
            /* ★変更点2：ぼかし効果を入れる */
            /* これで後ろの文字が重なっても「すりガラス越し」のように見えます */
            backdrop-filter: blur(12px);
            -webkit-backdrop-filter: blur(12px); /* Safari用 */
            box-shadow: 0 4px 20px rgba(0,0,0,0.05);
        }

        .logo {
            font-family: 'Didot', 'Yu Mincho', serif;
            font-size: 1.5rem;
            letter-spacing: 0.2em;
            font-weight: 300;
        }

        nav ul {
            display: flex;
            list-style: none;
            gap: 2.5rem;
        }

        nav a {
            text-decoration: none;
            color: var(--ink-black);
            font-size: 0.9rem;
            letter-spacing: 0.1em;
            position: relative;
            transition: var(--transition-smooth);
        }

        nav a::after {
            content: '';
            position: absolute;
            bottom: -5px;
            left: 0;
            width: 0;
            height: 1px;
            background: var(--iron-navy);
            transition: width 0.4s ease;
        }

        nav a:hover::after {
            width: 100%;
        }

        /* ヘッダー内のボタンデザイン（Contact用） */
        nav a.nav-btn {
            border: 1px solid var(--iron-navy);
            padding: 0.6rem 1.5rem;
            transition: all 0.3s ease;
        }

        /* ホバー時の下線アニメーションを無効化（ボタン用） */
        nav a.nav-btn::after {
            display: none;
        }

        /* ボタンのホバーエフェクト */
        nav a.nav-btn:hover {
            background-color: var(--iron-navy);
            color: white;
            transform: translateY(-2px);
            box-shadow: 0 4px 10px rgba(23, 28, 97, 0.2);
        }

        /* ========================================
           Hero Section (The Entrance)
           背景スライドショー対応・中央にキャッチコピー配置
        ======================================== */
        .hero {
            min-height: 100vh;
            min-height: 100dvh; /* 全画面表示 */
            display: flex;
            justify-content: center;
            align-items: center;
            position: relative;
            overflow: hidden;
            
            /* ヘッダーが被る分、文字位置を微調整したい場合はpadding-topを入れる */
            /* padding-top: 80px; */
        }

        /* ★ここが「白いスモーク」の正体 */
        .hero::after {
            content: '';
            position: absolute;
            top: 0;
            left: 0;
            width: 100%;
            /* ★修正：200px → 150px (ヘッダーが薄くなった分、影も短くして写真をクリアにする) */
            height: 150px; 
            background: linear-gradient(to bottom, rgba(250, 250, 250, 0.9) 0%, rgba(250, 250, 250, 0) 100%);
            z-index: 1;
            pointer-events: none;
        }

        /* 中央のキャッチコピー（z-indexを上げてスモークより手前に） */
        .hero-text {
            position: relative;
            z-index: 2; 
            text-align: center;
            padding: 3rem;
            opacity: 0;
            transform: translateY(30px);
            animation: heroTextFade 1.5s ease 1s forwards;
        }

        /* 背景スライドショー用コンテナ */
        .hero-background {
            position: absolute;
            inset: 0;
            z-index: 0;
        }

        .hero-slide {
            position: absolute;
            inset: 0;
            opacity: 0;
            transition: opacity 2s ease-in-out;
        }

        .hero-slide.active {
            opacity: 1;
        }

        .hero-slide img {
            width: 100%;
            height: 100%;
            object-fit: cover;
            filter: grayscale(100%) brightness(0.8);
        }

        /* 可読性確保用の白フィルター */
        .hero-overlay {
            position: absolute;
            inset: 0;
            background: rgba(250, 250, 250, 0.6);
            z-index: 1;
        }

        /* キャッチコピー（中央配置） */
        .hero-text {
            position: relative;
            z-index: 2;
            text-align: center;
            padding: 3rem;
            opacity: 0;
            transform: translateY(30px);
            animation: heroTextFade 1.5s ease 1s forwards;
        }

        @keyframes heroTextFade {
            to {
                opacity: 1;
                transform: translateY(0);
            }
        }

        .hero-text h1 {
            font-size: clamp(2.5rem, 6vw, 4.5rem);
            margin-bottom: 2rem;
            line-height: 1.6;
            text-shadow: 0 2px 20px rgba(255, 255, 255, 0.8);
        }

        .hero-text p {
            font-family: 'Didot', serif;
            font-size: clamp(1rem, 2.5vw, 1.4rem);
            color: #444;
            letter-spacing: 0.15em;
            text-shadow: 0 1px 10px rgba(255, 255, 255, 0.8);
        }

        /* Concept Section - 3ブロック構成に変更、white-space: nowrap で改行制御 */
        /* ========================================
           Concept Section (Philosophy) - 縦書き
        ======================================== */
        .concept {
            padding: 15rem 10%;
            display: flex;
            flex-direction: column;
            justify-content: center;
            align-items: center;
            min-height: 100vh;
        }

        .concept-container {
            writing-mode: vertical-rl;
            display: flex;
            gap: 4rem;
            justify-content: center;
            align-items: flex-start;
            margin-bottom: 5rem;
        }

        .concept-btn-wrapper {
            writing-mode: horizontal-tb;
        }

        .concept-block {
            display: flex;
            flex-direction: column;
        }

        .vertical-text {
            text-orientation: upright;
            white-space: nowrap;
            line-height: 2.2;
            font-family: "Yu Mincho", "YuMincho", "Hiragino Mincho ProN", "HG明朝E", serif;
        }

        .title-block h2 {
            font-size: 2.5rem;
            color: var(--ink-black);
            font-weight: 400;
            letter-spacing: 0.1em;
        }

        .body-block p {
            font-size: 1.1rem;
            color: var(--ink-gray);
            font-weight: 300;
            letter-spacing: 0.08em;
        }

        /* レスポンシブ対応: 768px以下で横書きに切り替え */
        @media (max-width: 768px) {
            .concept-container {
                writing-mode: horizontal-tb;
                flex-direction: column;
                gap: 3rem;
                text-align: center;
            }

            .vertical-text {
                white-space: normal;
            }

            .title-block h2 {
                font-size: 1.8rem;
            }

            .body-block p {
                font-size: 1rem;
            }
        }

        /* ========================================
           Business Model Section (The Structure)
        ======================================== */
        .business-model {
            padding: 15rem 10%;
            min-height: 100vh;
        }

        .section-title {
            text-align: center;
            font-size: 2.5rem;
            font-weight: 300;
            letter-spacing: 0.15em;
            margin-bottom: 1rem;
        }

        .section-subtitle {
            text-align: center;
            font-family: var(--didot);
            font-size: 1rem;
            color: var(--color-text-light);
            letter-spacing: 0.1em;
            margin-bottom: 4rem;
        }

        .phases-container {
            display: flex;
            justify-content: center;
            align-items: flex-start;
            gap: 3rem;
            max-width: 1200px;
            margin: 0 auto;
        }

        .phase {
            text-align: center;
            flex: 1;
            max-width: 300px;
        }

        .phase-number {
            font-family: var(--didot);
            font-size: 1.2rem;
            color: var(--color-accent);
            margin-bottom: 1rem;
            letter-spacing: 0.1em;
        }

        .phase-title {
            font-size: 1.8rem;
            font-weight: 400;
            margin-bottom: 0.8rem;
            letter-spacing: 0.08em;
        }

        .phase-label {
            font-family: var(--didot);
            font-size: 0.9rem;
            color: var(--color-text-light);
            margin-bottom: 1.5rem;
            letter-spacing: 0.1em;
        }

        .phase-description {
            font-size: 0.95rem;
            line-height: 1.9;
            color: #555;
        }

        .phase-line {
            flex-grow: 1;
            height: 1px;
            background-color: rgba(17, 17, 17, 0.1);
            margin-top: 1.5rem;
        }

        @media (max-width: 768px) {
            .phases-container {
                flex-direction: column;
                gap: 4rem;
            }

            .phase-line {
                display: none;
            }

            .phase {
                max-width: 100%;
            }
        }

        /* ========================================
           Exhibition Section (Portfolio) - 額縁演出
        ======================================== */
        .exhibition {
            padding: 15rem 10%;
            min-height: 100vh;
        }

        /* タブナビゲーションのデザイン */
        .tab-navigation {
            display: flex;
            justify-content: center;
            gap: 3rem;
            margin-bottom: 4rem;
        }

        .tab-btn {
            background: none;
            border: none;
            font-family: 'Yu Mincho', serif; /* 和文は明朝体で上品に */
            font-size: 1.1rem;
            color: #888; /* 非アクティブ時はグレー */
            cursor: pointer;
            padding-bottom: 0.5rem;
            border-bottom: 1px solid transparent;
            transition: all 0.3s ease;
            letter-spacing: 0.1em;
        }

        .tab-btn:hover {
            color: var(--iron-navy);
        }

        /* アクティブなタブのデザイン */
        .tab-btn.active {
            color: var(--iron-navy);
            border-bottom: 1px solid var(--iron-navy);
        }

        /* コンテンツの表示制御 */
        .tab-content {
            display: none; /* デフォルトは非表示 */
            animation: fadeInTab 0.6s ease forwards; /* 切り替え時のふわっとアニメーション */
        }

        .tab-content.active {
            display: block; /* activeクラスがついたら表示 */
        }

        @keyframes fadeInTab {
            from { opacity: 0; transform: translateY(10px); }
            to { opacity: 1; transform: translateY(0); }
        }

        /* スマホ対応：タブの間隔を調整 */
        @media (max-width: 768px) {
            .tab-navigation {
                gap: 1.5rem;
            }
            .tab-btn {
                font-size: 0.9rem;
            }
        }

        .exhibition-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
            gap: 4rem;
            margin-top: 5rem;
        }

        .exhibition-item {
            position: relative;
            overflow: hidden;
            cursor: pointer;
            background: white;
            padding: 1.5rem;
            box-shadow: 0 2px 20px rgba(0, 0, 0, 0.08);
            transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
        }

        .exhibition-item:hover {
            transform: translateY(-8px);
            box-shadow: 0 8px 40px rgba(0, 0, 0, 0.15);
        }

        .exhibition-item img {
            width: 100%;
            height: 350px;
            object-fit: cover;
            display: block;
            transition: transform 0.6s cubic-bezier(0.4, 0, 0.2, 1);
        }

        .exhibition-item:hover img {
            transform: scale(1.08);
        }

        .exhibition-title {
            position: absolute;
            bottom: 0;
            left: 0;
            right: 0;
            background: rgba(23, 28, 97, 0.95);
            color: white;
            padding: 1.5rem;
            transform: translateY(100%);
            transition: transform 0.4s cubic-bezier(0.4, 0, 0.2, 1);
            font-family: var(--serif);
            font-size: 1.1rem;
            letter-spacing: 0.08em;
        }

        .exhibition-item:hover .exhibition-title {
            transform: translateY(0);
        }

        .view-all-btn {
            display: inline-block;
            margin-top: 4rem;
            padding: 1rem 3rem;
            background: transparent;
            border: 1px solid var(--iron-navy);
            color: var(--iron-navy);
            text-decoration: none;
            font-family: var(--didot);
            letter-spacing: 0.1em;
            transition: all 0.3s ease;
        }

        .view-all-btn:hover {
            background: var(--iron-navy);
            color: white;
        }


        /* ========================================
           Members Section (The Curators)
        ======================================== */
        .members {
            padding: 15rem 10%;
            min-height: 100vh;
        }

        .members-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
            gap: 4rem;
            margin-top: 5rem;
        }

        .member-card {
            text-align: center;
        }

        .member-image {
            width: 100%;
            height: 380px;
            overflow: hidden;
            margin-bottom: 2rem;
            box-shadow: 0 4px 20px rgba(0, 0, 0, 0.1);
            transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
        }

        .member-image img {
            width: 100%;
            height: 100%;
            object-fit: cover;
            filter: grayscale(100%);
            transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
        }

        .member-card:hover .member-image {
            transform: translateY(-8px);
            box-shadow: 0 12px 35px rgba(0, 0, 0, 0.2);
        }

        .member-card:hover .member-image img {
            filter: grayscale(0%);
            transform: scale(1.05);
        }

        .member-role {
            font-family: var(--didot);
            font-size: 0.85rem;
            letter-spacing: 0.15em;
            color: var(--iron-navy);
            margin-bottom: 0.5rem;
            text-transform: uppercase;
        }

        .member-name {
            font-size: 1.2rem;
            letter-spacing: 0.08em;
        }

        /* ========================================
           Guidance Section (Entrance Choice)
        ======================================== */
        .guidance {
            padding: 10rem 0;
        }

        .guidance-container {
            display: grid;
            grid-template-columns: repeat(3, 1fr);
            min-height: 70vh;
        }

        .guidance-box {
            padding: 5rem 3rem;
            display: flex;
            flex-direction: column;
            justify-content: center;
            align-items: center;
            text-align: center;
            border: 1px solid #E0E0E0;
            cursor: pointer;
            transition: var(--transition-smooth);
            position: relative;
            overflow: hidden;
        }

        .guidance-box::before {
            content: '';
            position: absolute;
            inset: 0;
            background: var(--iron-navy);
            transform: translateY(100%);
            transition: var(--transition-smooth);
            z-index: 0;
        }

        .guidance-box:hover::before {
            transform: translateY(0);
        }

        .guidance-content {
            position: relative;
            z-index: 1;
            transition: var(--transition-smooth);
        }

        .guidance-box:hover .guidance-content {
            color: white;
        }

        .guidance-label {
            font-family: 'Didot', serif;
            font-size: 0.9rem;
            letter-spacing: 0.2em;
            margin-bottom: 2rem;
            opacity: 0.7;
        }

        .guidance-title {
            font-size: 1.8rem;
            margin-bottom: 2rem;
            letter-spacing: 0.1em;
        }

        .guidance-desc {
            font-size: 0.95rem;
            line-height: 1.9;
            opacity: 0.8;
        }

        /* ========================================
           Footer
        ======================================== */
        footer {
            background: var(--ink-black);
            color: white;
            padding: 5rem 5%;
            text-align: center;
        }

        .footer-logo {
            font-family: 'Didot', serif;
            font-size: 1.8rem;
            letter-spacing: 0.2em;
            margin-bottom: 2rem;
        }

        .footer-sns {
            display: flex;
            justify-content: center;
            gap: 2rem;
            margin-bottom: 3rem;
        }

        .footer-sns a {
            color: white;
            text-decoration: none;
            font-size: 0.9rem;
            letter-spacing: 0.1em;
            transition: var(--transition-smooth);
        }

        .footer-sns a:hover {
            color: var(--iron-navy);
            filter: brightness(2);
        }

        .copyright {
            font-size: 0.8rem;
            opacity: 0.6;
            letter-spacing: 0.1em;
        }

        /* ========================================
           スクロールアニメーション用クラス
        ======================================== */
        .fade-in {
            opacity: 0;
            transform: translateY(40px);
            transition: var(--transition-smooth);
        }

        .fade-in.visible {
            opacity: 1;
            transform: translateY(0);
        }

        /* ========================================
           レスポンシブ対応 (Mobile)
        ======================================== */
        @media (max-width: 768px) {
            /* --- Header: 固定・透明化 --- */
            header {
                position: fixed; /* 写真の上に固定 */
                top: 0;
                left: 0;
                width: 100%;
                padding: 1.2rem 5%;
                background-color: transparent; /* 最初は透明 */
                /* 要素を左右端に配置 */
                justify-content: space-between; 
            }

            /* スクロールしたら白背景 */
            header.scrolled {
                padding: 1.2rem 5%;
                background-color: rgba(250, 250, 250, 0.7);
                box-shadow: 0 4px 10px rgba(0,0,0,0.05);
            }

            /* メニュー展開時は背景を白く固定 */
            /* :has非対応ブラウザ向けに、JSでbodyにクラスがついた場合などを想定しても良いが、
               現状のモダンブラウザならこれでOK */
            body:has(.nav-menu.active) header {
                background-color: var(--canvas-white);
            }

            /* --- Hamburger Icon --- */
            .hamburger {
                display: block;
                width: 30px;
                height: 20px;
                position: relative;
                z-index: 1001;
                cursor: pointer;
            }
            /* ... (ハンバーガーの中身のCSSは以前のまま変更なし) ... */
            .hamburger span {
                display: block;
                width: 100%;
                height: 1px;
                background-color: var(--ink-black);
                position: absolute;
                transition: all 0.4s ease;
            }
            .hamburger span:nth-child(1) { top: 0; }
            .hamburger span:nth-child(2) { top: 50%; transform: translateY(-50%); }
            .hamburger span:nth-child(3) { bottom: 0; }
            .hamburger.active span:nth-child(1) { top: 50%; transform: translateY(-50%) rotate(45deg); }
            .hamburger.active span:nth-child(2) { opacity: 0; }
            .hamburger.active span:nth-child(3) { bottom: 50%; transform: translateY(50%) rotate(-45deg); }


            /* --- Mobile Menu --- */
            .nav-menu {
                position: fixed;
                top: 0;
                right: -100%;
                width: 100%;
                height: 100vh;
                background-color: var(--canvas-white);
                display: flex;
                flex-direction: column;
                justify-content: center;
                align-items: center;
                transition: right 0.4s cubic-bezier(0.4, 0, 0.2, 1);
                z-index: 1000;
            }
            .nav-menu.active { right: 0; }
            .nav-menu ul { flex-direction: column; gap: 3rem; align-items: center; }
            .nav-menu a { font-size: 1.2rem; font-family: var(--didot); }


            /* --- Hero: 全画面 + スモーク調整 --- */
            .hero {
                padding: 0 5%; /* 上下余白ゼロで全画面に */
                min-height: 100dvh; /* スマホのアドレスバー考慮 */
            }

            .hero-text h1 { font-size: 2rem; }
            .hero-text p { font-size: 0.9rem; }

            /* スマホ用の白いスモーク */
            /* PC(200px)より少し狭くして、写真の顔などを隠さないようにする */
            .hero::after {
                content: '';
                position: absolute;
                top: 0;
                left: 0;
                width: 100%;
                height: 140px; /* ★高さ調整：ロゴ周辺だけを白くする */
                background: linear-gradient(to bottom, rgba(250, 250, 250, 0.9) 0%, rgba(250, 250, 250, 0) 100%);
                z-index: 1;
                pointer-events: none;
            }


            /* --- 以下、他のセクション（以前の調整済みコード） --- */
            .concept { padding: 8rem 5%; }
            .concept-container {
                writing-mode: horizontal-tb;
                flex-direction: column;
                gap: 3rem;
                text-align: center;
                align-items: center;
                width: 100%;
            }
            .concept-block { width: 100%; align-items: center; }
            .vertical-text { white-space: normal; line-height: 2.0; display: inline-block; }
            .title-block h2 { font-size: 1.6rem; }
            .body-block p { font-size: 1rem; text-align: center; }

            .business-model { padding: 8rem 5%; }
            .phases-container { flex-direction: column; gap: 5rem; }
            .phases-container::before { display: none; }

            .exhibition { padding: 8rem 5%; }
            .tab-navigation { gap: 1.5rem; }
            .tab-btn { font-size: 0.9rem; }
            .exhibition-grid { grid-template-columns: 1fr; gap: 3rem; }
            .exhibition-image { height: 240px; }

            .members { padding: 8rem 5%; }
            .members-grid { grid-template-columns: 1fr; gap: 3rem; }

            .guidance-container { grid-template-columns: 1fr; }
            .guidance-box { padding: 4rem 2rem; min-height: 40vh; }

            footer { padding: 4rem 5%; }
        }