/* =========================================
       ✨ モダン 認証ページ (Auth UI)
       ========================================= */
    :root {
        --primary: #00c9a7;
        --primary-light: #e0fdf9;
        --text-main: #1a202c;
        --text-muted: #718096;
        --bg-gray: #f8fafc;
        --radius-lg: 32px;
        --shadow-md: 0 15px 35px rgba(0,0,0,0.06);
    }

    body { background: var(--bg-gray); }

    .auth-container {
        display: flex;
        align-items: center;
        justify-content: center;
        min-height: calc(100vh - 120px);
        padding: 40px 20px;
        animation: fadeUp 0.6s cubic-bezier(0.2, 0.8, 0.2, 1);
    }

    @keyframes fadeUp {
        from { opacity: 0; transform: translateY(20px); }
        to { opacity: 1; transform: translateY(0); }
    }

    /* 🃏 カード本体 */
    .auth-card {
        background: white;
        width: 100%;
        max-width: 440px;
        padding: 50px 40px;
        border-radius: var(--radius-lg);
        border: 1px solid #edf2f7;
        box-shadow: var(--shadow-md);
        box-sizing: border-box;
    }

    /* 🏷️ ヘッダー */
    .auth-header {
        text-align: center;
        margin-bottom: 35px;
    }
    
    .auth-icon {
        font-size: 44px;
        margin-bottom: 15px;
        display: inline-block;
        animation: wave 2.5s infinite;
        transform-origin: 70% 70%;
    }
    
    @keyframes wave {
        0% { transform: rotate(0deg); }
        10% { transform: rotate(14deg); }
        20% { transform: rotate(-8deg); }
        30% { transform: rotate(14deg); }
        40% { transform: rotate(-4deg); }
        50% { transform: rotate(10deg); }
        60% { transform: rotate(0deg); }
        100% { transform: rotate(0deg); }
    }

    .auth-title {
        font-size: 28px;
        font-weight: 900;
        color: var(--text-main);
        margin: 0 0 8px;
        letter-spacing: -0.5px;
    }
    
    .auth-subtitle {
        color: var(--text-muted);
        font-size: 14px;
        font-weight: 500;
        margin: 0;
    }

    /* 📝 フォーム要素 */
    .auth-form .form-group {
        margin-bottom: 24px;
    }
    
    .auth-form label {
        display: block;
        font-weight: 800;
        margin-bottom: 8px;
        color: var(--text-main);
        font-size: 13px;
    }
    
    .auth-form input:not([type="checkbox"]) {
        width: 100%;
        padding: 16px 20px;
        background-color: var(--bg-gray);
        border: 2px solid #edf2f7;
        border-radius: 16px;
        box-sizing: border-box;
        font-size: 15px;
        font-weight: 500;
        color: var(--text-main);
        font-family: inherit;
        outline: none;
        transition: all 0.3s cubic-bezier(0.2, 0.8, 0.2, 1);
    }
    
    /* 💡 フォーカス時の美しいリングエフェクト */
    .auth-form input:not([type="checkbox"]):focus {
        border-color: var(--primary);
        background-color: white;
        box-shadow: 0 0 0 4px var(--primary-light);
    }
    
    .auth-form input[type="checkbox"] {
        margin-right: 8px;
        accent-color: var(--primary);
        transform: scale(1.1);
        cursor: pointer;
    }

    /* ⚠️ エラーメッセージ */
    .auth-error {
        background: #fef2f2;
        color: #ef4444;
        padding: 14px 20px;
        border-radius: 16px;
        margin-bottom: 24px;
        font-size: 13px;
        font-weight: 700;
        display: flex;
        align-items: center;
        gap: 10px;
        border: 1px solid #fee2e2;
    }

    /* 🔘 ボタン */
    .btn-submit {
        width: 100%;
        padding: 18px;
        background: var(--text-main);
        color: white;
        border: none;
        border-radius: 16px;
        font-weight: 900;
        font-size: 16px;
        cursor: pointer;
        transition: 0.3s cubic-bezier(0.2, 0.8, 0.2, 1);
        box-shadow: 0 8px 20px rgba(26, 32, 44, 0.15);
        margin-top: 10px;
    }
    
    .btn-submit:hover {
        transform: translateY(-3px);
        box-shadow: 0 12px 25px rgba(26, 32, 44, 0.25);
        background: #2d3748;
    }

    /* 🔗 フッターリンク */
    .auth-footer {
        text-align: center;
        margin-top: 35px;
        padding-top: 25px;
        border-top: 2px dashed #edf2f7;
    }
    
    .auth-footer p {
        color: var(--text-muted);
        font-size: 13px;
        font-weight: 500;
        margin: 0 0 8px;
    }
    
    .auth-footer a {
        color: var(--primary);
        font-weight: 800;
        text-decoration: none;
        font-size: 14px;
        transition: 0.2s;
    }
    
    .auth-footer a:hover {
        color: var(--primary-dark);
        text-decoration: underline;
    }

    /* 📱 レスポンシブ対応 */
    @media (max-width: 768px) {
        .auth-container { padding: 20px 15px; min-height: calc(100vh - 80px); }
        .auth-card { padding: 40px 25px; border-radius: 24px; }
        .auth-title { font-size: 24px; }
        .auth-icon { font-size: 36px; }
        .auth-form input:not([type="checkbox"]) { padding: 14px 16px; font-size: 14px; }
        .btn-submit { padding: 16px; }
    }