/* --- 変数定義 --- */
:root {
    --color-gold: #c09f58;
    --color-wine-red: #8c2a32; /* 差し色（ワインレッド） */
    --color-dark-gray: #222222;
    --color-base-bg: #1a1a1a;
    --color-base-text: #e5e5e5;
}

/* --- 基本設定 --- */
body {
    font-family: 'Noto Serif JP', serif;
    background-color: var(--color-base-bg);
    color: var(--color-base-text);
}

h1, h2, h3, h4, h5, h6 {
    font-family: 'Crimson Text', serif;
}

/* --- カラーユーティリティ --- */
.text-gold {
    color: var(--color-gold);
}

.bg-dark-gray {
    background-color: var(--color-dark-gray);
}

/* --- ナビゲーション --- */
.nav-link {
    position: relative;
    transition: color 0.3s ease-out;
}
.nav-link:hover {
    color: var(--color-gold);
}
.nav-link::after {
    content: '';
    position: absolute;
    width: 100%;
    height: 1px;
    background-color: var(--color-wine-red);
    bottom: -4px;
    left: 0;
    transform: scaleX(0);
    transform-origin: right;
    transition: transform 0.4s ease-out;
}
.nav-link:hover::after {
    transform: scaleX(1);
    transform-origin: left;
}


/* ローディングスピナーのスタイル */
.loader {
    border: 4px solid #f3f3f3;
    border-top: 4px solid var(--color-gold);
    border-radius: 50%;
    width: 40px;
    height: 40px;
    animation: spin 1s linear infinite;
    margin: 20px auto;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

/* トップへ戻るボタンのスタイル */
.to-top-btn {
    position: fixed;
    bottom: 20px;
    right: 20px;
    background-color: var(--color-gold);
    color: var(--color-base-bg);
    width: 50px;
    height: 50px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 20px;
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.3);
    text-decoration: none;
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.3s, visibility 0.3s, background-color 0.3s, transform 0.3s;
    z-index: 1000;
}

.to-top-btn:hover {
    background-color: var(--color-wine-red);
    color: var(--color-base-text);
    transform: translateY(-5px);
}

.to-top-btn.show {
    opacity: 1;
    visibility: visible;
}

/* スクロールアニメーション用のスタイル */
.fade-in-element {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.8s ease-out, transform 0.8s ease-out;
}

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