/* ==========================================================================
   大日本帝国憲法 現代語訳・解説ナビ - 和モダン・プレミアムデザインシステム
   ========================================================================== */

/* 変数定義（デザインシステム） */
:root {
    /* フォントファミリー */
    --font-serif: 'Noto Serif JP', 'Georgia', serif;
    --font-sans: 'Outfit', 'Helvetica Neue', 'Arial', 'Hiragino Kaku Gothic ProN', sans-serif;

    /* アニメーション時間 */
    --transition-fast: 0.2s cubic-bezier(0.16, 1, 0.3, 1);
    --transition-medium: 0.4s cubic-bezier(0.16, 1, 0.3, 1);
    --transition-slow: 0.8s cubic-bezier(0.16, 1, 0.3, 1);

    /* レイアウトトークン */
    --border-radius-sm: 8px;
    --border-radius-md: 16px;
    --border-radius-lg: 24px;
    --shadow-sm: 0 4px 10px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 10px 25px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 20px 50px rgba(0, 0, 0, 0.2);
}

/* ダークモード用トークン (デフォルト) */
[data-theme="dark"] {
    --color-bg-base: #0c0d10;
    --color-bg-surface: rgba(22, 24, 30, 0.7);
    --color-bg-surface-solid: #16181e;
    --color-bg-surface-hover: rgba(30, 33, 41, 0.8);
    --color-border: rgba(212, 175, 55, 0.15); /* 金色の薄いボーダー */
    --color-border-active: rgba(212, 175, 55, 0.4);
    
    --color-text-primary: #f3f4f6;
    --color-text-secondary: #d1d5db;
    --color-text-muted: #9ca3af;

    /* 和のテーマカラー */
    --color-gold: #d4af37;        /* 真鍮・黄金 */
    --color-gold-hover: #e5c158;
    --color-crimson: #b53d35;     /* 漆赤・朱色 */
    --color-crimson-hover: #c94c43;
    --color-ink: #1a1a1a;         /* 墨色 */
    --color-navy: #1f2d3d;        /* 藍鼠 */

    /* 特殊効果 */
    --glass-blur: blur(12px);
    --glass-bg: rgba(22, 24, 30, 0.65);
    --glow-color-1: rgba(181, 61, 53, 0.15); /* 赤いグロウ */
    --glow-color-2: rgba(212, 175, 55, 0.15); /* 金のグロウ */
    
    /* ユーティリティ */
    --color-success: #10b981;
    --color-danger: #ef4444;
    --color-info: #3b82f6;
}

/* ライトモード用トークン */
[data-theme="light"] {
    --color-bg-base: #f9f8f4; /* 温かみのある和紙のような白 */
    --color-bg-surface: rgba(255, 255, 255, 0.8);
    --color-bg-surface-solid: #ffffff;
    --color-bg-surface-hover: rgba(243, 240, 233, 0.9);
    --color-border: rgba(181, 61, 53, 0.15); /* 赤の薄いボーダー */
    --color-border-active: rgba(181, 61, 53, 0.4);
    
    --color-text-primary: #1c1c1e;
    --color-text-secondary: #3a3a3c;
    --color-text-muted: #7c7c80;

    /* 和のテーマカラー（明度調整） */
    --color-gold: #aa8513;        
    --color-gold-hover: #bc9823;
    --color-crimson: #9e2a22;     
    --color-crimson-hover: #b53d35;
    --color-ink: #f0ede5;         
    --color-navy: #eef2f7;        

    /* 特殊効果 */
    --glass-blur: blur(12px);
    --glass-bg: rgba(255, 255, 255, 0.75);
    --glow-color-1: rgba(181, 61, 53, 0.05);
    --glow-color-2: rgba(212, 175, 55, 0.05);

    /* ユーティリティ */
    --color-success: #059669;
    --color-danger: #dc2626;
    --color-info: #2563eb;
}

/* ==========================================================================
   ベース・スクロールバー・全体レイアウト
   ========================================================================== */

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html, body {
    margin: 0;
    padding: 0;
    overflow-x: hidden;
}

body {
    background-color: var(--color-bg-base);
    color: var(--color-text-primary);
    font-family: var(--font-sans);
    line-height: 1.6;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    position: relative;
    transition: background-color var(--transition-medium), color var(--transition-medium);
}

/* スクロールバーのカスタマイズ */
::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}

::-webkit-scrollbar-track {
    background: var(--color-bg-base);
}

::-webkit-scrollbar-thumb {
    background: var(--color-border);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--color-gold);
}

/* 背景グロウのコンテナ */
.bg-glow-wrapper {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    overflow: hidden;
    pointer-events: none;
    z-index: -1;
}

/* 背景グロウエフェクト */
.bg-glow {
    position: absolute;
    width: 600px;
    height: 600px;
    border-radius: 50%;
    filter: blur(120px);
    pointer-events: none;
    z-index: -1;
    opacity: 0.6;
    transition: all var(--transition-slow);
}

.bg-glow-1 {
    top: -10%;
    left: -10%;
    background: var(--glow-color-1);
}

.bg-glow-2 {
    bottom: -10%;
    right: -10%;
    background: var(--glow-color-2);
}

/* ==========================================================================
   ヘッダー（和モダン・ガラスモルフィズム）
   ========================================================================== */

.app-header {
    background: var(--glass-bg);
    backdrop-filter: var(--glass-blur);
    border-bottom: 1px solid var(--color-border);
    padding: 12px 24px;
    transition: background-color var(--transition-medium), border-color var(--transition-medium);
}

.header-container {
    max-width: 1440px;
    margin: 0 auto;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 20px;
}

.logo-area {
    display: flex;
    flex-direction: column;
}

.logo-area .badge {
    align-self: flex-start;
    background: linear-gradient(135deg, var(--color-crimson), var(--color-gold));
    color: #fff;
    font-size: 10px;
    font-weight: 800;
    padding: 2px 8px;
    border-radius: 20px;
    text-transform: uppercase;
    letter-spacing: 1px;
    margin-bottom: 4px;
}

.logo-area h1 {
    font-family: var(--font-serif);
    font-size: 20px;
    font-weight: 800;
    color: var(--color-text-primary);
    letter-spacing: 0.5px;
}

.logo-area h1 .subtitle {
    font-size: 14px;
    font-weight: 400;
    color: var(--color-text-secondary);
    margin-left: 8px;
}

/* タブナビゲーション */
.nav-tabs {
    display: flex;
    gap: 8px;
}

.tab-btn {
    display: flex;
    align-items: center;
    gap: 8px;
    background: transparent;
    border: 1px solid transparent;
    color: var(--color-text-secondary);
    padding: 8px 18px;
    border-radius: var(--border-radius-sm);
    font-size: 14px;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-fast);
}

.tab-btn:hover {
    background: var(--color-bg-surface-hover);
    color: var(--color-gold);
}

.tab-btn.active {
    background: rgba(212, 175, 55, 0.08);
    border-color: var(--color-border-active);
    color: var(--color-gold);
    box-shadow: inset 0 0 10px rgba(212, 175, 55, 0.05);
}

.tab-btn .icon {
    width: 18px;
    height: 18px;
}

/* 各種アクション（テーマ切り替え） */
.theme-btn {
    background: var(--color-bg-surface-hover);
    border: 1px solid var(--color-border);
    color: var(--color-text-primary);
    width: 38px;
    height: 38px;
    border-radius: 50%;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all var(--transition-fast);
}

.theme-btn:hover {
    border-color: var(--color-gold);
    color: var(--color-gold);
    transform: rotate(15deg);
}

.theme-btn .icon {
    width: 20px;
    height: 20px;
}

/* テーマ切り替え用のアイコン表示制御 */
[data-theme="dark"] .sun-icon { display: block; }
[data-theme="dark"] .moon-icon { display: none; }
[data-theme="light"] .sun-icon { display: none; }
[data-theme="light"] .moon-icon { display: block; }

/* ==========================================================================
   メインコンテンツレイアウト
   ========================================================================== */

.app-main {
    flex: 1;
    max-width: 1440px;
    width: 100%;
    margin: 0 auto;
    padding: 24px;
    position: relative;
}

/* タブコンテンツの表示切り替え */
.tab-content {
    display: none;
    animation: fadeIn var(--transition-medium);
}

.tab-content.active {
    display: block;
}

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

/* ==========================================================================
   タブ1: 憲法リーダー (Reader)
   ========================================================================== */

.reader-container {
    display: grid;
    grid-template-columns: 280px 1fr;
    gap: 24px;
    align-items: start;
}

/* 目次サイドバー */
.reader-sidebar {
    position: sticky;
    top: 24px;
    display: flex;
    flex-direction: column;
    gap: 16px;
    max-height: calc(100vh - 48px);
    overflow-y: auto;
    padding-right: 4px;
}

.sidebar-block {
    background: var(--color-bg-surface-solid);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius-md);
    padding: 16px;
    box-shadow: var(--shadow-sm);
}

.sidebar-block h3 {
    font-size: 13px;
    font-weight: 800;
    color: var(--color-gold);
    margin-bottom: 12px;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    border-left: 3px solid var(--color-crimson);
    padding-left: 8px;
}

/* 検索ボックス */
.search-input-wrapper {
    position: relative;
    display: flex;
    align-items: center;
}

.search-input-wrapper input {
    width: 100%;
    background: var(--color-bg-base);
    border: 1px solid var(--color-border);
    color: var(--color-text-primary);
    padding: 10px 32px 10px 14px;
    border-radius: var(--border-radius-sm);
    font-size: 13px;
    outline: none;
    transition: all var(--transition-fast);
}

.search-input-wrapper input:focus {
    border-color: var(--color-gold);
    box-shadow: 0 0 8px rgba(212, 175, 55, 0.2);
}

.clear-btn {
    position: absolute;
    right: 10px;
    background: transparent;
    border: none;
    color: var(--color-text-muted);
    font-size: 18px;
    cursor: pointer;
    display: none;
}

.clear-btn:hover {
    color: var(--color-danger);
}

/* セグメントコントロール（トグルボタン風） */
.option-group {
    margin-bottom: 12px;
}

.option-group:last-child {
    margin-bottom: 0;
}

.option-group label {
    display: block;
    font-size: 11px;
    color: var(--color-text-muted);
    margin-bottom: 6px;
    font-weight: 600;
}

.segmented-control {
    display: flex;
    background: var(--color-bg-base);
    border: 1px solid var(--color-border);
    padding: 3px;
    border-radius: var(--border-radius-sm);
    gap: 2px;
}

.control-btn {
    flex: 1;
    background: transparent;
    border: none;
    color: var(--color-text-secondary);
    padding: 6px 4px;
    font-size: 11px;
    font-weight: 600;
    border-radius: calc(var(--border-radius-sm) - 2px);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.control-btn:hover {
    color: var(--color-gold);
}

.control-btn.active {
    background: var(--color-bg-surface-solid);
    color: var(--color-gold);
    box-shadow: var(--shadow-sm);
    border: 1px solid rgba(212, 175, 55, 0.2);
}

/* 章ナビゲーション */
.chapter-list {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 4px;
}

.chapter-nav-item {
    width: 100%;
    text-align: left;
    background: transparent;
    border: none;
    color: var(--color-text-secondary);
    padding: 8px 12px;
    border-radius: var(--border-radius-sm);
    font-size: 12.5px;
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    transition: all var(--transition-fast);
}

.chapter-nav-item:hover {
    background: var(--color-bg-surface-hover);
    color: var(--color-gold);
    padding-left: 16px;
}

.chapter-nav-item.active {
    background: rgba(181, 61, 53, 0.08);
    color: var(--color-crimson);
    font-weight: 600;
}

.chapter-nav-item .count-pill {
    background: var(--color-ink);
    color: var(--color-text-muted);
    font-size: 10px;
    padding: 2px 6px;
    border-radius: 10px;
}

.chapter-nav-item.active .count-pill {
    background: var(--color-crimson);
    color: #fff;
}

/* 右側メインエリア */
.reader-main {
    display: flex;
    flex-direction: column;
    gap: 24px;
}

.preamble-selector-area {
    background: var(--color-bg-surface-solid);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius-md);
    padding: 16px 24px 24px 24px;
    box-shadow: var(--shadow-md);
}

.preamble-header h2 {
    font-family: var(--font-serif);
    font-size: 22px;
    color: var(--color-text-primary);
    margin-bottom: 6px;
    font-weight: 800;
}

.preamble-header p {
    font-size: 13px;
    color: var(--color-text-muted);
    margin-bottom: 12px;
}

.preamble-tabs {
    display: flex;
    border-bottom: 1px solid var(--color-border);
    gap: 16px;
    margin-bottom: 12px;
}

.preamble-tab {
    background: transparent;
    border: none;
    border-bottom: 2px solid transparent;
    color: var(--color-text-secondary);
    padding: 8px 12px 10px 12px;
    font-family: var(--font-serif);
    font-size: 15px;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-fast);
}

.preamble-tab:hover {
    color: var(--color-crimson);
}

.preamble-tab.active {
    color: var(--color-crimson);
    border-bottom-color: var(--color-crimson);
    font-weight: 800;
}

.preamble-content-card {
    display: flex;
    flex-direction: column;
    gap: 12px;
    animation: fadeIn var(--transition-medium);
}

.preamble-title-section {
    display: flex;
    align-items: baseline;
    gap: 8px;
}

.preamble-title-section h3 {
    font-family: var(--font-serif);
    font-size: 18px;
    color: var(--color-gold);
}

.preamble-title-section .ruby {
    font-size: 12px;
    color: var(--color-text-muted);
}

.preamble-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 20px;
}

@media (min-width: 900px) {
    .preamble-grid {
        grid-template-columns: 1.1fr 0.9fr;
    }
}

.preamble-original {
    background: var(--color-bg-base);
    border-radius: var(--border-radius-sm);
    padding: 12px 16px 16px 16px;
    font-family: var(--font-serif);
    font-size: 15px;
    line-height: 1.8;
    max-height: 280px;
    overflow-y: auto;
    border-left: 4px solid var(--color-gold);
}

.preamble-original p {
    margin-top: 6px;
    margin-bottom: 0;
    white-space: pre-wrap;
}

.preamble-translation {
    background: var(--color-bg-base);
    border-radius: var(--border-radius-sm);
    padding: 12px 16px 16px 16px;
    font-size: 14.5px;
    line-height: 1.7;
    max-height: 280px;
    overflow-y: auto;
    border-left: 4px solid var(--color-crimson);
}

.preamble-translation p {
    margin-top: 6px;
    margin-bottom: 0;
    white-space: pre-wrap;
}

.preamble-expl-panel {
    background: rgba(212, 175, 55, 0.04);
    border: 1px dashed var(--color-border);
    border-radius: var(--border-radius-sm);
    padding: 16px;
    font-size: 13.5px;
}

.preamble-expl-panel h4 {
    color: var(--color-gold);
    margin-bottom: 8px;
    font-size: 14px;
    font-weight: 800;
}

/* 条文リストヘッダー */
.articles-list-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: 2px solid var(--color-border-active);
    padding-bottom: 10px;
    margin-top: 12px;
}

.articles-list-header h2 {
    font-family: var(--font-serif);
    font-size: 24px;
    color: var(--color-text-primary);
    font-weight: 800;
}

.count-badge {
    background: var(--color-crimson);
    color: #fff;
    font-size: 12px;
    font-weight: 800;
    padding: 4px 12px;
    border-radius: 20px;
}

/* 条文カードコンテナとカード */
.articles-grid {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.article-card {
    background: var(--color-bg-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius-md);
    padding: 24px;
    box-shadow: var(--shadow-sm);
    display: flex;
    flex-direction: column;
    gap: 16px;
    transition: transform var(--transition-fast), border-color var(--transition-fast), box-shadow var(--transition-fast);
    position: relative;
    overflow: hidden;
}

.article-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 6px;
    height: 100%;
    background: var(--color-gold);
    transition: background var(--transition-fast);
}

.article-card:hover {
    transform: translateY(-2px);
    border-color: var(--color-border-active);
    box-shadow: var(--shadow-md);
}

.article-card:hover::before {
    background: var(--color-crimson);
}

.article-card-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 12px;
}

.article-title-area {
    display: flex;
    align-items: center;
    gap: 12px;
}

.article-number {
    font-family: var(--font-serif);
    font-size: 18px;
    font-weight: 800;
    color: var(--color-gold);
    background: rgba(212, 175, 55, 0.08);
    padding: 4px 12px;
    border-radius: var(--border-radius-sm);
    border: 1px solid var(--color-border);
}

.article-chapter-tag {
    font-size: 11px;
    font-weight: 600;
    color: var(--color-text-muted);
}

.article-tags {
    display: flex;
    gap: 6px;
    flex-wrap: wrap;
}

.tag {
    font-size: 10.5px;
    font-weight: 600;
    background: var(--color-ink);
    color: var(--color-text-secondary);
    padding: 2px 8px;
    border-radius: 4px;
    border: 1px solid var(--color-border);
}

/* カードの中身（タブ・パネル構成） */
.card-sections {
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.card-section {
    display: flex;
    flex-direction: column;
    gap: 6px;
}

.card-section.hidden {
    display: none;
}

.section-label {
    font-size: 11px;
    font-weight: 800;
    color: var(--color-text-muted);
    text-transform: uppercase;
    letter-spacing: 0.5px;
    display: flex;
    align-items: center;
    gap: 6px;
}

.section-label::before {
    content: '';
    width: 6px;
    height: 6px;
    border-radius: 50%;
    background: var(--color-gold);
}

.section-label.label-translation::before {
    background: var(--color-crimson);
}

.section-label.label-explanation::before {
    background: var(--color-info);
}

.text-original {
    font-family: var(--font-serif);
    font-size: 16px;
    line-height: 1.8;
    color: var(--color-text-primary);
    white-space: pre-wrap;
    padding-left: 12px;
}

.text-translation {
    font-size: 15px;
    line-height: 1.7;
    color: var(--color-text-secondary);
    white-space: pre-wrap;
    padding-left: 12px;
}

.text-explanation {
    font-size: 13.5px;
    line-height: 1.6;
    color: var(--color-text-muted);
    background: rgba(255, 255, 255, 0.02);
    border: 1px solid var(--color-border);
    padding: 14px;
    border-radius: var(--border-radius-sm);
}

/* ==========================================================================
   タブ2: 統治構造図解 (Visualizer)
   ========================================================================== */

.visualizer-container {
    display: flex;
    flex-direction: column;
    gap: 24px;
}

.visualizer-header {
    text-align: center;
    max-width: 800px;
    margin: 0 auto;
}

.visualizer-header h2 {
    font-family: var(--font-serif);
    font-size: 26px;
    margin-bottom: 8px;
    font-weight: 800;
}

.visualizer-header p {
    font-size: 14px;
    color: var(--color-text-muted);
}

.visualizer-content {
    display: grid;
    grid-template-columns: 1.2fr 0.8fr;
    gap: 24px;
    align-items: start;
}

@media (max-width: 1024px) {
    .visualizer-content {
        grid-template-columns: 1fr;
    }
}

.svg-wrapper {
    background: var(--color-bg-surface-solid);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius-lg);
    padding: 16px;
    box-shadow: var(--shadow-md);
    aspect-ratio: 4/3;
    display: flex;
    align-items: center;
    justify-content: center;
}

/* SVGノード・コネクションスタイル */
.svg-node {
    cursor: pointer;
    transition: transform var(--transition-medium);
}

.svg-node:hover {
    transform: scale(1.05) translate(var(--x, 0), var(--y, 0));
}

/* 個別ノードのカラー */
.node-bg {
    fill: var(--color-bg-base);
    stroke: var(--color-border);
    stroke-width: 2.5;
    transition: all var(--transition-fast);
}

.node-title {
    fill: var(--color-text-primary);
    font-size: 13.5px;
    font-weight: 800;
    text-anchor: middle;
    pointer-events: none;
}

.node-subtitle {
    fill: var(--color-text-muted);
    font-size: 10.5px;
    text-anchor: middle;
    pointer-events: none;
}

/* ホバー時の挙動・ハイライト */
.svg-node:hover .node-bg {
    stroke-width: 4;
}

#node-emperor:hover .node-bg { stroke: var(--color-gold); }
#node-military:hover .node-bg { stroke: var(--color-crimson); }
#node-cabinet:hover .node-bg { stroke: var(--color-info); }
#node-diet:hover .node-bg { stroke: var(--color-success); }
#node-courts:hover .node-bg { stroke: var(--color-text-secondary); }
#node-subjects:hover .node-bg { stroke: var(--color-gold); }

/* コネクションライン */
.conn-line {
    fill: none;
    stroke: var(--color-border);
    stroke-width: 2;
    transition: all var(--transition-medium);
}

.conn-line.dotted {
    stroke-dasharray: 6, 6;
}

.conn-line.gold-line {
    stroke: var(--color-border-active);
}

.conn-line.military-line {
    stroke: var(--color-crimson);
    stroke-width: 3;
}

.conn-line.danger-line {
    stroke: var(--color-danger);
}

.conn-text {
    font-size: 10.5px;
    fill: var(--color-text-muted);
    text-anchor: middle;
    pointer-events: none;
    font-weight: 600;
}

.text-military {
    fill: var(--color-crimson);
    font-weight: 800;
}

.text-danger {
    fill: var(--color-danger);
}

/* タイポグラフィ */
.title-gold {
    fill: var(--color-gold);
    font-size: 16px;
    font-family: var(--font-serif);
}

/* 動的ハイライト用CSSクラス */
.svg-node.focused .node-bg {
    stroke-width: 5;
    fill: var(--color-bg-surface-hover);
}
#node-emperor.focused .node-bg { stroke: var(--color-gold); }
#node-military.focused .node-bg { stroke: var(--color-crimson); }
#node-cabinet.focused .node-bg { stroke: var(--color-info); }
#node-diet.focused .node-bg { stroke: var(--color-success); }
#node-courts.focused .node-bg { stroke: var(--color-text-secondary); }
#node-subjects.focused .node-bg { stroke: var(--color-gold); }

/* 図解詳細パネル */
.visualizer-details-panel {
    background: var(--color-bg-surface-solid);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius-lg);
    padding: 24px;
    box-shadow: var(--shadow-md);
    min-height: 400px;
    display: flex;
    flex-direction: column;
}

.panel-placeholder {
    margin: auto;
    text-align: center;
    max-width: 300px;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 12px;
}

.placeholder-icon {
    width: 48px;
    height: 48px;
    color: var(--color-border-active);
}

.panel-placeholder h3 {
    font-size: 16px;
    color: var(--color-text-secondary);
}

.panel-placeholder p {
    font-size: 12.5px;
    color: var(--color-text-muted);
}

.panel-content {
    animation: fadeIn var(--transition-medium);
    display: flex;
    flex-direction: column;
    gap: 18px;
}

.panel-content.hidden {
    display: none;
}

.panel-content-header {
    border-bottom: 2px solid var(--color-border);
    padding-bottom: 12px;
}

.panel-content-header h3 {
    font-family: var(--font-serif);
    font-size: 20px;
    color: var(--color-gold);
    font-weight: 800;
}

.panel-content-header .badge {
    display: inline-block;
    background: rgba(181, 61, 53, 0.1);
    color: var(--color-crimson);
    font-size: 11px;
    font-weight: 800;
    padding: 2px 8px;
    border-radius: 4px;
    margin-top: 4px;
}

.panel-content-body {
    font-size: 14px;
    color: var(--color-text-secondary);
    line-height: 1.7;
}

.panel-related-title {
    font-size: 12px;
    font-weight: 800;
    color: var(--color-text-muted);
    border-top: 1px solid var(--color-border);
    padding-top: 16px;
    margin-bottom: 10px;
}

.related-articles {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.related-article-link {
    display: flex;
    flex-direction: column;
    gap: 6px;
    background: var(--color-bg-base);
    border: 1px solid var(--color-border);
    padding: 12px;
    border-radius: var(--border-radius-sm);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.related-article-link:hover {
    border-color: var(--color-gold);
    background: var(--color-bg-surface-hover);
}

.related-article-link h4 {
    font-size: 13.5px;
    color: var(--color-gold);
    display: flex;
    justify-content: space-between;
}

.related-article-link p {
    font-size: 12.5px;
    color: var(--color-text-muted);
}

/* ==========================================================================
   タブ4: 学習クイズ (Quiz)
   ========================================================================== */

.quiz-container {
    max-width: 700px;
    margin: 0 auto;
    display: flex;
    flex-direction: column;
    gap: 24px;
}

.quiz-header {
    text-align: center;
}

.quiz-header h2 {
    font-family: var(--font-serif);
    font-size: 26px;
    margin-bottom: 8px;
    font-weight: 800;
}

.quiz-header p {
    font-size: 14px;
    color: var(--color-text-muted);
}

.quiz-card {
    background: var(--color-bg-surface-solid);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius-lg);
    padding: 32px;
    box-shadow: var(--shadow-md);
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.quiz-progress {
    display: flex;
    flex-direction: column;
    gap: 6px;
}

.quiz-progress span {
    font-size: 12px;
    font-weight: 800;
    color: var(--color-gold);
}

.progress-bar-bg {
    background: var(--color-bg-base);
    height: 6px;
    border-radius: 3px;
    overflow: hidden;
}

.progress-bar-fill {
    background: linear-gradient(90deg, var(--color-gold), var(--color-crimson));
    height: 100%;
    border-radius: 3px;
    transition: width var(--transition-medium);
}

.quiz-question {
    font-family: var(--font-serif);
    font-size: 18px;
    color: var(--color-text-primary);
    line-height: 1.6;
    font-weight: 800;
}

.quiz-options {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.quiz-option {
    background: var(--color-bg-base);
    border: 1px solid var(--color-border);
    padding: 16px 20px;
    border-radius: var(--border-radius-md);
    cursor: pointer;
    font-size: 14px;
    font-weight: 600;
    color: var(--color-text-secondary);
    text-align: left;
    transition: all var(--transition-fast);
    outline: none;
}

.quiz-option:hover:not(:disabled) {
    border-color: var(--color-gold);
    background: var(--color-bg-surface-hover);
    transform: translateX(4px);
}

/* クイズ回答後の状態 */
.quiz-option.correct {
    background: rgba(16, 185, 129, 0.08);
    border-color: var(--color-success);
    color: var(--color-success);
}

.quiz-option.wrong {
    background: rgba(239, 68, 68, 0.08);
    border-color: var(--color-danger);
    color: var(--color-danger);
}

.quiz-option:disabled {
    cursor: not-allowed;
    opacity: 0.6;
}

/* フィードバック表示 */
.quiz-feedback {
    border-top: 1px solid var(--color-border);
    padding-top: 20px;
    display: flex;
    flex-direction: column;
    gap: 12px;
    animation: fadeIn var(--transition-medium);
}

.quiz-feedback.hidden {
    display: none;
}

.feedback-header {
    display: flex;
    align-items: center;
    gap: 8px;
}

.feedback-header h4 {
    font-size: 16px;
    font-weight: 800;
}

.quiz-feedback.correct-feedback h4 { color: var(--color-success); }
.quiz-feedback.wrong-feedback h4 { color: var(--color-danger); }

.feedback-explanation {
    font-size: 13.5px;
    color: var(--color-text-muted);
    line-height: 1.6;
    background: var(--color-bg-base);
    padding: 16px;
    border-radius: var(--border-radius-sm);
}

.action-btn {
    align-self: flex-end;
    background: linear-gradient(135deg, var(--color-gold), var(--color-crimson));
    color: #fff;
    border: none;
    padding: 10px 24px;
    border-radius: var(--border-radius-sm);
    font-size: 14px;
    font-weight: 800;
    cursor: pointer;
    box-shadow: var(--shadow-sm);
    transition: all var(--transition-fast);
}

.action-btn:hover {
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
    filter: brightness(1.1);
}

/* クイズ結果発表画面 */
.quiz-results-screen {
    background: var(--color-bg-surface-solid);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius-lg);
    padding: 48px 32px;
    text-align: center;
    box-shadow: var(--shadow-md);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 16px;
    animation: fadeIn var(--transition-medium);
}

.quiz-results-screen.hidden {
    display: none;
}

.congratulations-animation {
    font-size: 64px;
    animation: bounce 1.5s infinite;
}

@keyframes bounce {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-15px); }
}

.score-text {
    font-size: 20px;
    font-weight: 600;
}

.score-text span {
    font-size: 36px;
    font-family: var(--font-serif);
    color: var(--color-gold);
    font-weight: 800;
}

.quiz-results-screen .action-btn {
    align-self: center;
    margin-top: 12px;
}

/* ==========================================================================
   フッター
   ========================================================================== */

.app-footer {
    border-top: 1px solid var(--color-border);
    padding: 24px;
    text-align: center;
    font-size: 12.5px;
    color: var(--color-text-muted);
    background: var(--color-bg-surface-solid);
    margin-top: auto;
}

/* ==========================================================================
   レスポンシブデザイン（メディアクエリ）
   ========================================================================== */

@media (max-width: 1024px) {
    .reader-container {
        grid-template-columns: 1fr;
    }

    .reader-sidebar {
        position: relative;
        top: 0;
        max-height: none;
        overflow-y: visible;
    }
}

@media (max-width: 768px) {
    .app-header {
        padding: 12px 16px;
    }

    .header-container {
        flex-direction: column;
        align-items: stretch;
        gap: 12px;
    }

    .logo-area {
        align-items: center;
    }

    .logo-area h1 {
        text-align: center;
        font-size: 19px;
    }

    .logo-area h1 .subtitle {
        display: block;
        margin-left: 0;
        margin-top: 4px;
        font-size: 13px;
    }

    .nav-tabs {
        justify-content: space-around;
        overflow-x: auto;
        padding-bottom: 4px;
    }

    .tab-btn {
        padding: 6px 12px;
        font-size: 13px;
        white-space: nowrap;
    }

    .actions {
        display: flex;
        justify-content: center;
    }

    .app-main {
        padding: 16px;
    }

    .preamble-header {
        text-align: center;
    }

    .article-card {
        padding: 18px;
    }

    .article-card-header {
        flex-direction: column;
        align-items: flex-start;
        gap: 8px;
    }
}