/* =========================================
   1. Tokens & Colors
   ========================================= */
:root {
    /* --- FEAR (Default / Dark Mode) --- */
    --bg-app: #0e0e10;       /* APP 背景：深灰黑 */
    --bg-sidebar: #161618;   /* 側邊欄：稍亮 */
    --bg-paper: #1c1c1f;     /* 閱讀紙張：深色閱讀介面 */
    
    --text-main: #e4e4e7;    /* 主文字：鋅灰白 */
    --text-dim: #a1a1aa;     /* 次要文字 */
    
    --accent: #d8b4fe;       /* 預設強調色 (淡紫) */
    --border: #27272a;       /* 邊框 */
    
    --font-head: 'Cinzel', serif;
    --font-body: 'Noto Sans TC', sans-serif;
}

[data-theme="hope"] {
    /* --- HOPE (Light Mode) --- */
    --bg-app: #f4f4f5;       /* APP 背景：鋅灰 */
    --bg-sidebar: #ffffff;
    --bg-paper: #ffffff;     /* 閱讀紙張：純白 */
    
    --text-main: #18181b;    /* 主文字：近黑 */
    --text-dim: #52525b;
    
    --accent: #b45309;       /* 預設強調色 (深琥珀) */
    --border: #e4e4e7;
}

/* Base Reset */
* { box-sizing: border-box; margin: 0; padding: 0; }
ul, li { list-style: none !important; }

body {
    background: var(--bg-app);
    color: var(--text-main);
    font-family: var(--font-body);
    height: 100vh;
    overflow: hidden;
    transition: background 0.3s ease, color 0.3s ease;
}

/* App Layout */
.app-layout { display: flex; height: 100%; }

/* Sidebar */
.sidebar {
    width: 280px;
    background: var(--bg-sidebar);
    border-right: 1px solid var(--border);
    display: flex; flex-direction: column;
    z-index: 50;
    transition: transform 0.3s ease;
}

.sidebar-header { padding: 20px; border-bottom: 1px solid var(--border); }
.brand { font-family: var(--font-head); font-size: 1.4rem; color: var(--text-main); letter-spacing: 1px; }
.brand-sub { font-size: 0.75rem; color: var(--text-dim); text-transform: uppercase; display: block; margin-top: 4px; }

.tree-nav { flex: 1; overflow-y: auto; padding: 10px; }
.nav-item { margin-bottom: 1px; }
.nav-link { 
    display: flex; align-items: center; padding: 6px 8px; 
    border-radius: 6px; cursor: pointer; color: var(--text-dim); font-size: 0.95rem;
    transition: 0.2s;
}
.nav-link:hover { background: rgba(128,128,128,0.08); color: var(--text-main); }
.nav-link.active { background: rgba(128,128,128,0.12); color: var(--text-main); font-weight: 500; }
.nav-link.active .nav-text { color: var(--accent); }

.folder-icon { width: 24px; height: 24px; display: flex; align-items: center; justify-content: center; margin-right: 4px; opacity: 0.7; }
.nav-item.open > .nav-link .folder-icon svg { transform: rotate(90deg); }
.nav-item ul { display: none; padding-left: 16px; border-left: 1px solid var(--border); margin-left: 12px; }
.nav-item.open > ul { display: block; }

/* Main Content */
.main-content { flex: 1; display: flex; flex-direction: column; min-width: 0; }

.top-bar {
    height: 56px; border-bottom: 1px solid var(--border);
    display: flex; align-items: center; justify-content: space-between;
    padding: 0 20px; background: var(--bg-paper);
}
.breadcrumbs { font-size: 0.9rem; color: var(--text-dim); font-family: var(--font-head); }

/* Theme Button */
.theme-btn { 
    background: none; border: 1px solid var(--border); border-radius: 20px; 
    padding: 4px 12px; cursor: pointer; color: var(--text-dim); display: flex; gap: 8px;
}
.theme-btn:hover { border-color: var(--text-dim); color: var(--text-main); }
[data-theme="hope"] .icon-fear { opacity: 0.3; }
[data-theme="fear"] .icon-hope { opacity: 0.3; }

/* Reader Container (核心修改：穩固的紙張模式) */
.reader-container {
    flex: 1;
    overflow: hidden; /* 外部不捲動 */
    background: var(--bg-app);
    display: flex;
    justify-content: center;
}

.reader-paper {
    width: 100%;
    max-width: 900px; /* 限制最大寬度，避免文字過長 */
    background: var(--bg-paper);
    height: 100%;
    border-left: 1px solid var(--border);
    border-right: 1px solid var(--border);
    position: relative;
    /* 讓 iframe 在這個紙張範圍內 */
}

iframe { width: 100%; height: 100%; border: none; display: block; }

/* Mobile */
@media (max-width: 768px) {
    .sidebar { position: fixed; height: 100%; transform: translateX(-100%); }
    .sidebar.active { transform: translateX(0); }
    .reader-paper { border: none; max-width: 100%; }
}