:root {
    --bg-color: #f4f4f4;
    --editor-bg: #1e1e1e;
    --editor-text: #d4d4d4;
    --preview-bg: #ffffff;
    --border-color: #ddd;
    --toolbar-bg: #333;
    --toolbar-text: #fff;
    --status-bar-bg: #2d2d2d;
    --status-bar-text: #ccc;
}

body {
    margin: 0;
    padding: 0;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    height: 100vh;
    display: flex;
    flex-direction: column;
    background-color: var(--bg-color);
}

/* --- Header & Toolbar --- */
header {
    background-color: var(--toolbar-bg);
    color: var(--toolbar-text);
    padding: 0 15px;
    height: 60px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    box-shadow: 0 2px 5px rgba(0,0,0,0.2);
    z-index: 10;
    flex-shrink: 0;
}

.header-left {
    display: flex;
    align-items: center;
    gap: 10px;
}

.app-logo { height: 32px; width: auto; }

/* ★★★ 修正點 1：加上 header 前綴，避免影響內容 ★★★ */
header h1 { 
    margin: 0; 
    font-size: 1.2rem; 
    white-space: nowrap; 
    font-weight: bold;
}

.toolbar-groups { display: flex; align-items: center; gap: 15px; }
.tool-group { display: flex; align-items: center; gap: 5px; padding: 0 10px; border-right: 1px solid #555; }
.tool-group:last-child { border-right: none; }

.toolbar button, .toolbar select, .search-bar button {
    background: #555;
    border: 1px solid #666;
    color: white;
    padding: 5px 10px;
    cursor: pointer;
    border-radius: 4px;
    font-size: 0.9rem;
    transition: background 0.2s;
}
.toolbar button:hover, .search-bar button:hover { background: #666; }
.toolbar button:active { transform: translateY(1px); }
.toolbar select { padding: 4px; background: #555; color: white; }

/* --- Search Bar --- */
#search-bar {
    background-color: #444;
    padding: 8px 20px;
    display: none;
    align-items: center;
    gap: 10px;
    border-bottom: 1px solid #555;
    flex-shrink: 0;
}
#search-bar input { padding: 5px; border-radius: 3px; border: none; outline: none; }
.close-btn { background: transparent !important; border: none !important; margin-left: auto; font-size: 1.2rem; }

/* --- Main Container --- */
.main-container {
    display: flex;
    flex: 1;
    overflow: hidden;
    position: relative;
}

#editor-container {
    width: 50%;
    display: flex;
    flex-direction: column;
    border-right: 1px solid var(--border-color);
}

textarea#source-input {
    width: 100%;
    height: 100%;
    border: none;
    resize: none;
    padding: 20px;
    font-family: 'Consolas', 'Monaco', 'Courier New', monospace;
    font-size: 16px;
    line-height: 1.6;
    background-color: var(--editor-bg);
    color: var(--editor-text);
    box-sizing: border-box;
    outline: none;
}

#preview-container {
    width: 50%;
    padding: 30px; /* 增加內距讓畫面更好看 */
    padding-bottom: 50px;
    overflow-y: auto;
    background-color: var(--preview-bg);
    box-sizing: border-box;
}

/* --- Status Bar --- */
#status-bar {
    height: 25px;
    background-color: var(--status-bar-bg);
    color: var(--status-bar-text);
    display: flex;
    align-items: center;
    padding: 0 15px;
    font-size: 0.8rem;
    border-top: 1px solid #444;
    flex-shrink: 0;
}

#file-input-element { display: none; }

/* ★★★ 修正點 2：Markdown 內容樣式優化 (GitHub 風格) ★★★ */
/* 使用 #preview-container 增加權重，確保樣式生效 */

.markdown-body { 
    line-height: 1.6; 
    color: #24292e; 
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;
}

#preview-container h1 { font-size: 2em; margin-bottom: 16px; font-weight: 600; border-bottom: 1px solid #eaecef; padding-bottom: .3em; line-height: 1.25; }
#preview-container h2 { font-size: 1.5em; margin-bottom: 16px; font-weight: 600; border-bottom: 1px solid #eaecef; padding-bottom: .3em; line-height: 1.25; }
#preview-container h3 { font-size: 1.25em; margin-bottom: 16px; font-weight: 600; line-height: 1.25; }
#preview-container h4 { font-size: 1em; margin-bottom: 16px; font-weight: 600; line-height: 1.25; }
#preview-container h5 { font-size: 0.875em; margin-bottom: 16px; font-weight: 600; line-height: 1.25; }
#preview-container h6 { font-size: 0.85em; margin-bottom: 16px; font-weight: 600; color: #6a737d; line-height: 1.25; }

.markdown-body p { margin-bottom: 16px; margin-top: 0; }
.markdown-body ul, .markdown-body ol { padding-left: 2em; margin-bottom: 16px; margin-top: 0; }

.markdown-body blockquote { 
    border-left: 4px solid #dfe2e5; 
    color: #6a737d; 
    padding: 0 1em; 
    margin: 0 0 16px 0; 
}

.markdown-body img { max-width: 100%; background-color: #fff; }

.markdown-body pre { 
    background-color: #1e1e1e; 
    padding: 16px; 
    border-radius: 6px; 
    overflow: auto; 
    margin-bottom: 16px;
}

.markdown-body pre code { 
    background-color: transparent; 
    padding: 0; 
    font-family: 'Consolas', monospace; 
    color: #d4d4d4; 
    font-size: 85%;
}

.markdown-body code:not(pre code) { 
    background-color: rgba(27,31,35,.05); 
    padding: .2em .4em; 
    border-radius: 3px; 
    font-family: monospace; 
    font-size: 85%;
}

/* 表格樣式 */
.markdown-body table {
    border-spacing: 0;
    border-collapse: collapse;
    margin-bottom: 16px;
    width: max-content;
    max-width: 100%;
}
.markdown-body table th, .markdown-body table td {
    padding: 6px 13px;
    border: 1px solid #dfe2e5;
}
.markdown-body table th {
    font-weight: 600;
    background-color: #f6f8fa;
}
.markdown-body table tr:nth-child(2n) {
    background-color: #f6f8fa;
}