:root { --bg: #eef2f3; --card: white; --text: #333; }
body.dark-mode { --bg: #1a1a1a; --card: #2d2d2d; --text: #f0f0f0; }
body { background: var(--bg); color: var(--text); font-family: 'Segoe UI', sans-serif; display: flex; justify-content: center; padding: 20px; transition: 0.3s; }
.container { background: var(--card); padding: 25px; border-radius: 15px; box-shadow: 0 10px 30px rgba(0,0,0,0.2); width: 100%; max-width: 450px; text-align: center; }
.header { display: flex; justify-content: space-between; align-items: center; margin-bottom: 20px; }
#fileList { list-style: none; padding: 0; margin: 20px 0; border: 2px dashed #bbb; border-radius: 8px; min-height: 100px; }
#fileList li { background: var(--card); border: 1px solid #444; margin: 8px; padding: 10px; cursor: grab; border-radius: 6px; display: flex; justify-content: space-between; font-size: 14px; }
.btn-select { background: #007bff; color: white; border: none; padding: 10px 20px; border-radius: 5px; cursor: pointer; width: 100%; }
.btn-merge { background: #28a745; color: white; border: none; padding: 15px; border-radius: 8px; cursor: pointer; width: 100%; font-size: 18px; font-weight: bold; margin-top: 10px; }
.remove-btn { background: #ff4d4d; color: white; border: none; border-radius: 4px; padding: 2px 8px; cursor: pointer; }
select { width: 100%; padding: 8px; margin-top: 5px; border-radius: 5px; background: var(--card); color: var(--text); }
#status { margin-top: 15px; color: #28a745; font-weight: bold; }