:root {
    --bg-color: #f5f5f7;
    --card-bg: #ffffff;
    --text-primary: #333333;
    --text-secondary: #888888;
    --border-color: #e0e0e0;
    --primary-color: #007bff;
    --primary-hover: #0056b3;
    --danger-color: #dc3545;
    --input-bg: #ffffff;
    --shadow: 0 2px 8px rgba(0,0,0,0.05);
}

body.dark-mode {
    --bg-color: #1a1a1a;
    --card-bg: #2d2d2d;
    --text-primary: #e0e0e0;
    --text-secondary: #aaaaaa;
    --border-color: #444444;
    --input-bg: #3d3d3d;
    --shadow: 0 2px 8px rgba(0,0,0,0.3);
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Arial, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-primary);
    transition: background-color 0.3s, color 0.3s;
}

.container { max-width: 900px; margin: 0 auto; padding: 15px; }

header {
    display: flex; justify-content: space-between; align-items: center;
    margin-bottom: 20px;
}

h1 { font-size: 24px; font-weight: 600; }

.card {
    background-color: var(--card-bg);
    border-radius: 12px;
    padding: 20px;
    margin-bottom: 20px;
    box-shadow: var(--shadow);
}

/* 按钮与输入框 */
.btn {
    padding: 6px 14px; border-radius: 6px; border: 1px solid transparent;
    cursor: pointer; font-size: 14px; transition: all 0.2s; display: inline-block;
    text-decoration: none;
}
.btn-primary { background-color: var(--primary-color); color: white; }
.btn-primary:hover { background-color: var(--primary-hover); }
.btn-primary:disabled { opacity: 0.6; cursor: wait; }

.btn-outline { background-color: transparent; border-color: var(--border-color); color: var(--text-primary); }
.btn-outline:hover { background-color: var(--bg-color); border-color: var(--text-secondary); }

.btn-sm { padding: 4px 8px; font-size: 12px; border-radius: 4px; }
.btn-danger { background-color: transparent; border-color: var(--danger-color); color: var(--danger-color); }
.btn-danger:hover { background-color: var(--danger-color); color: white; }

.input-group { display: flex; gap: 8px; flex: 1; }
input[type="text"] {
    flex: 1; padding: 8px;
    border: 1px solid var(--border-color); border-radius: 6px;
    background-color: var(--input-bg); color: var(--text-primary);
}

.file-trigger {
    padding: 8px 12px; border: 1px solid var(--border-color); border-radius: 6px;
    background-color: var(--input-bg); color: var(--text-secondary);
    cursor: pointer; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; max-width: 200px;
}
.file-trigger:hover { border-color: var(--primary-color); }

/* 布局：操作栏 */
.action-bar { display: flex; justify-content: space-between; align-items: center; gap: 15px; flex-wrap: wrap; }
.upload-group { flex: 1; min-width: 280px; }

/* 列表头部与面包屑 */
.list-header { 
    display: flex; justify-content: space-between; align-items: flex-end; 
    margin-bottom: 15px; border-bottom: 1px solid var(--border-color); padding-bottom: 10px;
}
.breadcrumbs { margin-top: 5px; color: var(--text-secondary); font-size: 14px; }
.breadcrumbs a { color: var(--primary-color); text-decoration: none; }
.breadcrumbs .sep { margin: 0 4px; color: var(--border-color); }
.stats { text-align: right; font-size: 12px; color: var(--text-secondary); line-height: 1.4; }

/* 文件列表项 */
.file-item {
    display: flex; justify-content: space-between; align-items: center;
    padding: 12px 0; border-bottom: 1px solid var(--border-color);
}
.file-item:last-child { border-bottom: none; }

.file-info { display: flex; align-items: center; gap: 12px; flex: 1; overflow: hidden; }
.file-thumb {
    width: 36px; height: 36px; object-fit: cover; border-radius: 4px;
    background: #f0f0f0; display: flex; align-items: center; justify-content: center;
    font-size: 18px; border: 1px solid var(--border-color);
}
.folder-icon { background: transparent; border: none; font-size: 24px; }
.folder-item { background-color: rgba(128,128,128, 0.03); padding-left: 5px; padding-right: 5px; border-radius: 6px; margin-bottom: 4px;}

.file-name { font-weight: 500; color: var(--text-primary); text-decoration: none; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.file-meta { font-size: 12px; color: var(--text-secondary); margin-left: 10px; }

.file-actions { display: flex; gap: 6px; align-items: center; }
.file-date { font-size: 12px; color: var(--text-secondary); margin-right: 8px; }

.empty-tip { text-align: center; color: var(--text-secondary); padding: 30px; }

/* 响应式 */
@media (max-width: 600px) {
    .mobile-hide { display: none; }
    .action-bar { flex-direction: column; align-items: stretch; }
    .header-actions { display: flex; gap: 5px; }
    .btn { padding: 6px 10px; font-size: 12px; }
    .list-header { flex-direction: column; align-items: flex-start; gap: 10px; }
}