:root {
    --primary-color: #f25822; /* Orange identity */
    --primary-hover: #d44a1b;
    --bg-light: #f8f9fa;
    --border-color: #e0e0e0;
}

#merge_pdf_Grid {
    max-width: 1000px;
    margin: 20px auto;
    padding: 20px;
    font-family: 'Arial', sans-serif;
    background: #fff;
}

.pdf-upload-zone {
    border: 3px dashed #f25822;
    border-radius: 20px;
    padding: 60px 40px;
    text-align: center;
    background: #fff;
    cursor: pointer;
    transition: all 0.3s ease;
    margin: 40px auto;
    max-width: 800px;
}

.pdf-upload-zone:hover {
    background: #fff9f7;
    border-color: #d44a1b;
}

.upload-inner i {
    font-size: 80px;
    color: #f25822;
    margin-bottom: 20px;
}

.file-list {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
    gap: 20px;
    margin-top: 30px;
    min-height: 100px;
}

.file-item {
    background: #fff;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 15px;
    position: relative;
    box-shadow: 0 2px 5px rgba(0,0,0,0.05);
    transition: transform 0.2s;
    cursor: grab;
    display: flex;
    flex-direction: column;
    align-items: center;
    text-align: center;
}

.file-item:active {
    cursor: grabbing;
}

.file-item:hover {
    transform: translateY(-5px);
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
}

.file-item .file-icon {
    font-size: 40px;
    color: #ef4444;
    margin-bottom: 10px;
}

.file-item .file-name {
    font-size: 13px;
    font-weight: 600;
    color: #333;
    word-break: break-all;
    max-width: 100%;
}

.file-remove {
    position: absolute;
    top: -10px;
    right: -10px;
    background: #ef4444;
    color: white;
    width: 24px;
    height: 24px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 12px;
    cursor: pointer;
    box-shadow: 0 2px 4px rgba(0,0,0,0.2);
}

.merge-actions {
    display: flex;
    justify-content: center;
    gap: 15px;
    margin-top: 40px;
}

.btn-merge {
    background: var(--primary-color);
    color: white;
    border: none;
    padding: 15px 40px;
    border-radius: 50px;
    font-size: 18px;
    font-weight: bold;
    cursor: pointer;
    box-shadow: 0 4px 6px rgba(242, 88, 34, 0.3);
    transition: all 0.3s ease;
}

.btn-merge:hover {
    background: var(--primary-hover);
    transform: scale(1.05);
}

.btn-sort {
    background: #6c757d;
    color: white;
    border: none;
    padding: 15px 30px;
    border-radius: 50px;
    font-size: 16px;
    cursor: pointer;
}

.progress-merge {
    width: 100%;
    background-color: #eee;
    border-radius: 10px;
    margin-top: 20px;
    display: none;
    overflow: hidden;
}

.progress-merge-bar {
    width: 0%;
    height: 10px;
    background-color: var(--primary-color);
    transition: width 0.3s;
}

.sortable-ghost {
    opacity: 0.4;
    border: 2px dashed var(--primary-color);
}