If the options in the layout editor are insufficient for the layout you want to use, you can build it yourself as an HTML file. This requires technical knowledge.
To customize a layout further, it's best to initially create it as thoroughly as possible in the layout editor. This minimizes the amount of work needed for adjustments later on. Once you've built the layout in the layout editor, you can export it (see Layout Importing) to download as a ZIP file.
After downloading the ZIP file, open and extract it. Inside, you'll find about four files. Open the "version.config" file and replace the content "dompdf1" with "custom_dompdf".
The HTML layout itself can be found in the "template.html" file. Here, you can make desired changes to the HTML structure. The layout uses mustache script language alongside HTML to convert the layout into an invoice.
Note: When modifying the HTML layout, you can use HTML and CSS. However, not all HTML and CSS options are available. To position elements fixedly, it's best to use pixels (the width of a PDF file is typically 1600px).
Once you've made changes to the files, add them back into the ZIP file so it can be added as a new layout.
To re-import a customized layout, go to the Layout overview, select "More actions" > "Import". Provide a new name and select the ZIP file containing the exported layout. You can now preview the customized layout. Please note that changes can no longer be made via the layout editor once you've customized the layout in this way.
Similarly, you can replace an existing layout to adjust it for existing invoices. Click on the desired layout and choose "Actions" > "Replace". Select the ZIP file with the previously exported layout. However, it's recommended to keep the original layout so it can still be adjusted later via the layout editor.