We are sure you've already completed the setup steps in the Zebra/Brother Setup, so we'll move on.
Please go to the File>Page Setup options in Firefox and confirm that the 'Shrink to fit page' option is not enabled.
Now that we have that out of the way, I believe the solution is in the Windows Printer Driver settings. I'm not sure what stock you're using since Brother has a lot of choices, so I'll cover scenarios for the continuous non-stop roll & pre-sized labels.
- Go to Windows Control Panel>Devices and Printers>Right Click on the Brother>Printing Preferences
This will display the Driver settings for your device, which should appear similar to the screenshot below. These should be made to match what you have input into InventoryLab for your Label's dimensions.
We highly suggest creating a new Label Definition for your FBA Labels, as opposed to changing the values each time they need to be modified.
To do this, click on the Label Format Definitions button near the bottom of the dialog box. A new Settings dialog will appear with the current configuration shown, as depicted in the image below.*
If you use 100' continuous stock, you'll be able to set the label height to your choice (we personally like 1.22" height since that covers all UPC barcodes on Media items)*
If your stock has individual labels on the roll, you must use the Width and Height of the actual stock because a mismatch will cause an error or bad print output*
Now you'll need to set your Width from the dropdown box, select a single value.
Type the label Height into the field provided and don't change the "Feed" value unless it's anything other than the minimum allowed value.
Next, at the top of the dialog box is a text field where the name of the Label Definition is. Change it to a custom value, like "FBA Labels" or whatever you'd prefer, and click the Save button to add the definition to the driver's list of presets.
Click on OK to close this dialog box and return to the Driver settings dialog box. The definition you just saved should have its values applied to the current settings. If they aren't, click the Format dropdown and select the name of the definition you just saved and the values will be applied.
The orientation should match the Label Stock orientation so the image depicted in Settings showing how the text will print is correct (you can always switch this if it prints the wrong direction). Click on Apply, then click on OK to close the dialog box and save the settings.
A final thing to check would be the type of labels you are using. Currently, the sample address labels that come with a new Brother printer cause trouble in the Firefox browser. This can cause your labels not to print in Landscape orientation regardless of your settings. To solve this, please order a full set of Brother labels for your printer. A recommended label type is dk1209, which are small address labels.
Everything should begin to print correctly now.
The settings for JS Print in the File>Page Setup area of Firefox should be responsive now and resolve your output.