MacOS Sierra High comes with preinstalled postfix. Follow these steps to configure it on a local system:
sudo nano /etc/postfix/sasl_passwd- Add this to the file
| <style id="fslightbox-customizations"> | |
| a.open-gallery > img { | |
| width: 80%; | |
| max-width: 745px; | |
| border: 3px dashed white; | |
| } | |
| .fslightbox-container { | |
| background: black; | |
| } | |
| </style> |