Thunderbird color by categories (working on v115.2.0)

TbColorCategories.md

Thunderbird color by categories

• Navigate to Help > Troubleshooting Information > Profile Directory > Open Directory
• Close Thunderbird
• Create a folder named chrome (all lowercase)
• Create a file named userChrome.css
• Insert

/* Calendar  - set event category colour instead of calendar colour */

.calendar-category-box{     margin:0 0 0 -200px !important;     min-width: 200px !important;     }    
.alarm-icons-box,.reminder-icon{     margin:0 0 0 0!important;     }    
.event-name-label,.item-time-label,.alarm-icons-box,.reminder-icon{     z-index:100000!important;     }     
.calendar-item-flex{     padding:0!important;     }     
.calendar-month-day-box-list-item{     margin:0!important;     }     
.calendar-color-box{     border:none!important;     }      
.event-name-label{     white-space:break-spaces !important;     }    

• Save the File
• Open Thunderbird
• Go to Settings > General > Config Editor
• Set toolkit.legacyUserProfileCustomizations.stylesheets to true
• Restart Thunderbird
• Done!