New Tab Countdown v2 - With dark mode

This is a fork of the New Tab Countdown with Dark mode and extra countdowns. New Tab Countdown replaces the default new tab with customizable countdowns. You can add or remove countdowns, and can select a time remaining format (in seconds, minutes, hours, days, or weeks) and a specified end date (day, week, month, year, or a custom date and description) for each countdown.