A simple yet customizable countdown timer web component that can be easily integrated into any web project. This component is designed to display a countdown to a specified date, complete with a customizable heading, subheading, and theme.

• Dynamic Countdown: Counts down to a specified date and time.
• Customizable: Allows setting a heading, subheading, and theme via attributes.
• Responsive Design: Adapts to different screen sizes for optimal viewing.
• Light/Dark Themes: Supports "dark" and "light" themes to match your site's design.

To use the countdown-timer in your project, simply include the JavaScript file that contains the class definition for the component. A CDN link is provided below for easy integration:

<script src="https://www.unpkg.com/@allensulzen/countdown-timer@latest/countdown-timer.min.js"></script>

To add a countdown timer to your webpage, you can include the countdown-timer element with the desired attributes:

<countdown-timer
    date="YYYY-MM-DDThh:mm:ss"
    heading="Event Starts In"
    subheading="Don't miss out!"
    theme="dark"
    message="The event has begun!"
    link="https://example.com"
    linktext="Learn More"
></countdown-timer>

• date (required): The target date and time for the countdown. Format: YYYY-MM-DDThh:mm:ss.
• heading (optional): A heading text displayed above the countdown.
• subheading (optional): A subheading text displayed below the countdown.
• theme (optional): Theme for the countdown timer. Currently supports "dark" and "light" (default).
• message (optional): A message displayed when the countdown reaches zero.
• link (optional): A URL for a page to visit when the countdown is complete.
• linktext (optional): The text for the link displayed after the countdown ends.

The component can be styled further using CSS. It is structured to allow easy customization of its parts. Here are some classes you can target:

• .countdown-timer__title: The container for the heading.
• .countdown-timer__content: The container for the countdown counters.
• .countdown-timer__content__counter: The individual counter for days, hours, minutes, and - seconds.
• .countdown-timer__content__counter.skeleton: Targets the skeleton screen counters for loading state.
• .countdown-timer__label: The container for the subheading.

The component does not use shadow DOM, so you can style it as you please.

.countdown-timer.theme--dark .countdown-timer__content__counter {
    background-color: #333;
    color: #fff;
}

• startTimer(): Starts the countdown timer.
• stopTimer(): Stops the countdown timer.

The countdown-timer component is built with standard web technologies, making it compatible with most modern browsers that support Web Components and Custom Elements.