It sounds like you need to make sure that the Tailwind CSS classes are being compiled into your project. You can do this by adding the Tailwind CSS configuration file to your project and then running the Tailwind CSS build command.
For example, if you are using the Tailwind CLI, you can run the following command to build your Tailwind CSS configuration file:
npx tailwindcss build tailwind.config.js -o tailwind.css
Once you have done this, you should be able to use the Tailwind CSS classes in your project. For example, you can add the line-through class to your Vue component like this:
{{voyagetask.name}}
<span class="line-through">{{voyagetask.name}}</span>