Guidance required to create a simple and free website with html and css

Hi there,
I have been learning html css and I am planning to create simple and free website which can help to detect ai generated content and can also provide suggestions how to improve their content. the web site design which i am looking for similar to this website ai to humanize text converter. Do i need to learn javascript for functionalities which i am looking for or will this work fine in html css and importing any framework. Thank you so much in advance.