Bootstrap vs CSS Flexible Box vs CSS grid

i am new to web development , i am in a confusion to choose which web technology to choose for a RESPONSIVE and LIGHT-WEIGHT web page such a way that i can make changes in future like make making it into application for smart phone using frameworks like vuejs . can any one give a feed back based on their experience in web development and application development by consider following parameter
fast loading
light weight
easy to build and maintain

you dropped so many things on the table haha. Web development is very big and complicated. In general, JavaScript is considered fast for web browsers. If you consider to make apps for mobile phones in the future, you have 2 options. First, you can make the website responsive to work on mobile phones. Second, you can build an app using React Native which is mobile application framework or Flutter …etc. You can not say which one is easy both of them are the same, just it depends on what developers prefer. For example, with React you can write HTML code in JavaScript files and is called JSX which is the opposite of Angular you have to write your HTML code in the same HTML file. Both frameworks have support and updates constantly. I do not know vue js.