## CSS media query

CSS media query:

    /* Larger than mobile */
    @media (min-width: 400px) { /* specific rules go here */ }

    /* Larger than phablet */
    @media (min-width: 550px) { /* specific rules go here */ }

    /* Larger than tablet */
    @media (min-width: 750px) { /* specific rules go here */ }

    /* Larger than desktop */
    @media (min-width: 1000px) { /* specific rules go here */ }

    /* Larger than Desktop HD */
    @media (min-width: 1200px) { /* specific rules go here */ }

- Viewport Sizer - Devices

Have your breakpoints make sense for your design!!
Start with one breakpoint.