JSFiddle - React, Tailwind, and code Playground

HTML

<ul class="main-header__list" style="">
  <li>
    <a class="main-header__link" href="/#about">Про нас</a>
  </li>
  <li>
    <a class="main-header__link" href="#block">Команда</a>
  </li>
</ul>

  <p>Lorem ipsum dolor sit amet, consectetur adipisicing elit. Ipsum quae inventore tempora, ex ullam id atque dolor ab, labore earum a optio, illum repellendus ea modi nostrum eum laborum eligendi!</p>
  
    <p>Lorem ipsum dolor sit amet, consectetur adipisicing elit. Ipsum quae inventore tempora, ex ullam id atque dolor ab, labore earum a optio, illum repellendus ea modi nostrum eum laborum eligendi!</p>
    
      <p>Lorem ipsum dolor sit amet, consectetur adipisicing elit. Ipsum quae inventore tempora, ex ullam id atque dolor ab, labore earum a optio, illum repellendus ea modi nostrum eum laborum eligendi!</p>
      
        <p>Lorem ipsum dolor sit amet, consectetur adipisicing elit. Ipsum quae inventore tempora, ex ullam id atque dolor ab, labore earum a optio, illum repellendus ea modi nostrum eum laborum eligendi!</p>
<section id="block">
<h3>block</h3>
  <p>Lorem ipsum dolor sit amet, consectetur adipisicing elit. Ipsum quae inventore tempora, ex ullam id atque dolor ab, labore earum a optio, illum repellendus ea modi nostrum eum laborum eligendi!</p>
</section>

<section id="/#about">
<h4>about</h4>
  <p>Lorem ipsum dolor sit amet, consectetur adipisicing elit. Ipsum quae inventore tempora, ex ullam id atque dolor ab, labore earum a optio, illum repellendus ea modi nostrum eum laborum eligendi!</p>
</section>

JavaScript

$(document).ready(function() {

  $('a[href^="#"], a[href^="/#"]').click(function(e) {
  e.preventDefault();
    var sel= $(e.currentTarget).attr('href');
    
    if(sel[0] !== '#') var $target= $(document.getElementById(sel));

    var $target = $target || $(sel);
    
    $(document.documentElement).animate({
      scrollTop: $target.offset().top
    }, 800);
    return false;
  });

});