JSFiddle - React, Tailwind, and code Playground

by Константин Дралюк

HTML

<div class="layout">
  <div class="base">
    <div class="aside">
      <div class="nav">
        <div class="nav__item">
          <span>whfe</span>
        </div>
        <div class="nav__item">
          <span>wefewfe</span>
        </div>
        <div class="nav__item">
          <span>wefe</span>
        </div>
        <div class="nav__item active">
          <span>weewfe</span>
        </div>
        <div class="sub">
          <div class="nav__item">
            <span>weewfe</span>
          </div>
          <div class="nav__item active">
            <span>weffe</span>
          </div>
          <div class="nav__item">
            <span>wef2fe</span>
          </div>
        </div>
        <div class="nav__item">
          <span>weffe</span>
        </div>
        <div class="nav__item">
          <span>wef2fe</span>
        </div>
      </div>
    </div>
    <div class="main">
      <div class="h1">
        <span>frefrhf fueruifiref rfeurf</span>
      </div>
      <div class="text">
        <span>frefrhf fueruifiref rfeurf</span><span>frefrhf fueruifiref rfeurf</span><span>frefrhf fueruifiref rfeurf</span><span>frefrhf fueruifiref rfeurf</span><br><span>frefrhf fueruifiref rfeurf</span><span>frefrhf fueruifiref rfeurf</span><span>frefrhf fueruifiref rfeurf</span><span>frefrhf fueruifiref rfeurf</span><span>frefrhf fueruifiref rfeurf</span><br><span>frefrhf fueruifiref rfeurf</span><span>frefrhf fueruifiref rfeurf</span><br><br><span>frefrhf fueruifiref rfeurf</span><span>frefrhf fueruifiref rfeurf</span><br><span>frefrhf fueruifiref rfeurf</span><span>frefrhf fueruifiref rfeurf</span><span>frefrhf fueruifiref rfeurf</span><span>frefrhf fueruifiref rfeurf</span><span>frefrhf fueruifiref rfeurf</span><span>frefrhf fueruifiref rfeurf</span><br><br><span>frefrhf fueruifiref rfeurf</span><span>frefrhf fueruifiref rfeurf</span>
      </div>
    </div>
  </div>
</div>

SCSS

html, body {
  height: 100%;
  background: #ededed;
  font-family: Arial, "Helvetica Neue", Helvetica, sans-serif;
}
.layout {
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
}
.base {
  box-shadow: 0 .4vw 3.5vw 0 #ddd;
  border-radius: .6vw;
  overflow: hidden;
  height: 80%;
  width: 80%;
  display: flex;
  align-items: stretch;
}
.aside {
  width: 20%;
  background: linear-gradient(45deg, #673AB7, #D500F9);
  flex-grow: 0;
  flex-shrink: 0;
}
.main {
  width: 100%;
}
.nav {
  height: 100%;
  &__item {
    height: 3vw;
    display: flex;
    align-items: center;
    padding: 0 8%;
    color: transparent;
    font-size: .7vw;
    letter-spacing: 1vw;
    position: relative;
    margin: 0 0 1px 0;
    box-shadow: 0 1px 0 1px rgba(#fff, .1);
    transition: .35s ease;
    cursor: pointer;
    &:hover, &.active {
      span {
        background: #fff;
      }
    }
    &.active {
      background: rgba(#fff, .3);
    }
    span {
      background: rgba(#fff, .7);
      transition: .3s ease
    }
  }
}
.sub {
  margin-top: -1px;
  position: relative;
  background: rgba(#4527A0, .5);
  .nav__item {
    margin: 0;
    box-shadow: none;
    padding-left: 2.5vw;
    &.active {
      background: transparent;
    }
  }
}

.main {
  padding: 2vw;
  color: transparent;
  span {
    background: rgba(#000);
    transition: .3s ease
  }
}

.header {
  height: 3vw;
  background: #f5f5f5;
  display: flex;
  font-size: 1.3vw;
  align-items: center;
  padding: 0 1.5vw; 
  color: #666;
}

.h1 {
  font-size: 2vw;
  margin-bottom: 2vw;
  opacity: .6;
}
.text {
  font-size: 1vw;
  opacity: .3;
  letter-spacing: .8vw;
  line-height: 1.5;
}