JSFiddle - React, Tailwind, and code Playground

HTML

<section class="welcome-screen">
  <div class="content">
    <img src="https://www.luck.org.pl/assets/logo-shadow.png">
    <div class="header-container">
      <h1>Aplikacja już dostępna!</h1>
      <h2>Wpisz nazwę Twojego wydarzenia</h2>
      <div class="first-step-happening-form">
        <div class="lk-inline-input-form">
          <input class="lk-input" 
                 type="text"
                 placeholder="Nazwa wydarzenia..." >
          <a class="lk-button">Utwórz</a>
        </div>
      </div>
    </div>
    <a class="lk-button underline">Dowiedz się więcej</a>
  </div>
</section>

SCSS

section.welcome-screen {
  height: calc(100vh - 70px);
  width: 100%;
  max-width: 100%;

  @media screen and (min-width: 414px) {
    height: calc(100% - 50px);
  }

  .content {
    height: calc(100% - 113px);
    max-width: 1200px;
    margin: 0 auto;

    padding: 60px 15px 0px 15px;
    text-align: center;

    display: flex;
    flex-direction: column;
    justify-content: space-between;
    align-items: center;

    @media screen and (min-width: 414px) {
      padding: 70px 40px 30px 40px;
    }

    .header-container {
      padding-bottom: 65px;
    }

    .first-step-happening-form {
      padding: 10px 0 0 0;

      .lk-inline-input-form {
        width: 100%;
        max-width: 280px;
        margin: 0 auto;

        @media screen and (min-width: 414px) {
          max-width: 350px
        }
      }
    }
  }

  img {
    width: 165px;
    height: 165px;

    @media screen and (min-width: 414px) {
      width: 143px;
      height: 143px
    }

  }

  h1, h2 {
    font-size: 38px;
    font-weight: 300;
    opacity: 0.85;
    letter-spacing: 0px;
    margin: 5px 0;
    white-space: pre-line;
  }

  h2 {

    font-size: 24px;
    font-weight: 300;
    opacity: 0.85;
    letter-spacing: 0px;
    margin: 30px 0 0 0;
  }

  .lk-button.underline {

    font-size: 24px;
    font-weight: 300;
    opacity: 0.85;
    letter-spacing: 0px;
    text-transform: inherit;
  }
}

JavaScript

(function () {
  const welcomeScreen = document.getElementsByClassName('welcome-screen')[0];

  function returnStyleHeight(height) {
    return `${height}px`;
  }

  function getHeightNativeElement() {
    return Number(window.innerHeight);
  }

  window.addEventListener('onload', () => {
  console.log('getHeightNativeElement(): ', getHeightNativeElement())
    welcomeScreen.style.height = returnStyleHeight(getHeightNativeElement());
  });
})();