XXX
<script async src="https://pagead2.googlesyndication.com/pagead/js/adsbygoogle.js?client=ca-pub-7728763524859934"
     crossorigin="anonymous"></script>
     
<style>
  * {
    margin: 0;
    padding: 0;
  }

  body {

    display: flex;
    flex-wrap: wrap;
    text-overflow: ellipsis;
    align-items: center;
    justify-content: center;
    background-color: rgb(173, 176, 180);
    text-align: center;




  }

  .prihlaseni {
    color: black;
    position: absolute;
    top: 50%;
    left: 50%;
    height: 200px;
    width: 300px;
    margin: -100px 0 0 -150px;
    z-index: 10;
  }

  .prihlaseni div {
    font: 15px monospace;
  }

  .prihlaseni input {
    font: 15px monospace;
    border-radius: 5px;
  }

  .prihlaseni button {
    width: 8rem;
    font: 15px monospace;
    border-radius: 5px;
    background-color: rgb(126, 123, 123);
  }
</style>
 
<div class="prihlaseni" style="text-align:center; ">
  <form method="post" action="">
    <div>Jméno: </div><input style="text-align:center;" type="text" name="jmeno" /><br />
    <div>Heslo: </div><input style="text-align:center;" id="heslo" type="password" name="heslo" /><br /><br />

    <button>Přihlásit</button>


  </form>