White bar at the top of page

There is a white bar at the top of my website. When I scroll down and the background image goes up it disappears.

I have tried a lot of ways to solve the problem what I found online but I could not find the solution. I started it from a template and there was everything good there. I tried to compare the before-after but did not find any serios difference.

Image of the page

HTML:

<div id="topbar">
  <div class="container">
    <div class="social-links">
      <a href="#" class="facebook"><i class="fa fa-facebook"></i></a>
      <a href="#" class="instagram"><i class="fa fa-instagram"></i></a>
    </div>
  </div>
</div>

<div class="container">

  <div class="logo float-left">
    <h1 class="text-light"><a href="#intro" class="scrollto"><span>FutureCode</span></a></h1>
  </div>

  <nav class="main-nav float-right d-none d-lg-block">
    <ul>
      <li class="active"><a href="#intro">Kezdőlap</a></li>
      <li><a href="#about">Rólunk</a></li>
      <li><a href="#services">Szolgáltatásaink</a></li>
      <li><a href="#website">Weboldal készítés</a></li>
      <li><a href="#marketing">Marketing</a></li>
      <li><a href="#offer">Ajánlatkérés</a></li>
    </ul>
  </nav>

</div>
</header>

  <!-- Kezdolap -->
  <section id="intro" class="clearfix">
    <div class="container d-flex h-100">
      <div class="row justify-content-center align-self-center">
        <div class="col-md-6 intro-info order-md-first order-last">
          <h2>Egy merész ötlet<br>kell a legjobb <span>Weboldalakhoz!</span></h2>
      <div>
        <a href="#about" class="btn-get-started scrollto">Bővebben</a>
      </div>
    </div>

    <div class="col-md-6 intro-img order-md-last order-first">
      <img src="img/intro-img.svg" alt="futurecode intro" class="img-fluid">
    </div>
  </div>

</div>
 </section>

CSS:

body {
  background: #fff;
  color: #444;
  font-family: "Open Sans", sans-serif;
}

a {
  color: #1bb1dc;
  transition: 0.5s;
}

a:hover,
a:active,
a:focus {
  color: #0a98c0;
  outline: none;
  text-decoration: none;
}

p {
  padding: 0;
  margin: 0 0 30px 0;
}

h1,
h2,
h3,
h4,
h5,
h6 {
  font-family: "Montserrat", sans-serif;
  font-weight: 400;
  margin: 0 0 20px 0;
  padding: 0;
}

/* Prelaoder */

#preloader {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 9999;
  overflow: hidden;
  background: #fff;
}

#preloader:before {
  content: "";
  position: fixed;
  top: calc(50% - 30px);
  left: calc(50% - 30px);
  border: 6px solid #f2f2f2;
  border-top: 6px solid #1bb1dc;
  border-radius: 50%;
  width: 60px;
  height: 60px;
  -webkit-animation: animate-preloader 1s linear infinite;
  animation: animate-preloader 1s linear infinite;
}

@-webkit-keyframes animate-preloader {
  0% {
    -webkit-transform: rotate(0deg);
    transform: rotate(0deg);
  }

  100% {
    -webkit-transform: rotate(360deg);
    transform: rotate(360deg);
  }
}

@keyframes animate-preloader {
  0% {
    -webkit-transform: rotate(0deg);
    transform: rotate(0deg);
  }

  100% {
    -webkit-transform: rotate(360deg);
    transform: rotate(360deg);
  }
}

/*--------------------------------------------------------------
# Top Bar
--------------------------------------------------------------*/

#topbar {
  padding: 0 0 10px 0;
  font-size: 14px;
  transition: all 0.5s;
}

#topbar .social-links {
  text-align: right;
}

#topbar .social-links a {
  color: #535074;
  padding: 4px 12px;
  display: inline-block;
  line-height: 1px;
}

#topbar .social-links a:hover {
  color: #1bb1dc;
}

#topbar .social-links a:first-child {
  border-left: 0;
}

/*--------------------------------------------------------------
# Header
--------------------------------------------------------------*/

#header {
  height: 110px;
  transition: all 0.5s;
  z-index: 997;
  transition: all 0.5s;
  padding: 20px 0;
  position: fixed;
  left: 0;
  top: 0;
  right: 0;
  transition: all 0.5s;
  z-index: 997;
}

#header.header-scrolled,
#header.header-pages {
  height: 70px;
  padding: 15px 0;
  background-color: #fff;
  box-shadow: 0px 0px 30px rgba(127, 137, 161, 0.3);
}

#header.header-scrolled #topbar,
#header.header-pages #topbar {
  display: none;
}

#header .logo h1 {
  font-size: 36px;
  margin: 0;
  padding: 0;
  line-height: 1;
  font-weight: 400;
  letter-spacing: 3px;
  text-transform: uppercase;
}

#header .logo h1 a,
#header .logo h1 a:hover {
  color: #413e66;
  text-decoration: none;
}

#header .logo img {
  padding: 0;
  margin: 7px 0;
  max-height: 26px;
}

.main-pages {
  margin-top: 60px;
}