body {
	background-color: #f2f2f2;
}

.text-yellow {
    color: yellow;
}

.btn-vk {
  color: #fff;
  background-color: #4a76a8;
  border-color: #4a76a8;
  padding: 12px 30px;
}

.btn-vk:hover {
    color: #eee;
    text-decoration: none;
    background-color: #2d5380;
}

.bg-header {
  background-image: url(../images/3000.jpg);
  background-size: cover;
  background-attachment: fixed;
  background-position: center center;
}

.navbar-dark .navbar-brand-yellow {
    color: yellow;
}

img {
	max-width: 100%;
	padding: 30px;
}

iframe {
	border: 4px solid yellow;
}

.thumb-wrap {
  position: relative;
  padding-bottom: 56.25%; /* задаёт высоту контейнера для 16:9 (если 4:3 — поставьте 75%) */
  height: 0;
  overflow: hidden;
}
.thumb-wrap iframe {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  border-width: 0;
  outline-width: 0;
  border: 4px solid #fff;
}

/* mobile */
@media screen and (max-width: 768px) {
  .display-4 {
  	font-size: 30px;
  }
  #reg_button {
  	margin-bottom: 10px;
  	width: 100%;
  }
  .head-text {
    font-size: 30px;
    margin-top: 30px;
  }
}