header {
  background-image: url(images/main_banner.png);
  background-repeat: no-repeat;
  background-position: center;
  background-size:cover;
  width: 100vw;
  height: calc(100px + 20vw);
  max-height: 500px;
}
body {
    font-family: Arial, Helvetica, sans-serif;
    color: white;
    align-content: center;
    background-color: black;
    font-size: larger;
    margin: 0;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}
.navbar {
  text-align: center;
  line-height: 40px;
  background-color: black;
  color: white;
  top: 0;
  padding-top: 30px;
}
.navbar a {
  padding: 5px 5vw;
  color: white;
  text-decoration: none;
  white-space: nowrap;
}
.navbar a:visited {
  padding: 5px 5vw;
  color: white;
  text-decoration: none;
  white-space: nowrap;
}
.navbar a:hover {
  background:
    linear-gradient(135deg, transparent 5px, rgb(205,0,0) 0) top left,
    linear-gradient(-45deg, transparent 5px, rgb(205,0,0) 0) bottom left;
  background-size: 100% 60%;
  background-repeat: no-repeat;
  white-space: nowrap;
}
.navbar a.active {
  background:
    linear-gradient(135deg, transparent 5px, rgb(205,0,0) 0) top left,
    linear-gradient(-45deg, transparent 5px, rgb(205,0,0) 0) bottom left;
  background-size: 100% 60%;
  background-repeat: no-repeat;
  color: black;
  white-space: nowrap;
}
a {
  text-decoration: none;
  color:red;
}
a:visited {
  text-decoration: none;
  color:#b10000;
}
footer {
  padding-top: 100px;
  padding-bottom: 20px;
  position:sticky;
  width: 100%;
  color: white;
  margin-top: auto;
}
h1 {
  text-align: center;
}
table {
  margin-left: auto;
  margin-right: auto;
  border-spacing: 20px 0;
}
section {
  align-content: center;
  text-align: justify;
  padding-top: 15px;
  padding-bottom: 15px;
  padding-left: 15vw;
  padding-right: 15vw;
}
.container {
  display: flex;
  flex-direction: row;
  flex-wrap: wrap;
  justify-content: center;
  margin: auto;
}
div.gallery {
  width:auto;
  height:auto;
  margin: 10px;
  margin-bottom: 50px;
  border: 5px solid #2b2b2b;
}
div.gallery:hover {
  border: 5px solid #b20c0c;
}
.yt {
  position: relative;
  display: block;
  width: 90%; /* width of iframe wrapper */
  height: 0;
  margin: auto;
  padding: 0% 0% 56.25%; /* 16:9 ratio */
  overflow: hidden;
}
.yt iframe {
  position: absolute;
  top: 0; bottom: 0; left: 0;
  width: 100%;
  height: 100%;
  border: 0;
}
div.gallery img {
  width: 100%;
  height: auto;
}
div.desc {
  padding: 15px;
  text-align: center;
}
iframe {
  display: block;
  margin: 0 auto;
  border: 0;
}