html,
body {
  height: 100%;
}

body {
  padding-bottom: 20px;
  color: #333;
  text-shadow: 0 .05rem .1rem rgba(0, 0, 0, .5);
  /*box-shadow: inset 0 0 5rem rgba(0, 0, 0, .5);*/
}

.main {
    padding:20px;
}

/* Header */
#header {
    padding: 10px;
}

.masthead-brand {
  color: #f5f5f5;
  padding-left: 20px;
}

.nav-masthead .nav-link {
  padding: .25rem 0;
  font-weight: 700;
  color: rgba(255, 255, 255, .5);
  background-color: transparent;
  border-bottom: .25rem solid transparent;
}

.nav-masthead .nav-link:hover,
.nav-masthead .nav-link:focus {
  border-bottom-color: rgba(255, 255, 255, .25);
}

.nav-masthead .nav-link + .nav-link {
  margin-left: 1rem;
}

.nav-masthead .active {
  color: #f5f5f5;
  border-bottom-color: #f5f5f5;
}

@media (min-width: 48em) {
  .masthead-brand {
    float: left;
  }
  .nav-masthead {
    float: right;
    padding-right: 20px;
  }
}

/* image */
.img-heading {
  background: rgb(17, 20, 22) none repeat scroll 0% 0%;
  max-height: 75vh;
  max-width: calc(112.379vh);
  min-height: 300px;
  min-width: calc(449.516px);
  width: 585.483px;
  height: 390.75px;
}


/* sticky-footer */
.container {
  width: auto;
  max-width: 680px;
  padding: 0 15px;
}

.footer {
  background-color: #f5f5f5;
  text-align: center;
}

/* button-top */
#myBtn {
  display: none;
  position: fixed;
  bottom: 20px;
  right: 30px;
  z-index: 99;
  font-size: 22px;
  border: none;
  outline: none;
  background-color: #e65c00;
  color: white;
  cursor: pointer;
  padding: 15px;
  border-radius: 4px;
}

#myBtn:hover {
  background-color: #555;
}