body{
  display: block;
  position: relative;
  background-color: #f1f1f1;

}

hr{
  color: #123455;
}

.affix {
  top: 20px;
  width: 213px;
}

/* Dropdown Button */
.dropbtn:active,
.dropbtn:focus,
.dropbtn {
    background-color: #222;
    color: white;
    padding: 16px;
    border: none;
    cursor: pointer;
}

/* The container <div> - needed to position the dropdown content */
.dropdown {
    position: relative;
    display: inline-block;
}


/* Dropdown Content (Hidden by Default) */
.dropdown-content {
    display: none;
    position: absolute;
    background-color: #222;
    min-width: 160px;
    box-shadow: 0px 8px 16px 0px rgba(0,0,0,0.2);
    border-bottom-left-radius: 20px;
    border-bottom-right-radius: 20px;
    z-index: 2;
}

/* Links inside the dropdown */
.dropdown-content a {
    color: #fafafa;
    text-decoration: none;
    display: block;
  background-color: #4CAF50
}
.nav>li>a:hover{
  background-color: #252;
}
.nav .open>a, .nav .open>a:focus, .nav .open>a:hover {
    background-color: #555;
}

.navbar-nav>li>a:focus {
    background-color: #555;
    line-height: 20px;
}
.icon-bar {
  color: #4CAF50;
  border-color: #4CAF50;
  background-color: #4CAF50;
}

/* Change color of dropdown links on hover */
.dropdown-content a:focus,
.dropdown-content a:active,
.dropdown-content a:hover {background-color: #4CAF50;

}

/* Show the dropdown menu on hover */
.dropdown:hover .dropdown-content {
    display: block;
}

/* Change the background color of the dropdown button when the dropdown content is shown */
.dropdown:hover .dropbtn {
    background-color: #4CAF50;
}

figcaption {
    text-align: center;
}



.nav a{
color: #fafafa;
font-size: .96em;
}
.nav a:hover,
.nav a:active,
.nav a:focus{
color: #fafafa;
background-color: #222;
}





.navbar{
  margin-bottom: 0;
  border-radius: 0;
  margin: ;
  background-color: #222;
}
header{
display: flex;
}

#lateral.nav{
  float: right;
}

.jumbotron{
  background: url('images/earth_night2.jpg') ;

  /* fix background */
  background-attachment: fixed;
  /* Scale it nicely to the element */
  background-size: cover;
  text-align: center;
  height: 500px;
  padding-top: 170px;
  font-family: "Computer Modern";
  margin-top: 0px;
  color: #000;
}

.jumbotron h1{
    font-size: 90px;
    font-family: calibri;
    font-weight: bold;
    color: #363;
    -webkit-text-stroke-color: #ddd;
    -webkit-text-stroke-width: 2px;
}

.jumbotron h2{
    font-size: 50px;
    font-family: calibri;
    font-weight: bold;
    color: #363;
    -webkit-text-stroke-color: #ddd;
    -webkit-text-stroke-width: 1px;
}

.jumbotron p{
    font-size: 40px;
    font-family: calibri;
    font-weight: light;
    color: #363;
    -webkit-text-stroke-color: #000;
    -webkit-text-stroke-width: .2px;
}

h1,h2{
    text-align: center;

}

h3{
    text-align: center;
}

em{
  font-weight: bold;
}

div#main{
font-size: 25px;
text-align: justify;
}

footer{
  height: 4.3em;
  background-color:#222;
  text-align: center;
  padding-top: 0.7em;
  font-weight: 300;
  vertical-align: text-top;
  color: #eee;
  margin: 0;
}

img {
    display: block;
    margin: auto;
}

/*side-by-side images:*/

.main_block {
    width: 800px;
    border: 2px black solid;
}

.main_block: before, .main_block: after {
    overflow: hidden;
    content: "";
    display: table;
}

.main_block: after {
    clear: both;
}

.inner_block {
    display: inline-block;
    float: left;
    width: 50%;
}

.inner_block img {
    width: 100%;
    height: auto;
    vertical-align: middle;
}









.hidden { display: none; }

.fixed {
    position: fixed;
}

/* sidebar */
.bs-docs-sidebar {
    padding-left: 30px;
    margin-top: 20px;
    margin-bottom: 20px;
}

/* all links */
.bs-docs-sidebar .nav>li>a {
    color: #222;
    border-left: 2px solid transparent;
    padding: 4px 20px;
    font-size: 18px;
    font-weight: 100;
}

/* nested links */
.bs-docs-sidebar .nav .nav>li>a {
    padding-top: 1px;
    padding-bottom: 0px;
    padding-left: 30px;
    font-size: 16px;
    font-weight: 100;
}

/* active & hover links */
.bs-docs-sidebar .nav>.active>a,
.bs-docs-sidebar .nav>li>a:hover,
.bs-docs-sidebar .nav>li>a:focus {
    color: #222;
    text-decoration: none;
    background-color: transparent;
    border-left-color: #33cc59;
    border-width: medium;
    font-weight: 200;
}
/* all active links */
.bs-docs-sidebar .nav>.active>a,
.bs-docs-sidebar .nav>.active:hover>a,
.bs-docs-sidebar .nav>.active:focus>a {
    font-weight: 300;
}
/* nested active links */
.bs-docs-sidebar .nav .nav>.active>a,
.bs-docs-sidebar .nav .nav>.active:hover>a,
.bs-docs-sidebar .nav .nav>.active:focus>a {
    font-weight: bold;
}

/* hide inactive nested list */
.bs-docs-sidebar .nav ul.nav {
    display: none;
}
/* show active nested list */
.bs-docs-sidebar .nav>.active>ul.nav {
    display: block;
}