html{
  margin:2em 0em;
  background-color:#E2F8FE;
}

body{
  width:60em;
  background: #9ee8fa; /* Old browsers */
background: -moz-linear-gradient(top, #9ee8fa 0%, #fcfeff 36%); /* FF3.6+ */
background: -webkit-gradient(linear, left top, left bottom, color-stop(0%,#9ee8fa), color-stop(36%,#fcfeff)); /* Chrome,Safari4+ */
background: -webkit-linear-gradient(top, #9ee8fa 0%,#fcfeff 36%); /* Chrome10+,Safari5.1+ */
background: -o-linear-gradient(top, #9ee8fa 0%,#fcfeff 36%); /* Opera 11.10+ */
background: -ms-linear-gradient(top, #9ee8fa 0%,#fcfeff 36%); /* IE10+ */
background: linear-gradient(to bottom, #9ee8fa 0%,#fcfeff 36%); /* W3C */
filter: progid:DXImageTransform.Microsoft.gradient( startColorstr='#9ee8fa', endColorstr='#fcfeff',GradientType=0 ); /* IE6-9 */;
  margin:0 auto;
  padding:2em 3em;
  border:1px solid #aaa;
}

h1{
  text-align:center;
}

ul#menu{
  list-style-type:none;
  text-align:center;
}

ul#menu li{
  display:inline;
}


ul#menu li a{
  text-decoration:none;
  font-variant:small-caps;
  color:#4F747D;
  font-size:1.7em;
}

ul#menu li a:hover{
  color:#37D2F9;
}

ul#menu li a:visited{
  color:#4F4EB6;
}

a{
  color:#4F747D;
  text-decoration:none;
}

a:visited{
 color:#4F4EB6;
}

a:hover{
  color:#37D2F9;
  text-decoration:underline;
}



.importante{
  font-size:1.1em;
  color:#000;
}

.enunciado{
  font-style:italic;
  font-size:1.1em;
  color:#000;
  border-left:2px solid #333;
  padding-left:10px;
  margin-bottom:5px;
}

.demostracion{
  padding-left:12px;
}

.demostracion:after{
  content:'Q.E.D.'
}

.space { 
line-height: 10em; 
}