html, body , h1 {
    margin:0;
    padding:0;
}

html {
    background:rgb(254,255,216);
}

article, aside, section, header, footer, nav {
    display:block;
}

main {
    width:660px;
    background-color:rgb(255,255,255);
    font-family:Arial, Helvetica, sans-serif;
    font-size:14px;
    box-shadow: 0 0 10px #666;
    margin:10px auto;
    padding:10px;
}

#principal {
    background-color:rgb(240,240,240);
    border:1px dotted #666666;
    margin-top:20px;
}

section {
    height:100px;width:100px;padding:10px;
}

.janela1 {
    background-color:rgb(153,204,51);
    position: static;
    margin-top: 20px;
    margin-left: 20px;
}

.janela2 {
    background-color:rgb(255,204,51);
}

.janela3 {
    background-color:rgb(51,153,204);
}
p img{
    width: 2%;
    height: 2%;
}

footer p {
    text-align: center;
}
.ExP{
    text-align: justify;
    margin: 10px;
}
h1{
    text-align: center;
}
.redes img{
    width: 3%;
    height: 3%;
}
nav img {
    float: right;
    width: 15%;
    height: 15%;
    border-radius: 10px;
}