* { box-sizing: border-box; }
html, body, main { margin:0; padding:0; height:100%; }
button { background:none; border:none; cursor:pointer; }
.secao { display:block; width:100%; padding:15px; }
.pagina, janela { display:block; }
sobretela { position:fixed; top:0px; right:0px; bottom:0px; left:0px; background:rgba(255,255,255,0.8); display:none; overflow:auto; }

@media screen and (min-width:1024.1px){
	.janela { width:600px; margin:auto; margin-top:80px; margin-bottom:80px; box-shadow:2px 2px 8px #888; background:rgba(255,255,255); padding:20px; }
	.pagina { width:1200px; margin:auto; box-shadow:2px 2px 8px #888; background:rgba(255,255,255); padding:20px; }
}

@media screen and (min-width:800.1px) and (max-width: 1024px){
	.janela { width:600px; margin:auto; margin-top:60px; margin-bottom:80px; box-shadow:2px 2px 8px #888; background:rgba(255,255,255); padding:15px; }
	.pagina { width:800px; margin:auto; box-shadow:2px 2px 8px #888; background:rgba(255,255,255); padding:15px; }
}

@media screen and (min-width:512.1px) and (max-width: 800px){
	.janela { width:512px; margin:auto; margin-top:40px; margin-bottom:80px; box-shadow:2px 2px 8px #888; background:rgba(255,255,255); padding:10px; }
	.pagina { width:512px; margin:auto; box-shadow:2px 2px 8px #888; background:rgba(255,255,255); padding:10px; }
}

@media screen and (max-width:512px){
	.janela { width:100%; margin-top:40px; margin-bottom:80px; box-shadow:2px 2px 8px #888; background:rgba(255,255,255); padding:10px; }
	.pagina { width:100%; background:rgba(255,255,255); padding:10px; }
}