* {
    box-sizing: border-box;
}

html,
body {
    margin: 0;
    min-height: 100%;
    background-color: #000000;
    color: #ffffff;
    font-family: Arial, sans-serif;
}


/* Cabeçalho */

.cabecalho {
    width: 90%;
    max-width: 800px;

    margin: 40px auto 20px;
    text-align: center;
}

.cabecalho h1,
.cabecalho h2 {
    margin: 5px 0;
    color: #ffffff;
}


/* Caixa que contém o iframe */

.conteudo {
    width: 90%;
    max-width: 800px;

    margin: 0 auto;
    padding: 20px;

    background-color: #111111;
    border: 1px solid #333333;
}

.conteudo iframe {
    display: block;

    width: 100%;
    height: 540px;

    border: none;
    background-color: #111111;
}


/* Página artigos.html */

.artigo-atual {
    margin: 0;
    padding: 0;

    background-color: #111111;
    color: #ffffff;
}


/* Botões dos artigos */

.botao-artigo {
    display: flex;
    justify-content: space-between;
    align-items: center;

    width: 100%;
    padding: 16px;
    margin-bottom: 10px;

    background-color: #1d1d1d;
    color: #ffffff;

    border: 1px solid #383838;
    text-decoration: none;
}

.botao-artigo:hover {
    background-color: #292929;
}

.botao-artigo strong,
.botao-artigo span {
    color: #ffffff;
}


/* Artigo aberto */

article {
    min-height: 100vh;
    margin: 0;
    padding: 25px;

    background-color: #111111;
    color: #ffffff;

    line-height: 1.7;
}

article h3,
article p {
    color: #ffffff;
}

article p {
    text-indent: 30px;
}


/* Botão voltar */

.botao-voltar {
    display: inline-block;

    padding: 10px 15px;
    margin-bottom: 20px;

    background-color: #1d1d1d;
    color: #ffffff;

    border: 1px solid #383838;
    text-decoration: none;
}

.botao-voltar:hover {
    background-color: #292929;
}