*{
    margin:0;
    padding:0;
    box-sizing:border-box;
}

body{
    font-family:Arial, Helvetica, sans-serif;
    background:#111827;
    color:#fff;
    height:100vh;
    overflow:hidden;
}

.container{
    display:flex;
    height:100vh;
}

.sidebar{
    width:320px;
    background:#0f172a;
    border-right:1px solid #1e293b;
    overflow-y:auto;
}

.logo{
    padding:20px;
    font-size:22px;
    font-weight:bold;
    border-bottom:1px solid #1e293b;
}

.modulo{
    padding:15px;
}

.modulo-titulo{
    font-size:14px;
    font-weight:bold;
    color:#94a3b8;
    margin-bottom:10px;
    text-transform:uppercase;
}

.aula-item{
    background:#1e293b;
    padding:12px;
    border-radius:8px;
    margin-bottom:8px;
    cursor:pointer;
    transition:0.2s;
}

.aula-item:hover{
    background:#334155;
}

.aula-item.active{
    background:#2563eb;
}

.conteudo{
    flex:1;
    overflow-y:auto;
}

.video-box{
    padding:20px;
}

.video-box video{
    width:100%;
    max-height:75vh;
    background:#000;
    border-radius:12px;
}

.descricao-box{
    padding:20px;
}

#titulo-aula{
    margin-bottom:15px;
    font-size:28px;
}

#descricao-aula{
    line-height:1.7;
    color:#cbd5e1;
}

@media(max-width:900px){

    .container{
        flex-direction:column;
    }

    .sidebar{
        width:100%;
        height:300px;
    }

}