Não consgui alterar para lowercase

Nao sei o que esta dando errado pois o lowercase nao esta sendo aplicado nos links de navegação.

html

<aside class="menu-lateral">
            <h1>João da Silva</h1>
            <nav>
                <ul>
                    <li><a href="#"></a>Home</li>
                    <li><a href="#"></a>Protifolio</li>
                    <li><a href="#"></a>Sobre mim</li>
                    <li><a href="#"></a>Blog</li>
                    <li><a href="#"></a>Contato</li>
                </ul>
            </nav>

            <ul class="icones-sociais">
                <li><a href="http://www.github.com/joaodasilva"><img src="github.png" alt="Github"></a></li>
                <li><a href="http://www.twitter.com/joaodasilva"><img src="twitter.png" alt="Twitter"></a></li>
                <li><a href="https://br.linkedin.com/pub/joão-da-silva/32/4/508"><img src="linkedin.png" alt="Linkedin"></a></li>
            </ul>
        </aside>

css

body{
    font-family: "Crimson Text","Times New Roman",serif;
    background-color: : #F2FFFC;
    font-size: 120%;
    line-height: 1.5;

}
h1,h2{
    font-family: "Open Sans Condensed","Arial",sans-serif;
}
.titulo-principal{
    color: #FFFFFF;
    text-align: center;
    background-color: #851944;
    padding: 25px;
    border-bottom: 10px solid black;
    font-size: 60px;
    text-transform: uppercase;

}
p{
    text-align: justify;
    margin: 20px 0;
}
h2{
    font-size: 30px;
}


strong{
    font-weight: bold; 
}

em{
    font-style: oblique;
}

.citacao{
    background-color:#D9E5E3;
    border: 10px solid #C2CCCA;
    width: 250px;
    margin: 20px 40px;
}
.link-leiaMais{
    font-size: 25px;
    text-align: center;
    padding: 8px;
    margin: 16px;
    background-color: #E6E7E8;
    display: block;

}
.menu-lateral{
    background-color: #851944;
    color: #F2FFFC;
    text-align: center;
}


.menu-lateral a{
    color: #851944;
    font-family: "Open Sans Condensed",sans-serif;


}

main a{
    color: #851944;
}


.citacao,.menu-lateral,.rodape-pagina{
    padding: 20px;
}

.texto-centralizado{
    width: 720px;
    margin: auto;
    padding: 30px 0;    
}


.menu-lateral h1 {
    font-size: 30px;
    margin-bottom: 25px;
}
nav a {
    text-transform: lowercase;
}


.icones-sociais li{
    display: inline-block;
}
.rodape-pagina{
      background-color: #000;
    color: #F2FFFC;
}
article{
    border-bottom: 1px solid #ccc;
    padding-bottom: 30px;
    margin-bottom: 20px;
}