Bom dia Laís, tudo tranquilo?

Manda seu código aqui pra gente dar uma olhada.

<header class="cabecalhoPrincipal">
    <div class="container">
        <h1 class="cabecalhoPrincipal-titulo">
            <a href="#">Alurinha - Lais</a>
        </h1>

        <nav class="cabecalhoPrincipal-nav">
            <a class="cabecalhoPrincipal-nav-link" href="#">Home</a>
            <a class="cabecalhoPrincipal-nav-link" href="#">Cursos</a>
            <a class="cabecalhoPrincipal-nav-link" href="#">Sobre nós</a>
            <a class="cabecalhoPrincipal-nav-link" href="#">Contato</a>
            <a class="cabecalhoPrincipal-nav-link cabecalhoPrincipal-nav-link-app" href="#">Nosso APP</a>
        </nav>
    </div>

</header>

<main class="conteudoPrincipal">
    <div class="container">
        <h2 class="subtitulo">Nossos cursos</h2>

        <nav>
            <ul class="conteudoPrincipal-cursos">
                <li class="conteudoPrincipal-cursos-link"><a href="#">Java</a></li>
                <li class="conteudoPrincipal-cursos-link"><a href="#">PHP</a></li>
                <li class="conteudoPrincipal-cursos-link"><a href="#">Ruby on Rails</a></li>
                <li class="conteudoPrincipal-cursos-link"><a href="#">.NET</a></li>
                <li class="conteudoPrincipal-cursos-link"><a href="#">Pascal</a></li>
                <li class="conteudoPrincipal-cursos-link"><a href="#">Flexbox</a></li>
                <li class="conteudoPrincipal-cursos-link"><a href="#">Desenvolvimento Web</a></li>
                <li class="conteudoPrincipal-cursos-link"><a href="#">Java Web</a></li>
                <li class="conteudoPrincipal-cursos-link"><a href="#">Javascript</a></li>
                <li class="conteudoPrincipal-cursos-link"><a href="#">AngularJS</a></li>
                <li class="conteudoPrincipal-cursos-link"><a href="#">TDD com C</a></li>
                <li class="conteudoPrincipal-cursos-link"><a href="#">Redes de computadores</a></li>
                <li class="conteudoPrincipal-cursos-link"><a href="#">MySQL</a></li>
                <li class="conteudoPrincipal-cursos-link"><a href="#">MariaDB</a></li>
                <li class="conteudoPrincipal-cursos-link"><a href="#">Postegres</a></li>
                <li class="conteudoPrincipal-cursos-link"><a href="#">Lógica de programação</a></li>
                <li class="conteudoPrincipal-cursos-link"><a href="#">Lógica de programação</a></li>
                <li class="conteudoPrincipal-cursos-link"><a href="#">Lógica de programação</a></li>
            </ul>
        </nav>
    </div>

    <section class="videoSobre">
        <div class="container">
            <iframe class="videoSobre-video" width="560" height="315" src="https://www.youtube.com/embed/bIlOsJzBVaY?list=PLh2Y_pKOa4UcF1BYPJR3EIMRi3nWAUxIp" frameborder="0" allowfullscreen></iframe>

            <div class="videoSobre-sobre">
                <h2 class="videoSobre-sobre-title">Vantagens do Alurinha</h2>
                <ul class="videoSobre-sobre-list">
                    <li class="videoSobre-sobre-item">Estude onde quiser</li>
                    <li class="videoSobre-sobre-item">Novos cursos todos os meses</li>
                    <li class="videoSobre-sobre-item">Cursos compatíveis com o mercado</li>
                </ul>
                <button class="videoSobre-button">Cadastre-se já</button>
            </div>
        </div>
    </section>

</main>

<footer class="rodapePrincipal">
    <div class="container">

        <section class="rodapePrincipal-navMap">
            <h3 class="subtitulo">Mapa de cursos</h3>
            <nav class="rodapePrincipal-navMap-list">

                <h4 class="navmap-list-title navmap-list-title-backend">Linguagens Backend</h4>
                <a class="rodapePrincipal-navMap-link" href="#">Java</a>
                <a class="rodapePrincipal-navMap-link" href="#">PHP</a>
                <a class="rodapePrincipal-navMap-link" href="#">Pascal</a>
                <a class="rodapePrincipal-navMap-link" href="#">Scala</a>
                <a class="rodapePrincipal-navMap-link" href="#">Python</a>
                <a class="rodapePrincipal-navMap-link" href="#">Java Web</a>
                <a class="rodapePrincipal-navMap-link" href="#">Assembly</a>
                <a class="rodapePrincipal-navMap-link" href="#">Lógica de programação</a>

                <h4 class="navmap-list-title navmap-list-title-frontend">Linguagens Frontend</h4>
                <a class="rodapePrincipal-navMap-link" href="#">Flexbox</a>
                <a class="rodapePrincipal-navMap-link" href="#">Desenvolvimento Web</a>
                <a class="rodapePrincipal-navMap-link" href="#">Javascript</a>
                <a class="rodapePrincipal-navMap-link" href="#">AngularJS</a>
                <a class="rodapePrincipal-navMap-link" href="#">ReactJS</a>
                <a class="rodapePrincipal-navMap-link" href="#">Polymer</a>

                <h4 class="navmap-list-title navmap-list-title-framework">Frameworks</h4>
                <a class="rodapePrincipal-navMap-link" href="#">Ruby on Rails</a>
                <a class="rodapePrincipal-navMap-link" href="#">VRaptor</a>
                <a class="rodapePrincipal-navMap-link" href="#">SpringMVC</a>
                <a class="rodapePrincipal-navMap-link" href="#">NodeJS</a>
                <a class="rodapePrincipal-navMap-link" href="#">Django</a>
                <a class="rodapePrincipal-navMap-link" href="#">Bootstrap3</a>

                <h4 class="navmap-list-title navmap-list-title-bancoDeDados">Banco de dados</h4>
                <a class="rodapePrincipal-navMap-link" href="#">MySQL</a>
                <a class="rodapePrincipal-navMap-link" href="#">MariaDB</a>
                <a class="rodapePrincipal-navMap-link" href="#">Postegres</a>

            </nav>
        </section>

    </div>

    <section class="rodapePrincipal-patrocinadores">
        <div class="container">
            <ul class="rodapePrincipal-patrocinadores-list">
                <li>
                    <a class="rodapePrincipal-patrocinadores-list-link patrocinadores-list-link-alura" href="#">
                        <img src="img/logos/alura.svg" alt="Logo da Alura">
                    </a>
                </li>
                <li>
                    <a class="rodapePrincipal-patrocinadores-list-link patrocinadores-list-link-caelum" href="#">
                        <img src="img/logos/caelum.svg" alt="Logo da Caelum">
                    </a>
                </li>
                <li>
                    <a class="rodapePrincipal-patrocinadores-list-link patrocinadores-list-link-casaDoCodigo" href="#">
                        <img src="img/logos/cdc.svg" alt="Logo da Casa do Código">
                    </a>
                </li>
            </ul>
            <form class="rodapePrincipal-contatoForm" action="#">
                <fieldset>
                    <legend class="rodapePrincipal-contatoForm-legend" for="email-contato">Entre em contato conosco</legend>
                    <div class="rodapePrincipal-contatoForm-fieldset"> 
                        <input class="rodapePrincipal-contatoForm-emailInput" type="email" name="email-contato" id="email-contato">
                        <button class="rodapePrincipal-contatoForm-submit" type="submit">Enviar</button>
                    </div>
                </fieldset>
            </form>
        </div>
    </section>
</footer>

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