Minha imagem do cabeçalho não aparece | Bootstrap: criação de uma single-page responsiva

#accordion {
    margin-top: 20px;
}

html,
body {
    height: 100%;
}

.header {
    background-image: url(../img/castelo.jpg);
    background-size: cover;
    background-position: top center;
    height: 100%;
}

.titulo-depoimento {
    background: #0275d8;
    padding-top: 25px;
    padding-bottom: 25px;
    color: #fff;
    margin-bottom: 0;
    font-size: 24px;
}

.carousel-inner .item .img-dep1 {
    width: 100%;
    height: 200px;
}

.carousel-inner .item .img-dep2 {
    width: 100%;
    height: 200px;
}

.carousel-inner .item .img-dep3 {
    width: 100%;
    height: 200px;
}

.contato-select,
.grupo-radio {
    width: 50%;
    display: inline-block;
    vertical-align: top;
}

.grupo-radio .radio:first-child {
    margin-top: 0;
}

footer {
    background: #333;
    color: #fff;
    padding: 20px;
    margin-top:10px;
}

footer address:last-child {
    margin-bottom: 0;
}

<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8" />
    <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u" crossorigin="anonymous">
    <meta name="viewport" content="width=device-width, initial-scale=1" />
    <link href="css/estilos.css" rel="stylesheet" />
    <title></title>
</head>
<body>
    <header>
        <nav class="navbar navbar-default">
            <div class="container">
                <div class="navbar-header">
                    <button type="button" class="navbar-toggle collapsed" data-toggle="collapse" data-target="#collapse-navbar" aria-expanded="false">
                        <span class="sr-only">Toggle navigation</span>
                        <span class="icon-bar"></span>
                        <span class="icon-bar"></span>
                        <span class="icon-bar"></span>
                    </button>
                    <a class="navbar-brand" href="#">TopCasaFina Arquitetura</a>
                </div>
                <div class="collapse navbar-collapse" id="collapse-navbar">
                    <ul class="nav navbar-nav">
                        <li><a href="#sobre-nos">Sobre Nós</a></li>
                        <li><a href="#nossos-projetos">Nossos Projetos</a></li>
                        <li><a href="#depoimentos">Depoimentos</a></li>
                        <li><a href="#video">Video</a></li>
                        <li><a href="#contato">Contato</a></li>
                    </ul>
                </div>
            </div>
        </nav>
    </header>

Ja olhei o código todo e tudo parece estar certo...