body {
    margin: 0;
    font-family: Arial, Helvetica, sans-serif;
    min-width: 400px;
}

header {
    padding: 15px;
}

nav ul {
    list-style-type: none;
    margin: 0;
    margin-left: 10px;
    padding: 0;
}

nav ul li {
    display: inline-block;
}

nav ul li a {
    color: white;
    text-decoration: none;
    font-weight: 100;
}

nav ul li a:hover {
    font-weight: 400;
}

h2 {
    text-align: center;
    margin-top: 50px;
    margin-bottom: 0;
    font-size: 2m;
}

a {
    text-decoration: none;
}

a div h3 {
    font-size: 1.5em;
}

footer {
    border-top: 3px solid black;
    margin-top: 30px;
    padding: 30px;
}

.container {
    width: 1000px;
    margin: 0 auto;
}

.gauche-presentation {
    width: 50%;
}

.droite-presentation {
    width: 50%;
    text-align: center;
}

.droite-presentation img {
    width: 70%;
}

.texte-presentation {
    text-align: center;
}

.projet {
    background: black;
    border-radius: 5px;
    color: white;
    padding: 30px 25px;
    transition: all 0.3s;
    text-shadow: 0 0 15px black;
}

.projet:hover {
    opacity: 0.7;
}

.projet-1 {
    background: center url("images/jump-start.png");
    background-size: cover;
}

.projet-2 {
    background: center url("images/rodeo-pump.jpg");
    background-size: cover;
}

.projet-3 {
    background: center url("images/pac-man.jpg");
    background-size: cover;
}

.projet-4 {
    background: center url("images/mega-pop.jpg");
    background-size: cover;
}

.bouton-contact {
    background: black;
    color: white;
    padding: 15px 30px;
    margin-top: 15px;
}

#bienvenue {
    background-color: black;
    height: 100vh;
    color: white;
    overflow: hidden;
}

#flex-header {
    display: flex;
    justify-content: space-between;
}

#flex-presentation {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: calc(100vh - 50px);
}

#projet-grille {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    grid-auto-rows: minmax(70px, auto);
    grid-gap: 15px;
}

#contact {
    margin-top: 30px;
    text-align: center;
}

#jump-start {
    background: url('images/points.png'), center url('images/jump-start.png');
    background-size: cover;
    height: 100vh;
    color: white;
    overflow: hidden;
}

@media all and (max-width: 1130px) {
    .container {
        width: 700px;
    }

    #flex-presentation, .texte-presentation {
        padding: 15px;
    }

    #projet-grille {
        grid-template-columns: repeat(2, 1fr);
        padding: 30px;
    }
}

@media all and (max-width: 730px) {
    .container {
        width: 100%;
    }

    .gauche-presentation {
        width: 100%;
    }
}