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

body {
    font-family: Arial, sans-serif;
    background-color: #dfd7d3;
    text-align: center;
    background-image: repeating-radial-gradient(blue, white 10%, red 15%);
}

header {
    width: 100%;
    height: 250px;
    background: url('../images/Entreprises_1.png') no-repeat center/cover;
    display: flex;
    align-items: center;
    justify-content: center;
}

.header-img {
    display: none;
}

nav ul {
    list-style: none;
    display: flex;
    justify-content: left;
    padding: 10px;
}

nav ul li {
    margin: 0 15px;
}

nav ul li a {
    display: inline-block;
    width: 120px;
    height: 40px;
    line-height: 40px;
    text-align: center;
    color: white;
    text-decoration: none;
    font-size: 18px;
    background: url('../images/bouton-rouge.png') no-repeat center/cover;
    border-radius: 25px;
    box-shadow: inset 0 1px 3px rgba(255, 255, 255, 0.5), 0 2px 5px rgba(0, 0, 0, 0.5);
    transition: all 0.3s;
}

main {
    display: flex;
    justify-content: space-between;
    padding: 20px;
}

iframe {
    width: 70%;
    height: 400px;
    border: none;
    background-color: #7da5d8;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 24px;
    color: white;
}

aside {
    width: 25%;
    background-color: #e0d0c1;
    padding: 15px;
    text-align: left;
    background-image: linear-gradient(to bottom right, red, yellow);
}

aside h3 {
    color: purple;
    margin-bottom: 10px;
    text-align: center;
}


footer {
    margin-top: 20px;
    color: blue;
    padding: 10px;
    text-align: left;
}