css box model

index.html

<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>Find the precious!</title>
        <link rel="stylesheet" href="style.css">
    </head>
    <body>
        <nav>
            <ul>
                <li>FindThePrecious.com</li>
                <li>Fellows</li>
                <li>Contact us</li>
            </ul>
        </nav>
        <section>
            <div class="carousel"></div>
        </section>
        <section>
            <h2>Fellows wanted dead (or alive if you want to eat them later)</h2>
        </section>
        <section>
            <article></article>
            <article></article>
            <article></article>
        </section>
        <form>
            <h2>Contact us</h2>
            <input type="email" placeholder="@">
            <input type="text" placeholder="&#8962;">
            <input type="text" placeholder="I have seen one of them">
            <textarea placeholder="Your message"></textarea>
        </form>
    </body>
</html>


style.css

* {
    box-sizing: border-box;
}
html, body {
    margin: 0;
    padding: 0;
    background: #fff;
}

.menu {
    width: 100%;
    height: 70px;
    background: rgb(50, 50, 50);
    line-height: 70px;
}

.logo {
    padding: 0;
    margin: 0;
    color: rgb(200, 200, 200);
    margin-left: 30px;
    margin-right: 30px;
    font-size: 30px;
}

.m-left {
    float: left;
}

.m-right {
    float: left;
}

.m-link {
    text-decoration: none;
    color: rgb(200, 200, 200);
    font-size: 20px;
    padding: 22px;

}

.m-link:hover {
    background: rgb(200, 200, 200);
    color: rgb(50, 50, 50);
    padding: 22px;
}

.carousel {
    width: 100%;
    margin: 0 auto;
    padding: 180px;
    box-sizing: border-box;
    background: rgb(210, 210, 210);
}

.pitch {
    color: rgb(50, 50, 50);
    text-align: center;

}

.pitch span {
    font-size: 20px;
    color: rgb(100, 100, 100);
}

.contact-title {
    margin-left: 30px;
    color: rgb(50, 50, 50);
}

.article1 {
    width: 400px;
    height: 350px;
    background: rgb(210, 210, 210);
    margin-left: 30px;
    margin-bottom: 120px;
    float: left;

}

.article2 {
    width: 400px;
    height: 350px;
    background: rgb(210, 210, 210);
    margin-left: 30px;
    margin-bottom: 120px;
    float: left;
}

.article3 {
    width: 400px;
    height: 350px;
    background: rgb(210, 210, 210);
    margin-left: 30px;
    margin-bottom: 120px;
    float: left;
}


.hr {
    clear: both;
    margin: 0px 30px 0px 30px;
}

.input-email {
    background: #fff;
    border: 2px solid rgb(50, 50, 50);
    padding: 8px 1000px 8px 4px;
    margin: 0px 20px 20px 30px;
    border-radius: 4px;
}

.input-address {
    background: #fff;
    border: 2px solid rgb(50, 50, 50);
    padding: 8px 1000px 8px 4px;
    margin: 0px 20px 20px 30px;
    border-radius: 4px;


}

.input-class {
    background: #fff;
    border: 2px solid rgb(50, 50, 50);
    padding: 8px 850px 8px 4px;
    margin: 0px 20px 20px 30px;
    border-radius: 4px;
}

.message {
    background: #fff;
    border: 2px solid rgb(50, 50, 50);
    padding: 8px 0 8px 4px;
    margin: 0px 1800px 20px 30px;
    border-radius: 4px;
    min-width : 1180px;
    min-height : 120px;
    max-width : 1180px;
    max-height : 120px;
}

.champ {
    margin-bottom: 20px;
    margin-left: 150px;
}