横並びの３つの項目にマージンが効かない

<!doctype html>
<head><link rel="stylesheet" type="text/css" href="c.css"></head>
<body>
    <header>
        <div class="leftimg">
            <p>Progate</p>
        </div>
        <div class="rightobj">
            <ul>
                <li>Home</li>
                <li>About</li>
                <li>Contact</li>
            </ul>
        </div>
    </header>
    <div class="wrapper">
        <nav>
            <ul>
                <li>game</li>
                <li>playstion</li>
                <li>Nintend ds</li>
            </ul>
        </nav>
        <main>       
            <div class="what">
                <p>■ Whats new</p>
                <p>今週のピックアップ商品は</p>
                <p>妖怪ウオッチの腕時計です</p>
            </div>    
        </main>
        <aside>         
        </aside>
    </div>
    <footer>

    </footer>
    </body>
    </html>

body {
    margin:0;
    min-height:100vh;
    display:grid;
    grid-template-rows:100px 1fr 100px;
    grid-template-areas:"header" "wrapper" "footer";
}

header {
    grid-area:header;
    display:flex;
    border-bottom:4px solid gray;
    background-color:lightsteelblue;
}

.leftimg {
    flex:1;
    color:lightblue;
    font-size:30px;
    margin:auto 40px;
}

.rightobj {
    flex:2;
    margin:auto 0px;
}

.rightobj ul {
    display:flex;
  
}

.rightobj ul li {
    flex:1;
    list-style:none;
    margin-left:-80px;
    font-size:28px;
    color:lightsalmon;
}

.wrapper {
    grid-area:wrapper;
    display:grid;
    grid-template-columns:270px 1fr 240px;
    grid-template-areas:"left center right";  
}

nav {
    grid-area:left;
    border:1px solid gray;
    background-color:mediumaquamarine;
}

nav ul li {
    font-size:20px;
    color:lightskyblue;
    list-style:none;
}

main {
    grid-area:center;
    border:1px solid gray;
    background-color:lightskyblue;

}

.what {
    margin-top:30px;
    margin-left:50px;
    padding:20px;
    border:5px solid lightgray;
    border-radius:10px;
    width:500px;
    background-color:white;
    font-family:Georgia, 'Times New Roman', Times, serif;

}

aside {
    grid-area:right;
    border:1px solid gray;
    background-color:mediumaquamarine
}

footer {
    grid-area:footer;
    border:1px solid gray;
}