Grid Layout failing to align - html

Question

I am trying to achieve this, I want the nav and header tags to fill the left side.
html {
width: 100%;
overflow: hidden;
}
body {
display: grid;
grid-template-rows: 1fr 5fr 1fr;
grid-template-columns: 2fr 5fr 3fr;
grid-template-areas:
"header header"
"nav main"
"footer footer";
}
header {
background: yellowgreen;
}
nav {
background: lightblue;
}
main {
background: aliceblue;
}
footer {
background: lightgoldenrodyellow;
}
<header>Banner</header>
<nav>Navigation</nav>
<main>Main content</main>
<footer>Footer</footer>

Answer 1

You can try like this
.item1 { grid-area: header; }
.item2 { grid-area: menu; }
.item3 { grid-area: main; }
.item5 { grid-area: footer; }
.grid-container {
display: grid;
grid-template-areas:
'header main main main '
'menu main main main '
'menu footer footer footer ';
grid-gap: 10px;
background-color: #2196F3;
padding: 10px;
}
.grid-container > div {
background-color: rgba(255, 255, 255, 0.8);
text-align: center;
padding: 20px 0;
font-size: 30px;
}
<div class="grid-container">
<div class="item1">Header</div>
<div class="item2">Menu</div>
<div class="item3">Main</div>
<div class="item5">Footer</div>
</div>

Answer 2

Here's an example of how you could define grid-areas
html {
overflow: hidden;
}
body {
display: grid;
grid-template-rows: 25px 100px;
grid-template-columns: 80px 1fr;
grid-template-areas: "header main" "nav main" "nav footer";
}
body>header {
grid-area: header;
background-color: yellowgreen;
}
body>nav {
grid-area: nav;
background-color: lightblue;
}
body>main {
grid-area: main;
background-color: aliceblue;
}
body>footer {
grid-area: footer;
background-color: lightgoldenrodyellow;
}
<header>Banner</header>
<nav>Navigation</nav>
<main>Main content</main>
<footer>Footer</footer>