Css Grid - Top row restricted height

In my web app I am using css grid to build a basic home page. I want the top grid item: item-1 to be as tall as possible so that the whole grid fills the viewport. See image.

So that leaves no gap at the bottom. I have tried adjusting the height of the wrapper, the row height in grid-template-rows and changing the numbers in each individual item's grid-column value. How do I make item-1 cover more of the viewport and moves the 4 items below it down to touch the bottom?

.wrapper {
  margin-top: -25px;
  width:100vw;
  height: 70vh;
  // border: 2px solid #ccc;
  display: grid;
  grid-gap: 3px;
  grid-template-columns: repeat(4, 90px);
  grid-template-rows: repeat(4, 100px);
  justify-content: center;
  align-content: end;
  padding-bottom: 10px;
}

.box {
    background-color: #444;
    color: #fff;
    border-radius: 5px;
    padding: 10px;
    font-size: 150%;
    text-align: center;
  }

.item-1 {
  margin-top: 50px;
  background-image: url(../assets/imgs/placeholder.png);
  grid-column: 1 / 5;
  grid-row: 1 / 5;
}

.item-2 {
  grid-column: 1 / 3;
  background-color: rgba(250, 250, 250, 0.1);
}

.item-3 {
  grid-column: 3 / 5;
  background-color: rgba(250, 250, 250, 0.4);
}

.item-4 {
  grid-column: 1 / 3;
  background-color: rgba(250, 250, 250, 0.4);
}

.item-5 {
  grid-column: 3/ 5;
  background-color: rgba(250, 250, 250, 0.4);
}

<div class="wrapper">

    <div class="box item-1"></div>
    <div tappable (click)="loadAbout()" class="box item-2"><i class="icon fa fa-info"></i>About</div>
    <div tappable (click)="loadHowTo()" class="box item-3"><i class="icon fa fa-question"></i>How To</div>
  <div tappable (click)="loadList()" class="box item-4"><i class="icon fa fa-signal"></i>List</div>
<div tappable (click)="loadContact()" class="box item-5"><i class="icon fa fa-comments"></i>Contact Us</div>
</div>

Solution

Set the wrapper grid-template-rows to auto 100px 100px.

html,
body {
  font-family: Arial;
  margin: 0;
  padding: 0;
}

.grid {
  width: 100vw;
  height: 100vh;
  background: #333;
  display: grid;
  grid-template-rows: auto 100px 100px;
  grid-template-columns: repeat(4, 90px);
  grid-gap: 5px;
  justify-content: center;
}
.grid * {
  color: white;
  font-size: 120%;
  background: rgba(255, 255, 255, 0.3);
  display: flex;
  align-items: center;
  justify-content: center;
}
.grid .grid-item-1 {
  grid-column: 1 / 5;
  grid-row: 1;
}
.grid .grid-item-2,
.grid .grid-item-3 {
  grid-row: 2;
}
.grid .grid-item-4,
.grid .grid-item-5 {
  grid-row: 3;
}
.grid .grid-item-2,
.grid .grid-item-4 {
  grid-column: 1 / 3;
}
.grid .grid-item-3,
.grid .grid-item-5 {
  grid-column: 3 / 5;
}

<div class="grid">
  <div class="grid-item-1"></div>
  <div class="grid-item-2">about</div>
  <div class="grid-item-3">how to</div>
  <div class="grid-item-4">list</div>
  <div class="grid-item-5">contact us</div>
</div>