---
id: 5d822fd413a79914d39e9919
title: Step 80
challengeType: 0
dashedName: step-80
---

# --description--

When you increase the size of the left and right borders, the border on the bottom will expand to be the width of the combined left and right border widths. Add `2vw solid transparent` as the value of the `border-left` and `border-right` properties of `.fb1a`. They will be invisible, but it will make the border on the bottom `4vw` wide.

# --hints--

You should give `.fb1a` a `border-left` of `2vw solid transparent`.

```js
assert.equal(new __helpers.CSSHelp(document).getStyle(".fb1a")?.borderLeft, "2vw solid transparent");
```

You should give `.fb1a` a `border-right` of `2vw solid transparent`.

```js
assert.equal(new __helpers.CSSHelp(document).getStyle(".fb1a")?.borderRight, "2vw solid transparent");
```

# --seed--

## --seed-contents--

```html
<!DOCTYPE html>
<html lang="en">    
  <head>
    <meta charset="UTF-8">
    <title>City Skyline</title>
    <link href="styles.css" rel="stylesheet" />   
  </head>

  <body>
    <div class="background-buildings">
      <div></div>
      <div></div>
      <div class="bb1 building-wrap">
        <div class="bb1a bb1-window"></div>
        <div class="bb1b bb1-window"></div>
        <div class="bb1c bb1-window"></div>
        <div class="bb1d"></div>
      </div>
      <div class="bb2">
        <div class="bb2a"></div>
        <div class="bb2b"></div>
      </div>
      <div class="bb3"></div>
      <div></div>
      <div class="bb4 building-wrap">
        <div class="bb4a"></div>
        <div class="bb4b"></div>
        <div class="bb4c window-wrap">
          <div class="bb4-window"></div>
          <div class="bb4-window"></div>
          <div class="bb4-window"></div>
          <div class="bb4-window"></div>
        </div>
      </div>
      <div></div>
      <div></div>
    </div>

    <div class="foreground-buildings">
      <div></div>
      <div></div>
      <div class="fb1 building-wrap">
        <div class="fb1a"></div>
        <div class="fb1b"></div>
        <div class="fb1c"></div>
      </div>
      <div class="fb2"></div>
      <div></div>
      <div class="fb3"></div>
      <div class="fb4"></div>
      <div class="fb5"></div>
      <div class="fb6"></div>
      <div></div>
      <div></div>
    </div>
  </body>
</html>
```

```css
:root {
  --building-color1: #aa80ff;
  --building-color2: #66cc99;
  --building-color3: #cc6699;
  --building-color4: #538cc6;
  --window-color1: black;
  --window-color2: #8cd9b3;
  --window-color3: #d98cb3;
  --window-color4: #8cb3d9;
}

* {
  border: 1px solid black;
  box-sizing: border-box;
}

body {
  height: 100vh;
  margin: 0;
  overflow: hidden;
}

.background-buildings, .foreground-buildings {
  width: 100%;
  height: 100%;
  display: flex;
  align-items: flex-end;
  justify-content: space-evenly;
  position: absolute;
  top: 0;
}

.building-wrap {
  display: flex;
  flex-direction: column;
  align-items: center;
}

.window-wrap {
  display: flex;
  align-items: center;
  justify-content: space-evenly;
}

/* BACKGROUND BUILDINGS - "bb" stands for "background building" */
.bb1 {
  width: 10%;
  height: 70%;
}

.bb1a {
  width: 70%;
}
  
.bb1b {
  width: 80%;
}
  
.bb1c {
  width: 90%;
}

.bb1d {
  width: 100%;
  height: 70%;
  background: linear-gradient(
      var(--building-color1) 50%,
      var(--window-color1)
    );
}

.bb1-window {
  height: 10%;
  background: linear-gradient(
      var(--building-color1),
      var(--window-color1)
    );
}

.bb2 {
  width: 10%;
  height: 50%;
}

.bb2a {
  border-bottom: 5vh solid var(--building-color2);
  border-left: 5vw solid transparent;
  border-right: 5vw solid transparent;
}

.bb2b {
  width: 100%;
  height: 100%;
  background: repeating-linear-gradient(
      var(--building-color2),
      var(--building-color2) 6%,
      var(--window-color2) 6%,
      var(--window-color2) 9%
    );
}

.bb3 {
  width: 10%;
  height: 55%;
  background: repeating-linear-gradient(
      90deg,
      var(--building-color3),
      var(--building-color3),
      var(--window-color3) 15%
    );
}

.bb4 {
  width: 11%;
  height: 58%;
}

.bb4a {
  width: 3%;
  height: 10%;
  background-color: var(--building-color4);
}

.bb4b {
  width: 80%;
  height: 5%;
  background-color: var(--building-color4);
}
  
.bb4c {
  width: 100%;
  height: 85%;
  background-color: var(--building-color4);
}

.bb4-window {
  width: 18%;
  height: 90%;
  background-color: var(--window-color4);
}

/* FOREGROUND BUILDINGS - "fb" stands for "foreground building" */
.fb1 {
  width: 10%;
  height: 60%;
}
--fcc-editable-region--
.fb1a {
  border-bottom: 7vh solid var(--building-color4);
}
--fcc-editable-region--
.fb1b {
  width: 60%;
  height: 10%;
  background-color: var(--building-color4);
}
  
.fb1c {
  width: 100%;
  height: 80%;
  background: repeating-linear-gradient(
      90deg,
      var(--building-color4),
      var(--building-color4) 10%,
      transparent 10%,
      transparent 15%
    ),
    repeating-linear-gradient(
      var(--building-color4),
      var(--building-color4) 10%,
      var(--window-color4) 10%,
      var(--window-color4) 90%
    );
}

.fb2 {
  width: 10%;
  height: 40%;
  background-color: var(--building-color3);
}

.fb3 {
  width: 10%;
  height: 35%;
  background-color: var(--building-color1);
}
  
.fb4 {
  width: 8%;
  height: 45%;
  background-color: var(--building-color1);
  position: relative;
  left: 10%;
}

.fb5 {
  width: 10%;
  height: 33%;
  background-color: var(--building-color2);
  position: relative;
  right: 10%;
}

.fb6 {
  width: 9%;
  height: 38%;
  background-color: var(--building-color3);
}
    
```

