style.css

body {
  margin: 8% auto 0;
  padding: 0;
  max-width: 560px;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  font-size: 16px;
  color: #000;
  line-height: 1.42857143;
  background-color: #1c1f24;
}

p {
  margin: 0 0 10px;
}

.header {
  min-height: 62px;
  border-bottom: 1px solid #2f3235;
  box-sizing: border-box;
  font: 400 16px/1 Courier, monospace;
}

.heading {
  margin: 0;
  color: #fff;
  font-size: 24px;
  font-weight: 400;
  line-height: 1.7;
}

.error-code {
  color: #4e535a;
}

.logo-box {
  display: block;
  float: left;
  margin-left: -76px;
  padding: 15px;
  width: 32px;
  height: 32px;
  background-color: #f90;
}

.logo-box:hover,
.logo-box:active {
  background-color: #ffad33;
}

.logo {
  display: inline-block;
  vertical-align: top;
  fill: #fff;
}

.content {
  margin: 20px 0;
  color: #7f868f;
}

.title {
  margin: 0 0 10px;
  color: #fff;
}

.footer {
  margin: 10px -10px 0;
  padding: 0;
  font-size: 14px;
  list-style: none;
  color: #4e535a;
}

.footer li {
  display: inline-block;
}

.footer li:not(:last-child)::after {
  content: '·';
}

.footer a {
  margin: 0 10px;
  text-decoration: none;
  color: inherit;
}

.footer a:hover,
.footer a:focus {
  text-decoration: underline;
}

@media screen and (max-width: 768px) {
  body {
    margin: 8% 20px 0;
  }

  .logo-box {
    float: none;
    margin: 0 0 10px;
  }

  .heading {
    margin: 4px 0 10px;
    line-height: 1.3;
  }

  .footer li::after {
    display: none;
  }

  .footer li {
    display: block;
    margin: 8px 0;
  }
}