html {
  box-sizing: border-box;
  overflow-y: scroll;
}

*, *:before, *:after {
  box-sizing: inherit;
}

body {
  font-family: "Calibri", "Arial", sans-serif;
  max-width: 52rem;
  margin: auto;
  color: #222;
  padding: 0 1rem;  
}

header {
  margin-bottom: 3rem;
}

header h1 img {
  display: block;
  max-width: 70%;
  margin: 3rem auto;
}

header nav {
  border: 2px solid #222;
  border-left: none;
  border-right: none;
  padding: 1rem 0;
}

header nav ul {
  list-style: none;
  max-width: 70%;
  display: flex;
  flex-direction: row;
  justify-content: space-between;
  margin: auto;
  padding: 0;
}

header nav li {
  text-transform: uppercase;
  font-size: 1.25rem;
  font-weight: bold;
  margin: 0;
  padding-left: 1rem;
}

header nav li:first-child {
  padding-left: 0;
}

header nav a {
  color: #666;
  text-decoration: none;
}

header nav a.current {
  color: #333;
}

header nav a:hover {
  color: #000;
}

footer {
  border: 2px solid #222;
  border-left: none;
  border-right: none;
  margin-top: 3rem;
  padding: 1rem 0;
  text-align: center;
}

footer p {
  margin: 0;
}

main a, footer a {  
  text-decoration: none;
  color: #666;
}

main a:hover, footer a:hover {  
  color: #000;
}

footer span {
  white-space: nowrap;
}

/* page specific */

.about-us h2 {
  font-weight: normal;
}

.services h2 {
  border-bottom: 1px solid #ccc;
  padding-bottom: 1rem;
}

.clients ul {
  list-style: none;
  display: grid;
  grid-template-columns: repeat( 4, 1fr );
  grid-gap: 3rem;
  padding: 0;
}

.clients li {
  text-align: center;
}

/* ensure square aspect ratio */
.clients li div {
  width: 100%;
  padding-bottom: 100%;
  margin-bottom: 0.5rem;
  position: relative;
}

.clients img {
  position: absolute;
  display: block;
  margin: auto;
  width: 100%;
  height: 100%;
  object-fit: contain;
}

@media (max-width: 35rem) { 
  header h1 img {
    max-width: 100%;
  }

  header nav ul {
    max-width: 100%;
  }  

  header nav li {
    font-size: 1rem;
  }  

  .clients ul {
    grid-template-columns: repeat( 2, 1fr );
  }  
}