body {
  margin: 0;
  background: #eee;
}

.page-main {
  max-width: 800px;
  margin: 6px auto 0 auto;
}

/* TOP LEVEL IMAGE BAR LINKS */

.section-links {
  max-width: 800px;
  margin: 0 auto;
}

.section-link {
  display: block;
  margin: 0 0 6px 0;
}

.section-link img {
  display: block;
  width: 100%;
  max-width: 800px;
  height: auto;
  opacity: 1;
  transition: opacity 100ms ease;
}

.section-link:hover img {
  opacity: 0.6;
}

/* TOP NAV BAR */

.top-nav {
  position: sticky;
  top: 0;
  z-index: 100;
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  max-width: 800px;
  margin: 0 auto;
  background: #fff;
}

.top-nav.fade-under::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: -20px;
  height: 20px;
  pointer-events: none;
  z-index: 2;

  background: linear-gradient(
    to bottom,
    rgba(238,238,238,1) 0%,
    rgba(238,238,238,0) 100%
  );
}

/* NAV CELL TEXT */
.nav-cell {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 60px;
  padding: 0 1rem;
  color: #222;
  text-decoration: none;
  font: 20px Arial, sans-serif;
}

a.nav-cell:hover {
  background: #f6f6f6;
  color: #222;
}

.nav-cell.current {
  color: #222;
  font-weight: normal;
  background: #fff;
}

.nav-cell.empty {
  pointer-events: none;
}

/* REMOVE BLUE LINE AROUND VISITED IMAGE LINK */

a:focus-visible {
  outline: 2px solid #ddd;
  outline-offset: 3px;
}

/* HORIZONTAL RULE */

hr {
    max-width: 400px;
    margin: 2rem auto;
    border: 0;
    border-top: 1px solid #27f;
}

/* ASIDE */

.site-aside {
  max-width: 680px;
  margin: 1rem auto;
  color: #777;
  font-size: 1.0rem;
  font-style: italic;
  line-height: 1.25;
}

.site-aside p {
  margin: 0;
}

/* DETAILS */

.site-details {
  max-width: 680px;
  margin: 0.5rem auto;
  color: #222;
  font-size: 1.0rem;
  line-height: 1.4;
}

.site-details:hover {
  color: #27f;
  text-decoration: none;
}

.site-details p {
  margin: 0.75rem 0 0;
}

/* COPYRIGHT FOOTER */

.site-footer {
  max-width: 680px;
  margin: 0rem auto 0.5rem;
  padding-top: 0.0rem;
  color: #777;
  font-size: 0.75rem;
  font-family: Arial, sans-serif;
  text-align: center;
}

.site-footer p {
  margin: 0;
  font-size: inherit;
}

/* VIDEO (YouTube) */

.video-frame iframe {
  display: block;
  max-width: 100%;
  margin: 0 auto;
  border: 0;
}

/* IMAGE LINK */

.image-link {
  display: block;
  max-width: 680px;
  margin: 0.25rem auto;
}

.image-link img {
  display: block;
  max-width: 100%;
  height: auto;
  margin: 0 auto;
  opacity: 1.00;
  transition: opacity 100ms ease;
}

.image-link:hover img {
  opacity: 0.75;
}

/* TEXT LINK */

.internal-link {
  color: #222;
  font-size: 1.0rem;
  line-height: 1.4;
  text-decoration: none;
}

.internal-link:visited {
  color: #222;
}

.internal-link:hover {
  color: #27f;
  text-decoration: none;
}

/* EXTERNAL LINK */

.external-link {
  color: #222;
  font-size: 1.0rem;
  line-height: 1.4;
  text-decoration: none;
}

.external-link:visited {
  color: #222;
}

.external-link:hover {
  color: #27f;
  text-decoration: none;
}

.external-link:after {
  content: " ↗";
  font-size: 1.0em;
}

/* LAND ID HIGHER IN PAGE */

figure[id] {
  scroll-margin-top: 100px;
}