:root {
  --spacing: 12px;
  --base-width: 100vw;

  --col-count: 2;
  --col-spacing: var(--spacing);
  --col-width: calc((var(--base-width) - (var(--col-count) + 1) * var(--col-spacing)) / var(--col-count) - 1px);

  --thumbnail-size: var(--col-width);
  --thumbnail-spacing: var(--col-spacing);
  --thumbnail-transition: 0.3s;

  --color-accent: #FF4100;
  --color-highlight: #F5F4F0;

  --header-size: 3.5rem;
  --header-z-index: 10;

  font-family: 'Montserrat', sans-serif;
  padding: 0;
  margin: 0;
}

body {
  margin: 0;
  padding: 0;
  padding-top: var(--header-size);
  background-color: black;
}

.site-container {
  /* Setting overflow to auto is used here to contain the margins of child
   * elements, so that the background color of the container is respected
   * to the very edges of the child elements.
   */
  overflow: auto;
  background: white;
}

header, main, footer {
  padding: 0 var(--spacing);
  /* Setting overflow to auto is used here to contain the margins of child
   * elements, so that the background color of the container is respected
   * to the very edges of the child elements.
   */
  overflow: auto;
}

main {
  padding-top: var(--spacing);
  background-color: white;
}

footer {
  padding-top: var(--spacing);
  padding-bottom: calc(var(--spacing) * 4);
  background-color: black;
  color: white;
}

footer .social-media-label {
  font-weight: 300;
  font-size: 0.8rem;
  margin-bottom: 0.5rem;
  letter-spacing: initial;
}

footer .social-media a {
  display: inline-block;
  width: 1.2rem;
  height: 1.2rem;
  border-radius: 4px;
  margin-right: 0.25rem;
  background-color: white;
  color: black;
  text-align: center;
}

h1 {
  font-size: 2rem;
  font-weight: 300;
}

/* There may be other h1 elements in the main content, so we need to
 * distinguish them from the page title.
 */
main h1 {
  border-left: 1px solid var(--color-accent);
  padding: var(--spacing);
  margin-left: calc(-1 * var(--spacing));
  font-size: 2rem;
}

.visually-hidden {
  clip: rect(0 0 0 0);
  clip-path: inset(50%);
  height: 1px;
  overflow: hidden;
  position: absolute;
  white-space: nowrap;
  width: 1px;
}

.button {
  display: inline-block;
  padding: 1rem 1.5rem;
  background-color: black;
  text-decoration: none;
  color: white;
  font-size: 1rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05rem;
  transition: background-color 0.2s ease-in-out,
              color 0.2s ease-in-out;
}

.button:hover {
  background-color: var(--color-accent);
  color: black;
}

/* Header mobile menu toggle */

.logo {
  display: flex;
  align-items: center;
  position: fixed;
  top: 0;
  left: 0;
  width: calc(100% - var(--header-size));
  padding: var(--spacing);
  box-sizing: border-box;
  height: var(--header-size);
  z-index: var(--header-z-index);
  background-color: white;
}

.logo img {
  height: 3rem;
}

.menu-trigger {
  display: block;
  position: fixed;
  top: 0;
  right: 0;
  width: var(--header-size);
  height: var(--header-size);
  border: none;
  padding: 1.125rem;
  z-index: calc(var(--header-z-index) + 1);
  box-sizing: border-box;
  background-color: var(--color-accent);
  cursor: pointer;
  transition: width 0.2s ease-in-out,
              padding-left 0.2s ease-in-out;

  /* Counterintuitively, this is the transition-delay when transitioning TO
   * this state.
   */
  transition-delay: 0.2s;
}

.menu-panel-open .menu-trigger {
  width: 100%;
  padding-left: calc(100% - var(--header-size) + 1.125rem);

  /* Counterintuitively, this is the transition-delay when transitioning TO
   * this state.
   */
  transition-delay: 0s;
}

.menu-trigger-bars {
  position: relative;
  width: 1.25rem;
  height: 1.25rem;
}

.menu-trigger-bars .bar {
  position: absolute;
  display: block;
  width: 100%;
  height: 2px;
  background-color: white;
  transition: transform 0.2s ease-in-out,
              opacity 0.2s ease-in-out,
              top 0.2s ease-in-out,
              bottom 0.2s ease-in-out;
}

.menu-trigger-bars .bar:nth-child(1) {
  top: 0.125rem;
}
.menu-trigger-bars .bar:nth-child(2) {
  top: 50%;
  transform: translateY(-50%);
}
.menu-trigger-bars .bar:nth-child(3) {
  bottom: 0.125rem;
}

.menu-panel-open .menu-trigger-bars .bar:nth-child(1) {
  top: 50%;
  transform: translateY(-50%) rotate(45deg);
}
.menu-panel-open .menu-trigger-bars .bar:nth-child(2) {
  opacity: 0;
}
.menu-panel-open .menu-trigger-bars .bar:nth-child(3) {
  bottom: 50%;
  transform: translateY(50%) rotate(-45deg);
}

.site-header nav {
  position: fixed;
  z-index: var(--header-z-index);
  left: 0;
  top: 0;
  width: 100%;
  box-sizing: border-box;
  padding: calc(var(--spacing) * 4) var(--spacing);
  transform: translateY(-100%);
  background-color: black;
  transition: transform 0.2s ease-in-out;
}

.site-header nav a {
  display: block;
  margin-bottom: calc(var(--spacing) * 2);
  font-size: 1.25rem;
  font-weight: 700;
  text-decoration: none;
  color: white;
}

.menu-panel-open nav {
  transform: translateY(var(--header-size));

  /* Counterintuitively, this is the transition-delay when transitioning TO
   * this state.
   */
  transition-delay: 0.2s;
}

/* Home page */

.home-main {
  padding: 1rem 0 2rem 0;
  width: var(--base-width);
  margin: auto;
}

.home-main p {
  margin: var(--spacing);
}

.maps-year > header {
  margin-top: calc(2 * var(--spacing));
  padding: 0;
  font-size: 2rem;
}

.map-group {
  display: inline;
  background-color: var(--color-highlight);
  transition: border-width var(--thumbnail-transition),
              border-color var(--thumbnail-transition),
              background-color var(--thumbnail-transition),
              color var(--thumbnail-transition);
}

.map-group .day-label {
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05rem;

  position: relative;
  display: inline-block;
  margin: 0 calc(var(--thumbnail-spacing) / 2);
  padding: 0.75rem 0 0.25rem;
  width: var(--thumbnail-size);
  overflow: visible;
  font-size: 1rem;
  line-height: 1rem;
  text-align: left;
  text-wrap: nowrap;
  text-overflow: ellipsis;
}

.day-label + .map-entry {
  margin-left: calc(-1 * var(--thumbnail-size) - var(--thumbnail-spacing) / 2);
}

.map-entry {
  display: inline-block;
  margin: 2rem calc(var(--thumbnail-spacing) / 2) 0;
  vertical-align: top;
}

.map-entry .thumbnail {
  width: var(--thumbnail-size);
  height: var(--thumbnail-size);
  object-fit: cover;
  border: 1px solid black;
  border-radius: 5px;
  box-sizing: border-box;
  vertical-align: middle;
  transition: border-width var(--thumbnail-transition),
              border-color var(--thumbnail-transition),
              box-shadow var(--thumbnail-transition),
              filter var(--thumbnail-transition);
}

/* Map details */

.map-details .front-matter {
  font-weight: bold;
  margin-top: 1rem;
}

.map-details .creator,
.map-details .source-link {
  display: block;
}

.map-details img {
  max-width: 100%;
}

.map-details .default-content {
  text-align: center;
}

/*
  Media breakpoint definitions (borrowed from the Chrome dev tools):

  - small: 425px;
  - medium: 768px;
  - large: 1024px;
*/

@media screen and (width > 425px) {
  :root {
    --col-count: 3;
  }
}

@media screen and (width > 768px) {
  :root {
    --col-count: 4;
  }

  h1 {
    font-size: 4rem;
  }
}

@media screen and (width > 1024px) {
  :root {
    --col-count: 5;
    --base-width: 1024px;
    --wide-spacing: calc((100vw - 1024px) / 2);
  }

  header, main, footer {
    padding: 0 var(--wide-spacing);
  }
}

@media (hover: hover) {
  /* Hovering over any part of a day highlights the whole day. */

  .map-group:hover {
    background-color: black;
    color: white;
  }

  /* Thumbnails start off as grayscale, but all of a day's thumbnails get
  colored in when you hover over the day. */

  .map-entry .thumbnail {
    filter: grayscale();
    border-color: var(--color-highlight);

    transition: border-width var(--thumbnail-transition),
                border-color var(--thumbnail-transition),
                box-shadow var(--thumbnail-transition),
                filter var(--thumbnail-transition);
  }

  .map-group:hover .thumbnail {
    filter: none;
    border-color: black;
  }

  .map-entry .thumbnail:hover {
    border-width: 3px;
    border-color: var(--color-accent);
    box-shadow: 0 0 5px black;
  }
}