* {
  box-sizing: border-box;
}

html, body {
  position: absolute;
  top: 0;
  bottom: 0;
  left: 0;
  right: 0;
  margin: 0;
  border: 0;
  padding: 0;
  overflow: hidden;
  user-select: none;
}

body {
  font-family: 'Noto Sans', sans-serif;
  color: white;
}

#cover-image {
  z-index: 1;
  position: absolute;
  top: 0;
  bottom: 0;
  left: 0;
  right: 0;
  background-size: cover;
  background-repeat: no-repeat;
  background-attachment: fixed;
  background-position: center;
  /* Fallback if background image failed to load.*/
  background-color: #333;
  transition: opacity 1s linear;
}

#walk-canvas {
  width: 0;
  height: 0;
  touch-action: none;
}

.message {
  z-index: 300;
  position: absolute;
  width: 260px;
  top: 0;
  left: 0;
  padding: 1em;
  background-color: white;
  color: black;
  font-size: 16px;
  text-align: center;
}
.message > a {
  color: black;
}
.info-message {
  border: 2px solid yellow;
}
.error-message {
  border: 2px solid red;
}

.ui-panel {
  background-color: rgba(0, 0, 0, 0.6);
  font-size: 13px;
}
.ui-hoverable:hover {
   background: rgba(0, 0, 0, 1);
}

/* Reponsive UI dimensions and positions - large display */
.ui-top {
  top: 10px;
}
.ui-bottom {
  bottom: 10px;
}
.ui-left {
  left: 10px;
}
.ui-right {
  right: 10px;
}
.ui-center {
  left: 50%;
  transform: translate(-50%, 0);
}
.info-item {
  min-width: 60px;
  height: 60px;
}
.menu-item {
  min-width: 52px;
  height: 52px;
  padding: 13px 6px 13px 6px;
  line-height: 26px;
}
.menu-item > img {
  padding: 2px 0 1px 0;
}
.menu-button {
  font-size: 26px;
}
#secondary-progress-done {
  height: 8px;
}
#engine-logo {
  padding-top: 8px;
  padding-bottom: 8px;
  line-height: 34px;
}
#view-list-items {
  /* Make view-list not higher than half of the viewport:
       50vh + view_margin - ui_margin - (folder_margin + folder_height) */
  max-height: calc(50vh + 2px - 10px - (4px + 14px));
}
#view-list-items::-webkit-scrollbar,
#view-list-items::-webkit-scrollbar-thumb {
  width: 6px;
}
.ext-popup-content {
  /* 100vw - ui_margin - (ui_margin + close_button) */
  max-width: calc(100vw - 10px - (10px + 30px));
  /* 100vh - ui_margin - ui_margin */
  max-height: calc(100vh - 10px - 10px);
  font-size: 14px;
  user-select: text;
}

/* Reponsive UI dimensions and positions - small display */
@media (max-width: 639px), (max-height: 639px) {
  .ui-panel {
    font-size: 12px;
  }
  .ui-top {
    top: 5px;
  }
  .ui-bottom {
    bottom: 5px;
  }
  .ui-left {
   left: 5px;
  }
  .ui-right {
    right: 5px;
  }
  .info-item {
    min-width: 46px;
    height: 46px;
  }
  .menu-item {
    min-width: 42px;
    height: 42px;
    padding: 11px 6px 11px 6px;
    line-height: 20px;
  }
  .menu-item > img {
    padding: 2px 0 0 0;
  }
  .menu-button {
    font-size: 22px;
  }
  #secondary-progress-done {
    height: 4px;
  }
  #engine-logo {
    padding-top: 6px;
    padding-bottom: 6px;
    line-height: 30px;
  }
  #view-list-items {
    max-height: calc(50vh + 2px - 5px - (4px + 14px));
  }
  @media (min-width: 560px) and (max-height: 439px) {
    #view-list-items {
      /* If the small display is low but wide make the view-list taller:
           80vh + view_margin - ui_margin - (folder_margin + folder_height) -
             (ui_margin + menu_bar_height + ui_margin) - webkit_ui_height
         We use 80vh instead of 100vh because on mobile WebKit 100vh includes
         the browser UI.
       */
      max-height: calc(80vh + 2px - 5px - (4px + 14px) - (5px + 42px + 5px));
    }
  }
  #view-list-items::-webkit-scrollbar,
  #view-list-items::-webkit-scrollbar-thumb {
    width: 4px;
  }
  .ext-popup-content {
    max-width: calc(100vw - 5px - (5px + 30px));
    max-height: calc(100vh - 5px - 5px);
    font-size: 12px;
  }
}

.absolute-center {
  position: absolute;
  left: 50%;
  top: 50%;
  transform: translateX(-50%) translateY(-50%);
  /* For IE9: */
  -ms-transform: translateX(-50%) translateY(-50%);
}

#info-bar {
  z-index: 100;
  position: absolute;
  overflow: hidden;
  user-select: text;
}
#info-bar-slide {
  position: relative;
  left: 0;
  transition: left 1s ease;
}
#author-logo {
  display: inline-block;
  margin-right: 2px;
  background: none;
  text-align: center;
}
#author-logo > img {
  height: 100%;
}
#info-text {
  display: inline-block;
  padding: 5px 10px 3px 10px;
  vertical-align: top;
}
#info-text > div {
  display: table;
  height: 50%;
}
#info-title, #info-author {
  display: table-cell;
  height: 100%;
  line-height: 1;
  vertical-align: middle;
  /* For <a> */
  color: white;
  text-decoration: none;
}
#info-title {
  font-size: 1.4em;
}

#menu-bar {
  z-index: 102;
  position: absolute;
  overflow: hidden;
}
#menu-bar-slide {
  position: relative;
  right: 0;
  transition: right 1s ease;
}
.menu-item {
  display: inline-block;
  margin-left: 2px;
  vertical-align: top;
  text-align: center;
  cursor: pointer;
}
.menu-item > img {
  height: 100%;
  vertical-align: top;
}
#menu-bar-content {
  display: inline-block;
  padding-left: 2px;
}
#menu-bar-folder {
  min-width: 0px;
  width: 16px;
  padding-left: 6px;
  padding-right: 5px;
}
#menu-bar-folder > img {
  width: 100%;
  transition: transform 1s ease;
}
#menu-buttons {
  display: inline-block;
}
.menu-button {
  font-weight: 700;
}
#engine-logo {
  color: white;
  text-decoration: none;
}
#engine-logo-text {
  display: inline-block;
  margin-right: 6px;
  vertical-align: top;
}
#view-list {
  z-index: 101;
  position: absolute;
  overflow: hidden;
}
#view-list-slide {
  position: relative;
  top: 0;
  transition: top 1s ease;
}
#view-list-items {
  /* Negative margin to compensate for the first view having margin-top: 2px */
  margin-top: -2px;
  margin-bottom: 4px;
  overflow-x: hidden;
  scrollbar-width: thin;
  scrollbar-color: white rgba(0, 0, 0, 0.6);
  -ms-overflow-style: -ms-autohiding-scrollbar;
}
#view-list-items::-webkit-scrollbar {
  background-color: rgba(0, 0, 0, 0.6);
}
#view-list-items::-webkit-scrollbar-thumb {
  background-color: white;
}
.view {
  padding: 3px 9px;
  margin-top: 2px;
  line-height: 1.5;
  white-space: nowrap;
  cursor: pointer;
}
@-moz-document url-prefix() {
  @media (pointer: coarse) {
    /* In Firefox on touch devices the view-list scrollbar is positioned
       a few pixels to the left from the edge of the scrollable area, which looks
       strange. Fix it by adding a margin. Detect touch device based on how
       precise the primary pointing device is. */
    .view {
      margin-right: 4px;
    }
  }
}
#view-list-folder {
  height: 14px;
  padding-top: 5px;
  padding-bottom: 4px;
  text-align: center;
  cursor: pointer;
}
#view-list-folder > img {
  /* Using height: 100% does not work on Safari, so set height in pixels. */
  height: 5px;
  vertical-align: top;
}

#play-button {
  z-index: 200;
  max-width: 30vw;
  max-height: 35vh;
  cursor: pointer;
}

#help-and-primary-progress {
  z-index: 200;
  text-align: center;
}

.help {
  /* Such vertical margins here and in #primary-progress introduce
     5vh margin between the help and the progress indicator when they
     are shown together, while maintaining the vertical centering of these
     elements when they are shown stand-alone. */
  margin: 2.5vh auto;
  padding: 16px;
  font-size: 13px;
}
.close-help-button {
  float: right;
  width: 20px;
  height: 20px;
  margin: 2px 0;
  background-size: cover;
  cursor: pointer;
}
.help-columns {
  display: table;
  width: 100%;
  text-align: center;
}
.help-column3, .help-column3-sep, .help-column2, .help-column2-sep {
  display: table-cell;
  vertical-align: middle;
}
.help-column3 {
  width: 26%;
}
.help-column3-sep {
  width: 11%;
}
.help-column2 {
  width: 45%;
}
.help-column2-sep {
  width: 10%;
}

#desktop-help {
  width: 500px;
}
#desktop-help-switch {
  padding-left: 25%;
  width: 75%;
  font-size: 14px;
  text-align: center;
}
#desktop-help-switch > div {
  display: inline-block;
  width: 50%;
  border: 2px solid #4676cc;
  cursor: pointer;
}
#desktop-help-switch > div:nth-child(1) {
  border-right-width: 1px;
}
#desktop-help-switch > div:nth-child(2) {
  border-left-width: 1px;
}
#desktop-help-switch > div:hover {
  background-color: #23b5e9;
}
#desktop-help-switch > div.selected,
#desktop-help-switch > div.selected:hover {
  background-color: #3c66b0;
}

#desktop-basic-help h1 {
  margin-top: 24px;
  margin-bottom: 18px;
  font-size: 20px;
  font-weight: 700;
}
#desktop-basic-help img {
  height: 60px;
}

#advanced-desktop-help {
  max-height: calc(100vh - 200px);
  margin-top: 8px;
  overflow-y: auto;
  font-size: 12px;
}
#advanced-desktop-help h1 {
  margin-top: 20px;
  margin-bottom: 10px;
  font-size: 18px;
  font-weight: 700;
  text-align: center;
}
.help-how, .help-what {
  display: inline-block;
  width: 50%;
  padding: 4px 0;
  vertical-align: middle;
}
.help-how {
  padding-right: 5%;
  text-align: right;
}
.help-what {
  padding-left: 5%;
}
.help-key, .help-key-placeholder {
  display: inline-block;
  min-width: 22px;
  margin: 1px;
}
.help-key {
  line-height: 20px;
  padding: 0 4px;
  border: 1px solid;
  border-radius: 4px;
  text-align: center;
}

#mobile-help {
  width: 300px;
}
#mobile-help h1 {
  margin-top: 8px;
  margin-bottom: 14px;
  font-size: 16px;
  font-weight: 700;
}
#mobile-help img {
  height: 50px;
}

#primary-progress {
  /* z-index set to 200 for compatibility with customized indexes based on
     webwalk < 180, because previously #primary-progress was a top-level
     element. */
  z-index: 200;
  margin-top: 2.5vh;
  margin-bottom: 2.5vh;
  width: 25vw;
  max-height: 20vh;
  transition: opacity 0.5s linear;
}
#primary-progress > circle {
  fill: none;
}
#primary-progress > circle:nth-child(1) {
  stroke: rgba(0, 0, 0, 0.6);
}
#primary-progress-done {
  stroke: #3c66b0;
}

#secondary-progress {
  z-index: 200;
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  transition: opacity 0.5s linear;
}
#secondary-progress-done {
  width: 0px;
  background-color: #3c66b0;
}

.tour-on {
  animation: blinker 1s linear infinite;
}

@keyframes blinker {
  50% { opacity: 0; }
}

.active-view, .active-view:hover {
  background-color: #3c66b0;
}

.next-active-view, .next-active-view:hover {
  background-color: #284461;
}

.ext-popup {
  z-index: 104;
  position: absolute;
}
.ext-popup-content {
  display: inline-block;
  vertical-align: top;
  padding: 16px;
  overflow: auto;
  /* A bit darker than .ui-panel because large pop-ups often overlap with some
     UI elements */
  background-color: rgba(0, 0, 0, 0.8);
}
.ext-popup-close-button-panel {
  display: inline-block;
  vertical-align: top;
  margin-left: 4px;
  padding: 6px;
  background-color: rgba(0, 0, 0, 0.8);
}
.ext-popup-close-button {
  width: 18px;
  height: 18px;
  background-size: cover;
  cursor: pointer;
}