:root {
  --distant: 1000vw;
  --stage-size: 700px;
  --text-size: 14px;
  --input-size: 12px;
  --title-size: 36px;
  --subtitle-size: 18px;
  --block-line-height: 16px;
  --bg-color: #181000;
  --fg-color: #90d0a0;
  --link-color: #b0d0ff;
  --yes-color: #00b000;
  --no-color: #e04040;
  --maybe-color: #d09000;
  --light-color: #c0c0c0;
  --dark-color: #606060;
  --south-color: #e04040;
  --west-color: #d09000;
  --north-color: #a060ff;
  --east-color: #0080ff;
  --central-color: #00b000;
  --hint-layer: 1;
  --trail-layer: 2;
  --piece-layer: 3;
  --overlay-layer: 4;
  --filter-layer: 5;
}

@keyframes flicker {
  0% {
    background: radial-gradient(circle, transparent 30%, var(--bg-color) 100%);
    opacity: 0.3;
  }
  33% {
    background: radial-gradient(circle, transparent 25%, var(--bg-color) 95%);
    opacity: 0.275;
  }
  66% {
    background: radial-gradient(circle, transparent 30%, var(--bg-color) 95%);
    opacity: 0.25;
  }
  100% {
    background: radial-gradient(circle, transparent 25%, var(--bg-color) 100%);
    opacity: 0.275;
  }
}

@keyframes wobble {
  0% {
    transform: rotate(-5deg);
  }
  100% {
    transform: rotate(5deg);
  }
}

html,
body {
  height: 100%;
  margin: 0;
  overflow: hidden;
  touch-action: none;
  user-select: none;
  width: 100%;
}

.VIEWPORT {
  align-items: center;
  background-color: var(--bg-color);
  color: var(--fg-color);
  display: flex;
  font: var(--text-size)/1 sans-serif;
  inset: 0;
  justify-content: center;
  position: fixed;
}

.STAGE {
  box-sizing: border-box;
  height: var(--stage-size);
  padding: 10px;
  transform-origin: center center;
  width: var(--stage-size);
}
.STAGE::after,
.OVERLAY-backdrop::after {
  animation: flicker 0.5s ease-in-out infinite alternate;
  content: '';
  height: var(--stage-size);
  inset: 0;
  pointer-events: none;
  position: absolute;
  width: var(--stage-size);
  z-index: var(--filter-layer);
}

.TITLE {
  font-size: var(--title-size);
  font-weight: bold;
  left: 10px;
  position: absolute;
  top: 10px;
}

.TITLE-subtitle {
  font-size: var(--subtitle-size);
  left: 67px;
  position: relative;
  top: -4px;
}

.TITLE-byline {
  font-size: var(--text-size);
  font-weight: normal;
  left: 5px;
  position: relative;
}
.TITLE-byline a {
  color: var(--link-color);
  text-decoration: none;
}

.SCORES {
  display: flex;
  flex-direction: column;
  font-weight: bold;
  gap: 2px;
  position: absolute;
  right: 10px;
  text-align: right;
  top: 10px;
  width: 100px;
}

.SCORES-line--south {
  color: var(--south-color);
}
.SCORES-line--west {
  color: var(--west-color);
}
.SCORES-line--north {
  color: var(--north-color);
}
.SCORES-line--east {
  color: var(--east-color);
}
.SCORES-line--central {
  color: var(--central-color);
}

.CONTROLS {
  display: flex;
  flex-direction: column;
  gap: 8px;
  bottom: 10px;
  position: absolute;
}
.CONTROLS--left {
  left: 10px;
}
.CONTROLS--right {
  right: 10px;
  text-align: right;
}

.CONTROLS-block {
  display: flex;
  gap: 10px;
}

.CONTROLS-button {
  background-color: var(--fg-color);
  border: 0;
  border-radius: 10px;
  color: var(--bg-color);
  cursor: pointer;
  font-size: var(--text-size);
  font-weight: bold;
  height: 20px;
  line-height: 1;
  overflow: hidden;
  padding: 3px 10px;
}
.CONTROLS-button:active {
  opacity: 0.75;
}
.CONTROLS-button:disabled {
  cursor: default;
  opacity: 0.5;
  pointer-events: none;
}

.CONTROLS-button--south {
  background-color: var(--south-color);
}
.CONTROLS-button--west {
  background-color: var(--west-color);
}
.CONTROLS-button--north {
  background-color: var(--north-color);
}
.CONTROLS-button--east {
  background-color: var(--east-color);
}
.CONTROLS-button--central {
  background-color: var(--central-color);
}

.CONTROLS-input {
  display: flex;
  gap: 4px;
  height: 14px;
}
.CONTROLS-input input {
  appearance: textfield;
  -moz-appearance: textfield;
  background-color: var(--bg-color);
  border: 0;
  border-radius: 5px;
  color: var(--fg-color);
  font-size: var(--input-size);
  outline: 1px solid var(--fg-color);
  padding: 0 5px;
}
.CONTROLS-input input::-webkit-inner-spin-button,
.CONTROLS-input input::-webkit-outer-spin-button {
  -webkit-appearance: none;
}
.CONTROLS-input--timer input {
  width: 30px;
}

.CONTROLS-toggle {
  display: flex;
  gap: 3px;
}
.CONTROLS-toggle input {
  cursor: pointer;
  height: 8px;
  left: calc(var(--distant) * -1);
  margin: 0;
  position: relative;
  width: 28px;
}
.CONTROLS-toggle input:disabled {
  cursor: default;
  opacity: 0.5;
  pointer-events: none;
}
.CONTROLS-toggle input::before,
.CONTROLS-toggle input::after {
  background-color: var(--fg-color);
  border-radius: 7px;
  color: var(--bg-color);
  content: '';
  display: inline-block;
  height: 14px;
  left: var(--distant);
  opacity: 0.5;
  position: absolute;
  text-align: center;
  width: 14px;
}
.CONTROLS-toggle--south input:checked::before,
.CONTROLS-toggle--south input:checked::after {
  background-color: var(--south-color);
}
.CONTROLS-toggle--west input:checked::before,
.CONTROLS-toggle--west input:checked::after {
  background-color: var(--west-color);
}
.CONTROLS-toggle--north input:checked::before,
.CONTROLS-toggle--north input:checked::after {
  background-color: var(--north-color);
}
.CONTROLS-toggle--east input:checked::before,
.CONTROLS-toggle--east input:checked::after {
  background-color: var(--east-color);
}
.CONTROLS-toggle--central input:checked::before,
.CONTROLS-toggle--central input:checked::after {
  background-color: var(--central-color);
}
.CONTROLS-toggle input::before {
  width: 28px;
}
.CONTROLS-toggle input::after {
  left: var(--distant);
}
.CONTROLS-toggle input:checked::after {
  opacity: 1;
  left: calc(var(--distant) + 14px);
}

.CONTROLS-confirmation,
.CONTROLS-state,
.CONTROLS-timer {
  display: flex;
  gap: 5px;
}
.CONTROLS-confirmation :first-child,
.CONTROLS-state :first-child,
.CONTROLS-timer :first-child {
  flex: 1;
  padding-top: 3px;
}
.CONTROLS-confirmation .CONTROLS-button--yes,
.CONTROLS-confirmation .CONTROLS-button--no,
.CONTROLS-state .CONTROLS-button--export,
.CONTROLS-state .CONTROLS-button--import,
.CONTROLS-timer .CONTROLS-button--pause,
.CONTROLS-timer .CONTROLS-button--play {
  background-position: center;
  background-repeat: no-repeat;
  background-size: 12px;
  padding: 3px 0;
  width: 20px;
}
.CONTROLS-state .CONTROLS-button--success,
.CONTROLS-confirmation .CONTROLS-button--yes {
  background-color: var(--yes-color);
}
.CONTROLS-confirmation .CONTROLS-button--yes::after {
  content: '✔';
}
.CONTROLS-state .CONTROLS-button--error,
.CONTROLS-confirmation .CONTROLS-button--no {
  background-color: var(--no-color);
}
.CONTROLS-confirmation .CONTROLS-button--no::after {
  content: '✘';
}
.CONTROLS-state .CONTROLS-button--export {
  background-image: url('copy.svg');
  background-size: 16px;
}
.CONTROLS-state .CONTROLS-button--import {
  background-image: url('paste.svg');
  background-size: 16px;
}
.CONTROLS-timer .CONTROLS-button--pause {
  background-color: var(--maybe-color);
  background-image: url('pause.svg');
}
.CONTROLS-timer .CONTROLS-button--play {
  background-color: var(--yes-color);
  background-image: url('play.svg');
  display: none;
}
.CONTROLS-timer--paused .CONTROLS-button--pause {
  display: none;
}
.CONTROLS-timer--paused .CONTROLS-button--play {
  display: block;
}

.BOARD {
  display: grid;
  grid-template-columns: repeat(17, 40px);
  grid-template-rows: repeat(17, 40px);
}

.BOARD-square {
  align-items: center;
  display: flex;
  height: 40px;
  justify-content: center;
  pointer-events: none;
  width: 40px;
}
.BOARD--disabled .BOARD-square {
  pointer-events: none;
}
.BOARD-square--light {
  background-color: var(--light-color);
}
.BOARD-square--dark {
  background-color: var(--dark-color);
}
.BOARD-square--active,
.BOARD-square--target {
  cursor: pointer;
  pointer-events: auto;
}
.BOARD-square--active::after,
.BOARD-square--target::after,
.BOARD-square--hint::after {
  content: '';
  height: 40px;
  opacity: 0.4;
  position: absolute;
  width: 40px;
  z-index: var(--hint-layer);
}
.BOARD-square--south::after {
  background-color: var(--south-color);
}
.BOARD-square--west::after {
  background-color: var(--west-color);
}
.BOARD-square--north::after {
  background-color: var(--north-color);
}
.BOARD-square--east::after {
  background-color: var(--east-color);
}
.BOARD-square--central::after {
  background-color: var(--central-color);
}

.BOARD-piece {
  align-items: center;
  border-radius: 50%;
  color: var(--bg-color);
  display: flex;
  font-size: 28px;
  height: 30px;
  justify-content: center;
  line-height: 1;
  position: relative;
  width: 30px;
  z-index: var(--piece-layer);
}
.BOARD-square--selected .BOARD-piece,
.BOARD-capture .BOARD-piece {
  outline: 3px solid var(--bg-color);
}
.BOARD-square--danger .BOARD-piece::after {
  animation: wobble 0.1s ease-in-out infinite alternate;
}
.BOARD-capture--south .BOARD-piece {
  outline-color: var(--south-color);
}
.BOARD-capture--west .BOARD-piece {
  outline-color: var(--west-color);
}
.BOARD-capture--north .BOARD-piece {
  outline-color: var(--north-color);
}
.BOARD-capture--east .BOARD-piece {
  outline-color: var(--east-color);
}
.BOARD-capture--central .BOARD-piece {
  outline-color: var(--central-color);
}
.BOARD-piece--south {
  background-color: var(--south-color);
}
.BOARD-piece--west {
  background-color: var(--west-color);
}
.BOARD--rotate-pieces .BOARD-piece--west {
  transform: rotate(90deg);
}
.BOARD-piece--north {
  background-color: var(--north-color);
}
.BOARD--rotate-pieces .BOARD-piece--north {
  transform: rotate(180deg);
}
.BOARD-piece--east {
  background-color: var(--east-color);
}
.BOARD--rotate-pieces .BOARD-piece--east {
  transform: rotate(-90deg);
}
.BOARD-piece--central {
  background-color: var(--central-color);
}
.BOARD-piece--pawn::after {
  content: '♟';
  font-size: 18px;
}
.BOARD-piece--central.BOARD-piece--pawn::after {
  content: '♙';
}
.BOARD-piece--knight::after {
  content: '♞';
}
.BOARD-piece--central.BOARD-piece--knight::after {
  content: '♘';
}
.BOARD-piece--bishop::after {
  content: '♝';
}
.BOARD-piece--central.BOARD-piece--bishop::after {
  content: '♗';
}
.BOARD-piece--rook::after {
  content: '♜';
}
.BOARD-piece--central.BOARD-piece--rook::after {
  content: '♖';
}
.BOARD-piece--queen::after {
  content: '♛';
}
.BOARD-piece--central.BOARD-piece--queen::after {
  content: '♕';
}
.BOARD-piece--king::after {
  content: '♚';
}
.BOARD-piece--central.BOARD-piece--king::after {
  content: '♔';
}

.TRAIL {
  height: 30px;
  left: calc(var(--x) * 1px);
  position: absolute;
  top: calc(var(--y) * 1px);
  transform: rotate(calc(atan2(
    (var(--target-y) - var(--y)),
    (var(--target-x) - var(--x))
  )));
  transform-origin: 0 50%;
  width: calc(sqrt(
    (var(--target-x) - var(--x)) * (var(--target-x) - var(--x)) +
    (var(--target-y) - var(--y)) * (var(--target-y) - var(--y))
  ) * 1px);
  z-index: var(--trail-layer);
}
.TRAIL--south {
  background: linear-gradient(to right, transparent, var(--south-color));
}
.TRAIL--west {
  background: linear-gradient(to right, transparent, var(--west-color));
}
.TRAIL--north {
  background: linear-gradient(to right, transparent, var(--north-color));
}
.TRAIL--east {
  background: linear-gradient(to right, transparent, var(--east-color));
}
.TRAIL--central {
  background: linear-gradient(to right, transparent, var(--central-color));
}

.OVERLAY {
  inset: 0;
  position: absolute;
  z-index: var(--overlay-layer);
}

.OVERLAY-backdrop {
  background-color: var(--bg-color);
  opacity: 0.75;
  width: 100%;
  height: 100%;
}

.OVERLAY-close-button {
  color: var(--fg-color);
  content: '✖';
  cursor: pointer;
  height: 17px;
  padding-top: 3px;
  position: absolute;
  right: 0;
  text-align: center;
  top: 0;
  width: 20px;
}
.OVERLAY-close-button::after {
  content: '✖';
}

.OVERLAY-modal {
  background-color: var(--bg-color);
  border-radius: 8px;
  border: 3px solid var(--fg-color);
  display: flex;
  flex-direction: column;
  gap: 8px;
  left: 50%;
  max-height: 90%;
  overflow: auto;
  padding: 10px;
  position: absolute;
  scrollbar-color: var(--fg-color) transparent;
  top: 50%;
  transform: translate(-50%, -50%);
  width: 450px;
}
.OVERLAY-modal::-webkit-scrollbar {
  height: 16px;
  width: 16px;
}
.OVERLAY-modal::-webkit-scrollbar-track {
  background: transparent;
}
.OVERLAY-modal::-webkit-scrollbar-thumb {
  background-color: transparent;
  border: 3px solid var(--bg-color);
  border-radius: 8px;
}

.OVERLAY-title {
  font-size: var(--subtitle-size);
  font-weight: bold;
  margin-bottom: 5px;
  text-align: center;
}

.OVERLAY-block {
  align-items: center;
  line-height: var(--block-line-height);
}

.OVERLAY-list {
  line-height: var(--block-line-height);
  list-style-position: outside;
  list-style-type: disc;
  margin: 0;
  padding: 0;
}
.OVERLAY-list li {
  margin-left: 20px;
}

.OVERLAY-text--italic,
.OVERLAY-link--italic {
  font-style: italic;
}
.OVERLAY-text--central {
  color: var(--central-color);
}
.OVERLAY-link {
  color: var(--link-color);
  text-decoration: none;
}