* {
  box-sizing: border-box;
  margin: 0;
}

body {
  font-family:
    system-ui,
    -apple-system,
    sans-serif;
  background: #161512;
  color: #bababa;
  min-height: 100dvh;
  display: flex;
  justify-content: center;
  align-items: center;
  padding: 20px;
}

@keyframes timer-shrink {
  to {
    transform: scaleX(0);
  }
}

#timer-bar {
  position: fixed;
  bottom: 0;
  left: 0;
  width: 100%;
  height: 6px;
  background: rgba(255, 255, 255, 0.9);
  transform-origin: left;
  transition: opacity 0.3s;
  animation: timer-shrink 60s linear forwards paused;
}

#timer-bar.running {
  animation-play-state: running;
}

main {
  display: flex;
  gap: 40px;
  --aside-width: 380px;
  --board-size: min(
    calc(100dvh - 160px),
    calc(100vw - var(--aside-width) - 80px)
  );
}

#board {
  position: relative;
  width: var(--board-size);
  height: var(--board-size);
  border-radius: 4px;
  overflow: hidden;
  flex-shrink: 0;
}

aside {
  display: flex;
  flex-direction: column;
  gap: 20px;
  width: var(--aside-width);
  height: var(--board-size);
  flex-shrink: 0;
}

#rating {
  font-size: 42px;
  font-weight: 600;
  font-variant-numeric: tabular-nums;
  text-align: right;
}

#rating .crown {
  height: 1em;
  vertical-align: -0.1em;
}

#feedback {
  padding: 16px 20px;
  border-radius: 4px;
  font-size: 17px;
  background: #262421;
  transition:
    background 0.15s,
    color 0.15s;
}

#feedback.success {
  background: #264d12;
  color: #8bc34a;
}

#feedback.error {
  background: #4d1212;
  color: #e57373;
}

#feedback.neutral {
  background: #262421;
  color: #888;
}

nav {
  display: grid;
}

nav button {
  padding: 16px 24px;
  border: none;
  border-radius: 4px;
  font-size: 16px;
  font-weight: 500;
  cursor: pointer;
  text-align: center;
  transition: background 0.15s;
}

nav button[hidden] {
  display: block;
  visibility: hidden;
  pointer-events: none;
}

#solution-btn,
#next-btn {
  grid-row: 1;
  grid-column: 1;
}

#solution-btn {
  background: #302e2b;
  color: #bababa;
}

#solution-btn:hover {
  background: #3d3935;
}

#next-btn {
  background: #629924;
  color: #fff;
}

#next-btn:hover {
  background: #72a934;
}

#lichess-link {
  margin-top: auto;
  background: #302e2b;
  color: #bababa;
  padding: 16px 24px;
  border-radius: 4px;
  font-size: 16px;
  font-weight: 500;
  text-align: center;
  text-decoration: none;
  transition: background 0.15s;
}

#lichess-link[hidden] {
  display: block;
  visibility: hidden;
  pointer-events: none;
}

#lichess-link:hover {
  background: #3d3935;
}

#chart {
  height: 200px;
  overflow: hidden;
}

.chart-tooltip {
  position: absolute;
  padding: 6px 10px;
  background: #1e1e1e;
  border-radius: 4px;
  color: #fff;
  font-size: 12px;
  pointer-events: none;
  transform: translateX(-50%);
  z-index: 100;
}

.u-cursor-pt {
  border-radius: 50%;
}

/* Chessground theme */

.cg-wrap cg-board {
  background-image: url("https://lichess1.org/assets/images/board/blue.png");
}

.cg-wrap square.move-dest {
  background: radial-gradient(rgba(20, 85, 30, 0.5) 19%, rgba(0, 0, 0, 0) 20%);
}

.cg-wrap square.oc.move-dest {
  background: radial-gradient(
    transparent 0%,
    transparent 79%,
    rgba(20, 85, 0, 0.3) 80%
  );
}

.cg-wrap square.last-move {
  background-color: rgba(155, 199, 0, 0.41);
}

.cg-wrap square.selected {
  background-color: rgba(20, 85, 30, 0.5);
}

.cg-wrap square.check {
  background: radial-gradient(
    ellipse at center,
    rgba(255, 0, 0, 1) 0%,
    rgba(231, 0, 0, 1) 25%,
    rgba(169, 0, 0, 0) 89%,
    rgba(158, 0, 0, 0) 100%
  );
}

/* Pieces - Kosal set */

.cg-wrap piece.white.king {
  background-image: url("https://lichess1.org/assets/piece/kosal/wK.svg");
}
.cg-wrap piece.white.queen {
  background-image: url("https://lichess1.org/assets/piece/kosal/wQ.svg");
}
.cg-wrap piece.white.rook {
  background-image: url("https://lichess1.org/assets/piece/kosal/wR.svg");
}
.cg-wrap piece.white.bishop {
  background-image: url("https://lichess1.org/assets/piece/kosal/wB.svg");
}
.cg-wrap piece.white.knight {
  background-image: url("https://lichess1.org/assets/piece/kosal/wN.svg");
}
.cg-wrap piece.white.pawn {
  background-image: url("https://lichess1.org/assets/piece/kosal/wP.svg");
}
.cg-wrap piece.black.king {
  background-image: url("https://lichess1.org/assets/piece/kosal/bK.svg");
}
.cg-wrap piece.black.queen {
  background-image: url("https://lichess1.org/assets/piece/kosal/bQ.svg");
}
.cg-wrap piece.black.rook {
  background-image: url("https://lichess1.org/assets/piece/kosal/bR.svg");
}
.cg-wrap piece.black.bishop {
  background-image: url("https://lichess1.org/assets/piece/kosal/bB.svg");
}
.cg-wrap piece.black.knight {
  background-image: url("https://lichess1.org/assets/piece/kosal/bN.svg");
}
.cg-wrap piece.black.pawn {
  background-image: url("https://lichess1.org/assets/piece/kosal/bP.svg");
}

/* Promotion UI */

#promotion-choice {
  position: absolute;
  inset: 0;
  z-index: 100;
  background: rgba(0, 0, 0, 0.4);
}

.promotion-square {
  position: absolute;
  width: 12.5%;
  height: 12.5%;
  background: #b0b0b0;
  border-radius: 50%;
  box-shadow: inset 0 0 20px 3px #808080;
  cursor: pointer;
  transition: all 0.15s;
}

.promotion-square:hover {
  border-radius: 0;
  box-shadow: inset 0 0 48px 8px hsl(22, 100%, 42%);
}

.promotion-piece {
  width: 100%;
  height: 100%;
  background-size: cover;
  pointer-events: none;
  transform: scale(0.85);
  transition: transform 0.15s;
}

.promotion-square:hover .promotion-piece {
  transform: scale(1);
}

.promotion-piece.queen.white {
  background-image: url("https://lichess1.org/assets/piece/kosal/wQ.svg");
}
.promotion-piece.rook.white {
  background-image: url("https://lichess1.org/assets/piece/kosal/wR.svg");
}
.promotion-piece.bishop.white {
  background-image: url("https://lichess1.org/assets/piece/kosal/wB.svg");
}
.promotion-piece.knight.white {
  background-image: url("https://lichess1.org/assets/piece/kosal/wN.svg");
}
.promotion-piece.queen.black {
  background-image: url("https://lichess1.org/assets/piece/kosal/bQ.svg");
}
.promotion-piece.rook.black {
  background-image: url("https://lichess1.org/assets/piece/kosal/bR.svg");
}
.promotion-piece.bishop.black {
  background-image: url("https://lichess1.org/assets/piece/kosal/bB.svg");
}
.promotion-piece.knight.black {
  background-image: url("https://lichess1.org/assets/piece/kosal/bN.svg");
}