:root {
  --bg:            #08090d;
  --panel:         #0c0e14;
  --panel-line:    #222;
  --board-light:   #e8e8e8;
  --board-dark:    #9c9c9c;
  --ink:           #e8e8e8;
  --ink-dim:       #888;
  --ink-muted:     #555;
  --danger:        #b5493f;
  --ok:            #6f9b6a;
  --move-dot:      rgba(232,232,232,0.3);
  --capture-ring:  rgba(181,73,63,0.8);
  --last-move:     rgba(232,232,232,0.1);
  --check-glow:    rgba(181,73,63,0.5);
  --btn-bg-hover:  #11131a;
  --btn-border:    #333;
  --btn-border-hov:#777;
  font-size: 16px;
}

/* ---------- Setup screen ---------- */
#setup {
  background: var(--panel);
  border: 1px solid var(--panel-line);
  border-radius: 8px;
  padding: 28px 32px 32px;
  width: min(520px, 92vw);
}

#setup h2 {
  font-weight: 400;
  font-size: 0.85rem;
  color: var(--ink-dim);
  letter-spacing: 0.03em;
  margin: 24px 0 10px;
}

#setup h2:first-of-type {
  margin-top: 0;
}

.toggle-group {
  display: flex;
  gap: 0;
}

.side-btn {
  flex: 1;
  padding: 10px;
  background: transparent;
  border: 1px solid var(--btn-border);
  color: var(--ink-dim);
  font-family: inherit;
  font-size: 0.85rem;
  cursor: pointer;
  transition: .2s;
}

.side-btn:first-child {
  border-radius: 8px 0 0 8px;
}

.side-btn:last-child {
  border-radius: 0 8px 8px 0;
}

.side-btn.active {
  background: var(--btn-bg-hover);
  border-color: var(--ink);
  color: var(--ink);
}

.side-btn:hover:not(.active) {
  border-color: var(--btn-border-hov);
  color: var(--ink);
}

.preset-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 8px;
  margin-bottom: 16px;
}

.preset-btn {
  background: transparent;
  border: 1px solid var(--btn-border);
  color: var(--ink-dim);
  padding: 10px 6px;
  border-radius: 6px;
  cursor: pointer;
  font-family: inherit;
  font-size: 0.8rem;
  transition: .2s;
}

.preset-btn:hover {
  border-color: var(--btn-border-hov);
  color: var(--ink);
}

.preset-btn.active {
  background: var(--btn-bg-hover);
  border-color: var(--ink);
  color: var(--ink);
}

#startBtn {
  margin-top: 22px;
  width: 100%;
  padding: 12px;
  background: transparent;
  color: var(--ink);
  border: 1px solid var(--btn-border);
  border-radius: 8px;
  font-family: inherit;
  letter-spacing: 0.04em;
  font-size: 0.9rem;
  cursor: pointer;
  transition: .2s;
}

#startBtn:hover {
  background: var(--btn-bg-hover);
  border-color: var(--btn-border-hov);
}

/* ---------- Game screen ---------- */
#game {
  display: none;
  gap: 28px;
  align-items: flex-start;
  flex-wrap: wrap;
  justify-content: center;
}

.board-wrap {
  position: relative;
}

#board {
  display: grid;
  grid-template-columns: repeat(8, min(11vw, 64px));
  grid-template-rows: repeat(8, min(11vw, 64px));
  border: 6px solid var(--board-dark);
  border-radius: 3px;
  box-shadow: 0 12px 40px rgba(0,0,0,0.5);
}

.sq {
  position: relative;
  display: flex; align-items: center; justify-content: center;
  font-size: min(7.5vw, 44px);
  cursor: pointer;
  user-select: none;
  line-height: 1;
}

.sq.light { background: var(--board-light); }
.sq.dark  { background: var(--board-dark); }

.sq .piece {
  filter: drop-shadow(0 2px 1px rgba(0,0,0,0.35));
  transition: transform .08s;
}

.sq.white-piece .piece {
  color: #fff;
  -webkit-text-stroke: 1.5px #555;
  text-shadow: 0 2px 3px rgba(0,0,0,0.25);
}

.sq.black-piece .piece {
  color: #1a1a1a;
}

.sq.selected::after {
  content: "";
  position: absolute;
  inset: 0;
  box-shadow: inset 0 0 0 3px var(--ink);
}

.sq.last-move {
  background-image: linear-gradient(var(--last-move), var(--last-move));
}

.sq.in-check {
  background-image: radial-gradient(circle, var(--check-glow) 40%, transparent 72%);
}

.sq .dot {
  position: absolute;
  width: 26%;
  height: 26%;
  border-radius: 50%;
  background: var(--move-dot);
  pointer-events: none;
}

.sq .ring {
  position: absolute;
  inset: 6%;
  border-radius: 50%;
  box-shadow: inset 0 0 0 4px var(--capture-ring);
  pointer-events: none;
}

/* ---------- Side panel ---------- */
#side {
  width: min(320px, 92vw);
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.panel-box {
  background: var(--panel);
  border: 1px solid var(--panel-line);
  border-radius: 8px;
  padding: 14px 18px;
  transition: border-color .2s, background .2s;
}

#enginePanel .label {
  font-size: 0.72rem;
  letter-spacing: 0.06em;
  color: var(--ink-dim);
  display: block;
  margin-bottom: 6px;
}

#enginePanel .time {
  font-size: 1rem;
  color: var(--ink);
}

#enginePanel.active {
  border-color: var(--ink);
  background: var(--btn-bg-hover);
}

#enginePanel.active .time {
  color: var(--ink);
}

.engine-bar {
  margin-top: 10px;
  height: 4px;
  background: var(--panel-line);
  border-radius: 2px;
  overflow: hidden;
}

.engine-bar-fill {
  height: 100%;
  width: 0%;
  background: var(--ink);
  transition: width .1s linear;
}

#status {
  font-size: 0.92rem;
  min-height: 1.4em;
  color: var(--ink);
}

.captured {
  min-height: 2.2em;
  font-size: 1.3rem;
  letter-spacing: 2px;
  padding-top: 10px;
  padding-bottom: 10px;
}

.captured .cap-label {
  display: block;
  font-size: 0.65rem;
  letter-spacing: 0.06em;
  color: var(--ink-dim);
  margin-bottom: 4px;
}

#history {
  font-family: "Courier New", monospace;
  font-size: 0.8rem;
  max-height: 180px;
  overflow-y: auto;
  color: var(--ink-dim);
}

#history .mv-num {
  color: var(--ink);
  margin-right: 4px;
}

#controls {
  display: flex;
  gap: 10px;
}

#controls button {
  flex: 1;
  background: transparent;
  border: 1px solid var(--btn-border);
  color: var(--ink-dim);
  padding: 10px;
  border-radius: 6px;
  font-family: inherit;
  font-size: 0.75rem;
  letter-spacing: 0.04em;
  cursor: pointer;
  transition: .2s;
}

#controls button:hover {
  border-color: var(--btn-border-hov);
  color: var(--ink);
}

/* ---------- Modals ---------- */
.modal-backdrop {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.7);
  display: none;
  align-items: center;
  justify-content: center;
  z-index: 50;
}

.modal-backdrop.show {
  display: flex;
}

.modal {
  background: var(--panel);
  border: 1px solid var(--panel-line);
  border-radius: 8px;
  padding: 28px 32px;
  text-align: center;
  max-width: 90vw;
}

.modal h3 {
  margin: 0 0 14px;
  font-weight: 400;
  color: var(--ink);
  letter-spacing: 0.03em;
}

#promoChoices {
  display: flex;
  gap: 10px;
  justify-content: center;
}

#promoChoices button {
  font-size: 2.2rem;
  background: var(--bg);
  border: 1px solid var(--btn-border);
  border-radius: 6px;
  padding: 6px 12px;
  cursor: pointer;
  color: var(--ink);
  transition: .2s;
}

#promoChoices button:hover {
  border-color: var(--ink);
}

#gameOverText {
  font-size: 1rem;
  margin-bottom: 16px;
  color: var(--ink);
}

#gameOverBackdrop button {
  background: transparent;
  color: var(--ink);
  border: 1px solid var(--btn-border);
  padding: 10px 22px;
  border-radius: 8px;
  cursor: pointer;
  font-family: inherit;
  letter-spacing: 0.04em;
  transition: .2s;
}

#gameOverBackdrop button:hover {
  background: var(--btn-bg-hover);
  border-color: var(--btn-border-hov);
}

@media (max-width: 700px) {
  #board {
    grid-template-columns: repeat(8, min(11vw, 44px));
    grid-template-rows: repeat(8, min(11vw, 44px));
  }
  .sq { font-size: min(7.5vw, 32px); }
  .preset-grid { grid-template-columns: repeat(2, 1fr); }
}