@import url('https://fonts.googleapis.com/css2?family=Plus+Jakarta+Sans:wght@300;400;500;600;700;800&family=JetBrains+Mono:wght@400;500;600;700&display=swap');

:root {
  /* Color System - Deep Slate & Apple Glass */
  --bg-dark: #06070a;
  --bg-gradient: radial-gradient(circle at 50% -20%, #1e2235 0%, #06070a 100%);
  --panel-bg: linear-gradient(135deg, rgba(255, 255, 255, 0.07) 0%, rgba(255, 255, 255, 0.02) 100%);
  --panel-border: rgba(255, 255, 255, 0.08);
  --panel-glow: 0 20px 50px rgba(0, 0, 0, 0.4), inset 0 1px 0 0 rgba(255, 255, 255, 0.12), inset 0 0 0 1px rgba(255, 255, 255, 0.02);
  
  --text-primary: #f8fafc;
  --text-secondary: #94a3b8;
  --text-dim: #64748b;
  
  --accent-gold: #fbbf24;
  --accent-gold-glow: rgba(251, 191, 36, 0.12);
  --accent-teal: #10b981;
  --accent-teal-glow: rgba(16, 185, 129, 0.12);
  
  --danger: #f87171;
  --danger-glow: rgba(248, 113, 113, 0.12);
  
  /* Board Palette - Soft Contrast Slate / Off-White */
  --sq-light: #f1f5f9;
  --sq-dark: #3b4252;
  
  --mono-font: 'JetBrains Mono', monospace;
  --sans-font: 'Plus Jakarta Sans', -apple-system, sans-serif;
  
  --transition-smooth: all 0.25s cubic-bezier(0.4, 0, 0.2, 1);
  --radius-lg: 20px;
  --radius-md: 12px;
  --radius-sm: 8px;
}

* {
  box-sizing: border-box;
}

@media (prefers-reduced-motion: reduce) {
  * { 
    animation-duration: 0.001ms !important; 
    animation-iteration-count: 1 !important; 
    transition-duration: 0.001ms !important; 
  }
}

.sr-only {
  position: absolute; 
  width: 1px; 
  height: 1px; 
  padding: 0; 
  margin: -1px; 
  overflow: hidden;
  clip: rect(0,0,0,0); 
  white-space: nowrap; 
  border: 0;
}

.skip-link {
  position: absolute; 
  left: 16px; 
  top: -60px; 
  background: var(--text-primary); 
  color: var(--bg-dark); 
  padding: 10px 18px;
  border-radius: var(--radius-sm); 
  z-index: 100; 
  font-weight: 600; 
  text-decoration: none; 
  transition: top 0.2s cubic-bezier(0.4, 0, 0.2, 1);
  box-shadow: 0 4px 12px rgba(255, 255, 255, 0.15);
}

.skip-link:focus { 
  top: 16px; 
}

a, button, select, input, .sq { 
  outline-offset: 4px; 
}

a:focus-visible, button:focus-visible, select:focus-visible, input:focus-visible, .sq:focus-visible {
  outline: 2px solid var(--accent-teal); 
  outline-offset: 2px; 
  z-index: 9;
}

body {
  margin: 0; 
  background: var(--bg-dark);
  background-image: 
    radial-gradient(circle at 80% 20%, rgba(99, 102, 241, 0.15) 0%, transparent 50%),
    radial-gradient(circle at 20% 80%, rgba(16, 185, 129, 0.08) 0%, transparent 50%),
    var(--bg-gradient);
  color: var(--text-primary); 
  font-family: var(--sans-font);
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

header {
  padding: 40px 40px 20px; 
  display: flex; 
  align-items: center; 
  gap: 24px; 
  flex-wrap: wrap;
  max-width: 1300px;
  margin: 0 auto;
  width: 100%;
}

header h1 { 
  font-size: 24px; 
  margin: 0; 
  letter-spacing: -0.5px; 
  font-weight: 800;
  background: linear-gradient(135deg, #ffffff 40%, #cbd5e1 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

header h1 span {
  background: linear-gradient(135deg, var(--accent-gold) 30%, #fbbf24 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

header .sub { 
  color: var(--text-secondary); 
  font-size: 13px; 
  font-weight: 400;
  border-left: 1px solid rgba(255, 255, 255, 0.1);
  padding-left: 18px;
  max-width: 500px;
  opacity: 0.8;
}

.layout {
  display: grid; 
  grid-template-columns: minmax(360px, 500px) 1fr; 
  gap: 36px;
  padding: 10px 40px 60px; 
  align-items: start;
  max-width: 1300px;
  margin: 0 auto;
  width: 100%;
}

@media(max-width: 980px) { 
  .layout {
    grid-template-columns: 1fr;
    padding: 10px 16px 40px;
    gap: 24px;
  } 
  header {
    padding: 24px 16px 12px;
  }
  header .sub {
    border-left: none;
    padding-left: 0;
    margin-top: 8px;
    width: 100%;
  }
}

/* Board Frame and Container */
.board-wrap { 
  display: flex; 
  flex-direction: column; 
  gap: 16px; 
}

.board-frame {
  background: var(--panel-bg);
  backdrop-filter: blur(25px) saturate(190%);
  -webkit-backdrop-filter: blur(25px) saturate(190%);
  padding: 16px; 
  border-radius: var(--radius-lg);
  box-shadow: var(--panel-glow);
  border: 1px solid var(--panel-border);
  position: relative;
}

#board {
  display: grid; 
  grid-template-columns: repeat(8,1fr); 
  grid-template-rows: repeat(8,1fr);
  width: 100%; 
  aspect-ratio: 1/1; 
  border-radius: var(--radius-md);
  overflow: hidden;
  position: relative;
}

#overlay {
  position: absolute; 
  left: 16px; 
  top: 16px; 
  right: 16px; 
  bottom: 16px;
  pointer-events: none; 
  z-index: 5;
}

#overlay .arrow { 
  transition: opacity .3s ease; 
}

#overlay .node-pulse {
  fill: none; 
  stroke: var(--accent-teal); 
  stroke-width: 0.05;
  animation: nodepulse .65s cubic-bezier(0.1, 0.8, 0.3, 1) forwards;
}

@keyframes nodepulse {
  0% { r: 0.05; opacity: 1; } 
  100% { r: 0.48; opacity: 0; }
}

.sq { 
  position: relative; 
  display: flex; 
  align-items: center; 
  justify-content: center; 
  font-size: min(6vw, 42px); 
  cursor: pointer; 
  user-select: none;
  transition: background-color 0.2s ease, box-shadow 0.15s ease;
}

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

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

.sq .coord { 
  position: absolute; 
  font-size: 10px; 
  font-weight: 700;
  opacity: 0.45; 
  font-family: var(--mono-font);
  user-select: none;
  pointer-events: none;
}

.sq .coord.f { 
  bottom: 4px; 
  right: 5px;
}

.sq .coord.r { 
  top: 4px; 
  left: 5px;
}

.sq.light .coord { color: var(--sq-dark); }
.sq.dark .coord { color: var(--sq-light); }

.sq.selected { 
  box-shadow: inset 0 0 0 3px var(--accent-gold), 0 0 12px var(--accent-gold-glow); 
}

.sq.legal::after {
  content: ''; 
  position: absolute; 
  width: 14px; 
  height: 14px; 
  border-radius: 50%;
  background: rgba(16, 185, 129, 0.35);
  box-shadow: 0 0 6px rgba(16, 185, 129, 0.15);
  pointer-events: none;
}

.sq.capture::after { 
  content: '';
  position: absolute;
  width: 80%; 
  height: 80%; 
  border-radius: 50%;
  border: 3px solid rgba(248, 113, 113, 0.4);
  background: transparent;
  pointer-events: none;
  animation: pulseCapture 1.5s infinite ease-in-out;
}

@keyframes pulseCapture {
  0% { transform: scale(0.95); opacity: 0.8; }
  50% { transform: scale(1.02); opacity: 1; }
  100% { transform: scale(0.95); opacity: 0.8; }
}

.sq.lastmove { 
  box-shadow: inset 0 0 0 3px rgba(16, 185, 129, 0.3); 
  background: rgba(16, 185, 129, 0.06);
}

.sq.check { 
  background: radial-gradient(circle, rgba(224, 100, 88, 0.5) 0%, transparent 75%), var(--sq-dark); 
}

.piece { 
  pointer-events: none; 
  transition: transform 0.2s cubic-bezier(0.18, 0.89, 0.32, 1.28);
}

.sq:hover .piece {
  transform: scale(1.08);
}

.piece.white {
  color: #ffffff;
  -webkit-text-stroke: 1px rgba(10, 11, 14, 0.85);
  text-stroke: 1px rgba(10, 11, 14, 0.85);
  filter: drop-shadow(0 4px 6px rgba(0,0,0,0.25));
}

.piece.black {
  color: #1a202c;
  -webkit-text-stroke: 1px rgba(248, 250, 252, 0.85);
  text-stroke: 1px rgba(248, 250, 252, 0.85);
  filter: drop-shadow(0 4px 6px rgba(0,0,0,0.35));
}

/* Controls */
.controls { 
  display: flex; 
  gap: 10px; 
  flex-wrap: wrap; 
  align-items: center;
}

button {
  background: rgba(255, 255, 255, 0.03); 
  color: var(--text-secondary); 
  border: 1px solid rgba(255, 255, 255, 0.06);
  padding: 8px 16px; 
  border-radius: var(--radius-sm);
  cursor: pointer; 
  font-size: 13px; 
  font-weight: 500;
  font-family: inherit;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
  transition: var(--transition-smooth);
}

button:hover { 
  border-color: rgba(255, 255, 255, 0.15); 
  background: rgba(255, 255, 255, 0.08);
  color: var(--text-primary);
  transform: translateY(-1px);
}

button:active { 
  transform: translateY(0); 
}

button.primary { 
  background: var(--text-primary); 
  color: var(--bg-dark); 
  border: none;
  font-weight: 600;
}

button.primary:hover {
  background: #ffffff;
  box-shadow: 0 4px 16px rgba(255, 255, 255, 0.25);
  color: #000000;
}

select { 
  background: rgba(255, 255, 255, 0.03); 
  color: var(--text-secondary); 
  border: 1px solid rgba(255, 255, 255, 0.06); 
  padding: 8px 14px; 
  border-radius: var(--radius-sm);
  font-family: inherit;
  font-size: 13px;
  cursor: pointer;
  font-weight: 500;
  transition: var(--transition-smooth);
}

select:hover {
  border-color: rgba(255, 255, 255, 0.15);
  background: rgba(255, 255, 255, 0.08);
  color: var(--text-primary);
}

input[type=range] {
  -webkit-appearance: none; 
  appearance: none; 
  height: 4px; 
  background: rgba(255, 255, 255, 0.08); 
  border-radius: 99px;
  outline: none;
  transition: var(--transition-smooth);
}

input[type=range]::-webkit-slider-thumb {
  -webkit-appearance: none; 
  width: 14px; 
  height: 14px; 
  border-radius: 50%;
  background: var(--accent-teal);
  cursor: pointer; 
  border: 2px solid #0a0b0e;
  box-shadow: 0 0 8px var(--accent-teal-glow);
  transition: var(--transition-smooth);
}

input[type=range]::-webkit-slider-thumb:hover {
  transform: scale(1.2);
  background: #34d399;
}

input[type=range]::-moz-range-thumb {
  width: 14px; 
  height: 14px; 
  border-radius: 50%;
  background: var(--accent-teal); 
  cursor: pointer; 
  border: 2px solid #0a0b0e;
  box-shadow: 0 0 8px var(--accent-teal-glow);
  transition: var(--transition-smooth);
}

input[type=range]::-moz-range-thumb:hover {
  transform: scale(1.2);
  background: #34d399;
}

.status-line { 
  font-family: var(--mono-font); 
  font-size: 13px; 
  color: var(--text-secondary); 
  min-height: 20px;
  display: flex;
  align-items: center;
  gap: 6px;
}

.status-line b { 
  color: var(--accent-teal); 
}

.capt-row { 
  display: flex; 
  gap: 6px; 
  min-height: 24px; 
  font-size: 18px; 
  flex-wrap: wrap;
  align-items: center;
  color: var(--text-secondary);
}

/* Reasoning Panel - Apple Liquid Glass */
.think-panel {
  background: var(--panel-bg); 
  backdrop-filter: blur(25px) saturate(190%);
  -webkit-backdrop-filter: blur(25px) saturate(190%);
  border: 1px solid var(--panel-border); 
  border-radius: var(--radius-lg);
  padding: 24px; 
  display: flex; 
  flex-direction: column; 
  gap: 20px;
  max-height: calc(100vh - 60px); 
  overflow-y: auto;
  box-shadow: var(--panel-glow);
}

.think-panel h2 { 
  margin: 0; 
  font-size: 15px; 
  font-weight: 700;
  display: flex; 
  align-items: center; 
  gap: 10px;
  letter-spacing: 0.5px;
}

.dot { 
  width: 8px; 
  height: 8px; 
  border-radius: 50%;
  background: var(--text-dim); 
  transition: var(--transition-smooth);
}

.dot.live { 
  background: var(--accent-teal); 
  box-shadow: 0 0 12px var(--accent-teal); 
  animation: pulse 1.5s infinite;
}

@keyframes pulse { 
  0%, 100% { opacity: 1; transform: scale(1); } 
  50% { opacity: 0.35; transform: scale(1.15); } 
}

.metric-row { 
  display: grid; 
  grid-template-columns: repeat(4, 1fr); 
  gap: 10px;
}

.metric { 
  background: rgba(255, 255, 255, 0.02); 
  border: 1px solid rgba(255, 255, 255, 0.04); 
  border-radius: var(--radius-md);
  padding: 12px;
  display: flex;
  flex-direction: column;
  gap: 4px;
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.03);
  transition: var(--transition-smooth);
}

.metric:hover {
  background: rgba(255, 255, 255, 0.05);
  border-color: rgba(255, 255, 255, 0.08);
  transform: translateY(-2px);
}

.metric .v { 
  font-family: var(--mono-font); 
  font-size: 18px; 
  font-weight: 700; 
  color: var(--text-primary);
  letter-spacing: -0.5px;
}

.metric .l { 
  font-size: 9px; 
  color: var(--text-secondary); 
  text-transform: uppercase; 
  letter-spacing: 0.8px;
  font-weight: 600;
}

.eval-bar-wrap { 
  display: flex; 
  align-items: center; 
  gap: 12px; 
}

.eval-bar { 
  flex: 1; 
  height: 8px; 
  border-radius: 99px; 
  overflow: hidden; 
  background: rgba(255, 255, 255, 0.03); 
  border: 1px solid rgba(255, 255, 255, 0.04); 
  position: relative;
}

.eval-bar .fill { 
  position: absolute; 
  top: 0; 
  bottom: 0; 
  background: linear-gradient(90deg, var(--accent-teal), #34d399); 
  box-shadow: 0 0 8px var(--accent-teal-glow);
  border-radius: 99px;
  transition: width 0.3s cubic-bezier(0.4, 0, 0.2, 1), left 0.3s cubic-bezier(0.4, 0, 0.2, 1); 
}

.eval-num { 
  font-family: var(--mono-font); 
  font-size: 14px; 
  font-weight: 600;
  color: var(--text-primary);
  width: 60px; 
  text-align: right;
}

.section-label { 
  font-size: 10px; 
  text-transform: uppercase; 
  letter-spacing: 1.2px; 
  color: var(--text-secondary); 
  font-weight: 600;
  margin-bottom: 8px;
  margin-top: 4px;
  display: block;
}

.movecand { 
  font-family: var(--mono-font); 
  font-size: 12px; 
  border: 1px solid rgba(255, 255, 255, 0.04); 
  border-radius: var(--radius-md);
  overflow: hidden;
  background: rgba(255, 255, 255, 0.01);
}

.movecand table { 
  width: 100%; 
  border-collapse: collapse; 
}

.movecand th { 
  text-align: left; 
  padding: 8px 12px; 
  background: rgba(255, 255, 255, 0.03); 
  font-weight: 600; 
  color: var(--text-secondary); 
  font-size: 10px; 
  text-transform: uppercase;
  letter-spacing: 0.8px;
  border-bottom: 1px solid rgba(255, 255, 255, 0.04);
}

.movecand td { 
  padding: 8px 12px; 
  border-bottom: 1px solid rgba(255, 255, 255, 0.01); 
  color: var(--text-primary);
}

.movecand tr:last-child td {
  border-bottom: none;
}

.movecand tr.best td { 
  background: rgba(16, 185, 129, 0.05); 
  color: #34d399; 
  font-weight: 700;
}

.movecand tr.pruned td { 
  color: var(--danger); 
  opacity: .6; 
}

.badge { 
  display: inline-flex; 
  align-items: center;
  padding: 2px 8px; 
  font-size: 9px; 
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.4px;
  border-radius: 4px;
}

.badge.cap { 
  background: rgba(239, 68, 68, 0.12); 
  color: #fca5a5;
}

.badge.chk { 
  background: rgba(251, 191, 36, 0.12); 
  color: #fde047;
}

.log {
  font-family: var(--mono-font); 
  font-size: 11px; 
  line-height: 1.6; 
  white-space: pre-wrap;
  background: rgba(10, 11, 14, 0.45); 
  border: 1px solid rgba(255, 255, 255, 0.03); 
  border-radius: var(--radius-md);
  padding: 14px 16px;
  max-height: 260px; 
  overflow-y: auto; 
  color: #cbd5e1;
  box-shadow: inset 0 2px 8px rgba(0, 0, 0, 0.4);
}

.log .tag { color: var(--accent-gold); font-weight: 600; }
.log .tag2 { color: var(--accent-teal); font-weight: 600; }
.log .tag3 { color: var(--danger); font-weight: 600; }
.log .dim { color: var(--text-dim); }

.formula {
  font-family: var(--mono-font); 
  font-size: 11.5px; 
  line-height: 1.5;
  background: rgba(10, 11, 14, 0.45); 
  border: 1px solid rgba(255, 255, 255, 0.03);
  border-radius: var(--radius-md);
  padding: 14px 16px; 
  color: #cbd5e1;
  box-shadow: inset 0 2px 8px rgba(0, 0, 0, 0.4);
}

.formula .k { 
  color: var(--accent-gold); 
  font-weight: 600;
}

/* Scrollbars */
::-webkit-scrollbar { 
  width: 6px; 
  height: 6px;
}

::-webkit-scrollbar-thumb { 
  background: rgba(255, 255, 255, 0.12); 
  border-radius: 99px;
}

::-webkit-scrollbar-thumb:hover { 
  background: rgba(255, 255, 255, 0.2); 
}

::-webkit-scrollbar-track { 
  background: transparent;
}

#bg-canvas {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  z-index: -1;
  pointer-events: none;
  background: transparent;
}

/* GitHub Button - Customized from Uiverse.io */
.Btn {
  width: 38px;
  height: 38px;
  display: flex;
  align-items: center;
  justify-content: center;
  border: none;
  padding: 0;
  background-color: transparent;
  position: relative;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: var(--transition-smooth);
}

.svgContainer {
  width: 100%;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  background-color: transparent;
  backdrop-filter: blur(0px);
  -webkit-backdrop-filter: blur(0px);
  border-radius: var(--radius-sm);
  transition: var(--transition-smooth);
  border: 1px solid rgba(255, 255, 255, 0.08);
}

.svgContainer svg {
  width: 22px;
  height: 22px;
  transition: var(--transition-smooth);
}

.BG {
  position: absolute;
  content: "";
  width: 100%;
  height: 100%;
  background: #111520;
  border: 1px solid rgba(255, 255, 255, 0.05);
  z-index: -1;
  border-radius: var(--radius-sm);
  pointer-events: none;
  transition: var(--transition-smooth);
}

.Btn:hover .BG {
  transform: rotate(35deg);
  transform-origin: bottom;
}

.Btn:hover .svgContainer {
  background-color: rgba(255, 255, 255, 0.06);
  backdrop-filter: blur(4px);
  -webkit-backdrop-filter: blur(4px);
  border-color: rgba(255, 255, 255, 0.15);
}