:root {
  /* Colors */
  --bg-primary: #0a0e17;
  --bg-secondary: #0f1524;
  --card-bg: rgba(15, 21, 36, 0.7);
  --card-border: rgba(255, 255, 255, 0.08);
  
  --text-primary: #f8fafc;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;
  
  --primary: #00e5ff; /* Cyan glow */
  --primary-rgb: 0, 229, 255;
  --secondary: #d500f9; /* Pink/Purple glow */
  --secondary-rgb: 213, 0, 249;
  
  --accent-win: #10b981; /* Emerald */
  --accent-lose: #ef4444; /* Rose */
  
  --stone-black: #111827;
  --stone-black-glow: rgba(0, 229, 255, 0.4);
  --stone-white: #ffffff;
  --stone-white-glow: rgba(213, 0, 249, 0.4);
  
  --font-family: 'Outfit', 'Noto Sans KR', sans-serif;
  --transition-smooth: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  --shadow-glow-cyan: 0 0 15px rgba(0, 229, 255, 0.3);
  --shadow-glow-pink: 0 0 15px rgba(213, 0, 249, 0.3);
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  -webkit-tap-highlight-color: transparent;
}

body {
  font-family: var(--font-family);
  background-color: var(--bg-primary);
  background-image: 
    radial-gradient(at 0% 0%, rgba(0, 229, 255, 0.05) 0px, transparent 50%),
    radial-gradient(at 100% 0%, rgba(213, 0, 249, 0.05) 0px, transparent 50%),
    radial-gradient(at 50% 100%, rgba(15, 21, 36, 0.9) 0px, transparent 70%);
  background-attachment: fixed;
  color: var(--text-primary);
  min-height: 100vh;
  display: flex;
  justify-content: center;
  overflow-x: hidden;
  line-height: 1.5;
}

/* Scrollbar customization */
::-webkit-scrollbar {
  width: 8px;
}
::-webkit-scrollbar-track {
  background: var(--bg-primary);
}
::-webkit-scrollbar-thumb {
  background: var(--card-border);
  border-radius: 4px;
}
::-webkit-scrollbar-thumb:hover {
  background: var(--text-muted);
}

.app-container {
  width: 100%;
  max-width: 1200px;
  padding: 24px;
  display: flex;
  flex-direction: column;
  gap: 24px;
}

/* Header */
.app-header {
  text-align: center;
  margin-bottom: 8px;
  animation: fadeInDown 0.6s ease-out;
}

.logo-title {
  font-size: 2.5rem;
  font-weight: 800;
  letter-spacing: 2px;
  color: var(--text-primary);
  text-shadow: 0 0 20px rgba(255, 255, 255, 0.1);
}

.logo-title span {
  color: var(--primary);
  text-shadow: var(--shadow-glow-cyan);
}

.logo-subtitle {
  font-size: 0.95rem;
  color: var(--text-secondary);
  font-weight: 300;
  margin-top: 4px;
}

/* Main Layout */
.main-layout {
  display: grid;
  grid-template-columns: 320px 1fr;
  gap: 24px;
  align-items: start;
}

/* Card Styling (Glassmorphism) */
.card {
  background: var(--card-bg);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid var(--card-border);
  border-radius: 16px;
  padding: 20px;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.3);
  transition: var(--transition-smooth);
}

.card:hover {
  border-color: rgba(0, 229, 255, 0.2);
  box-shadow: 0 10px 35px rgba(0, 229, 255, 0.05);
}

.card-title {
  font-size: 1.15rem;
  font-weight: 600;
  margin-bottom: 16px;
  color: var(--text-primary);
  border-bottom: 1px solid rgba(255, 255, 255, 0.05);
  padding-bottom: 8px;
  letter-spacing: 0.5px;
}

/* Control Panel */
.control-panel {
  display: flex;
  flex-direction: column;
  gap: 20px;
  animation: fadeInLeft 0.6s ease-out;
}

/* Scoreboard */
.score-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 12px;
}

.score-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 12px 8px;
  border-radius: 12px;
  background: rgba(255, 255, 255, 0.02);
  border: 1px solid rgba(255, 255, 255, 0.03);
  transition: var(--transition-smooth);
}

.score-item.win { border-left: 3px solid var(--accent-win); }
.score-item.lose { border-left: 3px solid var(--accent-lose); }
.score-item.streak { border-left: 3px solid var(--primary); }
.score-item.max-streak { border-left: 3px solid var(--secondary); }

.score-label {
  font-size: 0.75rem;
  color: var(--text-secondary);
  margin-bottom: 4px;
}

.score-value {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--text-primary);
}

/* Settings */
.setting-group {
  margin-bottom: 16px;
}

.setting-label {
  display: block;
  font-size: 0.85rem;
  color: var(--text-secondary);
  margin-bottom: 8px;
}

/* Segmented Control */
.segmented-control {
  display: flex;
  background: rgba(0, 0, 0, 0.2);
  border-radius: 10px;
  padding: 3px;
  border: 1px solid rgba(255, 255, 255, 0.05);
  position: relative;
}

.segmented-control input[type="radio"] {
  display: none;
}

.segmented-control label {
  flex: 1;
  text-align: center;
  padding: 8px 0;
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--text-secondary);
  cursor: pointer;
  border-radius: 8px;
  transition: var(--transition-smooth);
  user-select: none;
}

.segmented-control input[type="radio"]:checked + label {
  background: var(--primary);
  color: var(--bg-primary);
  font-weight: 700;
  box-shadow: var(--shadow-glow-cyan);
}

/* Special color for secondary select option in segment */
.segmented-control.three-options input[value="easy"]:checked + label {
  background: #10b981;
  box-shadow: 0 0 10px rgba(16, 185, 129, 0.4);
}
.segmented-control.three-options input[value="medium"]:checked + label {
  background: var(--primary);
  box-shadow: var(--shadow-glow-cyan);
}
.segmented-control.three-options input[value="hard"]:checked + label {
  background: var(--secondary);
  box-shadow: var(--shadow-glow-pink);
}

/* Toggle Group */
.toggle-group {
  margin-top: 16px;
  display: flex;
  flex-direction: column;
  gap: 12px;
  border-top: 1px solid rgba(255, 255, 255, 0.05);
  padding-top: 16px;
}

.toggle-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.toggle-label {
  font-size: 0.85rem;
  color: var(--text-secondary);
}

/* Toggle Switch */
.switch {
  position: relative;
  display: inline-block;
  width: 44px;
  height: 24px;
}

.switch input {
  opacity: 0;
  width: 0;
  height: 0;
}

.slider {
  position: absolute;
  cursor: pointer;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background-color: rgba(255, 255, 255, 0.1);
  transition: .4s;
  border: 1px solid rgba(255, 255, 255, 0.05);
}

.slider:before {
  position: absolute;
  content: "";
  height: 16px;
  width: 16px;
  left: 3px;
  bottom: 3px;
  background-color: var(--text-primary);
  transition: .4s;
  box-shadow: 0 2px 4px rgba(0,0,0,0.4);
}

input:checked + .slider {
  background-color: rgba(0, 229, 255, 0.2);
  border-color: var(--primary);
}

input:checked + .slider:before {
  transform: translateX(20px);
  background-color: var(--primary);
  box-shadow: var(--shadow-glow-cyan);
}

.slider.round {
  border-radius: 24px;
}

.slider.round:before {
  border-radius: 50%;
}

/* Actions Buttons */
.action-buttons {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.btn {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 20px;
  border-radius: 12px;
  font-family: var(--font-family);
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  border: none;
  transition: var(--transition-smooth);
  user-select: none;
  width: 100%;
}

.btn-primary {
  background: linear-gradient(135deg, var(--primary) 0%, #00b0ff 100%);
  color: var(--bg-primary);
  box-shadow: var(--shadow-glow-cyan);
}

.btn-primary:hover:not(:disabled) {
  transform: translateY(-2px);
  box-shadow: 0 0 20px rgba(0, 229, 255, 0.5);
}

.btn-secondary {
  background: rgba(255, 255, 255, 0.03);
  color: var(--text-primary);
  border: 1px solid var(--card-border);
}

.btn-secondary:hover:not(:disabled) {
  background: rgba(255, 255, 255, 0.08);
  border-color: rgba(255, 255, 255, 0.15);
}

.btn:active:not(:disabled) {
  transform: translateY(1px);
}

.btn:disabled {
  opacity: 0.3;
  cursor: not-allowed;
  transform: none !important;
  box-shadow: none !important;
}

/* Board Area */
.board-area {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 16px;
  animation: fadeInRight 0.6s ease-out;
}

/* Turn Indicator Status Banner */
.status-banner {
  width: 100%;
  display: flex;
  align-items: center;
  gap: 12px;
  background: rgba(255, 255, 255, 0.02);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  border: 1px solid var(--card-border);
  border-radius: 12px;
  padding: 12px 20px;
  font-size: 0.95rem;
  font-weight: 500;
  box-shadow: 0 4px 15px rgba(0, 0, 0, 0.15);
}

.turn-indicator {
  width: 16px;
  height: 16px;
  border-radius: 50%;
  transition: var(--transition-smooth);
}

.turn-indicator.black {
  background: var(--stone-black);
  border: 2px solid var(--primary);
  box-shadow: var(--shadow-glow-cyan);
}

.turn-indicator.white {
  background: var(--stone-white);
  border: 2px solid var(--secondary);
  box-shadow: var(--shadow-glow-pink);
}

.turn-indicator.thinking {
  background: var(--text-muted);
  border: 2px solid transparent;
  animation: pulse 1s infinite alternate;
}

/* Canvas Board Wrapper */
.board-wrapper {
  background: rgba(10, 14, 23, 0.8);
  border: 2px solid rgba(255, 255, 255, 0.04);
  border-radius: 20px;
  padding: 10px;
  box-shadow: 
    0 15px 40px rgba(0, 0, 0, 0.5),
    inset 0 0 20px rgba(255, 255, 255, 0.02);
  position: relative;
  max-width: 100%;
}

.canvas-container {
  position: relative;
  width: 600px;
  height: 600px;
  max-width: 100%;
  max-height: 100%;
  aspect-ratio: 1 / 1;
}

#omok-canvas {
  width: 100%;
  height: 100%;
  display: block;
  cursor: crosshair;
  border-radius: 10px;
}

/* Mobile Placement Confirm Overlay Button */
.mobile-confirm-btn {
  position: absolute;
  bottom: 24px;
  left: 50%;
  transform: translateX(-50%);
  background: rgba(0, 229, 255, 0.85);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  color: var(--bg-primary);
  font-weight: 700;
  font-size: 1rem;
  padding: 12px 30px;
  border-radius: 30px;
  box-shadow: 0 4px 20px rgba(0, 229, 255, 0.4);
  cursor: pointer;
  transition: var(--transition-smooth);
  user-select: none;
  z-index: 5;
  border: 1px solid rgba(255, 255, 255, 0.2);
}

.mobile-confirm-btn:hover {
  background: #00e5ff;
  box-shadow: 0 4px 25px rgba(0, 229, 255, 0.6);
}

.mobile-confirm-btn.hidden {
  display: none;
  opacity: 0;
  transform: translate(-50%, 10px);
}

/* Instruction card */
.instructions-card {
  width: 100%;
  padding: 12px 16px;
}

.instruction-text {
  font-size: 0.8rem;
  color: var(--text-secondary);
  line-height: 1.45;
}

.instruction-text strong {
  color: var(--primary);
}

/* Game Over Modal overlay */
.modal-overlay {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(5, 7, 12, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 100;
  transition: opacity 0.4s ease;
}

.modal-overlay.hidden {
  display: none;
  opacity: 0;
  pointer-events: none;
}

.modal-content {
  background: linear-gradient(180deg, rgba(15, 21, 36, 0.95) 0%, rgba(10, 14, 23, 0.95) 100%);
  border: 1px solid rgba(255, 255, 255, 0.1);
  border-radius: 24px;
  width: 90%;
  max-width: 440px;
  padding: 30px;
  box-shadow: 
    0 25px 50px rgba(0, 0, 0, 0.6),
    0 0 40px rgba(0, 229, 255, 0.05);
  animation: modalSlideUp 0.4s cubic-bezier(0.34, 1.56, 0.64, 1);
}

.modal-header {
  text-align: center;
  margin-bottom: 20px;
}

.modal-tag {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 2px;
  padding: 4px 12px;
  border-radius: 20px;
  background: rgba(0, 229, 255, 0.1);
  color: var(--primary);
  border: 1px solid rgba(0, 229, 255, 0.2);
  margin-bottom: 8px;
}

.modal-tag.lose {
  background: rgba(239, 68, 68, 0.1);
  color: var(--accent-lose);
  border-color: rgba(239, 68, 68, 0.2);
}

.modal-title {
  font-size: 1.8rem;
  font-weight: 800;
  color: var(--text-primary);
}

.modal-body {
  text-align: center;
  margin-bottom: 24px;
  color: var(--text-secondary);
  font-size: 0.95rem;
}

.modal-stats {
  display: flex;
  justify-content: space-around;
  background: rgba(0, 0, 0, 0.2);
  border: 1px solid rgba(255, 255, 255, 0.03);
  border-radius: 16px;
  padding: 16px;
  margin-top: 20px;
}

.modal-stat-box {
  display: flex;
  flex-direction: column;
  align-items: center;
}

.m-stat-label {
  font-size: 0.75rem;
  color: var(--text-muted);
  margin-bottom: 4px;
}

.m-stat-val {
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--text-primary);
}

.modal-footer .btn-block {
  width: 100%;
}

/* Animations */
@keyframes pulse {
  from { opacity: 0.5; }
  to { opacity: 1; }
}

@keyframes fadeInDown {
  from {
    opacity: 0;
    transform: translateY(-20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes fadeInLeft {
  from {
    opacity: 0;
    transform: translateX(-30px);
  }
  to {
    opacity: 1;
    transform: translateX(0);
  }
}

@keyframes fadeInRight {
  from {
    opacity: 0;
    transform: translateX(30px);
  }
  to {
    opacity: 1;
    transform: translateX(0);
  }
}

@keyframes modalSlideUp {
  from {
    opacity: 0;
    transform: translateY(30px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* Responsive adjustments */
@media (max-width: 900px) {
  .main-layout {
    grid-template-columns: 1fr;
    gap: 20px;
  }
  
  .control-panel {
    order: 2; /* Put controls below board on tablet/mobile */
  }
  
  .board-area {
    order: 1;
  }
  
  .canvas-container {
    width: 100vw;
    height: 100vw;
    max-width: 520px;
    max-height: 520px;
  }
}

@media (max-width: 500px) {
  body {
    background-attachment: initial; /* performance booster on mobile */
  }
  
  .app-container {
    padding: 12px;
    gap: 16px;
  }
  
  .logo-title {
    font-size: 2rem;
  }
  
  .card {
    padding: 16px;
  }
  
  .canvas-container {
    max-width: 100%;
    max-height: 100%;
  }
}