:root {
  --bg-primary: #0D1117;
  --bg-secondary: #161B22;
  --bg-tertiary: #21262D;
  --text-primary: #F0F6FC;
  --text-secondary: #8B949E;
  --text-muted: #484F58;
  --accent: #3B82F6;
  --border: #30363D;
  --btn-bg: #21262D;
  --btn-active: #30363D;
  --overlay-bg: rgba(0, 0, 0, 0.85);
  --board-bg: #0A0E14;
}

@media (prefers-color-scheme: light) {
  :root {
    --bg-primary: #FFFFFF;
    --bg-secondary: #F6F8FA;
    --bg-tertiary: #E9ECF0;
    --text-primary: #1B1E28;
    --text-secondary: #57606A;
    --text-muted: #8C959F;
    --accent: #3182F6;
    --border: #D0D7DE;
    --btn-bg: #E9ECF0;
    --btn-active: #D0D7DE;
    --overlay-bg: rgba(255, 255, 255, 0.9);
    --board-bg: #F0F2F5;
  }
}

*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html, body {
  height: 100%;
  width: 100%;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Pretendard', 'Segoe UI', Roboto, sans-serif;
  background: var(--bg-primary);
  color: var(--text-primary);
  min-height: 100dvh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  overflow-x: hidden;
}

/* ===================== OVERLAY SCREENS ===================== */
.screen {
  display: none;
  position: fixed;
  inset: 0;
  background: var(--bg-primary);
  z-index: 100;
  align-items: center;
  justify-content: center;
  flex-direction: column;
  padding: 24px;
}

.screen.active {
  display: flex;
}

.screen-content {
  width: 100%;
  max-width: 480px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 24px;
}

/* ===================== START SCREEN ===================== */
#start-screen {
  backdrop-filter: blur(12px);
}

.game-title {
  font-size: clamp(2.4rem, 10vw, 3.6rem);
  font-weight: 800;
  letter-spacing: 0.08em;
  background: linear-gradient(135deg, var(--accent) 0%, #60A5FA 50%, #93C5FD 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  text-align: center;
  line-height: 1.1;
  filter: drop-shadow(0 0 24px rgba(59, 130, 246, 0.4));
}

.game-subtitle {
  font-size: 0.95rem;
  color: var(--text-secondary);
  text-align: center;
  letter-spacing: 0.04em;
}

.stats-panel {
  width: 100%;
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 16px 20px;
  display: flex;
  justify-content: space-around;
  gap: 12px;
}

.stat-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
}

.stat-value {
  font-size: 1.6rem;
  font-weight: 700;
  color: var(--accent);
}

.stat-label {
  font-size: 0.75rem;
  color: var(--text-muted);
  letter-spacing: 0.03em;
}

/* ===================== PLACE SCREEN ===================== */
#place-screen {
  overflow-y: auto;
}

.screen-title {
  font-size: 1.3rem;
  font-weight: 700;
  color: var(--text-primary);
  text-align: center;
}

.ship-list {
  width: 100%;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.ship-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 10px 14px;
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: 8px;
  font-size: 0.875rem;
  transition: border-color 0.2s;
}

.ship-item.placed {
  border-color: var(--accent);
  opacity: 0.7;
}

.ship-item.current {
  border-color: var(--accent);
  background: var(--bg-tertiary);
  box-shadow: 0 0 0 1px var(--accent);
}

.ship-name {
  font-weight: 600;
  color: var(--text-primary);
}

.ship-size-dots {
  display: flex;
  gap: 4px;
}

.ship-dot {
  width: 10px;
  height: 10px;
  border-radius: 2px;
  background: var(--text-muted);
}

.ship-item.placed .ship-dot,
.ship-item.current .ship-dot {
  background: var(--accent);
}

.ship-status {
  font-size: 0.75rem;
  color: var(--text-muted);
  min-width: 40px;
  text-align: right;
}

.ship-item.placed .ship-status {
  color: var(--accent);
}

/* ===================== GAME SCREEN ===================== */
#game-screen {
  background: var(--bg-primary);
  z-index: 10;
  position: relative;
  overflow-y: auto;
  align-items: flex-start;
  justify-content: flex-start;
}

.game-container {
  width: 100%;
  max-width: 480px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 12px;
  padding: 16px;
  min-height: 100dvh;
}

.game-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 4px 0;
}

.game-header-title {
  font-size: 1rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  background: linear-gradient(135deg, var(--accent), #60A5FA);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.turn-indicator {
  font-size: 0.8rem;
  font-weight: 600;
  padding: 4px 10px;
  border-radius: 20px;
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  color: var(--text-secondary);
  transition: all 0.3s;
}

.turn-indicator.player-turn {
  border-color: var(--accent);
  color: var(--accent);
}

.status-bar {
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 10px 14px;
  font-size: 0.875rem;
  color: var(--text-secondary);
  text-align: center;
  min-height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.3s;
}

.status-bar.hit { border-color: #EF4444; color: #EF4444; }
.status-bar.miss { border-color: var(--text-muted); color: var(--text-secondary); }
.status-bar.sunk { border-color: #F97316; color: #F97316; font-weight: 600; }
.status-bar.ai { border-color: var(--border); color: var(--text-secondary); }

/* ===================== BOARDS ===================== */
.boards-section {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.board-wrapper {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.board-label {
  font-size: 0.78rem;
  font-weight: 600;
  color: var(--text-muted);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  padding: 0 2px;
  display: flex;
  align-items: center;
  gap: 6px;
}

.board-label span.indicator {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--text-muted);
  display: inline-block;
}

.board-label.active span.indicator {
  background: var(--accent);
  box-shadow: 0 0 6px var(--accent);
}

.board-grid {
  display: grid;
  grid-template-columns: 20px repeat(10, 1fr);
  grid-template-rows: 20px repeat(10, 1fr);
  background: var(--board-bg);
  border: 1px solid var(--border);
  border-radius: 10px;
  overflow: hidden;
  aspect-ratio: 11/11;
  user-select: none;
}

.axis-label {
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.6rem;
  color: var(--text-muted);
  font-weight: 500;
}

.corner { background: var(--bg-secondary); }

.cell {
  border: 0.5px solid var(--border);
  position: relative;
  cursor: default;
  transition: background 0.15s;
  display: flex;
  align-items: center;
  justify-content: center;
}

.cell::after {
  content: '';
  position: absolute;
  inset: 2px;
  border-radius: 1px;
  transition: all 0.15s;
}

/* Ship cells on player board */
.cell.ship {
  background: rgba(59, 130, 246, 0.12);
}

.cell.ship::after {
  background: rgba(59, 130, 246, 0.35);
  border-radius: 2px;
}

/* Preview during placement */
.cell.preview-valid {
  background: rgba(59, 130, 246, 0.18);
}

.cell.preview-valid::after {
  background: rgba(59, 130, 246, 0.5);
}

.cell.preview-invalid {
  background: rgba(239, 68, 68, 0.12);
}

.cell.preview-invalid::after {
  background: rgba(239, 68, 68, 0.4);
}

/* Hit / Miss */
.cell.hit {
  background: rgba(239, 68, 68, 0.15);
}

.cell.hit::after {
  content: '';
  background: none;
}

.cell.hit .marker {
  color: #EF4444;
  font-size: 1.1em;
  font-weight: 900;
  line-height: 1;
  z-index: 2;
}

.cell.miss::after {
  background: var(--text-muted);
  border-radius: 50%;
  inset: 35%;
  opacity: 0.6;
}

/* Sunk ship overlay */
.cell.sunk {
  background: rgba(249, 115, 22, 0.15);
}

.cell.sunk .marker {
  color: #F97316;
  font-size: 1.1em;
  font-weight: 900;
  line-height: 1;
  z-index: 2;
}

/* Enemy board - clickable cells */
.enemy-board .cell:not(.hit):not(.miss):not(.sunk) {
  cursor: crosshair;
}

.enemy-board .cell:not(.hit):not(.miss):not(.sunk):hover {
  background: rgba(59, 130, 246, 0.1);
}

.enemy-board .cell:not(.hit):not(.miss):not(.sunk):active {
  background: rgba(59, 130, 246, 0.2);
}

/* Placement board */
.place-board .cell {
  cursor: crosshair;
}

.place-board .cell:hover:not(.ship) {
  background: rgba(59, 130, 246, 0.08);
}

/* ===================== SHIP TRACK (BOTTOM HUD) ===================== */
.ships-hud {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.hud-label {
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--text-muted);
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.ships-row {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
}

.ship-badge {
  display: flex;
  gap: 3px;
  align-items: center;
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 4px 7px;
  transition: all 0.3s;
}

.ship-badge.sunk {
  opacity: 0.4;
  border-style: dashed;
}

.ship-badge .block {
  width: 8px;
  height: 8px;
  border-radius: 1px;
  background: var(--accent);
}

.ship-badge.sunk .block {
  background: var(--text-muted);
}

/* ===================== BUTTONS ===================== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  padding: 12px 20px;
  border-radius: 10px;
  border: 1px solid var(--border);
  background: var(--btn-bg);
  color: var(--text-primary);
  font-family: inherit;
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.18s;
  letter-spacing: 0.02em;
  -webkit-tap-highlight-color: transparent;
}

.btn:hover {
  background: var(--btn-active);
  border-color: var(--accent);
}

.btn:active {
  transform: scale(0.97);
}

.btn-primary {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
}

.btn-primary:hover {
  background: #2563EB;
  border-color: #2563EB;
}

.btn-sm {
  padding: 8px 14px;
  font-size: 0.8rem;
  border-radius: 8px;
}

.btn-danger {
  border-color: #EF4444;
  color: #EF4444;
}

.btn-danger:hover {
  background: rgba(239, 68, 68, 0.1);
}

.btn-group {
  display: flex;
  gap: 8px;
  width: 100%;
}

.btn-group .btn {
  flex: 1;
}

.btn-full {
  width: 100%;
}

/* ===================== RESULT SCREEN ===================== */
#result-screen .screen-content {
  gap: 20px;
}

.result-emoji {
  font-size: 4rem;
  line-height: 1;
  filter: drop-shadow(0 4px 16px rgba(0, 0, 0, 0.3));
}

.result-title {
  font-size: 2rem;
  font-weight: 800;
  text-align: center;
  letter-spacing: 0.04em;
}

.result-title.win {
  background: linear-gradient(135deg, #3B82F6, #60A5FA, #93C5FD);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.result-title.lose {
  color: var(--text-secondary);
}

.result-desc {
  font-size: 0.9rem;
  color: var(--text-secondary);
  text-align: center;
  line-height: 1.5;
}

.result-stats {
  width: 100%;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 8px;
}

.result-stat {
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 12px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
}

.result-stat-val {
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--accent);
}

.result-stat-label {
  font-size: 0.72rem;
  color: var(--text-muted);
  text-align: center;
}

/* ===================== TOAST ===================== */
.toast-container {
  position: fixed;
  top: 16px;
  left: 50%;
  transform: translateX(-50%);
  z-index: 999;
  display: flex;
  flex-direction: column;
  gap: 8px;
  pointer-events: none;
  width: 90%;
  max-width: 360px;
}

.toast {
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 12px 16px;
  font-size: 0.875rem;
  color: var(--text-primary);
  text-align: center;
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.3);
  animation: toastIn 0.3s ease, toastOut 0.3s ease 1.7s forwards;
  backdrop-filter: blur(8px);
}

.toast.sunk-toast {
  border-color: #F97316;
  color: #F97316;
  background: rgba(249, 115, 22, 0.08);
}

@keyframes toastIn {
  from { opacity: 0; transform: translateY(-12px) scale(0.96); }
  to   { opacity: 1; transform: translateY(0) scale(1); }
}

@keyframes toastOut {
  from { opacity: 1; }
  to   { opacity: 0; transform: translateY(-8px); }
}

/* ===================== AI THINKING ANIMATION ===================== */
.thinking-dots {
  display: inline-flex;
  gap: 4px;
  align-items: center;
}

.thinking-dots span {
  width: 5px;
  height: 5px;
  border-radius: 50%;
  background: var(--text-muted);
  animation: bounce 0.9s infinite;
}

.thinking-dots span:nth-child(2) { animation-delay: 0.15s; }
.thinking-dots span:nth-child(3) { animation-delay: 0.3s; }

@keyframes bounce {
  0%, 80%, 100% { transform: scale(0.7); opacity: 0.4; }
  40% { transform: scale(1); opacity: 1; }
}

/* ===================== SUNK SHIP FLASH ===================== */
@keyframes sunkFlash {
  0%, 100% { background: rgba(249, 115, 22, 0.15); }
  50% { background: rgba(249, 115, 22, 0.35); }
}

.cell.sunk-flash {
  animation: sunkFlash 0.4s ease 3;
}

/* ===================== SCROLLBAR ===================== */
::-webkit-scrollbar { width: 4px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--border); border-radius: 2px; }

/* ===================== RESPONSIVE FINE-TUNE ===================== */
@media (max-height: 700px) {
  .game-container { gap: 8px; padding: 10px; }
  .boards-section { gap: 8px; }
}

@media (max-width: 360px) {
  .btn { padding: 10px 14px; font-size: 0.82rem; }
}