/* -------------------------------------------------------------
 * Stellar 64: Supernova - Core Style (index.css)
 * ------------------------------------------------------------- */

/* Reset & Base Variables */
:root {
  --color-bg: #03030c;
  --color-panel-bg: rgba(10, 10, 26, 0.6);
  --color-border: rgba(255, 255, 255, 0.08);
  --font-main: 'Outfit', sans-serif;
  --font-display: 'Space Grotesk', sans-serif;
  --board-size: min(440px, 92vw);
  --grid-gap: 12px;
  --cell-size: calc((var(--board-size) - (var(--grid-gap) * 6)) / 5);
}

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

body {
  background-color: var(--color-bg);
  color: #f1f5f9;
  font-family: var(--font-main);
  overflow-x: hidden;
  min-height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
}

/* 3D 스페이스 움직이는 배경 */
.stars-bg {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: radial-gradient(circle at center, rgba(16, 16, 48, 0.4) 0%, rgba(3, 3, 12, 1) 80%),
              url('data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" width="200" height="200"><circle cx="15" cy="20" r="1" fill="%23fff" opacity="0.3"/><circle cx="115" cy="80" r="1.5" fill="%23fff" opacity="0.7"/><circle cx="75" cy="140" r="0.8" fill="%23fff" opacity="0.4"/><circle cx="180" cy="170" r="1.2" fill="%23fff" opacity="0.6"/></svg>');
  z-index: -2;
  animation: bg-pan 120s linear infinite;
}

.nebula-bg {
  position: fixed;
  top: -50%;
  left: -50%;
  width: 200%;
  height: 200%;
  background: radial-gradient(circle at 30% 40%, rgba(99, 102, 241, 0.15) 0%, transparent 40%),
              radial-gradient(circle at 70% 60%, rgba(244, 63, 94, 0.12) 0%, transparent 40%);
  z-index: -1;
  filter: blur(80px);
  animation: nebula-rotate 80s ease-in-out infinite alternate;
}

@keyframes bg-pan {
  from { background-position: 0 0; }
  to { background-position: 1000px 1000px; }
}

@keyframes nebula-rotate {
  from { transform: rotate(0deg) scale(1); }
  to { transform: rotate(360deg) scale(1.1); }
}

/* 메인 레이아웃 컨테이너 */
.game-container {
  display: flex;
  flex-direction: column;
  align-items: center;
  width: 100%;
  max-width: 480px;
  padding: 16px;
  z-index: 10;
}

/* 헤더 섹션 */
.game-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  width: 100%;
  margin-bottom: 12px;
}

.title-section {
  display: flex;
  flex-direction: column;
}

.logo-text {
  font-family: var(--font-display);
  font-weight: 800;
  font-size: 2.2rem;
  letter-spacing: -1px;
  background: linear-gradient(135deg, #38bdf8, #818cf8, #f43f5e);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  filter: drop-shadow(0 0 15px rgba(56, 189, 248, 0.3));
}

.sub-logo {
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 3px;
  color: #94a3b8;
  text-transform: uppercase;
}

.stats-section {
  display: flex;
  gap: 8px;
}

.stat-box {
  background: var(--color-panel-bg);
  border: 1px solid var(--color-border);
  backdrop-filter: blur(8px);
  padding: 6px 12px;
  border-radius: 8px;
  text-align: center;
  min-width: 65px;
}

.stat-box.highlight {
  border-color: rgba(251, 191, 36, 0.4);
  background: rgba(251, 191, 36, 0.05);
}

.stat-label {
  font-size: 0.6rem;
  font-weight: 600;
  color: #94a3b8;
  letter-spacing: 1px;
  margin-bottom: 2px;
}

.stat-value {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 1.1rem;
}

/* 별 온도 패널 */
.status-panel {
  width: 100%;
  background: var(--color-panel-bg);
  border: 1px solid var(--color-border);
  backdrop-filter: blur(8px);
  padding: 12px;
  border-radius: 12px;
  margin-bottom: 16px;
}

.gauge-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 6px;
}

.status-label {
  font-size: 0.8rem;
  font-weight: 600;
  color: #cbd5e1;
}

.temp-text {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 0.95rem;
  color: #38bdf8;
  text-shadow: 0 0 8px rgba(56, 189, 248, 0.4);
}

.progress-bar-container {
  width: 100%;
  height: 8px;
  background: rgba(255, 255, 255, 0.05);
  border-radius: 4px;
  overflow: hidden;
  margin-bottom: 6px;
  border: 1px solid rgba(255, 255, 255, 0.05);
}

.progress-bar {
  height: 100%;
  background: linear-gradient(90deg, #0ea5e9, #f43f5e);
  box-shadow: 0 0 10px rgba(244, 63, 94, 0.5);
  transition: width 0.3s ease;
}

.stellar-state-text {
  font-size: 0.75rem;
  color: #94a3b8;
  text-align: center;
  font-weight: 400;
}

/* 컨트롤 패널 */
.control-panel {
  display: flex;
  width: 100%;
  gap: 8px;
  margin-bottom: 16px;
}

.btn {
  flex: 1;
  border: none;
  padding: 10px 14px;
  border-radius: 8px;
  font-family: var(--font-main);
  font-weight: 600;
  font-size: 0.85rem;
  cursor: pointer;
  transition: all 0.2s ease;
  display: inline-flex;
  justify-content: center;
  align-items: center;
}

.btn-primary {
  background: linear-gradient(135deg, #6366f1, #4f46e5);
  color: #fff;
  box-shadow: 0 4px 12px rgba(99, 102, 241, 0.3);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 16px rgba(99, 102, 241, 0.5);
}

.btn-secondary {
  background: rgba(255, 255, 255, 0.08);
  color: #cbd5e1;
  border: 1px solid var(--color-border);
}

.btn-secondary:hover {
  background: rgba(255, 255, 255, 0.15);
  color: #fff;
}

.btn-info {
  background: rgba(14, 165, 233, 0.15);
  color: #38bdf8;
  border: 1px solid rgba(14, 165, 233, 0.3);
}

.btn-info:hover {
  background: rgba(14, 165, 233, 0.25);
}

/* 4x4 게임 보드 */
.board-wrapper {
  background: radial-gradient(circle at center, rgba(30, 30, 60, 0.3) 0%, rgba(10, 10, 20, 0.7) 100%);
  border: 1px solid rgba(255, 255, 255, 0.1);
  border-radius: 16px;
  padding: var(--grid-gap);
  box-shadow: 0 20px 40px rgba(0, 0, 0, 0.5),
              0 0 30px rgba(99, 102, 241, 0.1);
}

.game-board {
  position: relative;
  width: var(--board-size);
  height: var(--board-size);
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  grid-template-rows: repeat(5, 1fr);
  gap: var(--grid-gap);
  user-select: none;
  touch-action: none;
}

/* 격자 배경 셀 */
.grid-cell {
  width: 100%;
  height: 100%;
  background: rgba(255, 255, 255, 0.02);
  border: 1px solid rgba(255, 255, 255, 0.03);
  border-radius: 10px;
}

/* 동적 타일 컨테이너 */
.tile-container {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: 10;
  pointer-events: none; /* 슬라이드 스와이프를 막지 않기 위해 */
}

/* 개별 원소 타일 */
.tile {
  position: absolute;
  width: var(--cell-size);
  height: var(--cell-size);
  border-radius: 10px;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  font-family: var(--font-display);
  font-weight: 800;
  text-align: center;
  transition: transform 0.12s ease-in-out, scale 0.12s ease-in-out, rotate 0.12s ease-in-out;
  scale: 1;
  animation: spawn-tile 0.2s cubic-bezier(0.175, 0.885, 0.32, 1.275);
  box-shadow: 0 4px 10px rgba(0,0,0,0.3);
  cursor: pointer; /* 초신성핵 터치 유도용 */
  pointer-events: auto; /* 타일 클릭은 막지 않음 */
}

/* 타일 배치 위치 유틸리티 (0~4 인덱스 대응) */
.tile-position-0-0 { transform: translate(calc(var(--grid-gap) * 1 + var(--cell-size) * 0), calc(var(--grid-gap) * 1 + var(--cell-size) * 0)); }
.tile-position-0-1 { transform: translate(calc(var(--grid-gap) * 2 + var(--cell-size) * 1), calc(var(--grid-gap) * 1 + var(--cell-size) * 0)); }
.tile-position-0-2 { transform: translate(calc(var(--grid-gap) * 3 + var(--cell-size) * 2), calc(var(--grid-gap) * 1 + var(--cell-size) * 0)); }
.tile-position-0-3 { transform: translate(calc(var(--grid-gap) * 4 + var(--cell-size) * 3), calc(var(--grid-gap) * 1 + var(--cell-size) * 0)); }
.tile-position-0-4 { transform: translate(calc(var(--grid-gap) * 5 + var(--cell-size) * 4), calc(var(--grid-gap) * 1 + var(--cell-size) * 0)); }

.tile-position-1-0 { transform: translate(calc(var(--grid-gap) * 1 + var(--cell-size) * 0), calc(var(--grid-gap) * 2 + var(--cell-size) * 1)); }
.tile-position-1-1 { transform: translate(calc(var(--grid-gap) * 2 + var(--cell-size) * 1), calc(var(--grid-gap) * 2 + var(--cell-size) * 1)); }
.tile-position-1-2 { transform: translate(calc(var(--grid-gap) * 3 + var(--cell-size) * 2), calc(var(--grid-gap) * 2 + var(--cell-size) * 1)); }
.tile-position-1-3 { transform: translate(calc(var(--grid-gap) * 4 + var(--cell-size) * 3), calc(var(--grid-gap) * 2 + var(--cell-size) * 1)); }
.tile-position-1-4 { transform: translate(calc(var(--grid-gap) * 5 + var(--cell-size) * 4), calc(var(--grid-gap) * 2 + var(--cell-size) * 1)); }

.tile-position-2-0 { transform: translate(calc(var(--grid-gap) * 1 + var(--cell-size) * 0), calc(var(--grid-gap) * 3 + var(--cell-size) * 2)); }
.tile-position-2-1 { transform: translate(calc(var(--grid-gap) * 2 + var(--cell-size) * 1), calc(var(--grid-gap) * 3 + var(--cell-size) * 2)); }
.tile-position-2-2 { transform: translate(calc(var(--grid-gap) * 3 + var(--cell-size) * 2), calc(var(--grid-gap) * 3 + var(--cell-size) * 2)); }
.tile-position-2-3 { transform: translate(calc(var(--grid-gap) * 4 + var(--cell-size) * 3), calc(var(--grid-gap) * 3 + var(--cell-size) * 2)); }
.tile-position-2-4 { transform: translate(calc(var(--grid-gap) * 5 + var(--cell-size) * 4), calc(var(--grid-gap) * 3 + var(--cell-size) * 2)); }

.tile-position-3-0 { transform: translate(calc(var(--grid-gap) * 1 + var(--cell-size) * 0), calc(var(--grid-gap) * 4 + var(--cell-size) * 3)); }
.tile-position-3-1 { transform: translate(calc(var(--grid-gap) * 2 + var(--cell-size) * 1), calc(var(--grid-gap) * 4 + var(--cell-size) * 3)); }
.tile-position-3-2 { transform: translate(calc(var(--grid-gap) * 3 + var(--cell-size) * 2), calc(var(--grid-gap) * 4 + var(--cell-size) * 3)); }
.tile-position-3-3 { transform: translate(calc(var(--grid-gap) * 4 + var(--cell-size) * 3), calc(var(--grid-gap) * 4 + var(--cell-size) * 3)); }
.tile-position-3-4 { transform: translate(calc(var(--grid-gap) * 5 + var(--cell-size) * 4), calc(var(--grid-gap) * 4 + var(--cell-size) * 3)); }

.tile-position-4-0 { transform: translate(calc(var(--grid-gap) * 1 + var(--cell-size) * 0), calc(var(--grid-gap) * 5 + var(--cell-size) * 4)); }
.tile-position-4-1 { transform: translate(calc(var(--grid-gap) * 2 + var(--cell-size) * 1), calc(var(--grid-gap) * 5 + var(--cell-size) * 4)); }
.tile-position-4-2 { transform: translate(calc(var(--grid-gap) * 3 + var(--cell-size) * 2), calc(var(--grid-gap) * 5 + var(--cell-size) * 4)); }
.tile-position-4-3 { transform: translate(calc(var(--grid-gap) * 4 + var(--cell-size) * 3), calc(var(--grid-gap) * 5 + var(--cell-size) * 4)); }
.tile-position-4-4 { transform: translate(calc(var(--grid-gap) * 5 + var(--cell-size) * 4), calc(var(--grid-gap) * 5 + var(--cell-size) * 4)); }

/* 원소 기호 및 질량수 스타일 */
.tile-symbol {
  font-size: 1.8rem;
  line-height: 1;
}

.tile-mass {
  position: absolute;
  top: 6px;
  right: 8px;
  font-size: 0.75rem;
  font-weight: 600;
  opacity: 0.85;
}

.tile-name {
  font-size: 0.65rem;
  font-weight: 400;
  opacity: 0.7;
  margin-top: 1px;
}

/* 타일별 스펙트럼 (디자인 테마) */
.tile-val-1 {
  background: linear-gradient(135deg, #bae6fd, #0284c7);
  color: #fff;
  box-shadow: 0 0 10px rgba(186, 230, 253, 0.4);
}

.tile-val-2 {
  background: linear-gradient(135deg, #38bdf8, #0369a1);
  color: #fff;
  box-shadow: 0 0 12px rgba(56, 189, 248, 0.5);
}

.tile-val-4 {
  background: linear-gradient(135deg, #fdba74, #ea580c);
  color: #fff;
  box-shadow: 0 0 15px rgba(253, 186, 116, 0.6);
}

.tile-val-8 {
  background: linear-gradient(135deg, #a7f3d0, #059669);
  color: #fff;
  box-shadow: 0 0 15px rgba(167, 243, 208, 0.6);
}

.tile-val-12 {
  background: linear-gradient(135deg, #c084fc, #7c3aed);
  color: #fff;
  box-shadow: 0 0 18px rgba(192, 132, 252, 0.6);
}

.tile-val-16 {
  background: linear-gradient(135deg, #f87171, #dc2626);
  color: #fff;
  box-shadow: 0 0 18px rgba(248, 113, 113, 0.6);
}

.tile-val-20 {
  background: linear-gradient(135deg, #f472b6, #db2777);
  color: #fff;
  box-shadow: 0 0 20px rgba(244, 114, 182, 0.7);
}

.tile-val-24 {
  background: linear-gradient(135deg, #fde047, #ca8a04);
  color: #0f172a;
  box-shadow: 0 0 20px rgba(253, 224, 71, 0.7);
}

.tile-val-28 {
  background: linear-gradient(135deg, #2dd4bf, #0f766e);
  color: #fff;
  box-shadow: 0 0 22px rgba(45, 212, 191, 0.7);
}

.tile-val-32 {
  background: linear-gradient(135deg, #fb7185, #be123c);
  color: #fff;
  box-shadow: 0 0 22px rgba(251, 113, 133, 0.7);
}

.tile-val-56 {
  background: linear-gradient(135deg, #cbd5e1, #475569);
  color: #fff;
  box-shadow: 0 0 25px rgba(203, 213, 225, 0.6);
  border: 2px solid #e2e8f0;
}

/* 초신성핵 특수 타일 (폭탄) */
.tile-val-supernova {
  background: radial-gradient(circle, #f43f5e 10%, #030008 80%);
  color: #fff;
  box-shadow: 0 0 30px rgba(244, 63, 94, 0.9),
              inset 0 0 15px rgba(255, 255, 255, 0.5);
  border: 2px dashed #f43f5e;
  animation: pulse-shake 0.8s infinite alternate;
}

.tile-val-supernova .tile-symbol {
  font-size: 2.2rem;
  filter: drop-shadow(0 0 8px #f43f5e);
}

@keyframes pulse-shake {
  0% {
    scale: 0.95;
    filter: brightness(0.9);
  }
  50% {
    scale: 1.03;
    rotate: 1deg;
  }
  100% {
    scale: 0.95;
    rotate: -1deg;
    filter: brightness(1.2);
    box-shadow: 0 0 35px rgba(244, 63, 94, 1),
                0 0 15px #f43f5e;
  }
}

/* 애니메이션 */
@keyframes spawn-tile {
  from {
    opacity: 0;
    scale: 0;
  }
  to {
    opacity: 1;
    scale: 1;
  }
}

.tile-merged {
  animation: merge-bounce 0.15s ease-out;
}

@keyframes merge-bounce {
  0% { scale: 1; }
  50% { scale: 1.15; }
  100% { scale: 1; }
}

/* 화면 흔들림 효과 (초신성 폭발 시 작동) */
.screen-shake {
  animation: shake 0.4s cubic-bezier(.36,.07,.19,.97) both;
}

@keyframes shake {
  10%, 90% { transform: translate3d(-1px, 0, 0); }
  20%, 80% { transform: translate3d(2px, 0, 0); }
  30%, 50%, 70% { transform: translate3d(-4px, 0, 0); }
  40%, 60% { transform: translate3d(4px, 0, 0); }
}

/* 푸터 */
.game-footer {
  margin-top: 20px;
  text-align: center;
  width: 100%;
}

.instruction {
  font-size: 0.8rem;
  color: #94a3b8;
  margin-bottom: 8px;
}

.key-badge {
  background: rgba(255,255,255,0.08);
  border: 1px solid var(--color-border);
  padding: 1px 6px;
  border-radius: 4px;
  font-size: 0.75rem;
}

.copyright {
  font-size: 0.7rem;
  color: #64748b;
}

/* 모달 스타일 */
.modal-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(3, 3, 12, 0.85);
  backdrop-filter: blur(12px);
  z-index: 300;
  display: flex;
  justify-content: center;
  align-items: center;
  transition: opacity 0.3s ease;
}

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

.modal-content {
  background: rgba(15, 15, 35, 0.95);
  border: 1px solid rgba(255, 255, 255, 0.1);
  box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.7),
              0 0 30px rgba(99, 102, 241, 0.2);
  width: 90%;
  max-width: 440px;
  border-radius: 16px;
  overflow: hidden;
  animation: modal-enter 0.3s cubic-bezier(0.175, 0.885, 0.32, 1.275);
}

.modal-content.large {
  max-width: 600px;
}

@keyframes modal-enter {
  from { transform: scale(0.9) translateY(20px); opacity: 0; }
  to { transform: scale(1) translateY(0); opacity: 1; }
}

.modal-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 16px 20px;
  border-bottom: 1px solid rgba(255, 255, 255, 0.05);
}

.modal-header h2 {
  font-family: var(--font-display);
  font-size: 1.3rem;
  font-weight: 700;
  color: #fff;
}

.btn-close {
  background: transparent;
  border: none;
  color: #94a3b8;
  font-size: 1.8rem;
  cursor: pointer;
}

.btn-close:hover {
  color: #fff;
}

.modal-body {
  padding: 20px;
  max-height: 70vh;
  overflow-y: auto;
}

/* 상점 스타일 */
.dust-wallet {
  text-align: center;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 1.2rem;
  background: rgba(251, 191, 36, 0.05);
  border: 1px solid rgba(251, 191, 36, 0.1);
  padding: 10px;
  border-radius: 8px;
  margin-bottom: 20px;
  color: #fbbf24;
}

.upgrade-list {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.upgrade-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
  background: rgba(255,255,255,0.02);
  border: 1px solid var(--color-border);
  padding: 12px;
  border-radius: 10px;
}

.upgrade-info h3 {
  font-size: 0.95rem;
  font-weight: 600;
  color: #fff;
  margin-bottom: 2px;
}

.upgrade-info p {
  font-size: 0.75rem;
  color: #94a3b8;
  margin-bottom: 6px;
  line-height: 1.3;
  max-width: 250px;
}

.upgrade-level {
  font-size: 0.7rem;
  color: #6366f1;
  font-weight: 600;
}

.btn-upgrade {
  background: linear-gradient(135deg, #d97706, #b45309);
  color: #fff;
  font-size: 0.8rem;
  padding: 8px 12px;
  border-radius: 6px;
  min-width: 100px;
}

.btn-upgrade:disabled {
  background: rgba(255,255,255,0.05);
  color: #64748b;
  cursor: not-allowed;
  transform: none;
  box-shadow: none;
}

/* 가이드 그리드 */
.guide-intro {
  font-size: 0.85rem;
  color: #cbd5e1;
  line-height: 1.5;
  margin-bottom: 16px;
}

.guide-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(110px, 1fr));
  gap: 10px;
  margin-bottom: 20px;
}

.guide-card {
  position: relative;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  height: 90px;
  border-radius: 8px;
  padding: 6px;
  text-align: center;
  box-shadow: 0 4px 6px rgba(0,0,0,0.2);
}

.guide-card .element-symbol {
  font-family: var(--font-display);
  font-size: 1.5rem;
  font-weight: 800;
}

.guide-card .element-mass {
  position: absolute;
  top: 4px;
  right: 6px;
  font-size: 0.65rem;
  font-weight: 700;
}

.guide-card .element-desc {
  font-size: 0.55rem;
  opacity: 0.8;
  margin-top: 4px;
  line-height: 1.2;
}

/* 가이드 카드 개별 테마 매핑 */
.guide-card.val-1 { background: linear-gradient(135deg, #bae6fd, #0284c7); color: #fff; }
.guide-card.val-2 { background: linear-gradient(135deg, #38bdf8, #0369a1); color: #fff; }
.guide-card.val-4 { background: linear-gradient(135deg, #fdba74, #ea580c); color: #fff; }
.guide-card.val-8 { background: linear-gradient(135deg, #a7f3d0, #059669); color: #fff; }
.guide-card.val-12 { background: linear-gradient(135deg, #c084fc, #7c3aed); color: #fff; }
.guide-card.val-16 { background: linear-gradient(135deg, #f87171, #dc2626); color: #fff; }
.guide-card.val-20 { background: linear-gradient(135deg, #f472b6, #db2777); color: #fff; }
.guide-card.val-24 { background: linear-gradient(135deg, #fde047, #ca8a04); color: #0f172a; }
.guide-card.val-28 { background: linear-gradient(135deg, #2dd4bf, #0f766e); color: #fff; }
.guide-card.val-32 { background: linear-gradient(135deg, #fb7185, #be123c); color: #fff; }
.guide-card.val-56 { background: linear-gradient(135deg, #cbd5e1, #475569); color: #fff; border: 1px solid #fff; }

.guide-rule-summary {
  background: rgba(255,255,255,0.02);
  border: 1px solid var(--color-border);
  padding: 12px 16px;
  border-radius: 8px;
}

.guide-rule-summary h3 {
  font-size: 0.9rem;
  color: #fff;
  margin-bottom: 8px;
}

.guide-rule-summary ul {
  padding-left: 16px;
}

.guide-rule-summary li {
  font-size: 0.75rem;
  color: #cbd5e1;
  margin-bottom: 6px;
  line-height: 1.4;
}

/* 폭발 파티클 */
.particle {
  position: absolute;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  pointer-events: none;
  z-index: 100;
  animation: particle-fly 0.6s cubic-bezier(0.1, 0.8, 0.3, 1) forwards;
}

@keyframes particle-fly {
  0% {
    transform: translate(0, 0) scale(1);
    opacity: 1;
  }
  100% {
    transform: translate(var(--tx), var(--ty)) scale(0);
    opacity: 0;
  }
}

/* 시작 화면 스타일 */
.start-screen-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: radial-gradient(circle at center, rgba(10, 10, 30, 0.98) 0%, rgba(3, 3, 12, 1) 100%);
  backdrop-filter: blur(15px);
  z-index: 200;
  display: flex;
  justify-content: center;
  align-items: center;
  transition: opacity 0.5s ease, visibility 0.5s ease;
}

.start-screen-overlay.fade-out {
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
}

.start-content {
  position: relative;
  text-align: center;
  display: flex;
  flex-direction: column;
  align-items: center;
  width: 90%;
  max-width: 420px;
  padding: 30px 20px;
  background: rgba(10, 10, 26, 0.6);
  border: 1px solid rgba(255, 255, 255, 0.05);
  border-radius: 20px;
  box-shadow: 0 0 40px rgba(99, 102, 241, 0.15);
}

.start-nebula {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 150px;
  height: 150px;
  background: radial-gradient(circle, rgba(99, 102, 241, 0.3) 0%, transparent 70%);
  filter: blur(20px);
  z-index: -1;
  animation: pulse-nebula 4s ease-in-out infinite alternate;
}

@keyframes pulse-nebula {
  from { transform: translate(-50%, -50%) scale(0.8); opacity: 0.6; }
  to { transform: translate(-50%, -50%) scale(1.2); opacity: 1; }
}

.start-logo {
  font-family: var(--font-display);
  font-weight: 800;
  font-size: 3rem;
  letter-spacing: -2px;
  background: linear-gradient(135deg, #38bdf8, #818cf8, #f43f5e);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  filter: drop-shadow(0 0 20px rgba(99, 102, 241, 0.4));
  margin-bottom: 2px;
}

.start-subtitle {
  font-size: 0.95rem;
  font-weight: 600;
  letter-spacing: 5px;
  color: #94a3b8;
  text-transform: uppercase;
  margin-bottom: 30px;
}

.start-description {
  margin-bottom: 35px;
}

.desc-title {
  font-size: 1.1rem;
  font-weight: 600;
  color: #e2e8f0;
  margin-bottom: 8px;
}

.desc-detail {
  font-size: 0.85rem;
  color: #94a3b8;
  line-height: 1.6;
}

/* 시작 화면 버튼 그룹 */
.start-action-group {
  display: flex;
  flex-direction: column;
  gap: 12px;
  width: 100%;
}

.btn-start {
  cursor: pointer;
  border: 1px solid rgba(255, 255, 255, 0.1);
  padding: 12px 24px;
  border-radius: 12px;
  font-family: var(--font-main);
  font-weight: 700;
  font-size: 0.95rem;
  color: #fff;
  transition: all 0.2s ease;
  user-select: none;
  width: 100%;
}

.btn-start-play {
  background: linear-gradient(135deg, #6366f1, #4f46e5);
  box-shadow: 0 8px 20px rgba(99, 102, 241, 0.4),
              0 0 10px rgba(99, 102, 241, 0.2);
}

.btn-start-play:hover {
  transform: translateY(-2px);
  box-shadow: 0 12px 25px rgba(99, 102, 241, 0.6),
              0 0 15px rgba(99, 102, 241, 0.3);
}

.btn-start-guide {
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid rgba(255, 255, 255, 0.08);
  color: #cbd5e1;
}

.btn-start-guide:hover {
  background: rgba(255, 255, 255, 0.12);
  color: #fff;
  transform: translateY(-2px);
}

/* 과학 모달 & 시각적 모식도 디자인 */
.science-modal-body {
  text-align: left;
  line-height: 1.6;
}

.science-section {
  background: rgba(255, 255, 255, 0.02);
  border: 1px solid rgba(255, 255, 255, 0.04);
  padding: 16px;
  border-radius: 12px;
  margin-bottom: 20px;
}

.science-section h3 {
  font-family: var(--font-display);
  font-size: 1.1rem;
  font-weight: 700;
  color: #f1f5f9;
  border-left: 3px solid #818cf8;
  padding-left: 10px;
  margin-bottom: 12px;
}

.science-section p {
  font-size: 0.85rem;
  color: #cbd5e1;
}

.section-desc {
  margin-bottom: 15px;
  color: #94a3b8 !important;
}

.highlight-badge {
  display: inline-block;
  padding: 2px 6px;
  border-radius: 4px;
  font-weight: 700;
  font-size: 0.75rem;
  margin: 0 2px;
}

.highlight-badge.H { background: rgba(56, 189, 248, 0.15); color: #38bdf8; border: 1px solid rgba(56, 189, 248, 0.3); }

/* 모식도 (Fusion Ladder Schematic) 스타일 */
.fusion-schematic {
  display: flex;
  flex-direction: column;
  gap: 16px;
  margin-top: 10px;
}

.schematic-step {
  border: 1px dashed rgba(255, 255, 255, 0.08);
  border-radius: 10px;
  padding: 12px;
  background: rgba(3, 3, 12, 0.4);
  position: relative;
}

.step-num {
  position: absolute;
  top: 8px;
  left: 8px;
  font-size: 0.65rem;
  font-weight: 700;
  color: #6366f1;
  text-transform: uppercase;
  letter-spacing: 1px;
  background: rgba(99, 102, 241, 0.1);
  padding: 2px 6px;
  border-radius: 4px;
}

.step-content {
  margin-top: 15px;
}

.node-row {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 10px;
  flex-wrap: wrap;
}

/* 원소 모식도 원형 구체 */
.schematic-node {
  width: 48px;
  height: 48px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-display);
  font-weight: 800;
  font-size: 0.95rem;
  color: #fff;
  user-select: none;
  position: relative;
  box-shadow: inset 0 0 10px rgba(255,255,255,0.2);
}

.schematic-node sup {
  font-size: 0.6rem;
  margin-left: 1px;
}

.schematic-node.val-1 {
  background: radial-gradient(circle at 35% 35%, #bae6fd 0%, #0284c7 80%);
  box-shadow: 0 0 10px rgba(56, 189, 248, 0.5);
}

.schematic-node.val-2 {
  background: radial-gradient(circle at 35% 35%, #38bdf8 0%, #0369a1 80%);
  box-shadow: 0 0 12px rgba(56, 189, 248, 0.6);
}

.schematic-node.val-4 {
  background: radial-gradient(circle at 35% 35%, #fdba74 0%, #ea580c 80%);
  box-shadow: 0 0 12px rgba(253, 186, 116, 0.6);
}

.schematic-node.val-8 {
  background: radial-gradient(circle at 35% 35%, #a7f3d0 0%, #059669 80%);
  box-shadow: 0 0 10px rgba(167, 243, 208, 0.5);
}

.schematic-node.val-12 {
  background: radial-gradient(circle at 35% 35%, #c084fc 0%, #7c3aed 80%);
  box-shadow: 0 0 12px rgba(192, 132, 252, 0.5);
}

.schematic-node.val-16 {
  background: radial-gradient(circle at 35% 35%, #f87171 0%, #dc2626 80%);
  box-shadow: 0 0 12px rgba(248, 113, 113, 0.5);
}

.schematic-node.val-20 {
  background: radial-gradient(circle at 35% 35%, #f472b6 0%, #db2777 80%);
  box-shadow: 0 0 12px rgba(244, 114, 182, 0.5);
}

.schematic-node.val-24 {
  background: radial-gradient(circle at 35% 35%, #fde047 0%, #ca8a04 80%);
  color: #0f172a;
  box-shadow: 0 0 12px rgba(253, 224, 71, 0.6);
}

.schematic-node.val-28 {
  background: radial-gradient(circle at 35% 35%, #2dd4bf 0%, #0f766e 80%);
  box-shadow: 0 0 12px rgba(45, 212, 191, 0.6);
}

.schematic-node.val-32 {
  background: radial-gradient(circle at 35% 35%, #fb7185 0%, #be123c 80%);
  box-shadow: 0 0 12px rgba(251, 113, 133, 0.6);
  border: 1px dashed #ef4444;
}

.schematic-node.val-56 {
  background: radial-gradient(circle at 35% 35%, #cbd5e1 0%, #475569 80%);
  box-shadow: 0 0 15px rgba(203, 213, 225, 0.6);
  border: 1.5px solid #e2e8f0;
}

.merge-plus {
  font-size: 1.1rem;
  font-weight: bold;
  color: #64748b;
}

.merge-arrow {
  font-size: 1.2rem;
  font-weight: bold;
  color: #818cf8;
}

.node-label {
  font-size: 0.75rem;
  color: #94a3b8;
  font-weight: 600;
  margin-left: 5px;
}

.node-detail {
  font-size: 0.8rem;
  color: #cbd5e1;
  line-height: 1.5;
  margin-top: 4px;
}

/* 헬륨 촉매 결합 사다리 (알파 사다리) */
.highlight-step {
  border: 1.5px solid rgba(99, 102, 241, 0.2);
  box-shadow: inset 0 0 15px rgba(99, 102, 241, 0.05);
}

.ladder-title {
  font-weight: 700;
  color: #fdba74;
  font-size: 0.9rem;
  margin-bottom: 8px;
  text-align: center;
}

.ladder-flow {
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin-top: 15px;
  background: rgba(0, 0, 0, 0.2);
  padding: 12px;
  border-radius: 8px;
}

.flow-item {
  display: flex;
  align-items: center;
  gap: 8px;
  border-bottom: 1px solid rgba(255,255,255,0.03);
  padding-bottom: 8px;
}

.flow-item:last-child {
  border-bottom: none;
  padding-bottom: 0;
}

.flow-plus {
  font-size: 0.75rem;
  color: #94a3b8;
  font-weight: 600;
}

.flow-desc {
  font-size: 0.7rem;
  color: #64748b;
}

.badge {
  font-size: 0.6rem;
  padding: 1px 4px;
  border-radius: 3px;
  font-weight: 700;
}

.badge-dead {
  background: rgba(239, 68, 68, 0.15);
  color: #ef4444;
  border: 1px solid rgba(239, 68, 68, 0.3);
  animation: pulse-dead 1.5s infinite alternate;
}

.flow-item.highlight-dead {
  background: rgba(239, 68, 68, 0.02);
  border-radius: 4px;
  padding: 4px;
  border: 1px dashed rgba(239, 68, 68, 0.1);
}

@keyframes pulse-dead {
  from { opacity: 0.8; }
  to { opacity: 1; box-shadow: 0 0 6px rgba(239, 68, 68, 0.3); }
}

.blink-text {
  animation: blink 1.5s infinite;
}

@keyframes blink {
  0%, 100% { opacity: 0.75; }
  50% { opacity: 1; }
}

.start-footer {
  margin-top: 25px;
  font-size: 0.75rem;
  color: #475569;
}

/* 액티브 아이템 바 */
.item-bar {
  display: flex;
  justify-content: center;
  width: 100%;
  margin: 12px 0 16px 0;
}

.btn-item {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 12px;
  background: rgba(239, 68, 68, 0.05);
  border: 1.5px solid rgba(239, 68, 68, 0.2);
  border-radius: 12px;
  padding: 10px 20px;
  color: #ef4444;
  cursor: pointer;
  transition: all 0.3s ease;
  width: 100%;
  max-width: 320px;
  font-family: var(--font-main);
  box-shadow: 0 4px 10px rgba(0, 0, 0, 0.3);
}

.btn-item:hover:not(:disabled) {
  background: rgba(239, 68, 68, 0.12);
  border-color: #ef4444;
  box-shadow: 0 0 15px rgba(239, 68, 68, 0.3);
  transform: translateY(-1px);
}

.btn-item:disabled {
  background: rgba(255, 255, 255, 0.02);
  border-color: rgba(255, 255, 255, 0.05);
  color: #475569;
  cursor: not-allowed;
  box-shadow: none;
}

.item-icon {
  font-size: 1.6rem;
  filter: drop-shadow(0 0 4px rgba(239, 68, 68, 0.2));
}

.btn-item:hover:not(:disabled) .item-icon {
  animation: spin-decay 2s linear infinite;
}

@keyframes spin-decay {
  from { transform: rotate(0deg); }
  to { transform: rotate(360deg); }
}

.item-text {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  text-align: left;
}

.item-title {
  font-weight: 700;
  font-size: 0.85rem;
}

.item-cost {
  font-size: 0.7rem;
  color: #fca5a5;
  font-weight: 600;
}

.btn-item:disabled .item-cost {
  color: #64748b;
}

/* 타겟 모드 활성화 시 게임 보드 특수 연출 */
.game-board.target-mode-active {
  border: 2px solid #ef4444;
  box-shadow: 0 0 30px rgba(239, 68, 68, 0.4),
              0 0 10px rgba(239, 68, 68, 0.2);
  animation: border-pulse-target 1.5s infinite alternate;
  cursor: crosshair;
}

@keyframes border-pulse-target {
  from { border-color: rgba(239, 68, 68, 0.4); box-shadow: 0 0 15px rgba(239, 68, 68, 0.2); }
  to { border-color: rgba(239, 68, 68, 1); box-shadow: 0 0 35px rgba(239, 68, 68, 0.5); }
}

.game-board.target-mode-active .tile {
  cursor: crosshair;
}

/* 타겟 모드 타겟 대상 타일 하이라이트 */
.game-board.target-mode-active .tile-val-32 {
  animation: target-blink 0.8s infinite alternate;
  border: 2.5px solid #ef4444;
  cursor: pointer;
  pointer-events: auto;
}

.game-board.target-mode-active .tile-val-32:hover {
  box-shadow: 0 0 25px #ef4444, 0 0 10px #ef4444;
  scale: 1.05;
  transition: all 0.15s ease;
}

@keyframes target-blink {
  from { box-shadow: 0 0 5px rgba(239, 68, 68, 0.4); }
  to { box-shadow: 0 0 20px rgba(239, 68, 68, 0.9); }
}

/* =============================================================
 * 과도한 몰입 방지용 하트 시스템 (Heart System Styles)
 * ============================================================= */

.hearts-panel {
  display: flex;
  justify-content: space-between;
  align-items: center;
  width: 100%;
  background: var(--color-panel-bg);
  border: 1px solid var(--color-border);
  backdrop-filter: blur(8px);
  padding: 10px 16px;
  border-radius: 12px;
  margin-bottom: 12px;
}

.hearts-info {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.hearts-label {
  font-size: 0.65rem;
  font-weight: 600;
  color: #94a3b8;
  letter-spacing: 1px;
}

.hearts-display {
  display: flex;
  gap: 4px;
  align-items: center;
}

.heart-slot {
  font-size: 1.15rem;
  line-height: 1;
  filter: drop-shadow(0 0 4px rgba(244, 63, 94, 0.4));
  transition: opacity 0.3s ease, filter 0.3s ease, transform 0.2s ease;
  user-select: none;
}

.heart-slot.empty {
  filter: grayscale(100%) opacity(0.2) drop-shadow(none);
}

.heart-slot.pulse {
  animation: heart-beat 0.6s infinite alternate cubic-bezier(0.25, 0.8, 0.25, 1);
}

@keyframes heart-beat {
  from { transform: scale(1); }
  to { transform: scale(1.2); }
}

.hearts-timer-container {
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  gap: 2px;
}

.timer-label {
  font-size: 0.6rem;
  font-weight: 600;
  color: #64748b;
  letter-spacing: 0.5px;
}

.timer-value {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 0.95rem;
  color: #f43f5e;
  text-shadow: 0 0 8px rgba(244, 63, 94, 0.3);
}

.timer-value.full {
  color: #10b981;
  text-shadow: 0 0 8px rgba(16, 185, 129, 0.3);
}

/* 시작 화면 하트 스타일 */
.start-hearts-section {
  margin: 10px 0 25px 0;
  padding: 14px 20px;
  background: rgba(255, 255, 255, 0.02);
  border: 1px solid rgba(255, 255, 255, 0.04);
  border-radius: 14px;
  width: 100%;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 10px;
}

.hearts-container {
  display: flex;
  align-items: center;
  gap: 12px;
}

.hearts-list {
  display: flex;
  gap: 4px;
}

.hearts-timer {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 0.85rem;
  color: #f43f5e;
  background: rgba(244, 63, 94, 0.1);
  padding: 2px 8px;
  border-radius: 6px;
  border: 1px solid rgba(244, 63, 94, 0.2);
  min-width: 54px;
  text-align: center;
}

.hearts-timer.full {
  color: #10b981;
  background: rgba(16, 185, 129, 0.1);
  border-color: rgba(16, 185, 129, 0.2);
}

.immersion-warning {
  font-size: 0.75rem;
  color: #94a3b8;
  line-height: 1.45;
  text-align: center;
}

/* 버튼 비활성화 효과 */
.btn-start-play:disabled {
  background: rgba(255, 255, 255, 0.03) !important;
  border-color: rgba(255, 255, 255, 0.05) !important;
  color: #475569 !important;
  box-shadow: none !important;
  cursor: not-allowed !important;
  transform: none !important;
}

.btn:disabled {
  background: rgba(255, 255, 255, 0.02) !important;
  border-color: rgba(255, 255, 255, 0.05) !important;
  color: #475569 !important;
  cursor: not-allowed !important;
  transform: none !important;
  box-shadow: none !important;
}

/* =============================================================
 * 모바일 최적화 및 스마트폰 해상도 대응 (Mobile Responsiveness)
 * ============================================================= */

/* 1. 일반적인 스마트폰 해상도 대응 (너비 480px 이하) */
@media (max-width: 480px) {
  body {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    overflow: hidden;
    padding: env(safe-area-inset-top) env(safe-area-inset-right) env(safe-area-inset-bottom) env(safe-area-inset-left);
  }

  :root {
    --board-size: min(340px, 86vw);
    --grid-gap: 8px;
  }

  .game-container {
    height: 100%;
    padding: 8px 12px;
    display: flex;
    flex-direction: column;
    justify-content: center;
    gap: 4px;
  }

  .logo-text {
    font-size: 1.8rem;
  }

  .sub-logo {
    font-size: 0.65rem;
    letter-spacing: 2px;
  }

  .game-header {
    margin-bottom: 6px;
    width: 100%;
  }

  .stat-box {
    padding: 4px 8px;
    min-width: 55px;
  }

  .stat-value {
    font-size: 0.95rem;
  }

  .hearts-panel {
    padding: 6px 12px;
    margin-bottom: 6px;
  }

  .heart-slot {
    font-size: 0.95rem;
  }

  .timer-value {
    font-size: 0.85rem;
  }

  .status-panel {
    padding: 8px;
    margin-bottom: 6px;
  }

  .status-label {
    font-size: 0.7rem;
  }

  .temp-text {
    font-size: 0.85rem;
  }

  .progress-bar-container {
    height: 6px;
  }

  .stellar-state-text {
    font-size: 0.65rem;
  }

  .control-panel {
    margin-bottom: 6px;
    gap: 6px;
  }

  .btn {
    padding: 8px;
    font-size: 0.75rem;
    border-radius: 6px;
  }

  .item-bar {
    margin: 6px 0;
  }

  .btn-item {
    padding: 8px 16px;
    border-radius: 10px;
    gap: 8px;
  }

  .item-icon {
    font-size: 1.3rem;
  }

  .item-title {
    font-size: 0.75rem;
  }

  .item-cost {
    font-size: 0.65rem;
  }

  .game-footer {
    margin-top: 6px;
  }

  .instruction {
    font-size: 0.7rem;
    margin-bottom: 2px;
    line-height: 1.3;
  }

  .copyright {
    font-size: 0.65rem;
  }

  /* 시작 화면 조절 */
  .start-content {
    padding: 20px 16px;
    width: 92%;
    max-width: 360px;
  }

  .start-logo {
    font-size: 2.4rem;
  }

  .start-subtitle {
    font-size: 0.8rem;
    letter-spacing: 4px;
    margin-bottom: 20px;
  }

  .start-description {
    margin-bottom: 20px;
  }

  .desc-title {
    font-size: 0.95rem;
    margin-bottom: 4px;
  }

  .desc-detail {
    font-size: 0.75rem;
    line-height: 1.4;
  }

  .start-hearts-section {
    margin: 5px 0 15px 0;
    padding: 10px 14px;
    border-radius: 10px;
  }

  .hearts-container {
    gap: 8px;
  }

  .hearts-timer {
    font-size: 0.75rem;
    padding: 1px 6px;
    min-width: 48px;
  }

  .immersion-warning {
    font-size: 0.65rem;
    line-height: 1.4;
  }

  .btn-start {
    padding: 10px 16px;
    font-size: 0.85rem;
    border-radius: 10px;
  }

  /* 모달 레이아웃 조절 */
  .modal-content {
    border-radius: 12px;
    width: 94%;
  }

  .modal-body {
    padding: 12px;
    max-height: 65vh;
  }
}

/* 2. 세로 해상도가 매우 좁은 스마트폰 대응 (예: iPhone SE, 구형 보급형 기기, 혹은 키보드가 띄워졌을 때 - 높이 700px 이하) */
@media (max-height: 700px) and (max-width: 480px) {
  :root {
    --board-size: min(280px, 75vw);
    --grid-gap: 6px;
  }

  .game-container {
    padding: 4px 8px;
    gap: 2px;
  }

  .logo-text {
    font-size: 1.5rem;
  }

  .sub-logo {
    font-size: 0.6rem;
    letter-spacing: 1.5px;
  }

  .stat-box {
    padding: 2px 6px;
    min-width: 48px;
  }

  .stat-label {
    font-size: 0.55rem;
  }

  .stat-value {
    font-size: 0.85rem;
  }

  .hearts-panel {
    padding: 4px 10px;
    margin-bottom: 4px;
    border-radius: 8px;
  }

  .hearts-label {
    font-size: 0.55rem;
  }

  .heart-slot {
    font-size: 0.85rem;
  }

  .timer-label {
    font-size: 0.55rem;
  }

  .timer-value {
    font-size: 0.8rem;
  }

  .status-panel {
    padding: 6px 8px;
    margin-bottom: 4px;
    border-radius: 8px;
  }

  .status-label {
    font-size: 0.65rem;
  }

  .temp-text {
    font-size: 0.75rem;
  }

  .progress-bar-container {
    height: 4px;
    margin-bottom: 4px;
  }

  .stellar-state-text {
    font-size: 0.6rem;
  }

  .control-panel {
    margin-bottom: 4px;
    gap: 4px;
  }

  .btn {
    padding: 6px;
    font-size: 0.7rem;
    border-radius: 6px;
  }

  .item-bar {
    margin: 4px 0;
  }

  .btn-item {
    padding: 6px 12px;
    border-radius: 8px;
  }

  .item-icon {
    font-size: 1.15rem;
  }

  .item-title {
    font-size: 0.7rem;
  }

  .item-cost {
    font-size: 0.6rem;
  }

  .game-footer {
    margin-top: 4px;
  }

  .instruction {
    font-size: 0.65rem;
  }

  .copyright {
    display: none; /* 극소형 화면에서는 저작권 표기를 가려 공간을 확보합니다 */
  }

  /* 시작 화면 조절 */
  .start-content {
    padding: 16px 12px;
    width: 95%;
  }

  .start-logo {
    font-size: 2rem;
  }

  .start-subtitle {
    font-size: 0.7rem;
    letter-spacing: 3px;
    margin-bottom: 12px;
  }

  .start-description {
    margin-bottom: 10px;
  }

  .desc-title {
    font-size: 0.85rem;
  }

  .desc-detail {
    font-size: 0.7rem;
    line-height: 1.35;
  }

  .start-hearts-section {
    margin: 4px 0 10px 0;
    padding: 8px 12px;
  }

  .immersion-warning {
    font-size: 0.6rem;
    line-height: 1.3;
  }

  .btn-start {
    padding: 8px 14px;
    font-size: 0.8rem;
  }

  .modal-body {
    max-height: 55vh;
  }
}