/* ==========================================================================
   Periodic Table Science Web Simulation - Premium Full-Screen Science Suite
   Harmonized 100% with Eclipse Simulation Layout & Design Suite
   ========================================================================== */

@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700;800&family=Noto+Sans+KR:wght@300;400;500;700;900&family=Outfit:wght@400;600;800&family=JetBrains+Mono:wght@500;700&display=swap');

:root {
  --bg-dark: #0a0e1a;
  --bg-gradient: radial-gradient(circle at top left, #08090f, #101422 65%, #05060b);
  --panel-bg: rgba(12, 16, 28, 0.7);
  --panel-border: rgba(255, 255, 255, 0.08);
  --card-bg: rgba(12, 15, 24, 0.9);
  --card-border: rgba(255, 255, 255, 0.08);
  
  --text-main: #f0f4f8;
  --text-muted: #8892a4;
  
  --accent-cyan: #00f2fe;
  --accent-blue: #38bdf8;
  --accent-purple: #c084fc;
  --accent-glow: rgba(0, 242, 254, 0.4);

  --font-family: 'Noto Sans KR', 'Inter', system-ui, -apple-system, sans-serif;

  /* Category Color Tokens */
  --cat-alkali: #f87171;
  --cat-alkaline-earth: #fb923c;
  --cat-transition: #facc15;
  --cat-post-transition: #a3e635;
  --cat-metalloid: #2dd4bf;
  --cat-reactive-nonmetal: #38bdf8;
  --cat-noble-gas: #c084fc;
  --cat-lanthanide: #f472b6;
  --cat-actinide: #fb7185;
  --cat-unknown: #94a3b8;
}

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

html, body {
  width: 100vw;
  height: 100vh;
  max-width: 100vw;
  max-height: 100vh;
  overflow: hidden;
  background: var(--bg-dark);
  color: var(--text-main);
  font-family: var(--font-family);
  display: flex;
  justify-content: center;
  align-items: center;
}

/* Custom Slim Scrollbars */
::-webkit-scrollbar {
  width: 4px;
  height: 0;
}
::-webkit-scrollbar-track {
  background: rgba(0, 0, 0, 0.25);
}
::-webkit-scrollbar-thumb {
  background: rgba(0, 242, 254, 0.35);
  border-radius: 4px;
}
::-webkit-scrollbar-thumb:hover {
  background: var(--accent-cyan);
}

/* 100% Full Screen App Container (Harmonized with Eclipse Simulation) */
.app-container {
  width: 100vw;
  max-width: 100%;
  height: 100vh;
  display: flex;
  flex-direction: column;
  padding: 12px 16px;
  gap: 12px;
  box-sizing: border-box;
  overflow: hidden;
}

/* Header Bar */
.app-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 10px 20px;
  background: var(--panel-bg);
  border: 1px solid var(--panel-border);
  border-radius: 12px;
  backdrop-filter: blur(16px);
  flex-shrink: 0;
  width: 100%;
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.4);
}

.header-left {
  display: flex;
  align-items: center;
  gap: 20px;
}

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
}

.logo-icon {
  width: 30px;
  height: 30px;
  background: linear-gradient(135deg, #00f2fe, #3b82f6);
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 15px;
  color: #000;
  box-shadow: 0 0 14px var(--accent-glow);
}

.logo h1 {
  font-family: 'Outfit', 'Noto Sans KR', sans-serif;
  font-size: 1.2rem;
  font-weight: 800;
  color: #ffffff;
  letter-spacing: -0.2px;
}

.nav-tabs {
  display: flex;
  gap: 6px;
  background: rgba(0, 0, 0, 0.4);
  padding: 4px;
  border-radius: 10px;
  border: 1px solid var(--panel-border);
}

.nav-tab {
  background: transparent;
  border: none;
  color: var(--text-muted);
  padding: 5px 18px;
  border-radius: 8px;
  font-family: var(--font-family);
  font-weight: 600;
  font-size: 0.85rem;
  cursor: pointer;
  transition: all 0.2s ease;
  display: flex;
  align-items: center;
  gap: 6px;
}

.nav-tab:hover {
  color: var(--text-main);
  background: rgba(255, 255, 255, 0.06);
}

/* Active tab style matching Eclipse simulation signature bright cyan button */
.nav-tab.active {
  background: #00f2fe;
  color: #000000;
  font-weight: 800;
  border: 1px solid #00f2fe;
  box-shadow: 0 0 16px var(--accent-glow);
}

/* Main Layout Container */
main {
  width: 100%;
  flex: 1;
  display: flex;
  flex-direction: column;
  height: 100%;
  overflow: hidden;
}

.tab-content {
  display: none;
  flex: 1;
  height: 100%;
  width: 100%;
  overflow: hidden;
}

.tab-content.active {
  display: flex !important;
  flex-direction: column;
  flex: 1;
  height: 100%;
  width: 100%;
  overflow: hidden;
  animation: fadeIn 0.2s ease-in-out;
}

#tab-compound.active {
  display: flex !important;
  flex-direction: column;
  flex: 1;
  height: 100%;
  width: 100%;
  overflow: hidden;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(2px); }
  to { opacity: 1; transform: translateY(0); }
}

/* Toolbar Panel */
.toolbar-panel {
  background: var(--panel-bg);
  backdrop-filter: blur(12px);
  border: 1px solid var(--panel-border);
  border-radius: 12px;
  padding: 6px 14px;
  margin-bottom: 8px;
  display: flex;
  gap: 10px;
  align-items: center;
  justify-content: space-between;
  flex-shrink: 0;
}

.search-box {
  position: relative;
  flex: 1;
  max-width: 340px;
}

.search-box i {
  position: absolute;
  left: 10px;
  top: 50%;
  transform: translateY(-50%);
  color: var(--text-muted);
  font-size: 0.8rem;
}

.search-box input {
  width: 100%;
  background: rgba(0, 0, 0, 0.4);
  border: 1px solid var(--panel-border);
  border-radius: 6px;
  padding: 5px 10px 5px 30px;
  color: var(--text-main);
  font-size: 0.8rem;
  outline: none;
  transition: all 0.2s ease;
}

.search-box input:focus {
  border-color: var(--accent-cyan);
  box-shadow: 0 0 8px var(--accent-glow);
}

.filter-group {
  display: flex;
  gap: 6px;
  align-items: center;
}

.select-control {
  background: rgba(0, 0, 0, 0.4);
  border: 1px solid var(--panel-border);
  border-radius: 6px;
  color: var(--text-main);
  padding: 5px 8px;
  font-size: 0.78rem;
  outline: none;
  cursor: pointer;
  transition: all 0.2s ease;
}

.select-control:focus, .select-control:hover {
  border-color: var(--accent-blue);
}

/* Category Legend Bar */
.category-legend-bar {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-bottom: 8px;
  justify-content: center;
  flex-shrink: 0;
}

.cat-badge {
  display: flex;
  align-items: center;
  gap: 5px;
  font-size: 0.72rem;
  font-weight: 600;
  padding: 2px 8px;
  border-radius: 10px;
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid rgba(255, 255, 255, 0.08);
}

.cat-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  box-shadow: 0 0 4px currentColor;
}

/* Heatmap Legend Bar */
.heatmap-legend-container {
  display: flex;
  align-items: center;
  gap: 8px;
  background: rgba(0,0,0,0.3);
  padding: 4px 10px;
  border-radius: 6px;
  border: 1px solid var(--panel-border);
  margin-bottom: 8px;
  justify-content: center;
  flex-shrink: 0;
}

.heatmap-bar {
  height: 6px;
  width: 140px;
  border-radius: 3px;
  background: linear-gradient(90deg, hsl(240, 85%, 45%), hsl(120, 85%, 45%), hsl(0, 85%, 45%));
}

/* Periodic Table Grid Container */
.ptable-container {
  background: var(--panel-bg);
  backdrop-filter: blur(14px);
  border: 1px solid var(--panel-border);
  border-radius: 12px;
  padding: 10px 12px;
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.5);
  display: flex;
  flex-direction: column;
  gap: 10px;
  overflow-y: auto;
  flex: 1;
}

/* Main Grid (1 Header Col + 18 Group Cols | 1 Header Row + 7 Period Rows) */
.ptable-grid {
  display: grid;
  grid-template-columns: 36px repeat(18, minmax(42px, 1fr));
  gap: 3px;
}

/* Group & Period Header Cells */
.header-cell {
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: 'JetBrains Mono', monospace;
  font-weight: 700;
  color: var(--text-muted);
  user-select: none;
}

.origin-header {
  font-size: 0.6rem;
  line-height: 1.1;
  color: rgba(148, 163, 184, 0.7);
  text-align: center;
}

.group-header {
  font-size: 0.8rem;
  border-bottom: 1px solid rgba(255, 255, 255, 0.1);
  margin-bottom: 2px;
  color: #93c5fd;
}

.period-header {
  font-size: 0.8rem;
  border-right: 1px solid rgba(255, 255, 255, 0.1);
  margin-right: 2px;
  color: #93c5fd;
}

/* Sub Grids for Lanthanides (57-70) & Actinides (89-102) */
.lanthanide-actinide-container {
  margin-top: 10px;
  padding-top: 10px;
  border-top: 1px dashed var(--panel-border);
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.sub-grid {
  display: grid;
  grid-template-columns: 36px repeat(18, minmax(42px, 1fr));
  gap: 3px;
}

.sub-grid-label-cell {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  padding-right: 6px;
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--cat-lanthanide);
  user-select: none;
  white-space: nowrap;
}

/* Element Cell Styling - PERFECT 1:1 SQUARE ASPECT RATIO */
.element-cell {
  aspect-ratio: 1 / 1;
  width: 100%;
  border-radius: 5px;
  padding: 2px 1px;
  display: flex;
  flex-direction: column;
  justify-content: space-around;
  align-items: center;
  cursor: pointer;
  position: relative;
  transition: all 0.15s cubic-bezier(0.4, 0, 0.2, 1);
  user-select: none;
  box-shadow: 0 2px 4px rgba(0,0,0,0.3);
}

.element-cell:hover {
  transform: translateY(-2px) scale(1.18);
  z-index: 30;
  box-shadow: 0 6px 16px rgba(0, 0, 0, 0.8), 0 0 12px var(--accent-glow);
  border-color: #ffffff !important;
}

.element-cell.dimmed {
  opacity: 0.15;
  filter: grayscale(90%);
}

.cell-top-bar {
  width: 100%;
  display: flex;
  justify-content: flex-start;
  padding: 0 2px;
}

.el-num {
  font-size: 0.58rem;
  color: rgba(255, 255, 255, 0.85);
  font-weight: 700;
  font-family: 'JetBrains Mono', monospace;
  line-height: 1;
}

.el-sym {
  font-family: 'Outfit', sans-serif;
  font-size: 1.05rem;
  font-weight: 800;
  text-align: center;
  margin: 0;
  letter-spacing: -0.2px;
  line-height: 1;
  color: #ffffff;
  text-shadow: 0 1px 2px rgba(0, 0, 0, 0.8);
}

.el-name {
  font-size: 0.62rem;
  text-align: center;
  white-space: nowrap;
  overflow: hidden;
  font-weight: 600;
  line-height: 1;
  color: rgba(255, 255, 255, 0.95);
  letter-spacing: -0.4px;
}

.el-weight {
  font-size: 0.52rem;
  color: rgba(255, 255, 255, 0.65);
  text-align: center;
  line-height: 1;
  font-family: 'JetBrains Mono', monospace;
}

/* Category Colors */
.category-alkali {
  background: linear-gradient(135deg, rgba(239, 68, 68, 0.35), rgba(153, 27, 27, 0.2));
  border: 1px solid rgba(239, 68, 68, 0.55);
}
.category-alkali .el-sym { color: #fca5a5; }

.category-alkaline-earth {
  background: linear-gradient(135deg, rgba(249, 115, 22, 0.35), rgba(194, 65, 12, 0.2));
  border: 1px solid rgba(249, 115, 22, 0.55);
}
.category-alkaline-earth .el-sym { color: #fdba74; }

.category-transition {
  background: linear-gradient(135deg, rgba(234, 179, 8, 0.25), rgba(161, 98, 7, 0.15));
  border: 1px solid rgba(234, 179, 8, 0.45);
}
.category-transition .el-sym { color: #fde047; }

.category-post-transition {
  background: linear-gradient(135deg, rgba(132, 204, 22, 0.25), rgba(77, 124, 15, 0.18));
  border: 1px solid rgba(132, 204, 22, 0.45);
}
.category-post-transition .el-sym { color: #bef264; }

.category-metalloid {
  background: linear-gradient(135deg, rgba(20, 184, 166, 0.35), rgba(15, 118, 110, 0.2));
  border: 1px solid rgba(20, 184, 166, 0.55);
}
.category-metalloid .el-sym { color: #5eead4; }

.category-reactive-nonmetal {
  background: linear-gradient(135deg, rgba(56, 189, 248, 0.35), rgba(3, 105, 161, 0.2));
  border: 1px solid rgba(56, 189, 248, 0.55);
}
.category-reactive-nonmetal .el-sym { color: #7dd3fc; }

.category-noble-gas {
  background: linear-gradient(135deg, rgba(168, 85, 247, 0.35), rgba(126, 34, 206, 0.2));
  border: 1px solid rgba(168, 85, 247, 0.55);
}
.category-noble-gas .el-sym { color: #c084fc; }

.category-lanthanide {
  background: linear-gradient(135deg, rgba(236, 72, 153, 0.35), rgba(190, 24, 93, 0.2));
  border: 1px solid rgba(236, 72, 153, 0.55);
}
.category-lanthanide .el-sym { color: #f472b6; }

.category-actinide {
  background: linear-gradient(135deg, rgba(251, 113, 133, 0.35), rgba(225, 29, 72, 0.2));
  border: 1px solid rgba(251, 113, 133, 0.55);
}
.category-actinide .el-sym { color: #fb7185; }

.category-unknown {
  background: linear-gradient(135deg, rgba(100, 116, 139, 0.25), rgba(51, 65, 85, 0.15));
  border: 1px solid rgba(100, 116, 139, 0.4);
}
.category-unknown .el-sym { color: #cbd5e1; }

/* General Button Base Styles */
.btn {
  background: rgba(255, 255, 255, 0.08);
  border: 1px solid var(--panel-border);
  color: var(--text-main);
  padding: 6px 14px;
  border-radius: 8px;
  font-size: 0.82rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s ease;
  display: flex;
  align-items: center;
  gap: 6px;
  user-select: none;
}

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

/* Secondary Button (e.g. Reset Button - Red Accent Glow matching Science Suite) */
.btn-secondary {
  background: rgba(239, 68, 68, 0.12);
  border: 1px solid rgba(239, 68, 68, 0.35);
  color: #fca5a5;
  padding: 5px 14px;
  border-radius: 8px;
  font-weight: 600;
  font-size: 0.78rem;
  font-family: var(--font-family);
  transition: all 0.2s ease;
}

.btn-secondary:hover {
  background: rgba(239, 68, 68, 0.25);
  color: #ffffff;
  border-color: rgba(239, 68, 68, 0.6);
  box-shadow: 0 0 14px rgba(239, 68, 68, 0.4);
}

/* Primary Glow Button (Matching Eclipse Simulation Bright Cyan Signature) */
.btn-primary-glow {
  background: #00f2fe;
  color: #000000;
  border: none;
  font-weight: 800;
  font-family: var(--font-family);
  font-size: 0.88rem;
  padding: 8px 20px;
  border-radius: 8px;
  box-shadow: 0 0 18px var(--accent-glow);
  transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
}

.btn-primary-glow:hover:not(:disabled) {
  box-shadow: 0 0 28px rgba(0, 242, 254, 0.85);
  transform: translateY(-1px) scale(1.02);
  color: #000000;
}

.btn-primary-glow:disabled {
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid rgba(255, 255, 255, 0.1);
  color: rgba(255, 255, 255, 0.3);
  box-shadow: none;
  cursor: not-allowed;
  opacity: 0.6;
}

/* ==========================================================================
   Compound Simulator - Full Screen Harmonized Design System
   ========================================================================== */

#compoundSimulatorContainer {
  height: 100%;
  width: 100%;
  flex: 1;
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

.compound-sim-layout {
  display: grid;
  grid-template-columns: 330px 1fr;
  gap: 16px;
  flex: 1;
  overflow: hidden;
  height: 100%;
  width: 100%;
  align-items: stretch;
}

.element-picker-panel {
  background: var(--panel-bg);
  backdrop-filter: blur(16px);
  border: 1px solid var(--panel-border);
  border-radius: 12px;
  padding: 16px;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.5);
  display: flex;
  flex-direction: column;
  height: 100%;
  overflow: hidden !important;
  flex-shrink: 0;
}

.reaction-chamber-panel {
  background: var(--panel-bg);
  backdrop-filter: blur(16px);
  border: 1px solid var(--panel-border);
  border-radius: 12px;
  padding: 16px;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.5);
  display: flex;
  flex-direction: column;
  height: 100%;
  overflow: hidden;
}

.chamber-body-scroll {
  flex: 1;
  overflow-y: auto;
  overflow-x: hidden;
  padding-right: 4px;
  display: flex;
  flex-direction: column;
}

.panel-header-title h3, .chamber-header h3 {
  font-family: 'Outfit', 'Noto Sans KR', sans-serif;
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--accent-cyan);
  display: flex;
  align-items: center;
  gap: 8px;
}

.subtitle {
  font-size: 0.76rem;
  color: var(--text-muted);
  margin-top: 2px;
  margin-bottom: 10px;
}

.picker-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  grid-template-rows: repeat(8, 1fr);
  gap: 4px;
  flex: 1;
  height: 100%;
  overflow: hidden !important;
  padding: 0;
}

.picker-card {
  height: 100%;
  aspect-ratio: auto;
  border-radius: 6px;
  background: linear-gradient(135deg, rgba(0, 242, 254, 0.12), rgba(59, 130, 246, 0.07));
  border: 1px solid rgba(0, 242, 254, 0.28);
  padding: 2px 1px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: space-around;
  cursor: pointer;
  transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
  color: var(--text-main);
  user-select: none;
  box-shadow: 0 2px 6px rgba(0, 0, 0, 0.3);
  width: 100%;
}

.picker-card:hover {
  transform: translateY(-1px) scale(1.04);
  background: linear-gradient(135deg, rgba(0, 242, 254, 0.28), rgba(59, 130, 246, 0.18));
  border-color: var(--accent-cyan);
  box-shadow: 0 0 16px var(--accent-glow);
  z-index: 5;
}

.p-num { font-size: 0.54rem; font-family: 'JetBrains Mono', monospace; color: var(--text-muted); line-height: 1; }
.p-sym { font-family: 'Outfit', sans-serif; font-size: 0.92rem; font-weight: 800; color: #ffffff; text-shadow: 0 0 8px rgba(0, 242, 254, 0.7); line-height: 1; }
.p-name { font-family: 'Noto Sans KR', sans-serif; font-size: 0.6rem; font-weight: 600; color: #cbd5e1; line-height: 1; white-space: nowrap; overflow: hidden; }

.chamber-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 10px;
  flex-shrink: 0;
}

.flask-display {
  background: rgba(8, 12, 24, 0.85);
  border: 1.5px dashed rgba(0, 242, 254, 0.35);
  border-radius: 14px;
  min-height: 90px;
  padding: 14px 20px;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: center;
  gap: 10px;
  margin-bottom: 10px;
  box-shadow: inset 0 0 35px rgba(0, 242, 254, 0.08);
  transition: all 0.25s ease;
  flex-shrink: 0;
}

.flask-display:hover {
  border-color: var(--accent-cyan);
  box-shadow: inset 0 0 40px rgba(0, 242, 254, 0.15);
}

.empty-flask-msg {
  color: var(--text-muted);
  font-size: 0.84rem;
  font-weight: 500;
  display: flex;
  align-items: center;
  gap: 10px;
}

.flask-item {
  background: linear-gradient(135deg, rgba(0, 242, 254, 0.2), rgba(59, 130, 246, 0.15));
  border: 1px solid rgba(0, 242, 254, 0.45);
  border-radius: 10px;
  padding: 5px 12px;
  display: flex;
  align-items: center;
  gap: 10px;
  box-shadow: 0 4px 14px rgba(0, 0, 0, 0.4), 0 0 10px rgba(0, 242, 254, 0.15);
  animation: popIn 0.2s ease-out;
}

@keyframes popIn {
  from { transform: scale(0.8); opacity: 0; }
  to { transform: scale(1); opacity: 1; }
}

.f-atom-badge {
  display: flex;
  align-items: center;
  gap: 6px;
}

.f-sym { font-family: 'Outfit', sans-serif; font-weight: 800; font-size: 1.05rem; color: #fff; text-shadow: 0 0 8px var(--accent-glow); }
.f-name { font-size: 0.78rem; font-weight: 600; color: #e2e8f0; }

.f-count-controls {
  display: flex;
  align-items: center;
  gap: 5px;
  background: rgba(0, 0, 0, 0.5);
  padding: 2px 6px;
  border-radius: 16px;
  border: 1px solid rgba(255, 255, 255, 0.15);
}

.count-btn {
  background: rgba(255, 255, 255, 0.1);
  border: 1px solid rgba(255, 255, 255, 0.2);
  color: #fff;
  font-weight: 800;
  cursor: pointer;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.75rem;
  transition: all 0.15s ease;
}

.count-btn:hover {
  background: var(--accent-cyan);
  color: #000;
  border-color: transparent;
}

.f-count {
  font-family: 'JetBrains Mono', monospace;
  font-weight: 700;
  font-size: 0.8rem;
  min-width: 12px;
  text-align: center;
}

.action-bar {
  display: flex;
  justify-content: flex-end;
  margin-bottom: 10px;
  flex-shrink: 0;
}

/* Chemical Reaction Result Card & Reaction Visualizer */
.reaction-result-card {
  background: linear-gradient(135deg, rgba(13, 22, 44, 0.95), rgba(8, 14, 28, 0.95));
  border-radius: 14px;
  padding: 16px 20px;
  border: 1px solid var(--panel-border);
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.6);
  animation: slideUp 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  margin-bottom: 10px;
}

@keyframes slideUp {
  from { opacity: 0; transform: translateY(10px); }
  to { opacity: 1; transform: translateY(0); }
}

.result-card-inner {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.result-top-bar {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.result-title-group {
  display: flex;
  align-items: center;
  gap: 10px;
}

.badge {
  font-size: 0.75rem;
  font-weight: 700;
  padding: 3px 10px;
  border-radius: 18px;
  display: flex;
  align-items: center;
  gap: 4px;
}

.badge-success {
  background: rgba(0, 242, 254, 0.15);
  color: var(--accent-cyan);
  border: 1px solid rgba(0, 242, 254, 0.4);
}

.badge-warning {
  background: rgba(239, 68, 68, 0.15);
  color: #fca5a5;
  border: 1px solid rgba(239, 68, 68, 0.4);
}

.bond-type-tag {
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--accent-purple);
  background: rgba(192, 132, 252, 0.12);
  padding: 3px 10px;
  border-radius: 10px;
  border: 1px solid rgba(192, 132, 252, 0.3);
}

.compound-title {
  font-family: 'Outfit', 'Noto Sans KR', sans-serif;
  margin: 0;
  font-size: 1.2rem;
  font-weight: 800;
}

.formula-highlight {
  color: var(--accent-cyan);
  text-shadow: 0 0 8px rgba(0, 242, 254, 0.4);
}

.visual-bond-diagram {
  margin-top: 2px;
}

.formula-visual {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: center;
  gap: 12px;
  background: rgba(0, 0, 0, 0.5);
  border: 1px solid rgba(255, 255, 255, 0.15);
  padding: 10px 14px;
  border-radius: 12px;
  box-shadow: inset 0 0 15px rgba(0, 0, 0, 0.6);
}

.atom-bubble {
  padding: 5px 12px;
  border-radius: 16px;
  font-family: 'Outfit', sans-serif;
  font-weight: 800;
  font-size: 1rem;
  background: linear-gradient(135deg, rgba(56, 189, 248, 0.4), rgba(3, 105, 161, 0.3));
  border: 1px solid var(--accent-cyan);
  color: #ffffff;
  display: flex;
  align-items: center;
  gap: 4px;
  box-shadow: 0 0 12px var(--accent-glow), 0 4px 10px rgba(0, 0, 0, 0.4);
}

.a-sym { font-weight: 800; }
.a-name { font-size: 0.72rem; font-weight: 600; color: rgba(255, 255, 255, 0.85); margin-left: 2px; }

.atom-bubble sub {
  font-size: 0.8rem;
  font-family: 'JetBrains Mono', monospace;
  margin-left: 1px;
  color: #e2e8f0;
}

.plus-sign {
  font-size: 1.2rem;
  font-weight: 800;
  color: var(--accent-cyan);
  text-shadow: 0 0 8px rgba(0, 242, 254, 0.6);
  user-select: none;
}

.arrow-sign {
  font-size: 1.3rem;
  font-weight: 800;
  color: #38bdf8;
  text-shadow: 0 0 10px rgba(56, 189, 248, 0.8);
  margin: 0 4px;
  user-select: none;
  animation: pulseArrow 1.5s infinite ease-in-out;
}

@keyframes pulseArrow {
  0%, 100% { transform: translateX(0); opacity: 0.8; }
  50% { transform: translateX(4px); opacity: 1; }
}

.molecule-badge {
  padding: 6px 14px;
  border-radius: 18px;
  font-family: 'Outfit', 'Noto Sans KR', sans-serif;
  font-weight: 800;
  color: #ffffff;
  border: 1px solid rgba(255, 255, 255, 0.4);
  display: flex;
  align-items: center;
  gap: 6px;
  animation: popIn 0.3s ease-out;
}

.m-formula { font-size: 1.05rem; font-weight: 800; }
.m-name { font-size: 0.75rem; font-weight: 600; opacity: 0.9; }

.result-info-grid {
  display: flex;
  flex-direction: column;
  gap: 6px;
  margin-top: 2px;
}

.info-pill {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.78rem;
}

.info-lbl {
  color: var(--text-muted);
  font-weight: 600;
  min-width: 64px;
}

.info-val {
  color: var(--accent-cyan);
  font-weight: 700;
  font-family: 'JetBrains Mono', monospace;
}

.info-desc-box {
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid rgba(255, 255, 255, 0.08);
  border-radius: 8px;
  padding: 6px 10px;
  font-size: 0.78rem;
  color: #cbd5e1;
  line-height: 1.35;
}

/* Collapsible Presets Section */
.preset-compounds {
  margin-top: 10px;
  padding-top: 10px;
  border-top: 1px dashed var(--panel-border);
  padding-bottom: 6px;
}

.preset-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  cursor: pointer;
  user-select: none;
  padding: 2px 0 6px 0;
  transition: color 0.2s ease;
}

.preset-header:hover h4 {
  color: var(--accent-cyan);
}

.preset-header h4 {
  font-size: 0.84rem;
  color: var(--text-muted);
  margin: 0;
  display: flex;
  align-items: center;
  gap: 6px;
  transition: color 0.2s ease;
}

.preset-toggle-badge {
  font-size: 0.72rem;
  color: var(--accent-cyan);
  background: rgba(0, 242, 254, 0.1);
  border: 1px solid rgba(0, 242, 254, 0.3);
  border-radius: 50%;
  width: 22px;
  height: 22px;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: transform 0.3s cubic-bezier(0.4, 0, 0.2, 1), background 0.2s ease, color 0.2s ease;
}

.preset-header:hover .preset-toggle-badge {
  background: var(--accent-cyan);
  color: #000;
  border-color: transparent;
}

.preset-compounds.collapsed .preset-toggle-badge {
  transform: rotate(180deg);
}

.preset-chips {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  padding-bottom: 6px;
  max-height: 600px;
  opacity: 1;
  transition: max-height 0.35s cubic-bezier(0.4, 0, 0.2, 1), opacity 0.25s ease, margin-top 0.3s ease;
  overflow: hidden;
  margin-top: 4px;
}

.preset-compounds.collapsed .preset-chips {
  max-height: 0;
  opacity: 0;
  margin-top: 0;
  padding-bottom: 0;
}

.preset-chip {
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid var(--panel-border);
  border-radius: 18px;
  padding: 4px 11px;
  color: var(--text-main);
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 5px;
  transition: all 0.2s ease;
  user-select: none;
}

.preset-chip:hover {
  background: linear-gradient(135deg, rgba(0, 242, 254, 0.2), rgba(59, 130, 246, 0.15));
  border-color: var(--accent-cyan);
  transform: translateY(-1px);
  box-shadow: 0 0 14px var(--accent-glow);
}

.chip-formula { font-family: 'Outfit', sans-serif; font-weight: 800; color: var(--accent-cyan); font-size: 0.84rem; }
.chip-name { font-size: 0.75rem; font-weight: 500; color: var(--text-main); }

.picker-card * {
  pointer-events: none;
}

.preset-chip * {
  pointer-events: none;
}

/* Modal Styling - Side by Side Layout with Arrow Navigation */
.modal-overlay {
  position: fixed;
  top: 0; left: 0; right: 0; bottom: 0;
  background: rgba(0, 0, 0, 0.82);
  backdrop-filter: blur(10px);
  z-index: 1000;
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.25s ease;
}

.modal-overlay.active {
  opacity: 1;
  pointer-events: auto;
}

.modal-card.side-by-side-modal {
  background: #0b1329;
  border: 1px solid var(--panel-border);
  border-radius: 20px;
  width: 92%;
  max-width: 920px;
  padding: 24px;
  box-shadow: 0 20px 50px rgba(0, 0, 0, 0.8), 0 0 35px var(--accent-glow);
  position: relative;
  transform: translateY(15px);
  transition: transform 0.25s ease;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 20px;
  align-items: center;
}

.modal-overlay.active .modal-card {
  transform: translateY(0);
}

/* Close & Navigation Arrow Buttons */
.modal-close {
  position: absolute;
  top: 16px;
  right: 18px;
  background: rgba(255, 255, 255, 0.1);
  border: 1px solid rgba(255, 255, 255, 0.2);
  border-radius: 50%;
  width: 32px;
  height: 32px;
  color: #fff;
  font-size: 1rem;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 25;
  transition: all 0.2s ease;
}

.modal-close:hover {
  background: rgba(239, 68, 68, 0.4);
  border-color: rgba(239, 68, 68, 0.8);
}

.modal-nav-btn {
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
  width: 44px;
  height: 44px;
  border-radius: 50%;
  background: rgba(13, 20, 36, 0.92);
  border: 1px solid var(--panel-border);
  color: var(--text-main);
  font-size: 1.1rem;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 20;
  transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
  box-shadow: 0 4px 14px rgba(0, 0, 0, 0.6);
}

.modal-nav-btn.nav-prev {
  left: -22px;
}

.modal-nav-btn.nav-next {
  right: -22px;
}

.modal-nav-btn:hover {
  background: linear-gradient(135deg, var(--accent-cyan), var(--accent-blue));
  color: #000;
  border-color: transparent;
  box-shadow: 0 0 16px var(--accent-glow);
  transform: translateY(-50%) scale(1.15);
}

/* Left Column: Atom Orbit Model */
.modal-left-atom {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  background: rgba(0, 0, 0, 0.35);
  border-radius: 14px;
  border: 1px solid var(--panel-border);
  padding: 14px;
  height: 100%;
  min-height: 360px;
  position: relative;
}

.modal-atom-header {
  font-family: 'Outfit', 'Noto Sans KR', sans-serif;
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--accent-cyan);
  margin-bottom: 8px;
  width: 100%;
  text-align: center;
}

canvas#modalBohrCanvas {
  width: 100%;
  height: 320px;
  display: block;
}

/* Right Column: Element Property Details */
.modal-right-info {
  display: flex;
  flex-direction: column;
  justify-content: center;
}

.modal-header-hero {
  display: flex;
  align-items: center;
  gap: 16px;
  margin-bottom: 16px;
  padding-bottom: 14px;
  border-bottom: 1px solid var(--panel-border);
}

.hero-sym-box {
  width: 64px;
  height: 64px;
  border-radius: 14px;
  background: linear-gradient(135deg, rgba(56, 189, 248, 0.25), rgba(168, 85, 247, 0.25));
  border: 1.5px solid rgba(56, 189, 248, 0.5);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  box-shadow: 0 0 16px rgba(56, 189, 248, 0.2);
}

.hero-num { font-size: 0.7rem; color: rgba(255, 255, 255, 0.8); font-family: 'JetBrains Mono', monospace; }
.hero-sym { font-family: 'Outfit', sans-serif; font-size: 1.6rem; font-weight: 800; color: #fff; text-shadow: 0 0 8px currentColor; }

.modal-grid-props {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 10px;
}

.prop-box {
  background: rgba(255, 255, 255, 0.04);
  padding: 8px 12px;
  border-radius: 8px;
  border: 1px solid rgba(255, 255, 255, 0.06);
}

.prop-lbl { font-size: 0.7rem; color: var(--text-muted); }
.prop-val { font-size: 0.88rem; font-weight: 600; margin-top: 2px; }

/* ==========================================================================
   Mobile Optimization Suite (Smartphones, Tablets, Touch Devices)
   ========================================================================== */

@media (max-width: 840px) {
  html, body {
    display: block !important;
    height: auto !important;
    min-height: 100vh;
    overflow-y: auto !important;
    -webkit-overflow-scrolling: touch;
  }

  .app-container {
    padding: 8px;
    gap: 8px;
    height: auto !important;
    min-height: 100vh;
    overflow: visible !important;
  }

  main {
    height: auto !important;
    overflow: visible !important;
    flex: none !important;
  }

  .app-header {
    flex-direction: column;
    gap: 12px;
    padding: 12px;
    align-items: stretch;
    border-radius: 12px;
  }

  .header-left {
    display: flex;
    justify-content: space-between;
    align-items: center;
    width: 100%;
  }

  .header-left .back-btn {
    padding: 6px 12px;
    font-size: 0.8rem;
  }

  .logo {
    justify-content: flex-start;
    gap: 8px;
  }

  .logo-icon {
    width: 26px;
    height: 26px;
    font-size: 13px;
    border-radius: 6px;
  }

  .logo h1 {
    font-size: 1.05rem;
    font-weight: 800;
  }

  .nav-tabs {
    width: 100%;
    display: flex;
    background: rgba(0, 0, 0, 0.5);
    border: 1px solid var(--panel-border);
    border-radius: 10px;
    padding: 4px;
    box-sizing: border-box;
  }

  .nav-tab {
    flex: 1;
    justify-content: center;
    align-items: center;
    text-align: center;
    padding: 6px 8px;
    font-size: 0.78rem;
    font-weight: 600;
    border-radius: 8px;
    color: var(--text-muted);
    background: transparent;
    border: 1px solid transparent;
    touch-action: manipulation;
    white-space: nowrap;
    gap: 4px;
  }

  .nav-tab.active {
    background: #00f2fe;
    color: #000000;
    font-weight: 800;
    border: 1px solid #00f2fe;
    box-shadow: 0 0 16px var(--accent-glow);
  }

  /* Periodic Table Mobile Layout */
  .toolbar-panel {
    flex-direction: column;
    align-items: stretch;
    gap: 8px;
    padding: 8px;
  }

  .search-box {
    max-width: 100%;
    width: 100%;
  }

  .search-box input {
    font-size: 0.85rem;
    padding: 8px 10px 8px 32px;
  }

  /* Hide filter dropdowns & category badges bar on mobile for maximum viewport space */
  .filter-group,
  .category-legend-bar {
    display: none !important;
  }

  .ptable-container {
    overflow-x: auto;
    overflow-y: auto;
    -webkit-overflow-scrolling: touch;
    padding: 8px;
    border-radius: 10px;
  }

  .ptable-grid, .sub-grid {
    min-width: 900px;
    gap: 2px;
  }

  /* Compound Simulator Mobile Layout - Single Page Seamless Natural Touch Scroll (Zero Scroll Traps) */
  .tab-content,
  .tab-content.active,
  #tab-compound,
  #tab-compound.active,
  #compoundSimulatorContainer,
  .compound-sim-layout {
    height: auto !important;
    min-height: min-content !important;
    overflow: visible !important;
    flex: none !important;
  }

  .compound-sim-layout {
    grid-template-columns: 1fr;
    gap: 12px;
    width: 100%;
  }

  .element-picker-panel,
  .reaction-chamber-panel,
  .chamber-body-scroll {
    height: auto !important;
    max-height: none !important;
    overflow: visible !important;
    flex: none !important;
    border-radius: 12px;
    padding: 12px;
  }

  .picker-grid {
    grid-template-columns: repeat(4, 1fr);
    grid-template-rows: auto !important;
    gap: 6px;
    height: auto !important;
    overflow: visible !important;
  }

  .picker-card {
    min-height: 52px;
    padding: 4px 2px;
    touch-action: manipulation;
  }

  .p-sym {
    font-size: 1rem;
  }

  .p-name {
    font-size: 0.64rem;
  }

  .reaction-chamber-panel {
    height: auto;
    border-radius: 12px;
    padding: 12px;
    overflow: visible;
  }

  .flask-display {
    min-height: 80px;
    padding: 10px;
    gap: 8px;
  }

  .flask-item {
    padding: 6px 10px;
  }

  .count-btn {
    width: 26px;
    height: 26px;
    font-size: 0.95rem;
    touch-action: manipulation;
  }

  .preset-chips {
    gap: 6px;
  }

  /* Hide representative compound preset guide on mobile as requested */
  .preset-compounds {
    display: none !important;
  }

  /* Modal Mobile Optimization */
  .modal-card.side-by-side-modal {
    width: 95%;
    max-height: 88vh;
    overflow-y: auto;
    grid-template-columns: 1fr;
    padding: 16px;
    gap: 14px;
    border-radius: 16px;
  }

  .modal-close {
    top: 12px;
    right: 12px;
    width: 36px;
    height: 36px;
  }

  .modal-nav-btn {
    width: 38px;
    height: 38px;
    font-size: 0.95rem;
  }

  .modal-nav-btn.nav-prev {
    left: 8px;
    top: 14px;
    transform: none;
  }

  .modal-nav-btn.nav-next {
    right: 52px;
    top: 14px;
    transform: none;
  }

  .modal-left-atom {
    min-height: 280px;
  }

  canvas#modalBohrCanvas {
    height: 250px;
  }

  .modal-grid-props {
    grid-template-columns: repeat(2, 1fr);
    gap: 8px;
  }

  .prop-box {
    padding: 6px 8px;
  }

  .prop-lbl { font-size: 0.66rem; }
  .prop-val { font-size: 0.82rem; }
}

@media (max-width: 480px) {
  .picker-grid {
    grid-template-columns: repeat(3, 1fr);
  }

  .modal-grid-props {
    grid-template-columns: 1fr;
  }

  .formula-visual {
    gap: 6px;
    padding: 8px;
  }

  .atom-bubble {
    padding: 4px 8px;
    font-size: 0.88rem;
  }
}

/* Back Button Style */
.back-btn {
  background: transparent;
  color: var(--text-main);
  border: 1px solid rgba(255, 255, 255, 0.15);
  padding: 8px 16px;
  border-radius: 8px;
  cursor: pointer;
  font-family: var(--font-family);
  font-weight: 600;
  font-size: 0.85rem;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  transition: all 0.2s;
}

.back-btn:hover {
  background: rgba(255, 255, 255, 0.08);
  border-color: rgba(255, 255, 255, 0.25);
}


@media (max-width: 420px) {
  .nav-tab {
    padding: 5px 4px;
    font-size: 0.72rem;
    gap: 3px;
  }
}