/* CSS Design System - SQL Cheat Sheet Hub & Interactive Playground */

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

:root {
  /* Color Tokens */
  --bg-main: hsl(224, 25%, 8%);
  --bg-sidebar: hsla(223, 22%, 11%, 0.85);
  --bg-card: hsla(223, 20%, 14%, 0.55);
  --bg-code: hsla(225, 25%, 6%, 0.85);
  
  --border-glass: hsla(220, 20%, 25%, 0.4);
  --border-glass-hover: hsla(220, 30%, 45%, 0.6);
  
  --accent-cyan: hsl(180, 100%, 48%);
  --accent-cyan-rgb: 0, 245, 245;
  --accent-blue: hsl(217, 91%, 60%);
  --accent-blue-rgb: 64, 137, 255;
  --accent-purple: hsl(272, 85%, 65%);
  --accent-pink: hsl(322, 100%, 60%);
  --accent-pink-rgb: 255, 51, 170;
  
  --success: hsl(145, 80%, 45%);
  --error: hsl(355, 80%, 60%);
  
  --text-primary: hsl(210, 20%, 98%);
  --text-secondary: hsl(215, 15%, 75%);
  --text-muted: hsl(215, 10%, 55%);
  
  /* Layout Constants */
  --sidebar-width: 280px;
  --header-height: 80px;
  
  /* Shadows & Filters */
  --glow-cyan: 0 0 15px hsla(180, 100%, 48%, 0.25);
  --glow-pink: 0 0 15px hsla(322, 100%, 60%, 0.25);
  --glass-shadow: 0 8px 32px 0 rgba(0, 0, 0, 0.4);
  --glass-blur: blur(12px);
}

/* Global resets & scrollbar */
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  scrollbar-width: thin;
  scrollbar-color: var(--border-glass) transparent;
}

body {
  font-family: 'Outfit', sans-serif;
  background-color: var(--bg-main);
  background-image: 
    radial-gradient(at 10% 20%, hsla(272, 85%, 65%, 0.08) 0px, transparent 50%),
    radial-gradient(at 90% 80%, hsla(180, 100%, 48%, 0.06) 0px, transparent 50%),
    radial-gradient(at 50% 50%, hsla(217, 91%, 60%, 0.05) 0px, transparent 60%);
  background-attachment: fixed;
  color: var(--text-primary);
  min-height: 100vh;
  display: flex;
  overflow-x: hidden;
}

/* Custom Scrollbar Styles */
::-webkit-scrollbar {
  width: 8px;
  height: 8px;
}
::-webkit-scrollbar-track {
  background: transparent;
}
::-webkit-scrollbar-thumb {
  background: var(--border-glass);
  border-radius: 20px;
}
::-webkit-scrollbar-thumb:hover {
  background: var(--border-glass-hover);
}

/* App Shell Layout */
#app-sidebar {
  width: var(--sidebar-width);
  background: var(--bg-sidebar);
  backdrop-filter: var(--glass-blur);
  border-right: 1px solid var(--border-glass);
  display: flex;
  flex-direction: column;
  position: fixed;
  top: 0;
  left: 0;
  bottom: 0;
  z-index: 100;
  padding: 2rem 1.5rem;
  transition: transform 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

#app-container {
  margin-left: var(--sidebar-width);
  flex: 1;
  display: flex;
  flex-direction: column;
  min-width: 0;
  position: relative;
}

#app-header {
  height: var(--header-height);
  border-bottom: 1px solid var(--border-glass);
  background: hsla(224, 25%, 8%, 0.7);
  backdrop-filter: var(--glass-blur);
  position: sticky;
  top: 0;
  z-index: 90;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 3rem;
}

#app-main {
  flex: 1;
  padding: 3rem;
  max-width: 1400px;
  width: 100%;
  margin: 0 auto;
}

/* Sidebar Styling */
.logo-container {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-bottom: 3rem;
}

.logo-icon {
  background: linear-gradient(135deg, var(--accent-cyan), var(--accent-blue));
  width: 40px;
  height: 40px;
  border-radius: 12px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 800;
  font-size: 1.25rem;
  color: var(--bg-main);
  box-shadow: 0 0 15px rgba(0, 245, 245, 0.4);
}

.logo-text h1 {
  font-size: 1.2rem;
  font-weight: 700;
  letter-spacing: 0.5px;
  background: linear-gradient(to right, var(--text-primary), var(--text-secondary));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.logo-text span {
  font-size: 0.75rem;
  color: var(--accent-cyan);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 2px;
  display: block;
}

.nav-section {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.nav-label {
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 1.5px;
  margin-bottom: 0.5rem;
  padding-left: 0.5rem;
}

.nav-item {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.85rem 1rem;
  border-radius: 10px;
  color: var(--text-secondary);
  text-decoration: none;
  font-weight: 500;
  font-size: 0.95rem;
  cursor: pointer;
  border: 1px solid transparent;
  transition: all 0.2s ease;
}

.nav-item:hover {
  background: hsla(220, 20%, 20%, 0.4);
  color: var(--text-primary);
  border-color: var(--border-glass);
}

.nav-item.active {
  background: linear-gradient(135deg, hsla(180, 100%, 48%, 0.1), hsla(217, 91%, 60%, 0.05));
  color: var(--accent-cyan);
  border-color: hsla(180, 100%, 48%, 0.25);
  box-shadow: var(--glow-cyan);
}

.sidebar-footer {
  margin-top: auto;
  border-top: 1px solid var(--border-glass);
  padding-top: 1.5rem;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.reset-db-btn {
  background: transparent;
  border: 1px dashed var(--accent-pink);
  color: var(--accent-pink);
  padding: 0.75rem 1rem;
  border-radius: 10px;
  font-family: inherit;
  font-weight: 600;
  font-size: 0.85rem;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  transition: all 0.2s ease;
}

.reset-db-btn:hover {
  background: hsla(322, 100%, 60%, 0.1);
  box-shadow: var(--glow-pink);
  border-style: solid;
}

.logo-author {
  font-size: 0.65rem;
  color: var(--text-muted);
  text-decoration: none;
  font-weight: 500;
  display: block;
  margin-top: 0.25rem;
  transition: color 0.2s ease;
}

.logo-author:hover {
  color: var(--accent-cyan);
}

.author-credits {
  font-size: 0.8rem;
  color: var(--text-muted);
  text-align: center;
  margin-top: 0.75rem;
  font-weight: 500;
}

.author-credits a {
  color: var(--accent-cyan);
  text-decoration: none;
  font-weight: 700;
  transition: color 0.2s ease, text-shadow 0.2s ease;
}

.author-credits a:hover {
  color: var(--text-primary);
  text-shadow: var(--glow-cyan);
}

/* Header Styling */
.search-wrapper {
  position: relative;
  width: 400px;
  max-width: 100%;
}

.search-wrapper svg {
  position: absolute;
  left: 1rem;
  top: 50%;
  transform: translateY(-50%);
  color: var(--text-muted);
  width: 18px;
  height: 18px;
  pointer-events: none;
}

.search-input {
  width: 100%;
  background: var(--bg-card);
  border: 1px solid var(--border-glass);
  border-radius: 12px;
  padding: 0.75rem 1rem 0.75rem 2.75rem;
  color: var(--text-primary);
  font-family: inherit;
  font-size: 0.95rem;
  outline: none;
  transition: all 0.25s ease;
}

.search-input:focus {
  border-color: var(--accent-cyan);
  box-shadow: var(--glow-cyan);
  background: hsla(223, 20%, 16%, 0.8);
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 1rem;
}

.badge-db {
  background: linear-gradient(135deg, hsla(145, 80%, 45%, 0.15), hsla(180, 100%, 48%, 0.05));
  border: 1px solid hsla(145, 80%, 45%, 0.3);
  color: var(--success);
  padding: 0.4rem 0.8rem;
  border-radius: 8px;
  font-size: 0.8rem;
  font-weight: 600;
  display: flex;
  align-items: center;
  gap: 0.4rem;
}

.badge-db span {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background-color: var(--success);
  box-shadow: 0 0 8px var(--success);
  display: inline-block;
}

/* Glass Cards and Content Panels */
.glass-panel {
  background: var(--bg-card);
  backdrop-filter: var(--glass-blur);
  border: 1px solid var(--border-glass);
  border-radius: 16px;
  padding: 2rem;
  box-shadow: var(--glass-shadow);
  margin-bottom: 2rem;
}

.page-title-section {
  margin-bottom: 2.5rem;
}

.page-title-section h2 {
  font-size: 1.8rem;
  font-weight: 700;
  letter-spacing: -0.5px;
  margin-bottom: 0.5rem;
}

.page-title-section p {
  color: var(--text-secondary);
  font-size: 1rem;
}

/* Views Management */
.view-content {
  display: none;
  animation: fadeIn 0.35s cubic-bezier(0.4, 0, 0.2, 1) forwards;
}

.view-content.active {
  display: block;
}

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

/* Cheat Sheet Cards Grid */
.cards-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(360px, 1fr));
  gap: 1.5rem;
}

.concept-card {
  background: var(--bg-card);
  backdrop-filter: var(--glass-blur);
  border: 1px solid var(--border-glass);
  border-radius: 14px;
  padding: 1.5rem;
  display: flex;
  flex-direction: column;
  transition: all 0.25s cubic-bezier(0.4, 0, 0.2, 1);
  box-shadow: var(--glass-shadow);
  position: relative;
  overflow: hidden;
}

.concept-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 2px;
  background: linear-gradient(90deg, var(--accent-cyan), var(--accent-blue));
  opacity: 0;
  transition: opacity 0.25s ease;
}

.concept-card:hover {
  transform: translateY(-4px);
  border-color: var(--border-glass-hover);
  box-shadow: 0 12px 40px 0 rgba(0, 0, 0, 0.5);
}

.concept-card:hover::before {
  opacity: 1;
}

.card-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  margin-bottom: 1rem;
}

.card-title {
  font-size: 1.15rem;
  font-weight: 600;
  color: var(--text-primary);
}

.card-badge {
  background: hsla(217, 91%, 60%, 0.15);
  color: var(--accent-blue);
  border: 1px solid hsla(217, 91%, 60%, 0.3);
  font-size: 0.7rem;
  font-weight: 600;
  padding: 0.2rem 0.5rem;
  border-radius: 6px;
  text-transform: uppercase;
}

.card-desc {
  font-size: 0.88rem;
  color: var(--text-secondary);
  line-height: 1.5;
  margin-bottom: 1.25rem;
  flex-grow: 1;
}

.code-block-wrapper {
  position: relative;
  margin-bottom: 1.25rem;
  border-radius: 8px;
  overflow: hidden;
}

.code-title {
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.5px;
  background-color: hsla(225, 25%, 4%, 0.9);
  padding: 0.4rem 0.75rem;
  border-bottom: 1px solid var(--border-glass);
}

.code-block {
  background: var(--bg-code);
  padding: 0.85rem 1rem;
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.82rem;
  color: var(--accent-cyan);
  white-space: pre-wrap;
  overflow-x: auto;
  border: 1px solid hsla(220, 20%, 25%, 0.1);
}

/* Synthwave Code Colors */
.code-sql-keyword { color: var(--accent-pink); font-weight: 600; }
.code-sql-table { color: var(--text-primary); }
.code-sql-column { color: var(--accent-cyan); }
.code-sql-string { color: hsl(95, 60%, 65%); }
.code-sql-operator { color: var(--accent-pink); }
.code-sql-number { color: hsl(35, 90%, 60%); }

.card-actions {
  display: flex;
  gap: 0.75rem;
  border-top: 1px solid var(--border-glass);
  padding-top: 1rem;
  margin-top: auto;
}

.btn-card {
  flex: 1;
  background: transparent;
  border: 1px solid var(--border-glass);
  color: var(--text-secondary);
  font-family: inherit;
  font-size: 0.82rem;
  font-weight: 500;
  padding: 0.6rem 0.8rem;
  border-radius: 8px;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.4rem;
  transition: all 0.2s ease;
}

.btn-card:hover {
  background: hsla(220, 20%, 20%, 0.4);
  color: var(--text-primary);
  border-color: var(--border-glass-hover);
}

.btn-card-primary {
  background: linear-gradient(135deg, var(--accent-cyan), var(--accent-blue));
  border: none;
  color: var(--bg-main);
  font-weight: 600;
  box-shadow: 0 4px 12px hsla(180, 100%, 48%, 0.15);
}

.btn-card-primary:hover {
  box-shadow: 0 4px 16px hsla(180, 100%, 48%, 0.35);
  transform: scale(1.02);
  color: var(--bg-main);
}

/* Interactive JOIN Visualizer View */
.join-visualizer-container {
  display: grid;
  grid-template-columns: 420px 1fr;
  gap: 2rem;
}

.join-controls {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.join-option-card {
  background: var(--bg-card);
  border: 1px solid var(--border-glass);
  border-radius: 12px;
  padding: 1.25rem;
  cursor: pointer;
  display: flex;
  gap: 1rem;
  align-items: center;
  transition: all 0.2s ease;
}

.join-option-card:hover {
  border-color: var(--border-glass-hover);
  background: hsla(223, 20%, 16%, 0.5);
}

.join-option-card.active {
  border-color: var(--accent-cyan);
  background: linear-gradient(135deg, hsla(180, 100%, 48%, 0.05), hsla(217, 91%, 60%, 0.02));
  box-shadow: var(--glow-cyan);
}

.join-radio {
  width: 18px;
  height: 18px;
  border-radius: 50%;
  border: 2px solid var(--border-glass);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  transition: all 0.2s ease;
}

.join-option-card.active .join-radio {
  border-color: var(--accent-cyan);
}

.join-option-card.active .join-radio::after {
  content: '';
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background-color: var(--accent-cyan);
}

.join-option-details h4 {
  font-size: 0.95rem;
  font-weight: 600;
  margin-bottom: 0.25rem;
}

.join-option-details p {
  font-size: 0.8rem;
  color: var(--text-secondary);
}

/* Venn Diagram SVG */
.join-diagram-pane {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 2rem;
}

.venn-svg-wrapper {
  background: hsla(225, 25%, 5%, 0.4);
  border: 1px solid var(--border-glass);
  border-radius: 16px;
  width: 100%;
  height: 300px;
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
  overflow: hidden;
}

.venn-svg-wrapper::after {
  content: '';
  position: absolute;
  inset: 0;
  background: radial-gradient(circle at center, hsla(180, 100%, 48%, 0.03) 0%, transparent 70%);
}

.venn-svg {
  width: 420px;
  height: 220px;
}

.venn-circle {
  fill: hsla(220, 20%, 30%, 0.15);
  stroke: var(--border-glass);
  stroke-width: 2px;
  transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
}

.venn-text {
  font-family: 'Outfit', sans-serif;
  font-size: 14px;
  font-weight: 700;
  fill: var(--text-secondary);
  pointer-events: none;
  transition: all 0.3s ease;
}

/* Venn diagram dynamic highlights */
.join-venn-left { fill: var(--venn-left-fill, hsla(220, 20%, 30%, 0.15)); }
.join-venn-right { fill: var(--venn-right-fill, hsla(220, 20%, 30%, 0.15)); }
.join-venn-intersect { fill: var(--venn-intersect-fill, hsla(220, 20%, 30%, 0.15)); }

/* SQL Sandbox / Playground Layout */
.playground-container {
  display: grid;
  grid-template-columns: 280px 1fr;
  gap: 2rem;
  align-items: start;
}

/* Schema Browser Panel */
.schema-panel {
  background: var(--bg-card);
  border: 1px solid var(--border-glass);
  border-radius: 14px;
  padding: 1.25rem;
  box-shadow: var(--glass-shadow);
  max-height: 800px;
  overflow-y: auto;
}

.schema-title {
  font-size: 0.9rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 1px;
  color: var(--text-secondary);
  border-bottom: 1px solid var(--border-glass);
  padding-bottom: 0.75rem;
  margin-bottom: 1rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.schema-table-item {
  margin-bottom: 0.75rem;
  border: 1px solid var(--border-glass);
  border-radius: 10px;
  overflow: hidden;
}

.schema-table-header {
  background: hsla(220, 20%, 20%, 0.3);
  padding: 0.65rem 0.85rem;
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.85rem;
  font-weight: 600;
  display: flex;
  justify-content: space-between;
  align-items: center;
  cursor: pointer;
  user-select: none;
  transition: background 0.2s ease;
}

.schema-table-header:hover {
  background: hsla(220, 20%, 20%, 0.6);
}

.schema-table-header span.toggle-icon {
  font-size: 0.7rem;
  color: var(--text-muted);
  transition: transform 0.2s ease;
}

.schema-table-item.expanded .schema-table-header span.toggle-icon {
  transform: rotate(90deg);
}

.schema-table-columns {
  display: none;
  background: hsla(225, 25%, 5%, 0.4);
  border-top: 1px solid var(--border-glass);
  padding: 0.5rem 0.85rem;
}

.schema-table-item.expanded .schema-table-columns {
  display: block;
}

.schema-column {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0.35rem 0;
  font-size: 0.78rem;
  border-bottom: 1px solid hsla(220, 20%, 25%, 0.2);
}

.schema-column:last-child {
  border-bottom: none;
}

.schema-col-name {
  font-family: 'JetBrains Mono', monospace;
  color: var(--text-secondary);
}

.schema-col-name.pk {
  color: hsl(45, 100%, 60%);
  display: flex;
  align-items: center;
  gap: 0.25rem;
}

.schema-col-name.fk {
  color: var(--accent-pink);
  display: flex;
  align-items: center;
  gap: 0.25rem;
}

.schema-col-type {
  font-family: 'JetBrains Mono', monospace;
  color: var(--text-muted);
  font-size: 0.72rem;
}

/* SQL Console Area */
.console-area {
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

.editor-wrapper {
  background: var(--bg-code);
  border: 1px solid var(--border-glass);
  border-radius: 14px;
  overflow: hidden;
  box-shadow: var(--glass-shadow);
  display: flex;
  flex-direction: column;
}

.editor-header {
  background: hsla(225, 25%, 4%, 0.9);
  padding: 0.75rem 1.5rem;
  border-bottom: 1px solid var(--border-glass);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.editor-title {
  font-size: 0.82rem;
  font-weight: 700;
  color: var(--text-secondary);
  text-transform: uppercase;
  letter-spacing: 1.5px;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.editor-title span.indicator {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background-color: var(--accent-cyan);
  box-shadow: var(--glow-cyan);
}

.sql-editor-textarea {
  width: 100%;
  min-height: 140px;
  background: transparent;
  border: none;
  padding: 1.25rem;
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.95rem;
  color: var(--text-primary);
  outline: none;
  resize: vertical;
  line-height: 1.6;
}

.editor-actions {
  background: hsla(225, 25%, 4%, 0.7);
  border-top: 1px solid var(--border-glass);
  padding: 0.75rem 1.25rem;
  display: flex;
  justify-content: space-between;
  gap: 1rem;
}

.btn-editor {
  background: transparent;
  border: 1px solid var(--border-glass);
  color: var(--text-secondary);
  font-family: inherit;
  font-size: 0.85rem;
  font-weight: 600;
  padding: 0.55rem 1.1rem;
  border-radius: 8px;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 0.4rem;
  transition: all 0.2s ease;
}

.btn-editor:hover {
  background: hsla(220, 20%, 20%, 0.4);
  color: var(--text-primary);
  border-color: var(--border-glass-hover);
}

.btn-editor-run {
  background: linear-gradient(135deg, var(--accent-cyan), var(--accent-blue));
  border: none;
  color: var(--bg-main);
  box-shadow: 0 4px 15px rgba(0, 245, 245, 0.25);
}

.btn-editor-run:hover {
  box-shadow: 0 4px 20px rgba(0, 245, 245, 0.45);
  transform: scale(1.02);
  color: var(--bg-main);
}

/* Results Display Panel */
.results-panel {
  min-height: 120px;
}

.results-header {
  font-size: 0.9rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 1px;
  color: var(--text-secondary);
  margin-bottom: 0.75rem;
  display: flex;
  justify-content: space-between;
}

.result-status-msg {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 1rem;
  border-radius: 10px;
  font-size: 0.9rem;
  font-weight: 500;
  margin-bottom: 1rem;
}

.result-status-msg.success {
  background: hsla(145, 80%, 45%, 0.1);
  border: 1px solid hsla(145, 80%, 45%, 0.25);
  color: var(--success);
}

.result-status-msg.error {
  background: hsla(355, 80%, 60%, 0.1);
  border: 1px solid hsla(355, 80%, 60%, 0.25);
  color: var(--error);
}

.results-table-wrapper {
  width: 100%;
  overflow-x: auto;
  border: 1px solid var(--border-glass);
  border-radius: 10px;
  background: hsla(223, 20%, 10%, 0.4);
}

.results-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.88rem;
  text-align: left;
}

.results-table th {
  background: hsla(220, 20%, 16%, 0.7);
  color: var(--text-primary);
  font-weight: 600;
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.8rem;
  padding: 0.85rem 1rem;
  border-bottom: 1px solid var(--border-glass);
  white-space: nowrap;
}

.results-table td {
  padding: 0.75rem 1rem;
  border-bottom: 1px solid hsla(220, 20%, 20%, 0.3);
  color: var(--text-secondary);
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.82rem;
  white-space: nowrap;
}

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

.results-table tr:hover td {
  background: hsla(220, 20%, 20%, 0.25);
  color: var(--text-primary);
}

.empty-results {
  padding: 3rem;
  text-align: center;
  color: var(--text-muted);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1rem;
}

.empty-results svg {
  color: hsla(220, 20%, 30%, 0.4);
  width: 48px;
  height: 48px;
}

/* Data Types Visual Grid */
.datatypes-section {
  margin-bottom: 2rem;
}

.datatype-group-title {
  font-size: 1.15rem;
  font-weight: 600;
  color: var(--accent-cyan);
  margin-bottom: 1rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.datatype-group-title::after {
  content: '';
  flex-grow: 1;
  height: 1px;
  background: linear-gradient(to right, hsla(180, 100%, 48%, 0.3), transparent);
}

.datatypes-list {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(290px, 1fr));
  gap: 1rem;
  margin-bottom: 2.5rem;
}

.datatype-card {
  background: var(--bg-card);
  border: 1px solid var(--border-glass);
  border-radius: 10px;
  padding: 1.25rem;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  transition: all 0.2s ease;
}

.datatype-card:hover {
  border-color: var(--border-glass-hover);
  background: hsla(223, 20%, 15%, 0.5);
  transform: translateY(-2px);
}

.datatype-card-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.datatype-name {
  font-family: 'JetBrains Mono', monospace;
  font-weight: 700;
  font-size: 0.95rem;
  color: var(--text-primary);
}

.datatype-size {
  background: hsla(322, 100%, 60%, 0.1);
  color: var(--accent-pink);
  border: 1px solid hsla(322, 100%, 60%, 0.2);
  font-size: 0.65rem;
  font-weight: 600;
  padding: 0.15rem 0.4rem;
  border-radius: 4px;
}

.datatype-desc {
  font-size: 0.8rem;
  color: var(--text-secondary);
  line-height: 1.4;
}

.datatype-example {
  background: var(--bg-code);
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.75rem;
  color: var(--accent-cyan);
  padding: 0.4rem 0.6rem;
  border-radius: 6px;
  margin-top: auto;
  border: 1px solid hsla(220, 20%, 20%, 0.3);
}

/* Category Headers in Reference */
.ref-category-header {
  grid-column: 1 / -1;
  font-size: 1.3rem;
  font-weight: 700;
  color: var(--text-primary);
  margin: 2rem 0 1rem 0;
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.ref-category-header::before {
  content: '';
  width: 4px;
  height: 20px;
  background: linear-gradient(to bottom, var(--accent-cyan), var(--accent-blue));
  border-radius: 20px;
  display: block;
}

/* Mobile & Responsive Adjustments */
.menu-toggle {
  display: none;
  background: transparent;
  border: none;
  color: var(--text-primary);
  cursor: pointer;
  align-items: center;
  justify-content: center;
  padding: 0.5rem;
  border-radius: 8px;
  transition: background 0.2s;
}

.menu-toggle:hover {
  background: hsla(220, 20%, 20%, 0.4);
}

@media (max-width: 1024px) {
  #app-sidebar {
    transform: translateX(-100%);
    box-shadow: 10px 0 30px rgba(0, 0, 0, 0.6);
  }
  
  #app-sidebar.open {
    transform: translateX(0);
  }
  
  #app-container {
    margin-left: 0;
  }
  
  #app-header {
    padding: 0 1.5rem;
  }
  
  #app-main {
    padding: 1.5rem;
  }
  
  .menu-toggle {
    display: flex;
  }
  
  .search-wrapper {
    width: 240px;
  }
  
  .join-visualizer-container {
    grid-template-columns: 1fr;
  }
  
  .playground-container {
    grid-template-columns: 1fr;
  }
  
  .console-area {
    order: 1;
  }
  
  .schema-panel {
    order: 2;
    max-height: 450px;
  }
}

@media (max-width: 768px) {
  .cards-grid {
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 1rem;
  }
  
  .venn-svg {
    max-width: 100%;
    height: auto;
  }
  
  .venn-svg-wrapper {
    height: auto;
    padding: 2rem 1rem;
  }
  
  .search-wrapper {
    width: 180px;
  }
}

@media (max-width: 576px) {
  #app-header {
    padding: 0 1rem;
    height: 70px;
  }
  
  #app-main {
    padding: 1.25rem 1rem;
  }
  
  .page-title-section {
    margin-bottom: 1.5rem;
  }
  
  .page-title-section h2 {
    font-size: 1.4rem;
  }
  
  .page-title-section p {
    font-size: 0.85rem;
  }
  
  .glass-panel {
    padding: 1.25rem;
    margin-bottom: 1.25rem;
  }
  
  .concept-card {
    padding: 1.25rem;
  }
  
  .card-actions {
    flex-direction: column;
    gap: 0.6rem;
  }
  
  .btn-card {
    width: 100%;
  }
  
  .search-wrapper {
    width: 140px;
  }
  
  .search-input {
    font-size: 0.85rem;
    padding: 0.6rem 0.8rem 0.6rem 2.2rem;
  }
  
  .search-wrapper svg {
    width: 14px;
    height: 14px;
    left: 0.8rem;
  }
  
  .badge-db {
    font-size: 0;
    padding: 0.5rem;
    border-radius: 50%;
    width: 32px;
    height: 32px;
    display: flex;
    align-items: center;
    justify-content: center;
    border: 1px solid hsla(145, 80%, 45%, 0.4);
  }
  
  .badge-db span {
    margin: 0;
  }
  
  .results-header {
    flex-direction: column;
    align-items: flex-start;
    gap: 0.75rem;
  }
  
  #join-try-playground-btn {
    width: 100%;
    text-align: center;
  }
}