/* 
 * styles.css
 * Core design system, variables, layouts, and rich animations 
 * for the Mental Maths cognitive trainer.
 */

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

:root {
  /* Color Palette - Cyber Neon Theme */
  --bg-dark: #080710;
  --bg-deep: #0c0a1a;
  --bg-surface: rgba(18, 15, 38, 0.6);
  --bg-surface-hover: rgba(26, 22, 54, 0.85);
  --border-glass: rgba(255, 255, 255, 0.08);
  --border-glass-active: rgba(255, 255, 255, 0.2);
  
  --primary: #8a2be2; /* Blue Violet */
  --primary-glow: rgba(138, 43, 226, 0.4);
  --accent-cyan: #00f0ff; /* Neon Cyan */
  --cyan-glow: rgba(0, 240, 255, 0.4);
  --accent-purple: #bd00ff; /* Neon Purple */
  --purple-glow: rgba(189, 0, 255, 0.4);
  --accent-green: #39ff14; /* Neon Green */
  --green-glow: rgba(57, 255, 20, 0.3);
  --accent-red: #ff3131; /* Neon Red */
  --red-glow: rgba(255, 49, 49, 0.4);
  
  --text-primary: #f3f0ff;
  --text-secondary: #a29dbd;
  --text-muted: #67637a;
  
  --font-sans: 'Outfit', sans-serif;
  --font-mono: 'JetBrains Mono', monospace;
  
  --transition-fast: 0.15s ease;
  --transition-normal: 0.3s cubic-bezier(0.25, 0.8, 0.25, 1);
  --transition-slow: 0.5s cubic-bezier(0.25, 0.8, 0.25, 1);
  
  --radius-sm: 8px;
  --radius-md: 16px;
  --radius-lg: 24px;
}

/* Base Settings */
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  -webkit-font-smoothing: antialiased;
}

body {
  font-family: var(--font-sans);
  background-color: var(--bg-dark);
  background-image: 
    radial-gradient(at 10% 10%, rgba(138, 43, 226, 0.15) 0px, transparent 50%),
    radial-gradient(at 90% 90%, rgba(0, 240, 255, 0.12) 0px, transparent 50%),
    radial-gradient(at 50% 50%, rgba(12, 10, 26, 1) 0px, rgba(8, 7, 16, 1) 100%);
  background-attachment: fixed;
  color: var(--text-primary);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  overflow-x: hidden;
}

/* Scrollbar Styling */
::-webkit-scrollbar {
  width: 8px;
  height: 8px;
}
::-webkit-scrollbar-track {
  background: var(--bg-dark);
}
::-webkit-scrollbar-thumb {
  background: var(--border-glass-active);
  border-radius: 4px;
}
::-webkit-scrollbar-thumb:hover {
  background: var(--primary);
}

/* Layout Structure */
header {
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  background: rgba(8, 7, 16, 0.7);
  border-bottom: 1px solid var(--border-glass);
  padding: 16px 24px;
  position: sticky;
  top: 0;
  z-index: 100;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo-section {
  display: flex;
  align-items: center;
  gap: 12px;
  cursor: pointer;
}

.logo-icon {
  background: linear-gradient(135deg, var(--primary), var(--accent-cyan));
  width: 40px;
  height: 40px;
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  color: #fff;
  box-shadow: 0 0 15px var(--primary-glow);
  font-weight: 800;
  font-size: 1.25rem;
}

.logo-text h1 {
  font-size: 1.4rem;
  font-weight: 700;
  background: linear-gradient(to right, #ffffff, var(--text-secondary));
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  letter-spacing: -0.5px;
}

.logo-text span {
  font-size: 0.75rem;
  color: var(--accent-cyan);
  font-family: var(--font-mono);
  letter-spacing: 1px;
  text-transform: uppercase;
}

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

/* Stats Badges in Header */
.header-stat {
  display: flex;
  align-items: center;
  gap: 8px;
  background: var(--bg-surface);
  border: 1px solid var(--border-glass);
  padding: 6px 12px;
  border-radius: 20px;
  font-size: 0.9rem;
  font-weight: 500;
}

.header-stat svg {
  width: 16px;
  height: 16px;
}

.stat-streak {
  color: #ff9d00;
  border-color: rgba(255, 157, 0, 0.2);
  box-shadow: 0 0 8px rgba(255, 157, 0, 0.1);
}

.stat-level {
  color: var(--accent-cyan);
  border-color: rgba(0, 240, 255, 0.2);
}

/* Toggle Switch Styling */
.switch-container {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.85rem;
  color: var(--text-secondary);
}

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

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

.slider {
  position: absolute;
  cursor: pointer;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background-color: var(--bg-deep);
  border: 1px solid var(--border-glass);
  transition: var(--transition-normal);
  border-radius: 24px;
}

.slider:before {
  position: absolute;
  content: "";
  height: 16px;
  width: 16px;
  left: 3px;
  bottom: 3px;
  background-color: var(--text-secondary);
  transition: var(--transition-normal);
  border-radius: 50%;
}

input:checked + .slider {
  background-color: rgba(138, 43, 226, 0.3);
  border-color: var(--primary);
}

input:checked + .slider:before {
  transform: translateX(20px);
  background-color: var(--accent-cyan);
  box-shadow: 0 0 10px var(--cyan-glow);
}

/* Main Container */
main {
  flex: 1;
  max-width: 1200px;
  width: 100%;
  margin: 0 auto;
  padding: 32px 24px;
  display: flex;
  flex-direction: column;
}

/* Utility Screens Hide/Show */
.screen {
  display: none;
  animation: fadeIn var(--transition-normal);
  flex-direction: column;
  flex: 1;
}

.screen.active {
  display: flex;
}

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

/* Card Elements - Glassmorphism */
.glass-card {
  background: var(--bg-surface);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid var(--border-glass);
  border-radius: var(--radius-lg);
  padding: 32px;
  transition: var(--transition-normal);
  position: relative;
  overflow: hidden;
}

.glass-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: linear-gradient(135deg, rgba(255,255,255,0.03) 0%, rgba(255,255,255,0) 100%);
  pointer-events: none;
}

/* BUTTONS */
.btn {
  font-family: var(--font-sans);
  font-weight: 600;
  font-size: 1rem;
  padding: 12px 24px;
  border-radius: var(--radius-md);
  border: 1px solid transparent;
  cursor: pointer;
  transition: var(--transition-normal);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  text-decoration: none;
}

.btn-primary {
  background: linear-gradient(135deg, var(--primary), var(--accent-purple));
  color: #fff;
  box-shadow: 0 4px 15px var(--primary-glow);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(138, 43, 226, 0.6);
  filter: brightness(1.1);
}

.btn-primary:active {
  transform: translateY(0);
}

.btn-secondary {
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid var(--border-glass);
  color: var(--text-primary);
}

.btn-secondary:hover {
  background: rgba(255, 255, 255, 0.1);
  border-color: var(--border-glass-active);
  transform: translateY(-1px);
}

.btn-cyan {
  background: linear-gradient(135deg, #0088cc, var(--accent-cyan));
  color: #0c0a1a;
  box-shadow: 0 4px 15px var(--cyan-glow);
  font-weight: 700;
}

.btn-cyan:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(0, 240, 255, 0.6);
  filter: brightness(1.1);
}

.btn-icon {
  width: 42px;
  height: 42px;
  padding: 0;
  border-radius: 50%;
}

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
  transform: none !important;
}

/* SCREEN: DASHBOARD / LANDING */
.dashboard-grid {
  display: grid;
  grid-template-columns: 2fr 1fr;
  gap: 32px;
  margin-top: 24px;
}

@media (max-width: 900px) {
  .dashboard-grid {
    grid-template-columns: 1fr;
  }
}

.welcome-banner {
  background: linear-gradient(135deg, rgba(26, 12, 54, 0.8), rgba(8, 7, 16, 0.9));
  border-left: 4px solid var(--accent-cyan);
  padding: 32px;
  border-radius: var(--radius-lg);
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  gap: 20px;
}

.welcome-banner h2 {
  font-size: 2.2rem;
  font-weight: 800;
  line-height: 1.2;
}

.welcome-banner p {
  color: var(--text-secondary);
  font-size: 1.1rem;
  max-width: 600px;
}

.mode-selection-section {
  margin-top: 32px;
}

.section-title {
  font-size: 1.4rem;
  font-weight: 700;
  margin-bottom: 20px;
  display: flex;
  align-items: center;
  gap: 10px;
}

.modes-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 24px;
}

.mode-card {
  cursor: pointer;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  min-height: 250px;
  height: 100%;
}

.mode-card:hover {
  transform: translateY(-5px);
  border-color: var(--primary);
  box-shadow: 0 8px 30px rgba(138, 43, 226, 0.2);
}

.mode-card.mode-chain:hover {
  border-color: var(--accent-purple);
  box-shadow: 0 8px 30px rgba(189, 0, 255, 0.2);
}

.mode-card.mode-decomp:hover {
  border-color: var(--accent-cyan);
  box-shadow: 0 8px 30px rgba(0, 240, 255, 0.2);
}

.mode-card.mode-academy:hover {
  border-color: var(--accent-green);
  box-shadow: 0 8px 30px rgba(57, 255, 20, 0.15);
}

.mode-card-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  margin-bottom: 20px;
}

.mode-icon-wrapper {
  width: 50px;
  height: 50px;
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
}

.mode-chain .mode-icon-wrapper {
  background: rgba(189, 0, 255, 0.1);
  color: var(--accent-purple);
}

.mode-decomp .mode-icon-wrapper {
  background: rgba(0, 240, 255, 0.1);
  color: var(--accent-cyan);
}

.mode-academy .mode-icon-wrapper {
  background: rgba(57, 255, 20, 0.1);
  color: var(--accent-green);
}

.mode-badge {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  font-weight: 700;
  text-transform: uppercase;
  padding: 4px 8px;
  border-radius: 4px;
  background: rgba(255,255,255,0.05);
  border: 1px solid var(--border-glass);
}

.mode-chain .mode-badge {
  color: var(--accent-purple);
  border-color: rgba(189, 0, 255, 0.2);
}

.mode-decomp .mode-badge {
  color: var(--accent-cyan);
  border-color: rgba(0, 240, 255, 0.2);
}

.mode-academy .mode-badge {
  color: var(--accent-green);
  border-color: rgba(57, 255, 20, 0.2);
}

.mode-card-body h3 {
  font-size: 1.4rem;
  font-weight: 700;
  margin-bottom: 10px;
}

.mode-card-body p {
  color: var(--text-secondary);
  font-size: 0.95rem;
  line-height: 1.5;
  margin-bottom: 24px;
}

.mode-card-footer {
  display: flex;
  align-items: center;
  gap: 8px;
  font-weight: 600;
  font-size: 0.9rem;
  transition: var(--transition-fast);
}

.mode-card:hover .mode-card-footer {
  gap: 12px;
}

.mode-chain .mode-card-footer { color: var(--accent-purple); }
.mode-decomp .mode-card-footer { color: var(--accent-cyan); }
.mode-academy .mode-card-footer { color: var(--accent-green); }

/* SIDEBAR STATS PANEL */
.stats-sidebar {
  display: flex;
  flex-direction: column;
  gap: 24px;
}

.stats-summary {
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.sidebar-stat-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding-bottom: 12px;
  border-bottom: 1px solid rgba(255, 255, 255, 0.05);
}

.sidebar-stat-label {
  color: var(--text-secondary);
  font-size: 0.95rem;
}

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

.progress-container {
  margin-top: 10px;
}

.progress-header {
  display: flex;
  justify-content: space-between;
  font-size: 0.85rem;
  color: var(--text-secondary);
  margin-bottom: 6px;
}

.progress-bar-bg {
  background: var(--bg-deep);
  height: 8px;
  border-radius: 4px;
  overflow: hidden;
  border: 1px solid var(--border-glass);
}

.progress-bar-fill {
  background: linear-gradient(to right, var(--primary), var(--accent-cyan));
  height: 100%;
  width: 0%;
  transition: width 0.6s cubic-bezier(0.25, 0.8, 0.25, 1);
  box-shadow: 0 0 10px var(--cyan-glow);
}

/* ACHIEVEMENTS GRID */
.achievements-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 12px;
  margin-top: 12px;
}

.achievement-icon {
  aspect-ratio: 1;
  background: var(--bg-deep);
  border: 1px solid var(--border-glass);
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: var(--transition-fast);
  color: var(--text-muted);
}

.achievement-icon.unlocked {
  border-color: var(--accent-cyan);
  color: var(--accent-cyan);
  box-shadow: 0 0 8px rgba(0, 240, 255, 0.15);
  background: rgba(0, 240, 255, 0.05);
}

.achievement-icon.unlocked:hover {
  transform: scale(1.1);
  box-shadow: 0 0 12px rgba(0, 240, 255, 0.3);
}

/* TOOLTIP STYLING */
[data-tooltip] {
  position: relative;
}

[data-tooltip]::before {
  content: attr(data-tooltip);
  position: absolute;
  bottom: 125%;
  left: 50%;
  transform: translateX(-50%) translateY(4px);
  background: #0c0a1a;
  border: 1px solid var(--border-glass-active);
  color: var(--text-primary);
  padding: 6px 12px;
  border-radius: 6px;
  font-size: 0.8rem;
  white-space: nowrap;
  opacity: 0;
  pointer-events: none;
  transition: var(--transition-fast);
  box-shadow: 0 4px 12px rgba(0,0,0,0.5);
  z-index: 10;
}

[data-tooltip]:hover::before {
  opacity: 1;
  transform: translateX(-50%) translateY(0);
}

/* SCREEN TEMPLATE: BACK NAVIGATION */
.screen-header {
  display: flex;
  align-items: center;
  gap: 16px;
  margin-bottom: 32px;
}

.screen-header h2 {
  font-size: 1.8rem;
  font-weight: 800;
}

.screen-description {
  color: var(--text-secondary);
  font-size: 1.05rem;
  margin-top: -24px;
  margin-bottom: 32px;
  max-width: 800px;
}

/* WRAPPERS FOR GAMEPLAY CONTENT */
.gameplay-layout {
  display: grid;
  grid-template-columns: 1.5fr 1fr;
  gap: 32px;
  align-items: start;
}

@media (max-width: 850px) {
  .gameplay-layout {
    grid-template-columns: 1fr;
  }
}

/* GAME CONFIG / START CARDS */
.config-card {
  display: flex;
  flex-direction: column;
  gap: 24px;
}

.config-group {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.config-group label {
  font-weight: 600;
  font-size: 0.95rem;
  color: var(--text-secondary);
}

.config-options {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(80px, 1fr));
  gap: 12px;
}

.config-btn {
  background: var(--bg-deep);
  border: 1px solid var(--border-glass);
  color: var(--text-secondary);
  padding: 10px;
  border-radius: var(--radius-sm);
  font-weight: 600;
  font-size: 0.9rem;
  cursor: pointer;
  transition: var(--transition-fast);
}

.config-btn:hover {
  background: rgba(255,255,255,0.03);
  border-color: var(--border-glass-active);
}

.config-btn.active {
  background: rgba(138, 43, 226, 0.15);
  border-color: var(--primary);
  color: var(--text-primary);
  box-shadow: 0 0 10px rgba(138, 43, 226, 0.2);
}

.config-decomp-btn.active {
  background: rgba(0, 240, 255, 0.15);
  border-color: var(--accent-cyan);
  color: var(--text-primary);
  box-shadow: 0 0 10px rgba(0, 240, 255, 0.2);
}

/* SCREEN: THE CHAIN PLAYING */
.play-card {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  min-height: 380px;
  text-align: center;
  position: relative;
}

.chain-number-box {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  min-height: 180px;
  animation: numberPulse var(--transition-normal);
}

.chain-op {
  font-size: 2rem;
  color: var(--accent-purple);
  font-weight: 700;
  margin-bottom: 10px;
}

.chain-num {
  font-size: 5rem;
  font-weight: 800;
  font-family: var(--font-mono);
  background: linear-gradient(to bottom, #ffffff, #dedede);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  line-height: 1;
}

@keyframes numberPulse {
  0% { transform: scale(0.8); opacity: 0; }
  100% { transform: scale(1); opacity: 1; }
}

/* PROGRESS BAR STICKY BOTTOM */
.chain-progress-indicator {
  display: flex;
  gap: 6px;
  margin-top: 32px;
  justify-content: center;
  width: 100%;
  max-width: 400px;
}

.progress-dot {
  flex: 1;
  height: 4px;
  background: rgba(255, 255, 255, 0.05);
  border-radius: 2px;
  transition: var(--transition-normal);
}

.progress-dot.active {
  background: var(--accent-purple);
  box-shadow: 0 0 8px var(--purple-glow);
}

.progress-dot.completed {
  background: var(--accent-green);
  box-shadow: 0 0 8px var(--green-glow);
}

/* INPUT FORM */
.input-section {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 20px;
  width: 100%;
  max-width: 400px;
  margin-top: 20px;
}

.input-section h3 {
  font-size: 1.3rem;
  color: var(--text-secondary);
}

.math-input-wrapper {
  width: 100%;
  position: relative;
}

.math-input {
  width: 100%;
  background: var(--bg-deep);
  border: 2px solid var(--border-glass);
  border-radius: var(--radius-md);
  padding: 16px;
  font-family: var(--font-mono);
  font-size: 2.2rem;
  font-weight: 700;
  color: #fff;
  text-align: center;
  outline: none;
  transition: var(--transition-normal);
}

.math-input:focus {
  border-color: var(--primary);
  box-shadow: 0 0 20px var(--primary-glow);
}

.decomp-input:focus {
  border-color: var(--accent-cyan);
  box-shadow: 0 0 20px var(--cyan-glow);
}

/* Shake wrong answers */
.wrong-shake {
  animation: shake 0.4s ease-in-out;
  border-color: var(--accent-red) !important;
  box-shadow: 0 0 20px var(--red-glow) !important;
}

@keyframes shake {
  0%, 100% { transform: translateX(0); }
  20%, 60% { transform: translateX(-10px); }
  40%, 80% { transform: translateX(10px); }
}

/* Success flash */
.success-glow {
  border-color: var(--accent-green) !important;
  box-shadow: 0 0 25px var(--green-glow) !important;
}

/* DECOMPOSITION LAB WORKSPACE */
.decomp-workspace {
  min-height: 400px;
  display: flex;
  flex-direction: column;
  gap: 24px;
}

.decomp-problem-display {
  background: var(--bg-deep);
  border: 1px solid var(--border-glass);
  border-radius: var(--radius-md);
  padding: 24px;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 16px;
}

.decomp-problem-text {
  font-size: 2.8rem;
  font-weight: 800;
  font-family: var(--font-mono);
  letter-spacing: -1px;
}

.decomp-steps-area {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.decomp-step-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  background: rgba(255, 255, 255, 0.02);
  border: 1px dashed var(--border-glass);
  padding: 16px 24px;
  border-radius: var(--radius-md);
  font-family: var(--font-mono);
  animation: slideIn var(--transition-normal);
}

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

.decomp-step-label {
  color: var(--text-secondary);
  font-size: 0.95rem;
  font-family: var(--font-sans);
}

.decomp-step-calc {
  font-size: 1.3rem;
  font-weight: 600;
}

.decomp-step-result {
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--accent-cyan);
}

/* MEMORY SLOTS PANEL (sidebar / floating) */
.memory-slots-panel {
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.slots-grid {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.memory-slot {
  background: var(--bg-deep);
  border: 1px solid var(--border-glass);
  border-radius: var(--radius-md);
  padding: 16px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  transition: var(--transition-normal);
}

.memory-slot.occupied {
  border-color: rgba(0, 240, 255, 0.3);
  background: rgba(0, 240, 255, 0.03);
}

.slot-label {
  font-size: 0.85rem;
  font-family: var(--font-mono);
  color: var(--text-muted);
}

.memory-slot.occupied .slot-label {
  color: var(--accent-cyan);
}

.slot-val {
  font-size: 1.4rem;
  font-weight: 700;
  font-family: var(--font-mono);
  color: var(--text-muted);
}

.memory-slot.occupied .slot-val {
  color: #fff;
  text-shadow: 0 0 10px var(--cyan-glow);
}

/* Fading mechanic styling */
.memory-slot.decaying {
  opacity: 0.4;
  border-color: rgba(255, 49, 49, 0.2);
}

.btn-store-slot {
  background: rgba(0, 240, 255, 0.1);
  border: 1px solid rgba(0, 240, 255, 0.2);
  color: var(--accent-cyan);
  padding: 6px 12px;
  border-radius: 6px;
  font-size: 0.8rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition-fast);
}

.btn-store-slot:hover {
  background: var(--accent-cyan);
  color: var(--bg-dark);
}

/* TECHNIQUE ACADEMY ACORDIAN/GRID */
.academy-layout {
  display: grid;
  grid-template-columns: 1fr;
  gap: 32px;
}

.tips-list {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 24px;
}

.tip-card {
  cursor: pointer;
  transition: var(--transition-normal);
}

.tip-card:hover {
  transform: translateY(-4px);
  border-color: var(--accent-green);
  box-shadow: 0 8px 25px rgba(57, 255, 20, 0.1);
}

.tip-card-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 12px;
}

.tip-meta {
  display: flex;
  align-items: center;
  gap: 12px;
}

.difficulty-badge {
  font-size: 0.75rem;
  font-weight: 700;
  padding: 2px 8px;
  border-radius: 12px;
}

.difficulty-badge.easy {
  background: rgba(57, 255, 20, 0.1);
  color: var(--accent-green);
  border: 1px solid rgba(57, 255, 20, 0.2);
}

.difficulty-badge.medium {
  background: rgba(255, 157, 0, 0.1);
  color: #ff9d00;
  border: 1px solid rgba(255, 157, 0, 0.2);
}

.difficulty-badge.hard {
  background: rgba(255, 49, 49, 0.1);
  color: var(--accent-red);
  border: 1px solid rgba(255, 49, 49, 0.2);
}

.tip-card h3 {
  font-size: 1.3rem;
  font-weight: 700;
  margin-bottom: 8px;
}

.tip-card p {
  color: var(--text-secondary);
  font-size: 0.9rem;
  line-height: 1.5;
  margin-bottom: 16px;
}

.tip-formula-bar {
  background: var(--bg-deep);
  padding: 8px 12px;
  border-radius: var(--radius-sm);
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--accent-cyan);
  display: inline-block;
}

/* TIP LESSON DETAIL SCREEN */
.lesson-card {
  display: grid;
  grid-template-columns: 1.2fr 1fr;
  gap: 32px;
}

@media (max-width: 850px) {
  .lesson-card {
    grid-template-columns: 1fr;
  }
}

.lesson-tutorial {
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.lesson-title-area {
  display: flex;
  align-items: center;
  gap: 16px;
}

.lesson-title-area h3 {
  font-size: 1.8rem;
  font-weight: 800;
}

.steps-list {
  display: flex;
  flex-direction: column;
  gap: 16px;
  margin-top: 12px;
}

.step-item {
  display: flex;
  gap: 16px;
  background: rgba(255,255,255,0.02);
  border: 1px solid var(--border-glass);
  padding: 16px;
  border-radius: var(--radius-md);
}

.step-num {
  width: 28px;
  height: 28px;
  background: rgba(57, 255, 20, 0.15);
  border: 1px solid var(--accent-green);
  color: var(--accent-green);
  font-family: var(--font-mono);
  font-weight: 700;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.step-text {
  font-size: 0.95rem;
  line-height: 1.6;
  color: var(--text-secondary);
}

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

/* INTERACTIVE PRACTICE BOARD inside Lesson */
.practice-board {
  background: var(--bg-deep);
  border: 1px solid var(--border-glass-active);
  border-radius: var(--radius-lg);
  padding: 32px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  min-height: 380px;
  position: relative;
}

.practice-streak-counter {
  position: absolute;
  top: 20px;
  right: 20px;
  display: flex;
  align-items: center;
  gap: 6px;
  color: var(--accent-green);
  font-family: var(--font-mono);
  font-size: 0.9rem;
  font-weight: 700;
  border: 1px solid rgba(57, 255, 20, 0.2);
  padding: 4px 10px;
  border-radius: 12px;
}

.practice-question {
  font-size: 3.5rem;
  font-weight: 800;
  font-family: var(--font-mono);
  margin-bottom: 24px;
}

.practice-answer-input {
  max-width: 280px;
}

/* FEEDBACK / MODALS */
.feedback-box {
  margin-top: 20px;
  width: 100%;
  max-width: 400px;
  border-radius: var(--radius-md);
  padding: 16px;
  font-size: 0.95rem;
  display: none;
  animation: slideIn var(--transition-normal);
}

.feedback-box.correct {
  display: block;
  background: rgba(57, 255, 20, 0.1);
  border: 1px solid rgba(57, 255, 20, 0.2);
  color: var(--accent-green);
}

.feedback-box.incorrect {
  display: block;
  background: rgba(255, 49, 49, 0.08);
  border: 1px solid rgba(255, 49, 49, 0.2);
  color: var(--accent-red);
}

.explanation-toggle {
  margin-top: 12px;
  background: transparent;
  border: none;
  color: var(--accent-cyan);
  cursor: pointer;
  font-family: var(--font-sans);
  font-size: 0.9rem;
  font-weight: 600;
  text-decoration: underline;
  display: block;
}

.explanation-details {
  display: none;
  margin-top: 12px;
  text-align: left;
  border-top: 1px solid rgba(255,255,255,0.05);
  padding-top: 12px;
}

.explanation-details.active {
  display: block;
}

.explanation-details ol {
  padding-left: 20px;
  color: var(--text-secondary);
  font-size: 0.85rem;
}

.explanation-details li {
  margin-bottom: 8px;
  line-height: 1.5;
}

/* RESULTS GAME SUMMARY CARDS */
.results-card {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  gap: 20px;
  animation: slideIn var(--transition-normal);
}

.results-glow-icon {
  width: 72px;
  height: 72px;
  background: rgba(138, 43, 226, 0.1);
  color: var(--primary);
  border: 1px solid var(--primary);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 0 20px var(--primary-glow);
  margin-bottom: 8px;
}

.results-score-label {
  font-size: 1rem;
  color: var(--text-secondary);
  text-transform: uppercase;
  letter-spacing: 1px;
}

.results-score-val {
  font-size: 3.5rem;
  font-weight: 800;
  font-family: var(--font-mono);
  color: #fff;
}

.results-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
  width: 100%;
  margin: 16px 0;
}

.results-grid-item {
  background: var(--bg-deep);
  border: 1px solid var(--border-glass);
  border-radius: var(--radius-md);
  padding: 12px;
}

.results-grid-label {
  font-size: 0.8rem;
  color: var(--text-secondary);
  margin-bottom: 4px;
}

.results-grid-val {
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: 1.1rem;
}

/* FULL STATS DASHBOARD SCREEN */
.stats-dashboard-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
  margin-bottom: 32px;
}

@media (max-width: 800px) {
  .stats-dashboard-grid {
    grid-template-columns: 1fr;
  }
}

.stats-card-main {
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  min-height: 140px;
}

.stats-card-label {
  font-size: 0.9rem;
  color: var(--text-secondary);
  margin-bottom: 8px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.stats-card-val {
  font-size: 2.2rem;
  font-weight: 800;
  font-family: var(--font-mono);
}

.stats-card-desc {
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-top: 8px;
}

.mastery-progress-row {
  display: flex;
  flex-direction: column;
  gap: 8px;
  margin-bottom: 20px;
}

.mastery-progress-header {
  display: flex;
  justify-content: space-between;
  font-size: 0.9rem;
  font-weight: 600;
}

/* AUDIO TOGGLE STYLING */
.audio-toggle-btn {
  background: none;
  border: none;
  color: var(--text-secondary);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 8px;
  border-radius: 50%;
  transition: var(--transition-fast);
  border: 1px solid transparent;
}

.audio-toggle-btn:hover {
  color: var(--text-primary);
  background: rgba(255,255,255,0.05);
  border-color: var(--border-glass);
}

.audio-toggle-btn.sound-enabled {
  color: var(--accent-cyan);
  background: rgba(0, 240, 255, 0.05);
  border-color: rgba(0, 240, 255, 0.2);
  text-shadow: 0 0 10px var(--cyan-glow);
}

/* GENERAL UTILS */
.text-cyan { color: var(--accent-cyan); }
.text-purple { color: var(--accent-purple); }
.text-green { color: var(--accent-green); }
.text-red { color: var(--accent-red); }

.flex-center {
  display: flex;
  align-items: center;
  justify-content: center;
}

.gap-10 { gap: 10px; }
.gap-20 { gap: 20px; }

.mt-20 { margin-top: 20px; }
.mb-20 { margin-bottom: 20px; }

/* CONFETTI / SPLASH DYNAMIC PARTICLE STYLING */
.success-particle {
  position: absolute;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  pointer-events: none;
  z-index: 100;
  animation: particleFloat 1s cubic-bezier(0.25, 1, 0.5, 1) forwards;
}

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

/* 
 * MOBILE VIEWPORTS OVERRIDE RULES 
 * Eliminates horizontal scroll, adapts card sizing and paddings for mobile screens.
 */
html, body {
  width: 100%;
  max-width: 100%;
  overflow-x: hidden;
  margin: 0;
  padding: 0;
}

@media (max-width: 600px) {
  main {
    padding: 16px 12px;
  }
  
  header {
    padding: 12px 16px;
  }
  
  .glass-card {
    padding: 20px 16px !important;
    border-radius: var(--radius-md);
  }
  
  .welcome-banner {
    padding: 24px 16px;
    border-radius: var(--radius-md);
  }
  
  .welcome-banner h2 {
    font-size: 1.6rem;
  }
  
  .welcome-banner p {
    font-size: 0.95rem;
  }
  
  .section-title {
    font-size: 1.25rem;
    margin-bottom: 16px;
  }
  
  .modes-grid {
    grid-template-columns: 1fr !important;
    gap: 16px;
  }
  
  .mode-card {
    min-height: 220px;
  }
  
  .stats-dashboard-grid {
    grid-template-columns: 1fr !important;
    gap: 16px;
  }
  
  .results-grid {
    grid-template-columns: 1fr !important;
    gap: 10px;
  }
  
  .config-options {
    grid-template-columns: repeat(2, 1fr) !important;
    gap: 8px;
  }
  
  .chain-num {
    font-size: 3.5rem;
  }
  
  .chain-op {
    font-size: 1.6rem;
  }
  
  .decomp-problem-text {
    font-size: 2rem;
  }
  
  .decomp-step-row {
    padding: 12px 16px;
    flex-direction: column;
    align-items: flex-start;
    gap: 12px;
  }
  
  .decomp-step-row > div {
    width: 100%;
  }
  
  .decomp-step-row input {
    width: 100% !important;
    max-width: 100% !important;
  }
  
  .lesson-card {
    grid-template-columns: 1fr !important;
    gap: 20px;
  }
  
  .practice-board {
    padding: 20px 16px;
    min-height: 320px;
  }
  
  .practice-question {
    font-size: 2.2rem;
    margin-bottom: 16px;
  }
  
  .practice-answer-input {
    max-width: 100% !important;
  }
  
  .input-section {
    width: 100%;
    max-width: 100%;
  }
  
  .btn {
    width: 100% !important; /* Stack action buttons on mobile */
  }
  
  .stats-sidebar {
    gap: 16px;
  }
}