:root {
  --bg-color: #fff;
  --text-color: #333;
  --tab-bg: #ddd;
  --tab-active: #4CAF50;
  --card-bg: #fff;
  --shadow: rgba(0,0,0,0.1);
  --button-bg: #2196F3;
  --focus: #ff9800;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg-color: #1e1e1e;
    --text-color: #fff;
    --tab-bg: #333;
    --tab-active: #00c853;
    --card-bg: #2b2b2b;
    --shadow: rgba(0,0,0,0.6);
    --button-bg: #1565C0;
  }
}

body.dark {
  --bg-color: #1e1e1e;
  --text-color: #fff;
  --tab-bg: #333;
  --tab-active: #00c853;
  --card-bg: #2b2b2b;
  --shadow: rgba(0,0,0,0.6);
  --button-bg: #1565C0;
}

* {
  transition: all 0.3s cubic-bezier(.4,0,.2,1);
  -webkit-tap-highlight-color: transparent;
  box-sizing: border-box;
}

body {
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, Arial, sans-serif;
  background: linear-gradient(135deg, var(--bg-color), #e8e8e8);
  color: var(--text-color);
  padding: 20px;
  margin: 0;
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
  -webkit-touch-callout: none;
  touch-action: manipulation;
}

body.dark {
  background: linear-gradient(135deg, var(--bg-color), #0d1117);
}

h1 {
  text-align: center;
  margin-bottom: 30px;
  font-size: 2.5em;
  text-shadow: 2px 2px 4px var(--shadow);
  background: linear-gradient(45deg, #4CAF50, #2196F3);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.tabs {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 10px;
  margin-bottom: 30px;
}

.tabs button {
  padding: 12px 25px;
  border: none;
  border-radius: 25px;
  background-color: var(--tab-bg);
  color: var(--text-color);
  font-size: 16px;
  cursor: pointer;
  font-weight: 500;
  transform: translateY(0);
  outline: none;
  user-select: none;
  -webkit-user-select: none;
  -webkit-tap-highlight-color: transparent;
}

.tabs button:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 12px var(--shadow);
}

.tabs button.active {
  background: linear-gradient(45deg, var(--tab-active), #45a049);
  color: white;
  box-shadow: 0 6px 20px rgba(76, 175, 80, 0.3);
  transform: translateY(-2px);
}

.tabs button:focus {
  outline: 2px solid var(--focus);
  outline-offset: 2px;
}

.tab-content {
  max-width: 900px;
  margin: auto;
  background: var(--card-bg);
  border-radius: 15px;
  padding: 30px;
  box-shadow: 0 8px 32px var(--shadow);
  display: none;
  backdrop-filter: blur(10px);
  border: 1px solid rgba(255, 255, 255, 0.1);
}

.tab-content.active {
  display: block;
  animation: slideInUp 0.6s ease-out;
}

@keyframes slideInUp {
  from { 
    opacity: 0; 
    transform: translateY(30px); 
  }
  to { 
    opacity: 1; 
    transform: translateY(0); 
  }
}

.accordion {
  width: 100%;
  padding: 15px 20px;
  font-size: 16px;
  text-align: left;
  background: linear-gradient(135deg, var(--tab-bg), rgba(255,255,255,0.1));
  border: none;
  border-radius: 10px;
  margin: 8px 0;
  cursor: pointer;
  font-weight: 500;
  position: relative;
  overflow: hidden;
  outline: none;
  user-select: none;
  -webkit-user-select: none;
  -webkit-tap-highlight-color: transparent;
}

.accordion:focus {
  outline: 2px solid var(--focus);
  outline-offset: 2px;
}

.accordion::before {
  content: '';
  position: absolute;
  top: 0;
  left: -100%;
  width: 100%;
  height: 100%;
  background: linear-gradient(90deg, transparent, rgba(255,255,255,0.2), transparent);
  transition: left 0.5s;
}

.accordion:hover::before {
  left: 100%;
}

.accordion:hover {
  transform: translateX(5px);
  box-shadow: 0 4px 15px var(--shadow);
}

.panel {
  padding: 20px;
  display: none;
  background: linear-gradient(135deg, var(--card-bg), rgba(255,255,255,0.05));
  box-shadow: inset 0 2px 10px var(--shadow);
  margin-bottom: 15px;
  border-radius: 10px;
  border-left: 4px solid var(--tab-active);
  word-break: break-word;
  -webkit-overflow-scrolling: touch;
  color: var(--text-color);
}

.panel.active {
  display: block;
  animation: expandPanel 0.3s ease-out;
}

@keyframes expandPanel {
  from { 
    opacity: 0; 
    max-height: 0; 
    padding: 0 20px;
  }
  to { 
    opacity: 1; 
    max-height: 500px; 
    padding: 20px;
  }
}

.center-button {
  text-align: center;
  margin-top: 40px;
}

.center-button button {
  padding: 15px 30px;
  font-size: 18px;
  border: none;
  border-radius: 25px;
  background: linear-gradient(45deg, var(--button-bg), #1976D2);
  color: white;
  cursor: pointer;
  font-weight: 600;
  box-shadow: 0 4px 15px rgba(33, 150, 243, 0.3);
  transform: translateY(0);
  outline: none;
  user-select: none;
  -webkit-user-select: none;
  -webkit-tap-highlight-color: transparent;
}

.center-button button:focus {
  outline: 2px solid var(--focus);
  outline-offset: 2px;
}

.center-button button:hover {
  transform: translateY(-3px);
  box-shadow: 0 6px 25px rgba(33, 150, 243, 0.4);
}

.settings {
  position: fixed;
  top: 30px;
  right: 30px;
  z-index: 1001;
}

.settings button {
  background: var(--card-bg);
  border: 2px solid var(--tab-active);
  font-size: 24px;
  color: var(--text-color);
  cursor: pointer;
  border-radius: 50%;
  width: 50px;
  height: 50px;
  box-shadow: 0 4px 15px var(--shadow);
}

.settings button:hover {
  transform: scale(1.1);
  box-shadow: 0 6px 20px var(--shadow);
}

.settings-panel {
  position: fixed;
  top: 0;
  right: -350px;
  width: 300px;
  height: 100vh;
  background: var(--card-bg);
  color: var(--text-color);
  box-shadow: -5px 0 25px var(--shadow);
  padding: 30px;
  transition: right 0.4s cubic-bezier(0.25, 0.46, 0.45, 0.94);
  z-index: 1000;
  backdrop-filter: blur(10px);
}

.settings-panel.active {
  right: 0;
}

.settings-panel h3 {
  margin-top: 20px;
  color: var(--tab-active);
  border-bottom: 2px solid var(--tab-active);
  padding-bottom: 10px;
}

.settings-panel button, .settings-panel a {
  width: 100%;
  padding: 15px;
  margin: 10px 0;
  font-size: 16px;
  border: none;
  border-radius: 10px;
  cursor: pointer;
  background: linear-gradient(135deg, var(--tab-bg), rgba(255,255,255,0.1));
  color: var(--text-color);
  text-align: left;
  text-decoration: none;
  display: block;
  font-weight: 500;
}

.settings-panel button:hover,
.settings-panel a:hover {
  background: linear-gradient(135deg, var(--tab-active), #45a049);
  color: white;
  transform: translateX(5px);
}

.feature-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 20px;
  margin: 20px 0;
}

.feature-card {
  background: linear-gradient(135deg, var(--card-bg), rgba(255,255,255,0.05));
  padding: 20px;
  border-radius: 15px;
  box-shadow: 0 4px 15px var(--shadow);
  border-left: 4px solid var(--tab-active);
  transform: translateY(0);
  color: var(--text-color);
  cursor: pointer;
  outline: none;
  user-select: none;
  -webkit-user-select: none;
  transition: all 0.3s cubic-bezier(.4,0,.2,1);
}

.feature-card:hover {
  transform: translateY(-5px);
  box-shadow: 0 8px 25px var(--shadow);
  background: linear-gradient(135deg, var(--tab-active), rgba(76, 175, 80, 0.1));
}

.feature-card:focus {
  outline: 2px solid var(--focus);
  outline-offset: 2px;
}

.feature-card:active {
  transform: translateY(-2px);
}

.feature-card h4 {
  margin-top: 0;
  color: var(--tab-active);
  font-size: 1.2em;
}

code {
  background: rgba(0,0,0,0.1);
  padding: 2px 6px;
  border-radius: 4px;
  font-family: 'Courier New', monospace;
  color: #e74c3c;
}

body.dark .panel,
body.dark .feature-card,
body.dark .settings-panel {
  color: var(--text-color);
}

.video-container {
  position: relative;
  width: 100%;
  max-width: 600px;
  margin: 20px auto;
  border-radius: 15px;
  overflow: hidden;
  box-shadow: 0 8px 25px var(--shadow);
}

video {
  width: 100%;
  height: auto;
}

@keyframes pulse {
  0%, 100% { transform: scale(1); }
  50% { transform: scale(1.05); }
}

.pulse {
  animation: pulse 2s infinite;
}

@keyframes rotateClockwise {
  0% { transform: rotate(0deg); }
  100% { transform: rotate(180deg); }
}

@keyframes rotateAntiClockwise {
  0% { transform: rotate(0deg); }
  100% { transform: rotate(-180deg); }
}

.rotate-clockwise {
  animation: rotateClockwise 0.5s linear;
}

.rotate-anticlockwise {
  animation: rotateAntiClockwise 0.5s linear;
}

.overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0,0,0,0.5);
  display: none;
  z-index: 999;
}

.overlay.active {
  display: block;
}

/* Feature Modal Styles */
.feature-modal {
  display: none;
  position: fixed;
  z-index: 2000;
  left: 0;
  top: 0;
  width: 100%;
  height: 100%;
  background-color: rgba(0, 0, 0, 0.8);
  animation: fadeIn 0.3s ease-out;
}

.feature-modal.active {
  display: block;
}

.feature-modal-content {
  background: var(--card-bg);
  margin: 5% auto;
  padding: 40px;
  border-radius: 20px;
  width: 90%;
  max-width: 800px;
  max-height: 80vh;
  overflow-y: auto;
  position: relative;
  box-shadow: 0 20px 60px var(--shadow);
  color: var(--text-color);
  animation: slideInModal 0.4s cubic-bezier(0.25, 0.46, 0.45, 0.94);
  border: 1px solid rgba(255, 255, 255, 0.1);
  backdrop-filter: blur(20px);
}

@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

@keyframes slideInModal {
  from { 
    transform: translateY(-50px);
    opacity: 0;
  }
  to { 
    transform: translateY(0);
    opacity: 1;
  }
}

.feature-close {
  color: var(--text-color);
  float: right;
  font-size: 35px;
  font-weight: bold;
  cursor: pointer;
  position: absolute;
  right: 20px;
  top: 15px;
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  transition: all 0.3s ease;
}

.feature-close:hover {
  background: var(--tab-active);
  color: white;
  transform: scale(1.1);
}

.feature-page {
  padding: 20px 0;
}

.feature-page h2 {
  color: var(--tab-active);
  font-size: 2.2em;
  margin-bottom: 20px;
  text-align: center;
  background: linear-gradient(45deg, var(--tab-active), #45a049);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.feature-page h3 {
  color: var(--tab-active);
  font-size: 1.4em;
  margin: 25px 0 15px 0;
  border-bottom: 2px solid var(--tab-active);
  padding-bottom: 8px;
}

.feature-page .highlight-box {
  background: linear-gradient(135deg, var(--tab-active), rgba(76, 175, 80, 0.1));
  padding: 20px;
  border-radius: 15px;
  margin: 20px 0;
  border-left: 5px solid var(--tab-active);
  color: var(--text-color);
}

.feature-page .code-block {
  background: rgba(0, 0, 0, 0.1);
  padding: 15px;
  border-radius: 10px;
  font-family: 'Courier New', monospace;
  margin: 15px 0;
  border: 1px solid var(--tab-bg);
  overflow-x: auto;
}

.feature-page .demo-button {
  background: linear-gradient(45deg, var(--button-bg), #1976D2);
  color: white;
  border: none;
  padding: 12px 25px;
  border-radius: 25px;
  cursor: pointer;
  font-size: 16px;
  font-weight: 600;
  margin: 10px 5px;
  transition: all 0.3s ease;
  box-shadow: 0 4px 15px rgba(33, 150, 243, 0.3);
}

.feature-page .demo-button:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(33, 150, 243, 0.4);
}

/* Media Queries */
@media (max-width: 768px) {
  body {
    padding: 5px;
  }
  
  h1 {
    font-size: 1.5em;
  }
  
  .tab-content {
    padding: 10px;
  }
  
  .settings-panel {
    width: 90vw;
    right: -100vw;
    min-width: 180px;
    max-width: 350px;
  }
  
  .feature-grid {
    grid-template-columns: 1fr;
  }
  
  .center-button button {
    width: 100%;
    font-size: 1em;
    padding: 12px 0;
  }
  
  .feature-modal-content {
    margin: 2% auto;
    padding: 20px;
    width: 95%;
    max-height: 90vh;
  }
  
  .feature-page h2 {
    font-size: 1.8em;
  }
}

@media (pointer: coarse) {
  .tabs button, .accordion, .center-button button {
    min-height: 48px;
    font-size: 1.1em;
  }
}