:root {
  --bg-dark: linear-gradient(to right, #0f2027, #203a43, #2c5364);
  --bg-light: linear-gradient(to right, #e0e0e0, #f5f5f5, #e0e0e0);
  --text-dark: #00ffcc;
  --text-light: #00695c;
  --card-dark: #111;
  --card-light: #f0f0f0;
  --accent-dark: #00ffcc;
  --accent-light: #00897b;
  --shadow-dark: #00ffcc55;
  --shadow-light: #00897b55;
}

body {
  font-family: 'Courier New', Courier, monospace;
  background: var(--bg-dark);
  color: var(--text-dark);
  animation: fadeIn 1s ease-in-out;
  transition: all 0.3s ease;
  min-height: 100vh;
  margin: 0;
  padding: 0;
  display: flex;
  justify-content: center;
  align-items: center;
}

body.light-mode {
  background: var(--bg-light);
  color: var(--text-light);
}

.container {
  width: 90%;
  max-width: 800px;
  margin: 0 auto;
  padding: 20px;
}

h1, h2, h3, p {
  animation: fadeSlide 0.5s ease-in-out;
}

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

@keyframes fadeSlide {
  from { opacity: 0; transform: translateY(20px); }
  to { opacity: 1; transform: translateY(0); }
}

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

.challenge, .landing, .leaderboard {
  margin-bottom: 30px;
  background-color: var(--card-dark);
  padding: 20px;
  border-radius: 10px;
  box-shadow: 0 0 10px var(--shadow-dark);
  transition: all 0.3s ease;
}

body.light-mode .challenge,
body.light-mode .landing,
body.light-mode .leaderboard {
  background-color: var(--card-light);
  box-shadow: 0 0 10px var(--shadow-light);
}

button {
  margin: 10px 0;
  padding: 10px;
  font-size: 16px;
  cursor: pointer;
  background-color: #222;
  color: var(--accent-dark);
  border: 1px solid var(--accent-dark);
  transition: all 0.3s ease;
  border-radius: 5px;
}

#startButton {
  font-family: 'Courier New', monospace;
  font-weight: bold;
  font-size: 18px;
  letter-spacing: 1px;
  padding: 12px 24px;
  display: block;
  margin: 20px auto 0;
}

body.light-mode button {
  background-color: #e0e0e0;
  color: var(--accent-light);
  border: 1px solid var(--accent-light);
}

button:hover {
  background-color: var(--accent-dark);
  color: #000;
  animation: pulse 0.5s;
}

body.light-mode button:hover {
  background-color: var(--accent-light);
}

input {
  padding: 8px;
  font-size: 16px;
  background-color: var(--card-dark);
  color: var(--text-dark);
  border: 1px solid var(--accent-dark);
  width: 80%;
  margin-bottom: 10px;
  border-radius: 5px;
  transition: all 0.3s ease;
}

body.light-mode input {
  background-color: var(--card-light);
  color: var(--text-light);
  border: 1px solid var(--accent-light);
}

#instructions {
  background-color: #00000080;
  padding: 15px;
  border-left: 4px solid var(--accent-dark);
  margin-bottom: 20px;
  transition: all 0.3s ease;
}

body.light-mode #instructions {
  background-color: #ffffff80;
  border-left: 4px solid var(--accent-light);
}

.hidden {
  display: none;
}

.score-entry {
  padding: 8px;
  margin: 5px 0;
  background-color: #00000030;
  border-radius: 5px;
  transition: all 0.3s ease;
  display: flex;
  justify-content: space-between;
}

body.light-mode .score-entry {
  background-color: #ffffff80;
}

.progress-container {
  width: 100%;
  height: 10px;
  background-color: #333;
  border-radius: 5px;
  margin: 10px 0;
}

body.light-mode .progress-container {
  background-color: #ddd;
}

.progress-bar {
  height: 100%;
  width: 0%;
  background-color: var(--accent-dark);
  border-radius: 5px;
  transition: width 0.5s ease;
}

body.light-mode .progress-bar {
  background-color: var(--accent-light);
}

.timer-container {
  width: 100%;
  height: 5px;
  background-color: #333;
  border-radius: 5px;
  margin: 10px 0;
  overflow: hidden;
}

body.light-mode .timer-container {
  background-color: #ddd;
}

.timer-bar {
  height: 100%;
  width: 100%;
  background-color: var(--accent-dark);
  transition: width 1s linear;
}

body.light-mode .timer-bar {
  background-color: var(--accent-light);
}

.time-display {
  font-family: 'Courier New', monospace;
  font-weight: bold;
  text-align: right;
  margin-top: 5px;
}

.theme-toggle {
  position: fixed;
  top: 20px;
  right: 20px;
  padding: 8px;
  border-radius: 50%;
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
}

.confetti {
  position: fixed;
  width: 10px;
  height: 10px;
  background-color: var(--accent-dark);
  animation: confetti-fall 5s linear forwards;
}

body.light-mode .confetti {
  background-color: var(--accent-light);
}

@keyframes confetti-fall {
  0% {
    transform: translateY(-100vh) rotate(0deg);
    opacity: 1;
  }
  100% {
    transform: translateY(100vh) rotate(360deg);
    opacity: 0;
  }
}

@media (max-width: 600px) {
  .container {
    width: 95%;
    padding: 10px;
  }
  
  input {
    width: 95%;
  }
  
  .score-entry {
    flex-direction: column;
  }
}
#game-container {
  max-width: 800px;
  margin: 0 auto;
  font-family: 'Courier New', monospace;
}

#options {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 10px;
  margin-top: 20px;
}

#options button {
  padding: 15px;
  background: #2c3e50;
  color: white;
  border: none;
  border-radius: 5px;
  cursor: pointer;
  transition: all 0.3s;
}

#options button:hover {
  background: #3960b2;
  transform: translateY(-2px);
}

#feedback {
  position: fixed;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  background: #1a1a2e;
  padding: 20px;
  border-radius: 10px;
  z-index: 100;
  box-shadow: 0 0 20px rgba(0,0,0,0.5);
}

.review-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 15px;
}

.review-item {
  background: rgba(255,255,255,0.1);
  padding: 15px;
  border-radius: 5px;
}
/* Add to existing CSS */
.pairs-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 15px;
  margin-top: 20px;
}

.names-column, .symbols-column {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.pair-btn {
  padding: 12px;
  text-align: center;
  border-radius: 8px;
  transition: all 0.3s ease;
  cursor: pointer;
  background: rgba(0, 255, 204, 0.1);
  border: 1px solid var(--accent-dark);
}

body.light-mode .pair-btn {
  background: rgba(0, 137, 123, 0.1);
  border: 1px solid var(--accent-light);
}

.pair-btn.selected {
  background: var(--accent-dark);
  color: #000;
  transform: scale(1.05);
  box-shadow: 0 0 10px var(--shadow-dark);
}

body.light-mode .pair-btn.selected {
  background: var(--accent-light);
  box-shadow: 0 0 10px var(--shadow-light);
}

.pair-btn.matched {
  background: #00cc00;
  color: #000;
  cursor: default;
  opacity: 0.7;
}

.pair-btn.incorrect {
  background: #cc0000;
  animation: shake 0.5s;
}

@keyframes shake {
  0%, 100% { transform: translateX(0); }
  20%, 60% { transform: translateX(-5px); }
  40%, 80% { transform: translateX(5px); }
}

.feedback-correct {
  background: rgba(0, 204, 0, 0.2);
  padding: 10px;
  border-radius: 5px;
  border-left: 3px solid #0c0;
  animation: fadeIn 0.5s;
}

/* Animated background */
body::before {
  content: '';
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: 
    linear-gradient(45deg, #0f202722 25%, transparent 25%) -50px 0,
    linear-gradient(-45deg, #0f202722 25%, transparent 25%) -50px 0,
    linear-gradient(45deg, transparent 75%, #0f202722 75%),
    linear-gradient(-45deg, transparent 75%, #0f202722 75%);
  background-size: 100px 100px;
  z-index: -1;
  animation: moveBackground 60s linear infinite;
}

body.light-mode::before {
  background: 
    linear-gradient(45deg, #e0e0e022 25%, transparent 25%) -50px 0,
    linear-gradient(-45deg, #e0e0e022 25%, transparent 25%) -50px 0,
    linear-gradient(45deg, transparent 75%, #e0e0e022 75%),
    linear-gradient(-45deg, transparent 75%, #e0e0e022 75%);
}

@keyframes moveBackground {
  0% { background-position: 0 0; }
  100% { background-position: 1000px 1000px; }
}

/* binary rain*/
.binary-rain {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: -2;
  overflow: hidden;
  pointer-events: none;
}

.binary-digit {
  position: absolute;
  color: rgba(0, 255, 204, 0.5);
  font-family: 'Courier New', monospace;
  font-size: 16px;
  animation: binary-fall linear infinite;
}

body.light-mode .binary-digit {
  color: rgba(0, 137, 123, 0.5);
}

@keyframes binary-fall {
  0% {
    transform: translateY(-100%);
  }
  100% {
    transform: translateY(100vh);
  }
}