body {
  font-family: Arial, sans-serif;
  background: #cfefff; /* light sky background */
  color: #ffffff;
  margin: 0;
  padding: 20px;
  display: flex;
  justify-content: center;
  min-height: 100vh;
}

.quiz-container {
  position: relative;
  max-width: 600px;
  background: #4e5c79; /* deep navy #1f2a40 */
  padding: 30px 20px;
  border-radius: 12px;
  box-shadow: 0 0 15px rgba(0, 173, 239, 0.3);
  width: 100%;
  box-sizing: border-box;
}

.title {
  text-align: center;
  margin-bottom: 20px;
  font-size: 2rem;
  color: #00b7ff; /* clean bright blue */
  text-shadow: 0 0 8px rgba(0, 183, 255, 0.3);
}

.options-grid {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.option {
  padding: 12px;
  background-color: #2a3b5c; /* slightly lighter navy */
  border-radius: 6px;
  cursor: pointer;
  transition: background 0.3s ease;
}

.correct {
  background-color: #23d160 !important;
  color: white;/* modern green */
}

.wrong {
  background-color: #ff4d4f !important;
  color: white;/* bold red */
}

#nextBtn, #submitBtn {
  margin-top: 20px;
  padding: 12px;
  width: 100%;
  font-weight: bold;
  font-size: 1rem;
  border-radius: 6px;
  border: none;
  cursor: pointer;
}

#nextBtn {
  background-color: #00b7ff; /* sky blue */
  color: #ffffff;
}

#submitBtn {
  background-color: #ffc107; /* fresh yellow-orange */
  color: #1f2a40;
}

#scoreBox {
  margin-top: 30px;
  font-size: 1.2rem;
  color: #30ffce; /* mint green */
  text-align: center;
}

#timer, #questionTracker {
  position: absolute;
  top: 20px;
  background: #172233;
  padding: 6px 12px;
  border-radius: 8px;
  font-weight: bold;
}

#timer {
  right: 30px;
  color: #ffe600; /* bright yellow */
}

#questionTracker {
  left: 30px;
  color: #30ffce; /* mint green */
}

.navigation-buttons {
  display: flex;
  gap: 10px;
  margin-top: 20px;
  justify-content: center;
}

.navigation-buttons button {
  padding: 10px 20px;
  font-size: 16px;
  cursor: pointer;
  border: none;
  border-radius: 5px;
  background-color: #e0f7ff;
  color: #1f2a40;
  font-weight: bold;
}

.navigation-buttons button:hover {
  background-color: #bdefff;
}

#prevBtn.disabled,
#nextBtn.disabled {
  opacity: 0.5;
  cursor: not-allowed;
}
.chapter-select {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.chapter-select label,
.chapter-select select,
.chapter-select button {
  width: 100%;
  max-width: 100%;
  box-sizing: border-box;
}

select {
  padding: 8px;
  font-size: 1rem;
}
@media (max-width: 480px) {
  .title {
    font-size: 1.5rem;
  }

  select {
    font-size: 0.9rem;
  }

  button {
    font-size: 0.9rem;
    padding: 10px;
  }
}