body {
  background-color: #1e1e1e;
  color: #ffffff;
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  margin: 0;
}

#app {
  max-width: 800px;
  margin: 0 auto;
  padding: 20px;
}

header, footer {
  text-align: center;
  margin-bottom: 20px;
}

footer {
  margin-top: 40px;
  font-size: 14px;
  color: #888;
}

footer p {
  margin: 0;
}

h1, h2 {
  color: #00adb5;
}

.setting-group {
  margin-bottom: 25px;
}

.setting-group label {
  display: block;
  margin: 5px 0;
}

.checkbox-group, .radio-group {
  display: flex;
  flex-wrap: wrap;
}

.checkbox-group label, .radio-group label {
  margin-right: 15px;
}

input[type="number"] {
  width: 100%;
  padding: 8px;
  margin-top: 5px;
  background-color: #2e2e2e;
  border: 1px solid #444;
  color: #fff;
}

.action-buttons {
  margin-top: 20px;
  display: flex;
  flex-wrap: wrap;
}

.action-buttons button {
  margin-right: 10px;
  margin-bottom: 10px;
}

button {
  background-color: #00adb5;
  color: #ffffff;
  border: none;
  padding: 10px 20px;
  cursor: pointer;
}

button:hover {
  background-color: #009ba3;
}

button:disabled,
button.disabled {
  background-color: #555;
  cursor: not-allowed;
}

.hidden {
  display: none;
}

.options {
  margin-top: 20px;
}

.options button {
  background-color: #393e46;
  color: #eeeeee;
  border: none;
  padding: 10px 20px;
  margin-right: 10px;
  margin-bottom: 10px;
  cursor: pointer;
}

.options button:hover {
  background-color: #4e555b;
}

.options button.selected {
  background-color: #00adb5;
  color: #ffffff;
}

.options button.disabled {
  background-color: #555;
  cursor: not-allowed;
}

.review-question, .mistake {
  background-color: #2e2e2e;
  padding: 15px;
  margin-bottom: 10px;
  border-radius: 5px;
}

.review-question p, .mistake p {
  margin: 5px 0;
}

#return-main {
  margin-bottom: 15px;
}

#notification {
  position: fixed;
  top: 20px;
  right: 20px;
  background-color: #00adb5;
  color: #ffffff;
  padding: 15px;
  border-radius: 5px;
  z-index: 1000;
}

#notification.hide {
  display: none;
}

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

.quiz-header div {
  display: flex;
  flex-wrap: wrap;
  margin-top: 10px;
}

.quiz-header .custom-checkbox {
  margin-right: 15px;
}

.quiz-navigation {
  margin-top: 15px;
}

.quiz-navigation button {
  margin-right: 10px;
  margin-bottom: 10px;
}

.feedback-message {
  margin-top: 15px;
  font-size: 18px;
  font-weight: bold;
}

.feedback-correct {
  color: #28a745;
}

.feedback-incorrect {
  color: #dc3545;
}

/* Custom Checkboxes and Radio Buttons */
.custom-checkbox, .custom-radio {
  position: relative;
  padding-left: 25px;
  margin-bottom: 12px;
  cursor: pointer;
  user-select: none;
}

.custom-checkbox input, .custom-radio input {
  position: absolute;
  opacity: 0;
  cursor: pointer;
}

.checkmark, .radiomark {
  position: absolute;
  top: 0;
  left: 0;
  height: 18px;
  width: 18px;
  background-color: #2e2e2e;
  border: 1px solid #555;
  border-radius: 4px;
}

.custom-radio .radiomark {
  border-radius: 50%;
}

.custom-checkbox:hover input ~ .checkmark,
.custom-radio:hover input ~ .radiomark {
  background-color: #3e3e3e;
}

.custom-checkbox input:checked ~ .checkmark {
  background-color: #00adb5;
  border: none;
}

.custom-radio input:checked ~ .radiomark {
  background-color: #00adb5;
  border: none;
}

.checkmark:after, .radiomark:after {
  content: "";
  position: absolute;
  display: none;
}

.custom-checkbox input:checked ~ .checkmark:after {
  display: block;
}

.custom-checkbox .checkmark:after {
  left: 5px;
  top: 1px;
  width: 5px;
  height: 10px;
  border: solid #ffffff;
  border-width: 0 2px 2px 0;
  transform: rotate(45deg);
}

.custom-radio input:checked ~ .radiomark:after {
  display: block;
}

.custom-radio .radiomark:after {
  top: 4px;
  left: 4px;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: white;
}

/* Answer History Style Settings */
.history-container {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
}

.history-section {
  width: 48%;
  background-color: #2e2e2e;
  padding: 15px;
  margin-bottom: 10px;
  border-radius: 5px;
}

.history-section h3 {
  margin-top: 0;
}

.history-item {
  margin-bottom: 10px;
}

.history-item p {
  margin: 5px 0;
}

.history-filters {
  margin-bottom: 15px;
}

.custom-select {
  position: relative;
  display: inline-block;
  width: 200px;
}

.custom-select select {
  display: none;
}

.select-selected {
  background-color: #2e2e2e;
  color: #fff;
  padding: 8px 16px;
  border: 1px solid #555;
  cursor: pointer;
  user-select: none;
}

.select-selected:after {
  content: "";
  position: absolute;
  top: 14px;
  right: 10px;
  border: 6px solid transparent;
  border-color: #fff transparent transparent transparent;
}

.select-selected.select-arrow-active:after {
  border-color: transparent transparent #fff transparent;
  top: 7px;
}

.select-items div {
  color: #fff;
  padding: 8px 16px;
  cursor: pointer;
  background-color: #2e2e2e;
  border-bottom: 1px solid #555;
}

.select-items div:hover {
  background-color: #3e3e3e;
}

.select-hide {
  display: none;
}

/* Animations */
.fade-in {
  animation: fadeIn 0.5s forwards;
}

.fade-out {
  animation: fadeOut 0.5s forwards;
}

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

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

/* Progress Bar */
.progress-bar {
  width: 100%;
  background-color: #333;
  border-radius: 5px;
  margin-bottom: 15px;
}

.progress {
  height: 10px;
  background-color: #00adb5;
  border-radius: 5px;
  width: 0%;
}

/* Responsive Design */
@media (max-width: 600px) {
  #app {
    padding: 10px;
  }

  body {
    font-size: 14px;
  }

  .checkbox-group label, .radio-group label {
    margin-right: 10px;
  }

  .options button {
    width: 100%;
    margin-bottom: 10px;
  }

  .history-section {
    width: 100%;
  }

  .quiz-header {
    flex-direction: column;
    align-items: flex-start;
  }

  .quiz-header div {
    margin-top: 10px;
    flex-wrap: wrap;
  }

  .quiz-navigation {
    flex-direction: column;
  }

  .quiz-navigation button {
    width: 100%;
    margin-bottom: 10px;
  }

  .action-buttons {
    flex-direction: column;
  }

  .action-buttons button {
    width: 100%;
    margin-bottom: 10px;
  }
}