* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html,
body {
  height: 100%;
}

body {
  font-family: "Inter", Arial, sans-serif;
  display: flex;
  flex-direction: column;
  background-color: #0f0e2b;
  color: #e0d4f7;
  transition: all 0.3s ease;
  max-width: 100%;
  margin: 0 auto;
  padding: 0;
  text-align: center;
  font-size: 16px;
}

.gradient {
  background: linear-gradient(180deg, #2b1f55, #0f0e2b 80%);
  background-repeat: no-repeat;
  background-attachment: fixed;
  background-size: cover;
}

body.light-mode {
  background-color: #f5f5f7;
  color: #333333;
}

body.light-mode.gradient {
  background: linear-gradient(180deg, #ffffff, #f5f5f5 80%);
}

header {
  background-color: #1a1745;
  padding: 1rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  transition: all 0.3s ease;
}

body.light-mode header {
  background-color: #ffffff;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

.header-left {
  display: flex;
  align-items: center;
}

header img {
  width: 40px;
  height: 40px;
}

header h1 {
  font-size: 1.5rem;
  color: #b388ff;
  margin-left: 0.5rem;
  transition: all 0.3s ease;
}

body.light-mode header h1 {
  color: #7c4dff;
}

nav ul {
  display: flex;
  list-style: none;
  align-items: center;
}

nav ul li {
  margin-left: 1rem;
}

nav ul li a {
  color: #d1c4e9;
  text-decoration: none;
  font-weight: 600;
  font-size: 0.9rem;
  transition: all 0.3s ease;
  white-space: nowrap;
}

body.light-mode nav ul li a {
  color: #666666;
}

nav ul li a:hover {
  color: #b388ff;
}

body.light-mode nav ul li a:hover {
  color: #7c4dff;
}

.main {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 2rem 1rem;
  text-align: center;
  max-width: 900px;
  width: 100%;
  margin: 0 auto;
}

.main h2 {
  font-size: 2rem;
  color: #b388ff;
  margin: 1rem 0 0.5rem;
  line-height: 1.3;
  transition: all 0.3s ease;
}

body.light-mode .main h2 {
  color: #7c4dff;
}

.main p {
  color: #d1c4e9;
  font-size: 1rem;
  max-width: 800px;
  line-height: 1.6;
  padding: 0 1rem;
  transition: all 0.3s ease;
}

body.light-mode .main p {
  color: #666666;
}

.main-heading {
  color: #b388ff;
  font-size: 1.5rem;
  font-weight: 700;
  margin-bottom: 20px;
}

.flashcard {
  border: 1px solid #4b3b72;
  border-radius: 8px;
  padding: 20px;
  margin: 15px 0;
  background-color: #2e2b4f;
  box-shadow: 0 3px 6px rgba(200, 150, 255, 0.15);
  width: 100%;
  max-width: 800px;
}

body.light-mode .flashcard {
  background-color: #ffffff;
  border-color: #d1c4e9;
  box-shadow: 0 3px 6px rgba(0, 0, 0, 0.1);
  color: #333333;
}

#explanation {
  display: none;
  background-color: rgba(200, 150, 255, 0.15);
  border-radius: 5px;
  padding: 10px;
  margin-top: 10px;
  transition: all 0.3s ease;
}

body.light-mode #explanation {
  background-color: rgba(124, 77, 255, 0.1);
  color: #555555;
}

#progress-container {
  display: flex;
  justify-content: space-between;
  margin: 0 auto;
  width: 90%;
  max-width: 600px;
  padding: 8px;
}

#question {
  font-size: 1.3em;
  padding-bottom: 20px;
}

#question-counter {
  color: #c5a3ff;
}

body.light-mode .main-heading {
  color: #7c4dff;
}

body.light-mode #question-counter {
  color: #7c4dff;
}

#question-counter.hidden {
  opacity: 0;
  visibility: hidden;
}

#timer {
  color: #c5a3ff;
  margin-bottom: 5px;
}

body.light-mode #timer {
  color: #7c4dff;
}

button,
.cta {
  background-color: #7c4dff;
  color: white;
  border: none;
  padding: 12px 16px;
  margin: 2rem 0;
  border-radius: 6px;
  cursor: pointer;
  font-size: 16px;
  transition: background-color 0.3s ease;
}

button:hover,
.cta:hover {
  background-color: #9575cd;
}

#next-btn {
  margin-bottom: 10px;
}

#result {
  font-weight: bold;
  margin-top: 12px;
  font-size: 18px;
}

.correct {
  color: LimeGreen;
}

.incorrect {
  color: Tomato;
}

#options button {
  display: block;
  width: 100%;
  margin: 6px 0;
  background-color: #5e35b1;
  color: white;
  font-size: 16px;
  padding: 12px 0;
  transition: all 0.3s ease;
}

#options button:hover {
  background-color: #7e57c2;
}

#options button.selected {
  color: #333333;
  background-color: #f3e5f5;
}

body.light-mode #options button.selected {
  color: #f3e5f5;
  background-color: #2e2b4f;
}

body.light-mode #options button.selected:hover {
  background-color: #3d3968;
  color: #e0d4f7;
}

body.light-mode #options button {
  background-color: #7c4dff;
}

body.light-mode #options button:hover {
  background-color: #9575cd;
}

#final-result {
  background-color: #3e2c66;
  color: white;
  padding: 20px;
  border-radius: 8px;
  font-size: 18px;
  transition: all 0.3s ease;
  width: 100%;
  padding-bottom: 2rem;
}

body.light-mode #final-result {
  background-color: #f3e5f5;
  color: #333333;
  box-shadow: 0 3px 6px rgba(0, 0, 0, 0.1);
}

footer {
  background-color: #1a1745;
  padding: 1rem;
  text-align: center;
  margin-top: auto;
  transition: all 0.3s ease;
}

body.light-mode footer {
  background-color: #ffffff;
  box-shadow: 0 -2px 10px rgba(0, 0, 0, 0.1);
}

footer p {
  color: #a89ecd;
  font-size: 0.8rem;
  margin: 0;
  transition: all 0.3s ease;
}

body.light-mode footer p {
  color: #888888;
}

.theme-switch-wrapper {
  position: relative;
  display: flex;
  align-items: center;
}

.theme-switch {
  position: relative;
  display: inline-block;
  width: 60px;
  height: 30px;
  margin-left: 10px;
}

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

.slider {
  position: absolute;
  cursor: pointer;
  top: 0;
  left: -3px;
  right: 0;
  bottom: 0;
  background-color: #2c3e50;
  transition: 0.4s;
  border-radius: 34px;
}

.slider:before {
  position: absolute;
  content: "";
  height: 22px;
  width: 22px;
  left: 4px;
  bottom: 4px;
  background-color: #e0d4f7;
  transition: 0.4s;
  border-radius: 50%;
}

input:checked + .slider {
  background-color: #7c4dff;
}

input:checked + .slider:before {
  transform: translateX(30px);
}

.slider .icon {
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
  font-size: 12px;
  color: #e0d4f7;
}

.sun {
  left: 6px;
}

.moon {
  right: 6px;
}

.menu-toggle {
  display: none;
  cursor: pointer;
  padding: 0.5rem;
}

.menu-toggle span {
  display: block;
  width: 25px;
  height: 3px;
  background-color: #d1c4e9;
  margin: 5px 0;
  transition: all 0.3s ease;
}

body.light-mode .menu-toggle span {
  background-color: #666666;
}

@media (max-width: 768px) {
  body {
    padding: 0;
    font-size: 14px;
  }

  header {
    padding: 0.8rem;
    flex-direction: column;
    align-items: flex-start;
  }

  header h1 {
    font-size: 1.3rem;
    margin-left: 0;
  }

  .header-left {
    width: 100%;
    justify-content: space-between;
  }

  nav {
    width: 100%;
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.3s ease;
  }

  nav.active {
    max-height: 300px;
  }

  nav ul {
    flex-direction: column;
    padding: 1rem 0;
  }

  nav ul li {
    margin: 0.5rem 0;
    text-align: center;
  }

  nav ul li a {
    display: block;
    padding: 0.5rem;
  }

  .menu-toggle {
    display: block;
    order: 1;
  }

  .main {
    padding: 1.5rem;
  }

  .main h2 {
    font-size: 2rem;
  }

  .main p {
    font-size: 0.9rem;
    padding: 0;
  }

  .flashcard {
    padding: 15px;
    margin: 10px 0;
  }

  button {
    padding: 8px 12px;
    font-size: 14px;
    margin: 4px 0;
  }

  #options button {
    padding: 8px 0;
    font-size: 14px;
  }

  #result,
  #final-result {
    font-size: 15px;
  }

  #timer {
    font-size: 15px;
  }

  #progress-container {
    font-size: 0.9em;
    width: 95%;
  }

  .theme-switch {
    width: 50px;
    height: 25px;
  }

  .slider:before {
    height: 18px;
    width: 18px;
  }

  .theme-switch-wrapper {
    top: 10px;
    right: 10px;
  }

  #flashcard-container {
    width: 100%;
  }
}

@media (min-width: 769px) {
  #flashcard-container {
    width: 800px;
    max-width: 800px;
  }
}