:root {
  --primary-color: #46178f;
  --secondary-color: #25076b;
  --red: #e21b3c;
  --blue: #1368ce;
  --yellow: #d89e00;
  --green: #26890c;
  --text-light: #ffffff;
  --bg-light: #f2f2f2;
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  font-family: "Montserrat", sans-serif;
}

body {
  background-color: var(--bg-light);
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
}

.container {
  background-color: white;
  width: 100%;
  max-width: 600px;
  height: 100vh;
  position: relative;
  box-shadow: 0 0 20px rgba(0, 0, 0, 0.1);
  display: flex;
  flex-direction: column;
}

@media (min-width: 600px) {
  .container {
    height: 85vh;
    min-height: 650px;
    max-height: 900px;
    max-width: 700px;
    border-radius: 12px;
    overflow: hidden;
  }
}

.screen {
  display: none;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  height: 100%;
  width: 100%;
  padding: 2rem;
  text-align: center;
}

.screen.active {
  display: flex;
  animation: fadeIn 0.4s ease-in-out;
}

@keyframes fadeIn {
  from {
    opacity: 0;
    transform: scale(0.95);
  }
  to {
    opacity: 1;
    transform: scale(1);
  }
}

/* Start Screen */
#start-screen {
  background: linear-gradient(
    135deg,
    var(--primary-color),
    var(--secondary-color)
  );
  color: var(--text-light);
}

#start-screen h1 {
  font-size: 3.5rem;
  font-weight: 800;
  margin-bottom: 1rem;
  text-shadow: 2px 2px 0px rgba(0, 0, 0, 0.2);
}

#start-screen p {
  font-size: 1.2rem;
  margin-bottom: 3rem;
  opacity: 0.9;
}

.primary-btn {
  background-color: var(--bg-light);
  color: var(--primary-color);
  border: none;
  padding: 1rem 3rem;
  font-size: 1.5rem;
  font-weight: 800;
  border-radius: 8px;
  cursor: pointer;
  box-shadow: 0 6px 0px #cccccc;
  transition: all 0.1s ease;
}

.primary-btn:hover {
  transform: translateY(2px);
  box-shadow: 0 4px 0px #cccccc;
}

.primary-btn:active {
  transform: translateY(6px);
  box-shadow: none;
}

/* ============================================================
   Topic Selection Screen
   ============================================================ */
#topic-screen {
  background: linear-gradient(
    135deg,
    var(--primary-color),
    var(--secondary-color)
  );
  color: var(--text-light);
  justify-content: flex-start;
  padding-top: 3rem;
}

.back-btn {
  align-self: flex-start;
  background: none;
  border: none;
  color: inherit;
  font-size: 1.1rem;
  font-weight: 700;
  cursor: pointer;
  margin-bottom: 1rem;
  display: flex;
  align-items: center;
  opacity: 0.8;
  transition: opacity 0.2s, transform 0.2s;
}

.back-btn:hover {
  opacity: 1;
  transform: translateX(-4px);
}

#question-screen .back-btn {
  color: #555;
  margin-bottom: 0.5rem;
}

.topic-title {
  font-size: 2rem;
  font-weight: 800;
  margin-bottom: 2rem;
  text-shadow: 2px 2px 0px rgba(0, 0, 0, 0.2);
}

.topic-list {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  width: 100%;
  overflow-y: auto;
  max-height: 70%;
  padding: 0 0.5rem;
}

.topic-btn {
  background: rgba(255, 255, 255, 0.15);
  backdrop-filter: blur(4px);
  border: 2px solid rgba(255, 255, 255, 0.3);
  border-radius: 12px;
  padding: 1.2rem 1.5rem;
  font-size: 1.15rem;
  font-weight: 700;
  color: white;
  cursor: pointer;
  transition: all 0.2s ease;
  text-align: left;
  box-shadow: 0 4px 0px rgba(0, 0, 0, 0.2);
}

.topic-btn:hover {
  background: rgba(255, 255, 255, 0.28);
  transform: translateY(-2px);
  box-shadow: 0 6px 0px rgba(0, 0, 0, 0.2);
}

.topic-btn:active {
  transform: translateY(4px);
  box-shadow: none;
}

/* Loading Indicator */
.loading-indicator {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1.5rem;
}

.loading-indicator p {
  font-size: 1.2rem;
  opacity: 0.9;
}

.spinner {
  width: 48px;
  height: 48px;
  border: 5px solid rgba(255, 255, 255, 0.3);
  border-top-color: white;
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

@keyframes spin {
  to {
    transform: rotate(360deg);
  }
}

/* Error Container */
.error-container {
  margin-top: 1.5rem;
  padding: 1.2rem;
  background: rgba(226, 27, 60, 0.2);
  border: 2px solid rgba(226, 27, 60, 0.5);
  border-radius: 12px;
  width: 100%;
  animation: fadeIn 0.4s ease-in-out;
}

.error-text {
  font-size: 1rem;
  color: #ffcccc;
  margin-bottom: 1rem;
  line-height: 1.5;
  text-align: center;
}

/* ============================================================
   Question Screen
   ============================================================ */
#question-screen {
  background-color: var(--bg-light);
  justify-content: flex-start;
  overflow-y: auto;
}

.progress-container {
  display: flex;
  justify-content: space-between;
  width: 100%;
  font-weight: 600;
  color: #555;
  margin-bottom: 2rem;
  padding-bottom: 1rem;
  border-bottom: 2px solid #ddd;
  flex-shrink: 0;
}

#question-text {
  font-size: clamp(1rem, 4vw, 1.8rem);
  margin-bottom: 1.5rem;
  color: #333;
  min-height: 40px;
  display: block;
  flex-shrink: 0;
  word-break: break-word;
  white-space: pre-wrap;
  line-height: 1.4;
  text-align: left;
  width: 100%;
}

#question-text code {
  font-family: 'Courier New', Courier, monospace;
  background: #333;
  padding: 0.1em 0.4em;
  border-radius: 4px;
  font-size: 0.85em;
}

.options-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1rem;
  width: 100%;
  flex-shrink: 0;
}

@media (min-width: 400px) {
  .options-grid {
    grid-template-columns: 1fr 1fr;
    grid-template-rows: 1fr 1fr;
  }
}

.option-btn {
  border: none;
  border-radius: 8px;
  padding: 1rem;
  font-size: 1.2rem;
  font-weight: 700;
  color: white;
  cursor: pointer;
  box-shadow: 0 6px 0px rgba(0, 0, 0, 0.2);
  transition: all 0.1s;
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 100px;
  word-break: break-word;
}

.option-btn:hover {
  filter: brightness(1.1);
}

.option-btn:active {
  transform: translateY(6px);
  box-shadow: none;
}

.option-btn:disabled {
  cursor: default;
}

/* Base Colors for Options */
.option-btn:nth-child(1) {
  background-color: var(--red);
  box-shadow: 0 6px 0px #ab152d;
}
.option-btn:nth-child(2) {
  background-color: var(--blue);
  box-shadow: 0 6px 0px #0e4e9b;
}
.option-btn:nth-child(3) {
  background-color: var(--yellow);
  box-shadow: 0 6px 0px #a17600;
}
.option-btn:nth-child(4) {
  background-color: var(--green);
  box-shadow: 0 6px 0px #1c6609;
}

/* States */
.option-btn.correct {
  background-color: var(--green) !important;
  box-shadow: 0 6px 0px #1c6609 !important;
  animation: pulse 0.5s;
  transform: scale(1.05);
  z-index: 10;
}

.option-btn.wrong {
  background-color: var(--red) !important;
  box-shadow: 0 6px 0px #ab152d !important;
}

.option-btn.fade {
  opacity: 0.4;
  filter: grayscale(0.5);
}

@keyframes pulse {
  0% {
    transform: scale(1);
  }
  50% {
    transform: scale(1.1);
  }
  100% {
    transform: scale(1.05);
  }
}

/* Result Screen */
#result-screen {
  background: linear-gradient(
    135deg,
    var(--primary-color),
    var(--secondary-color)
  );
  color: var(--text-light);
}

#result-screen h2 {
  font-size: 2.5rem;
  margin-bottom: 1rem;
}

.score-text {
  font-size: 1.8rem;
  font-weight: 700;
  margin-bottom: 2rem;
  white-space: pre-line;
}

.feedback-icon {
  font-size: 5rem;
  margin-bottom: 2rem;
}

.hidden {
  display: none !important;
}

.feedback-container {
  margin-top: 1.5rem;
  padding: 1rem;
  background-color: white;
  border-radius: 8px;
  box-shadow: 0 4px 0px rgba(0, 0, 0, 0.1);
  animation: fadeIn 0.4s ease-in-out;
  flex-shrink: 0;
}

.explanation-text {
  font-size: 1.1rem;
  color: #333;
  margin-bottom: 1rem;
  line-height: 1.5;
  text-align: left;
}

.secondary-btn {
  background-color: var(--primary-color);
  color: white;
  border: none;
  padding: 0.8rem 2rem;
  font-size: 1.2rem;
  font-weight: 700;
  border-radius: 8px;
  cursor: pointer;
  box-shadow: 0 4px 0px var(--secondary-color);
  transition: all 0.1s ease;
  width: 100%;
}

.secondary-btn:hover {
  filter: brightness(1.1);
}

.secondary-btn:active {
  transform: translateY(4px);
  box-shadow: none;
}

.margin-top {
  margin-top: 1rem;
}