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

/* Body */
body {
  font-family: sans-serif;
  background-color: #fefefe;
  color: #222;
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
}

/* Hidden utility */
.hidden {
  display: none !important;
}

/* Home Screen */
.home-screen {
  display: flex;
  flex-direction: column;
  gap: 20px;
  text-align: center;
}
.home-screen h1 {
  font-size: 1.8rem;
}

/* Buttons */
button {
  padding: 15px 20px;
  font-size: 1rem;
  border: none;
  border-radius: 10px;
  background-color: #4caf50;
  color: white;
  cursor: pointer;
  transition: background 0.3s;
}
button:hover {
  background-color: #45a049;
}

/* Choose Table */
.choose-table-screen {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 20px;
}
.choose-table-screen h2 {
  font-size: 1.5rem;
}
.table-grid {
  display: grid;
  grid-template-columns: repeat(3, 80px);
  gap: 15px;
}
.table-btn {
  padding: 15px;
  font-size: 1.1rem;
  border: 2px solid #4caf50;
  border-radius: 8px;
  background-color: white;
  color: #4caf50;
  cursor: pointer;
  transition: 0.2s;
}
.table-btn:hover {
  background-color: #4caf50;
  color: white;
}

/* Practice Screen */
.practice-screen {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 20px;
}
.practice-screen h2 {
  font-size: 1.5rem;
}
.question-text {
  font-size: 1.4rem;
  font-weight: bold;
}
.options-grid {
  display: grid;
  grid-template-columns: repeat(2, 120px);
  gap: 15px;
}
.option-btn {
  padding: 12px;
  font-size: 1.1rem;
  border: 2px solid #4caf50;
  border-radius: 8px;
  background-color: white;
  color: #4caf50;
  cursor: pointer;
  transition: 0.2s;
}
.option-btn:disabled {
  cursor: default;
  opacity: 0.6;
}
.option-btn.correct {
  background-color: #4caf50;
  color: white;
  border-color: #388e3c;
}
.option-btn.wrong {
  background-color: #e57373;
  color: white;
  border-color: #c62828;
}
#next-btn {
  padding: 10px 20px;
  font-size: 1rem;
  border: none;
  border-radius: 8px;
  background-color: #1976d2;
  color: white;
  cursor: pointer;
  transition: background 0.3s;
}
#next-btn:hover {
  background-color: #1565c0;
}

/* Challenge Screen */
.challenge-screen {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 20px;
}
.countdown {
  font-size: 3rem;
  font-weight: bold;
}
.challenge-content .question-text {
  font-size: 1.4rem;
  font-weight: bold;
}
.options-grid-ch {
  display: grid;
  grid-template-columns: repeat(2, 120px);
  gap: 15px;
}
.timer {
  margin-top: 15px;
  font-size: 1rem;
  font-weight: bold;
}