html, body {
  height: 100%;
  overflow: hidden;
}
.intro-container {
  height: 100vh;
  padding: 24px;
  display: flex;
  flex-direction: column;
  justify-content: center; 
  align-items: center;
  gap: 32px;
}

.intro-header {
  text-align: center;
  max-width: 640px;
}

.game-title {
  margin-bottom: 12px;
}

.game-tagline {
  font-size: 1rem;
  opacity: 0.9;
}

.config-panel {
  width: 100%;
  max-width: 900px;
  height: 75vh;               
  display: flex;
  flex-direction: column;
  background: var(--bg-panel);
  border-radius: var(--radius-lg);
  border: 1px solid var(--border-soft);
  box-shadow: 0 20px 50px rgba(0, 0, 0, 0.35);
  overflow: hidden;
}

.config-body {
    padding: 28px;
              
}

.config-footer {
  padding: 20px;
  border-top: 1px solid var(--border-soft);
  display: flex;
  justify-content: center;
}

.config-section h2 {
  margin-bottom: 18px;
  color: var(--text-main);
   margin-top: 03px;   
}

.mode-options {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 18px;
}

.mode-card {
  position: relative;
  padding: 22px;
  border-radius: var(--radius-md);
  background: var(--bg-soft);
  border: 1px solid var(--border-soft);
  cursor: pointer;
  transition: all var(--transition-fast);
  font-weight: 500;
  text-align: center;
}

.mode-card input {
  display: none;
}

.mode-card:hover {
  transform: translateY(-2px);
  border-color: var(--accent-primary);
}

.mode-card input:checked + span {
  color: var(--accent-secondary);
}

.mode-card input:checked + span::after {
  content: " ✔";
  color: var(--accent-secondary);
}

.player-inputs {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 18px;
}

.difficulty-options {
  display: flex;
  gap: 22px;
  flex-wrap: wrap;
}

.difficulty-options label {
  padding: 10px 16px;
  border-radius: var(--radius-sm);
  background: var(--bg-soft);
  border: 1px solid var(--border-soft);
  cursor: pointer;
  transition: background var(--transition-fast);
  font-size: 0.9rem;
}

.difficulty-options input {
  margin-right: 6px;
}

.difficulty-options label:hover {
  background: rgba(127, 140, 255, 0.12);
}

.config-action {
  margin-top: 16px;
  display: flex;
  justify-content: center;
}


#startGameBtn {
  font-size: 1rem;
  padding: 14px 36px;
  letter-spacing: 0.6px;
}

@media (max-width: 768px) {
  .mode-options,
  .player-inputs {
    grid-template-columns: 1fr;
  }

  .config-panel {
    padding: 26px;
  }
}