:root {
  --primary-color: #4a90e2;
  --secondary-color: #f5a623;
  --background-color: #f0f2f5;
  --container-bg: #fff;
  --text-color: #333;
  --white: #fff;
}

body.dark-mode {
  --background-color: #1a1a1a;
  --container-bg: #2d2d2d;
  --text-color: #f0f2f5;
  --primary-color: #64b5f6;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica,
    Arial, sans-serif;
  background-color: var(--background-color);
  color: var(--text-color);
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
  margin: 0;
  transition: background-color 0.3s, color 0.3s;
}

.container {
  background-color: var(--container-bg);
  padding: 40px;
  border-radius: 12px;
  box-shadow: 0 10px 20px rgba(0, 0, 0, 0.1);
  text-align: center;
  transition: background-color 0.3s;
}

h1 {
  color: var(--primary-color);
  margin-bottom: 20px;
}

#theme-toggle {
  background-color: transparent;
  border: 2px solid var(--primary-color);
  color: var(--primary-color);
  padding: 5px 15px;
  font-size: 14px;
  border-radius: 20px;
  cursor: pointer;
  margin-bottom: 20px;
  transition: all 0.3s;
}

#theme-toggle:hover {
  background-color: var(--primary-color);
  color: var(--white);
}

#generate-btn {
  background-color: var(--primary-color);
  color: var(--white);
  border: none;
  padding: 15px 30px;
  font-size: 18px;
  font-weight: bold;
  border-radius: 8px;
  cursor: pointer;
  transition: background-color 0.3s, transform 0.2s;
  margin-bottom: 30px;
  display: block;
  margin-left: auto;
  margin-right: auto;
}

#generate-btn:hover {
  background-color: #357abd;
  transform: translateY(-2px);
}

#numbers-container {
  display: flex;
  justify-content: center;
  gap: 15px;
  min-height: 50px;
}

.number {
  background-color: var(--secondary-color);
  color: var(--white);
  width: 50px;
  height: 50px;
  display: flex;
  justify-content: center;
  align-items: center;
  font-size: 24px;
  font-weight: bold;
  border-radius: 50%;
  animation: pop-in 0.5s ease-out forwards;
}

@keyframes pop-in {
  0% {
    transform: scale(0);
    opacity: 0;
  }
  60% {
    transform: scale(1.1);
  }
  100% {
    transform: scale(1);
    opacity: 1;
  }
}