:root {
  --bg-color: #f0f2f5;
  --container-bg: white;
  --text-color: #333;
  --title-color: #1a73e8;
  --shadow-color: rgba(0, 0, 0, 0.1);
  --btn-bg: #1a73e8;
  --btn-hover: #1557b0;
}

body.dark-mode {
  --bg-color: #18191a;
  --container-bg: #242526;
  --text-color: #e4e6eb;
  --title-color: #4dadf7;
  --shadow-color: rgba(0, 0, 0, 0.3);
  --btn-bg: #4dadf7;
  --btn-hover: #3b8ac4;
}

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

.container {
  position: relative;
  text-align: center;
  background-color: var(--container-bg);
  padding: 2rem;
  border-radius: 1rem;
  box-shadow: 0 4px 6px var(--shadow-color);
  transition: background-color 0.3s, box-shadow 0.3s;
}

.theme-switch-wrapper {
  position: absolute;
  top: 1rem;
  right: 1.5rem;
}

.theme-toggle-btn {
  background: none;
  border: none;
  font-size: 1.5rem;
  cursor: pointer;
  padding: 5px;
  border-radius: 50%;
  transition: transform 0.2s;
}

.theme-toggle-btn:hover {
  transform: scale(1.1);
}

h1 {
  color: var(--title-color);
  margin-bottom: 2rem;
  transition: color 0.3s;
}

.lotto-wrapper {
  display: flex;
  flex-direction: column;
  gap: 15px;
  margin-bottom: 2rem;
}

.numbers-container {
  display: flex;
  gap: 10px;
  justify-content: center;
}

.ball {
  width: 50px;
  height: 50px;
  border-radius: 50%;
  display: flex;
  justify-content: center;
  align-items: center;
  font-weight: bold;
  font-size: 1.2rem;
  color: white;
  background-color: #ccc;
  transition: transform 0.3s ease;
}

.ball.active {
  transform: scale(1.1);
}

#generate-btn {
  padding: 10px 20px;
  font-size: 1rem;
  background-color: var(--btn-bg);
  color: white;
  border: none;
  border-radius: 5px;
  cursor: pointer;
  transition: background-color 0.2s, transform 0.1s;
}

#generate-btn:hover {
  background-color: var(--btn-hover);
}

#generate-btn:active {
  transform: scale(0.98);
}