:root {
  --bg-color: #f8f9fa;
  --container-bg: #ffffff;
  --text-color: #212529;
  --btn-bg: #e9ecef;
  --accent-color: #007bff;
  --accent-text: #ffffff;
  --ball-bg: #dee2e6;
}

[data-theme='dark'] {
  --bg-color: #1a1d20;
  --container-bg: #2b3035;
  --text-color: #f8f9fa;
  --btn-bg: #343a40;
  --accent-color: #3d8bfd;
  --accent-text: #ffffff;
  --ball-bg: #495057;
}

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

.container {
  background-color: var(--container-bg);
  padding: 2rem;
  border-radius: 20px;
  box-shadow: 0 10px 25px rgba(0,0,0,0.1);
  text-align: center;
  max-width: 400px;
  width: 90%;
}

.header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 2rem;
}

h1 {
  font-size: 1.5rem;
  margin: 0;
}

#theme-toggle {
  padding: 6px 12px;
  font-size: 0.8rem;
  background-color: var(--btn-bg);
  color: var(--text-color);
  border: none;
  border-radius: 8px;
  cursor: pointer;
}

.lotto-display {
  display: flex;
  justify-content: center;
  gap: 10px;
  margin: 2rem 0;
}

.ball {
  width: 45px;
  height: 45px;
  border-radius: 50%;
  display: flex;
  justify-content: center;
  align-items: center;
  font-weight: bold;
  background-color: var(--ball-bg);
  color: var(--text-color);
  transition: all 0.5s cubic-bezier(0.175, 0.885, 0.32, 1.275);
}

.ball.active {
  background-color: var(--accent-color);
  color: var(--accent-text);
  transform: scale(1.1);
}

.main-btn {
  width: 100%;
  padding: 12px;
  font-size: 1.1rem;
  font-weight: bold;
  background-color: var(--accent-color);
  color: var(--accent-text);
  border: none;
  border-radius: 12px;
  cursor: pointer;
  transition: transform 0.1s;
}

.main-btn:active {
  transform: scale(0.98);
}