:root {
  --bg-color: #f4f7f6;
  --container-bg: #ffffff;
  --text-color: #333333;
  --ball-placeholder: #dddddd;
  --ball-placeholder-text: #888888;
  --shadow: rgba(0,0,0,0.1);
}

.dark-mode {
  --bg-color: #1a1a1a;
  --container-bg: #2d2d2d;
  --text-color: #f4f7f6;
  --ball-placeholder: #444444;
  --ball-placeholder-text: #aaaaaa;
  --shadow: rgba(0,0,0,0.4);
}

body {
  font-family: 'Pretendard', sans-serif;
  background-color: var(--bg-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;
}

.theme-toggle {
  position: absolute;
  top: 20px;
  right: 20px;
}

#theme-btn {
  background-color: var(--container-bg);
  color: var(--text-color);
  border: 1px solid var(--text-color);
  padding: 8px 16px;
  font-size: 0.9rem;
}

.container {
  background: var(--container-bg);
  padding: 2rem;
  border-radius: 15px;
  box-shadow: 0 10px 25px var(--shadow);
  text-align: center;
  transition: background-color 0.3s, box-shadow 0.3s;
}

h1 {
  margin-bottom: 2rem;
}

.numbers-container {
  display: flex;
  gap: 15px;
  justify-content: center;
  margin-bottom: 2rem;
}

.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;
  box-shadow: 0 4px 6px rgba(0,0,0,0.1);
  transition: transform 0.3s ease;
}

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

.ball.placeholder {
  background-color: var(--ball-placeholder);
  color: var(--ball-placeholder-text);
}

/* 로또 공 색상 규정 (대략적) */
.ball-yellow { background-color: #fbc400; } /* 1-10 */
.ball-blue   { background-color: #69c8f2; } /* 11-20 */
.ball-red    { background-color: #ff7272; } /* 21-30 */
.ball-gray   { background-color: #aaa; }    /* 31-40 */
.ball-green  { background-color: #b0d840; } /* 41-45 */

button {
  padding: 12px 24px;
  font-size: 1.1rem;
  background-color: #4CAF50;
  color: white;
  border: none;
  border-radius: 8px;
  cursor: pointer;
  transition: background-color 0.2s, transform 0.1s;
}

button:hover {
  background-color: #45a049;
}

button:active {
  transform: scale(0.98);
}