:root {
  --bg-color: #f4f7f6;
  --text-color: #333;
  --container-bg: #fff;
  --ball-bg: #e0e0e0;
  --ball-text: #333;
  --btn-primary: #4caf50;
  --btn-primary-hover: #45a049;
  --btn-text: #fff;
  --shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
}

.dark-mode {
  --bg-color: #1a1a1a;
  --text-color: #f4f4f4;
  --container-bg: #2d2d2d;
  --ball-bg: #444;
  --ball-text: #fff;
  --btn-primary: #388e3c;
  --btn-primary-hover: #2e7d32;
  --btn-text: #fff;
  --shadow: 0 4px 10px rgba(0, 0, 0, 0.3);
}

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

.container {
  background-color: var(--container-bg);
  padding: 2rem;
  border-radius: 12px;
  box-shadow: var(--shadow);
  text-align: center;
  width: 90%;
  max-width: 500px;
}

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

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

.number-container {
  display: flex;
  justify-content: center;
  gap: 10px;
  margin-bottom: 2rem;
  flex-wrap: wrap;
}

.ball {
  width: 50px;
  height: 50px;
  background-color: var(--ball-bg);
  color: var(--ball-text);
  border-radius: 50%;
  display: flex;
  justify-content: center;
  align-items: center;
  font-weight: bold;
  font-size: 1.2rem;
  box-shadow: inset 0 -3px 5px rgba(0,0,0,0.1);
  transition: transform 0.2s ease, background-color 0.3s ease;
}

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

/* 로또 색상 (번호 범위에 따라 다르게) */
.ball.color-1 { background-color: #fbc02d; color: #fff; } /* 1-10 */
.ball.color-2 { background-color: #1976d2; color: #fff; } /* 11-20 */
.ball.color-3 { background-color: #d32f2f; color: #fff; } /* 21-30 */
.ball.color-4 { background-color: #757575; color: #fff; } /* 31-40 */
.ball.color-5 { background-color: #388e3c; color: #fff; } /* 41-45 */

.btn-generate {
  background-color: var(--btn-primary);
  color: var(--btn-text);
  border: none;
  padding: 0.8rem 1.5rem;
  font-size: 1.1rem;
  border-radius: 8px;
  cursor: pointer;
  width: 100%;
  transition: background-color 0.2s ease;
}

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

.btn-theme {
  background-color: transparent;
  border: 1px solid var(--text-color);
  color: var(--text-color);
  padding: 0.4rem 0.8rem;
  border-radius: 4px;
  cursor: pointer;
  font-size: 0.8rem;
}