:root {
  --primary-color: #4a90e2;
  --bg-color: #f0f2f5;
  --container-bg: #ffffff;
  --text-color: #333333;
  --ball-bg: #ffffff;
  --ball-border: #dddddd;
  --placeholder-color: #cccccc;
  --shadow-color: rgba(0, 0, 0, 0.1);
  --btn-hover-bg: #357abd;
}

[data-theme="dark"] {
  --bg-color: #1a1a1a;
  --container-bg: #2d2d2d;
  --text-color: #f5f5f5;
  --ball-bg: #3d3d3d;
  --ball-border: #4a4a4a;
  --placeholder-color: #666666;
  --shadow-color: rgba(0, 0, 0, 0.4);
  --btn-hover-bg: #5fa4f5;
}

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

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

#theme-btn {
  background: var(--container-bg);
  border: 1px solid var(--ball-border);
  border-radius: 50%;
  width: 45px;
  height: 45px;
  font-size: 1.2rem;
  cursor: pointer;
  display: flex;
  justify-content: center;
  align-items: center;
  box-shadow: 0 4px 8px var(--shadow-color);
  transition: all 0.3s ease;
}

.container {
  background: var(--container-bg);
  padding: 2.5rem;
  border-radius: 20px;
  box-shadow: 0 10px 25px var(--shadow-color);
  text-align: center;
  width: 90%;
  max-width: 500px;
  transition: background-color 0.3s ease, box-shadow 0.3s ease;
}

h1 {
  color: var(--text-color);
  margin-bottom: 2rem;
  font-size: 1.8rem;
}

.numbers-container {
  display: flex;
  flex-direction: column;
  gap: 20px;
  margin-bottom: 2rem;
}

.lotto-row {
  display: flex;
  justify-content: center;
  gap: 10px;
  padding-bottom: 15px;
  border-bottom: 1px dashed var(--ball-border);
}

.lotto-row:last-child {
  border-bottom: none;
}

.ball {
  width: 45px;
  height: 45px;
  border-radius: 50%;
  background: var(--ball-bg);
  border: 2px solid var(--ball-border);
  display: flex;
  justify-content: center;
  align-items: center;
  font-weight: bold;
  font-size: 1.1rem;
  box-shadow: 2px 4px 6px var(--shadow-color);
  transition: transform 0.3s ease, background 0.3s ease, border-color 0.3s ease, opacity 0.5s ease;
  color: var(--text-color);
}

.ball.placeholder {
  color: var(--placeholder-color);
  border-style: dashed;
}

/* 로또 번호대별 색상 (다크 모드에서도 가독성을 위해 살짝 조정 가능) */
.color-1 { background: #fbc400; color: white; border-color: #fbc400; }
.color-11 { background: #69c8f2; color: white; border-color: #69c8f2; }
.color-21 { background: #ff7272; color: white; border-color: #ff7272; }
.color-31 { background: #aaaaaa; color: white; border-color: #aaaaaa; }
.color-41 { background: #b0d840; color: white; border-color: #b0d840; }

#generate-btn {
  background-color: var(--primary-color);
  color: white;
  border: none;
  padding: 12px 30px;
  font-size: 1.1rem;
  font-weight: bold;
  border-radius: 30px;
  cursor: pointer;
  transition: all 0.2s ease;
  box-shadow: 0 4px 12px rgba(74, 144, 226, 0.3);
}

#generate-btn:hover {
  background-color: var(--btn-hover-bg);
  transform: translateY(-2px);
  box-shadow: 0 6px 16px rgba(74, 144, 226, 0.4);
}

#generate-btn:active {
  transform: translateY(0);
}

@media (max-width: 400px) {
  .ball {
    width: 45px;
    height: 45px;
    font-size: 1.1rem;
  }
}