:root {
  --bg-color: #f0f2f5;
  --container-bg: #ffffff;
  --text-color: #1a1a1a;
  --sub-text-color: #666666;
  --row-bg: #f8f9fa;
  --btn-gradient: linear-gradient(135deg, #4a90e2 0%, #357abd 100%);
  --toggle-btn-bg: #ffffff;
  --toggle-btn-shadow: 0 2px 8px rgba(0,0,0,0.1);
  --input-bg: #ffffff;
  --input-border: #dddddd;
  --divider-color: #eeeeee;
}

[data-theme='dark'] {
  --bg-color: #121212;
  --container-bg: #1e1e1e;
  --text-color: #e0e0e0;
  --sub-text-color: #b0b0b0;
  --row-bg: #2a2a2a;
  --btn-gradient: linear-gradient(135deg, #3a7bd5 0%, #00d2ff 100%);
  --toggle-btn-bg: #2a2a2a;
  --toggle-btn-shadow: 0 2px 8px rgba(0,0,0,0.4);
  --input-bg: #2a2a2a;
  --input-border: #444444;
  --divider-color: #333333;
}

body {
  font-family: 'Pretendard', -apple-system, BlinkMacSystemFont, system-ui, Roboto, 'Helvetica Neue', 'Segoe UI', 'Apple SD Gothic Neo', 'Noto Sans KR', 'Malgun Gothic', sans-serif;
  background-color: var(--bg-color);
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
  margin: 0;
  transition: background-color 0.3s ease;
}

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

#theme-btn {
  background: var(--toggle-btn-bg);
  border: none;
  width: 44px;
  height: 44px;
  border-radius: 50%;
  cursor: pointer;
  display: flex;
  justify-content: center;
  align-items: center;
  box-shadow: var(--toggle-btn-shadow);
  font-size: 1.2rem;
  transition: transform 0.2s, background-color 0.3s;
}

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

.container {
  background: var(--container-bg);
  padding: 2.5rem 1.5rem;
  border-radius: 24px;
  box-shadow: 0 12px 30px rgba(0,0,0,0.08);
  text-align: center;
  max-width: 500px;
  width: 90%;
  transition: background-color 0.3s ease;
}

h1 { 
  color: var(--text-color); 
  margin-bottom: 0.5rem; 
  font-size: 1.8rem;
  transition: color 0.3s ease;
}

p { 
  color: var(--sub-text-color); 
  margin-bottom: 2rem;
  font-size: 1rem;
  transition: color 0.3s ease;
}

#generate-btn {
  background: var(--btn-gradient);
  color: white;
  border: none;
  padding: 16px 32px;
  font-size: 1.1rem;
  font-weight: 700;
  border-radius: 12px;
  cursor: pointer;
  transition: transform 0.2s, box-shadow 0.2s, background 0.3s;
  margin-bottom: 2.5rem;
  width: 100%;
}

#generate-btn:hover { 
  transform: translateY(-2px);
  box-shadow: 0 5px 15px rgba(74, 144, 226, 0.4);
}

.lotto-row {
  display: flex;
  justify-content: center;
  gap: 8px;
  margin-bottom: 12px;
  padding: 12px;
  background: var(--row-bg);
  border-radius: 12px;
  transition: background-color 0.3s ease;
}

.ball {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  display: flex;
  justify-content: center;
  align-items: center;
  color: white;
  font-weight: bold;
  font-size: 1rem;
  text-shadow: 0 1px 2px rgba(0,0,0,0.2);
  box-shadow: inset -2px -2px 4px rgba(0,0,0,0.1), 2px 2px 4px rgba(0,0,0,0.05);
}

.range-1 { background-color: #fbc400; }
.range-11 { background-color: #69c8f2; }
.range-21 { background-color: #ff7272; }
.range-31 { background-color: #aaaaaa; }
.range-41 { background-color: #b0d840; }

.divider {
  border: 0;
  height: 1px;
  background: var(--divider-color);
  margin: 2rem 0;
}

.contact-section {
  text-align: left;
}

.contact-section h3 {
  color: var(--text-color);
  margin-bottom: 1rem;
  font-size: 1.2rem;
}

.form-group {
  margin-bottom: 1rem;
}

.form-group input, 
.form-group textarea {
  width: 100%;
  padding: 12px;
  border-radius: 8px;
  border: 1px solid var(--input-border);
  background-color: var(--input-bg);
  color: var(--text-color);
  font-family: inherit;
  font-size: 0.95rem;
  box-sizing: border-box;
  transition: border-color 0.2s, background-color 0.3s;
}

.form-group input:focus, 
.form-group textarea:focus {
  outline: none;
  border-color: #4a90e2;
}

.form-group textarea {
  height: 100px;
  resize: vertical;
}

#submit-btn {
  background: #333;
  color: white;
  border: none;
  padding: 12px 24px;
  border-radius: 8px;
  font-weight: 600;
  cursor: pointer;
  width: 100%;
  transition: background 0.2s;
}

[data-theme='dark'] #submit-btn {
  background: #444;
}

#submit-btn:hover {
  background: #000;
}

[data-theme='dark'] #submit-btn:hover {
  background: #555;
}

@media (max-width: 400px) {
  .ball {
    width: 32px;
    height: 32px;
    font-size: 0.9rem;
  }
  .lotto-row {
    gap: 5px;
  }
}