:root {
  --bg-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  --container-bg: rgba(255, 255, 255, 0.1);
  --text-color: #fff;
  --button-gradient: linear-gradient(45deg, #ff6b6b 0%, #f0932b 100%);
  --number-bg: #fff;
  --number-text: #333;
  --shadow-color: rgba(0, 0, 0, 0.3);
}

[data-theme="light"] {
  --bg-gradient: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
  --container-bg: rgba(255, 255, 255, 0.8);
  --text-color: #333;
  --button-gradient: linear-gradient(45deg, #4facfe 0%, #00f2fe 100%);
  --number-bg: #333;
  --number-text: #fff;
  --shadow-color: rgba(0, 0, 0, 0.1);
}

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

.container {
  position: relative;
  text-align: center;
  background-color: var(--container-bg);
  padding: 40px;
  border-radius: 15px;
  box-shadow: 0 10px 30px var(--shadow-color);
  transition: background-color 0.3s ease, box-shadow 0.3s ease;
}

h1 {
  margin-bottom: 30px;
  font-size: 2.5em;
  text-shadow: 2px 2px 5px rgba(0, 0, 0, 0.2);
}

#generate-button {
  padding: 15px 30px;
  font-size: 1.2em;
  color: #fff;
  background: var(--button-gradient);
  border: none;
  border-radius: 8px;
  cursor: pointer;
  transition: transform 0.2s ease, box-shadow 0.2s ease, background 0.3s ease;
  margin-bottom: 30px;
}

#generate-button:hover {
  transform: translateY(-3px);
  box-shadow: 0 6px 15px var(--shadow-color);
}

#numbers-display {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 15px;
  margin-top: 20px;
}

.number {
  display: inline-flex;
  justify-content: center;
  align-items: center;
  width: 50px;
  height: 50px;
  background-color: var(--number-bg);
  color: var(--number-text);
  border-radius: 50%;
  font-size: 1.5em;
  font-weight: bold;
  box-shadow: inset 0 0 10px rgba(0, 0, 0, 0.2);
  transition: background-color 0.3s ease, color 0.3s ease;
}

#theme-toggle {
  position: absolute;
  top: 10px;
  right: 10px;
  background: none;
  border: none;
  font-size: 1.5rem;
  cursor: pointer;
  color: var(--text-color);
  transition: color 0.3s ease;
}