:root {
  --bg-color: #f0f0f0;
  --text-color: #333;
  --container-bg: #fff;
  --number-bg: #fff;
  --number-text: #333;
  --btn-bg: #4CAF50;
  --btn-color: #fff;
  --shadow: rgba(0, 0, 0, 0.1);
}

body.dark-mode {
  --bg-color: #121212;
  --text-color: #e0e0e0;
  --container-bg: #1e1e1e;
  --number-bg: #333;
  --number-text: #fff;
  --btn-bg: #2e7d32;
  --btn-color: #fff;
  --shadow: rgba(0, 0, 0, 0.5);
}

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

.container {
  text-align: center;
  background-color: var(--container-bg);
  padding: 40px;
  border-radius: 20px;
  box-shadow: 0 10px 30px var(--shadow);
  transition: background-color 0.3s, box-shadow 0.3s;
}

h1 {
  margin-bottom: 30px;
}

.numbers-container {
  display: flex;
  gap: 15px;
  margin-bottom: 30px;
  justify-content: center;
  flex-wrap: wrap;
}

.number {
  width: 60px;
  height: 60px;
  border-radius: 50%;
  background-color: var(--number-bg);
  color: var(--number-text);
  display: flex;
  justify-content: center;
  align-items: center;
  font-size: 24px;
  font-weight: bold;
  box-shadow: 0 4px 10px var(--shadow);
  transition: transform 0.2s, background-color 0.3s, color 0.3s;
}

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

#generate-btn {
  padding: 12px 24px;
  font-size: 18px;
  cursor: pointer;
  border: none;
  background-color: var(--btn-bg);
  color: var(--btn-color);
  border-radius: 10px;
  box-shadow: 0 4px 15px var(--shadow);
  transition: background-color 0.3s, transform 0.1s;
}

#generate-btn:active {
  transform: scale(0.95);
}

#theme-toggle {
  position: fixed;
  top: 20px;
  right: 20px;
  padding: 10px;
  border-radius: 50%;
  width: 45px;
  height: 45px;
  display: flex;
  justify-content: center;
  align-items: center;
  cursor: pointer;
  background-color: var(--container-bg);
  color: var(--text-color);
  border: 1px solid var(--text-color);
  font-size: 20px;
  box-shadow: 0 2px 10px var(--shadow);
  transition: 0.3s;
}