:root {
    --primary-color: #ffffff;
    --secondary-color: #333333;
    --accent-color: #4CAF50;
    --background-color: #f0f2f5;
    --shadow-color: rgba(0, 0, 0, 0.1);
    --glow-color: rgba(76, 175, 80, 0.4);
    --text-color: #333333;
}

body.dark-mode {
    --primary-color: #1e1e1e;
    --secondary-color: #f0f0f0;
    --accent-color: #66bb6a;
    --background-color: #121212;
    --shadow-color: rgba(0, 0, 0, 0.5);
    --glow-color: rgba(102, 187, 106, 0.3);
    --text-color: #f0f0f0;
}

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

.container {
    text-align: center;
    background-color: var(--primary-color);
    padding: 40px;
    border-radius: 20px;
    box-shadow: 0 10px 30px var(--shadow-color);
    transition: background-color 0.3s ease, box-shadow 0.3s ease;
    width: 100%;
    max-width: 400px;
}

h1 {
    color: var(--secondary-color);
    margin-bottom: 30px;
}

.numbers {
    display: flex;
    justify-content: center;
    gap: 12px;
    margin-bottom: 35px;
    flex-wrap: wrap;
}

.number {
    width: 50px;
    height: 50px;
    display: flex;
    justify-content: center;
    align-items: center;
    background-color: var(--accent-color);
    color: white;
    font-size: 20px;
    font-weight: bold;
    border-radius: 50%;
    box-shadow: 0 4px 10px var(--shadow-color);
    animation: popIn 0.3s ease-out forwards;
}

@keyframes popIn {
    0% { transform: scale(0); opacity: 0; }
    80% { transform: scale(1.1); }
    100% { transform: scale(1); opacity: 1; }
}

#generate {
    background-color: var(--accent-color);
    color: white;
    border: none;
    padding: 15px 35px;
    font-size: 18px;
    font-weight: 600;
    border-radius: 12px;
    cursor: pointer;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    box-shadow: 0 4px 15px var(--glow-color);
}

#generate:hover {
    transform: translateY(-3px);
    box-shadow: 0 8px 25px var(--glow-color);
    filter: brightness(1.1);
}

#generate:active {
    transform: translateY(-1px);
}

/* Theme Toggle Button */
.theme-toggle {
    position: fixed;
    top: 20px;
    right: 20px;
    background: var(--primary-color);
    border: 2px solid var(--accent-color);
    color: var(--secondary-color);
    width: 45px;
    height: 45px;
    border-radius: 50%;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 20px;
    box-shadow: 0 4px 12px var(--shadow-color);
    transition: all 0.3s ease;
}

.theme-toggle:hover {
    transform: rotate(15deg) scale(1.1);
}