:root {
    /* Dark Theme (Moonlit Starlit Forest) */
    --bg-color: #0a0f1a; /* Deep midnight blue */
    --forest-overlay: linear-gradient(180deg, rgba(10, 15, 26, 0.8) 0%, rgba(26, 46, 26, 0.9) 100%);
    --container-bg: rgba(255, 255, 255, 0.05);
    --text-color: #e0e0e0;
    --accent-color: #a5c9e8; /* Moon blue-white */
    --shadow-color: rgba(0, 0, 0, 0.8);
    --lucky-glow: #ffffff;
    --forest-img: url('https://www.transparenttextures.com/patterns/dark-wood.png');
}

[data-theme="light"] {
    /* Light Theme (Sunlit Forest) */
    --bg-color: #e8f5e9;
    --forest-overlay: radial-gradient(circle at 20% 20%, rgba(255, 253, 208, 0.4) 0%, rgba(76, 175, 80, 0.2) 60%);
    --container-bg: rgba(255, 255, 255, 0.7);
    --text-color: #1b5e20;
    --accent-color: #5d4037; /* Earthy brown */
    --shadow-color: rgba(0, 0, 0, 0.1);
    --lucky-glow: #ffd54f; /* Golden glow */
    --forest-img: url('https://www.transparenttextures.com/patterns/natural-paper.png');
}

body {
    background-color: var(--bg-color);
    background-image: var(--forest-overlay), var(--forest-img);
    color: var(--text-color);
    font-family: 'Garamond', 'Apple SD Gothic Neo', serif;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
    transition: all 0.5s ease;
    overflow: hidden;
    position: relative;
}

/* Star Effect for Dark Mode */
body::before {
    content: "";
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-image: 
        radial-gradient(1px 1px at 20px 30px, #eee, rgba(0,0,0,0)),
        radial-gradient(1px 1px at 40px 70px, #fff, rgba(0,0,0,0)),
        radial-gradient(2px 2px at 50px 160px, #ddd, rgba(0,0,0,0)),
        radial-gradient(2px 2px at 90px 40px, #fff, rgba(0,0,0,0)),
        radial-gradient(1px 1px at 130px 80px, #fff, rgba(0,0,0,0)),
        radial-gradient(2px 2px at 160px 120px, #ddd, rgba(0,0,0,0));
    background-repeat: repeat;
    background-size: 200px 200px;
    opacity: 0;
    transition: opacity 0.5s ease;
    z-index: -1;
}

[data-theme="dark"] body::before {
    opacity: 0.3;
}

/* Moon/Sun Effect */
body::after {
    content: "";
    position: absolute;
    top: 10%;
    right: 15%;
    width: 80px;
    height: 80px;
    border-radius: 50%;
    transition: all 0.8s cubic-bezier(0.4, 0, 0.2, 1);
    z-index: -1;
}

/* Moon */
[data-theme="dark"] body::after {
    background: #f4f4f4;
    box-shadow: 0 0 40px #a5c9e8, inset -10px -10px 20px rgba(0,0,0,0.1);
}

/* Sun */
[data-theme="light"] body::after {
    background: #fff9c4;
    box-shadow: 0 0 60px #fff176, 0 0 100px rgba(255, 241, 118, 0.3);
    top: 5%;
    right: 10%;
}

.controls {
    position: absolute;
    top: 20px;
    right: 20px;
    display: flex;
    gap: 10px;
    z-index: 10;
}

.icon-btn {
    background: var(--container-bg);
    border: 1px solid var(--accent-color);
    color: var(--text-color);
    padding: 8px 16px;
    border-radius: 20px;
    cursor: pointer;
    font-size: 0.9em;
    backdrop-filter: blur(10px);
    transition: all 0.3s;
}

.icon-btn:hover {
    background: var(--accent-color);
    color: var(--bg-color);
    transform: scale(1.05);
}

.container {
    text-align: center;
    background-color: var(--container-bg);
    padding: 50px;
    border-radius: 30px;
    box-shadow: 0 20px 50px var(--shadow-color);
    backdrop-filter: blur(15px);
    width: 90%;
    max-width: 480px;
    border: 1px solid rgba(255, 255, 255, 0.1);
    transition: all 0.5s ease;
}

h1 {
    font-size: 2.8em;
    margin-bottom: 15px;
    color: var(--accent-color);
    transition: color 0.5s ease;
}

p {
    font-size: 1.1em;
    margin-bottom: 40px;
    line-height: 1.6;
}

#generate-btn {
    background-color: var(--accent-color);
    color: var(--bg-color);
    border: none;
    padding: 18px 40px;
    font-size: 1.3em;
    border-radius: 15px;
    cursor: pointer;
    transition: all 0.3s cubic-bezier(0.175, 0.885, 0.32, 1.275);
    font-weight: bold;
    box-shadow: 0 6px 20px var(--shadow-color);
}

#generate-btn:hover {
    transform: translateY(-4px) scale(1.02);
    box-shadow: 0 10px 30px var(--shadow-color);
}

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

lucky-number {
    display: block;
    font-size: 6em;
    margin: 30px 0;
    color: var(--accent-color);
    text-shadow: 0 0 30px var(--lucky-glow);
    transition: all 0.5s ease;
}