:root {
    --primary-color: #4a90e2;
    --background-color: #f0f2f5;
    --text-color: #333;
    --container-bg: #fff;
    --shadow-color: rgba(0, 0, 0, 0.1);
    --ball-shadow: rgba(0, 0, 0, 0.2);
    --transition-speed: 0.3s;
    --gradient-bg: linear-gradient(to right top, #d16ba5, #c777b9, #ba83ca, #aa8fd8, #9a9ae1, #8aa7ec, #79b3f4, #69bff8, #52cffe, #41dfff, #46eefa, #5ffbf1);
}

[data-theme="dark"] {
    --primary-color: #5da9ff;
    --background-color: #1a1a2e;
    --text-color: #e0e0e0;
    --container-bg: #16213e;
    --shadow-color: rgba(0, 0, 0, 0.4);
    --ball-shadow: rgba(0, 0, 0, 0.4);
    --gradient-bg: linear-gradient(to right top, #0f2027, #203a43, #2c5364);
}

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

.container {
    position: relative;
    text-align: center;
    background: var(--container-bg);
    padding: 40px;
    border-radius: 15px;
    box-shadow: 0 10px 30px var(--shadow-color);
    width: 90%;
    max-width: 400px;
    transition: background var(--transition-speed) ease, box-shadow var(--transition-speed) ease;
}

.theme-toggle {
    position: absolute;
    top: 15px;
    right: 15px;
    background: none;
    border: none;
    cursor: pointer;
    font-size: 1.5em;
    padding: 5px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: transform 0.2s ease;
    color: var(--text-color);
}

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

h1 {
    color: var(--primary-color);
    margin-bottom: 30px;
    font-size: 2em;
    transition: color var(--transition-speed) ease;
}

.lotto-container {
    display: flex;
    justify-content: center;
    gap: 15px;
    margin-bottom: 30px;
    flex-wrap: wrap;
    min-height: 50px;
}

.lotto-ball {
    width: 50px;
    height: 50px;
    border-radius: 50%;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 1.5em;
    font-weight: bold;
    color: #fff;
    box-shadow: 0 4px 10px var(--ball-shadow);
    animation: popIn 0.5s ease-out forwards;
}

.generate-btn {
    background-color: var(--primary-color);
    color: #fff;
    border: none;
    padding: 15px 30px;
    font-size: 1.2em;
    border-radius: 10px;
    cursor: pointer;
    transition: background-color var(--transition-speed) ease, transform 0.2s ease, box-shadow var(--transition-speed) ease;
    box-shadow: 0 5px 15px var(--shadow-color);
}

.generate-btn:hover {
    filter: brightness(1.1);
    transform: translateY(-2px);
}

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

@keyframes popIn {
    0% {
        transform: scale(0.5);
        opacity: 0;
    }
    100% {
        transform: scale(1);
        opacity: 1;
    }
}