body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    margin: 0;
    transition: background-color 0.3s ease, color 0.3s ease;
}

:root {
    --bg-color: #f0f2f5;
    --text-color: #333;
    --container-bg-color: #fff;
    --h1-color: #1a73e8;
    --number-bg-color: #e8f0fe;
    --number-color: #1967d2;
    --btn-bg-color: #1a73e8;
    --btn-text-color: #fff;
    --btn-hover-bg-color: #186bd6;
    --svg-background: url('data:image/svg+xml,%3Csvg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 80 80" width="80" height="80"%3E%3Crect fill="%23f9fafb" width="80" height="80"%3E%3C/rect%3E%3Cg fill-rule="evenodd"%3E%3Cg fill="%23d4d4d8" fill-opacity="0.4"%3E%3Cpath d="M0 0h40v40H0V0zm40 40h40v40H40V40z" /%3E%3C/g%3E%3C/g%3E%3C/svg%3E');
}

body.dark-mode {
    --bg-color: #121212;
    --text-color: #e0e0e0;
    --container-bg-color: #1e1e1e;
    --h1-color: #bb86fc;
    --number-bg-color: #3f3f3f;
    --number-color: #e0e0e0;
    --btn-bg-color: #bb86fc;
    --btn-text-color: #121212;
    --btn-hover-bg-color: #a362ff;
    --svg-background: url('data:image/svg+xml,%3Csvg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 80 80" width="80" height="80"%3E%3Crect fill="%231e1e1e" width="80" height="80"%3E%3C/rect%3E%3Cg fill-rule="evenodd"%3E%3Cg fill="%23444444" fill-opacity="0.4"%3E%3Cpath d="M0 0h40v40H0V0zm40 40h40v40H40V40z" /%3E%3C/g%3E%3C/g%3E%3C/svg%3E');
}

body {
    background-image: var(--svg-background);
}

.container {
    background-color: var(--container-bg-color);
    padding: 2rem;
    border-radius: 1rem;
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.1), 0 5px 10px rgba(0, 0, 0, 0.04);
    text-align: center;
    width: 90%;
    max-width: 400px;
    position: relative;
}

.theme-switch-container {
    position: absolute;
    top: 1rem;
    right: 1rem;
}

.theme-switch {
    position: relative;
    display: inline-block;
    width: 50px;
    height: 24px;
}

.theme-switch input {
    opacity: 0;
    width: 0;
    height: 0;
}

.slider {
    position: absolute;
    cursor: pointer;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: #ccc;
    transition: .4s;
    border-radius: 24px;
}

.slider:before {
    position: absolute;
    content: "";
    height: 16px;
    width: 16px;
    left: 4px;
    bottom: 4px;
    background-color: white;
    transition: .4s;
    border-radius: 50%;
}

input:checked + .slider {
    background-color: var(--btn-bg-color);
}

input:checked + .slider:before {
    transform: translateX(26px);
}

h1 {
    color: var(--h1-color);
    margin-bottom: 1.5rem;
}

.numbers-container {
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    gap: 1rem;
    margin-bottom: 2rem;
}

.number {
    width: 50px;
    height: 50px;
    border-radius: 50%;
    background-color: var(--number-bg-color);
    color: var(--number-color);
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 1.5rem;
    font-weight: bold;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
}

#generate-btn {
    background-color: var(--btn-bg-color);
    color: var(--btn-text-color);
    border: none;
    padding: 1rem 2rem;
    font-size: 1rem;
    font-weight: bold;
    border-radius: 0.5rem;
    cursor: pointer;
    transition: all 0.3s ease;
    box-shadow: 0 4px 14px rgba(0,0,0,0.2);
}

#generate-btn:hover {
    background-color: var(--btn-hover-bg-color);
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(0,0,0,0.3);
}

#generate-btn:active {
    transform: translateY(0);
    box-shadow: 0 4px 14px rgba(0,0,0,0.2);
}