* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Arial', sans-serif;
}

body {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    background-color: var(--bg-color);
    color: var(--text-color);
    transition: all 0.3s ease;
}

:root {
    --bg-color: #f0f0f0;
    --text-color: #333;
    --card-bg: #fff;
    --primary-color: #007bff;
    --border-color: #ddd;
    --shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
    --watermark-color: #666;
}

body.dark {
    --bg-color: #1a1a1a;
    --text-color: #f0f0f0;
    --card-bg: #2a2a2a;
    --primary-color: #1e90ff;
    --border-color: #444;
    --shadow: 0 4px 8px rgba(0, 0, 0, 0.3);
    --watermark-color: #aaa;
}

.container {
    background: var(--card-bg);
    padding: 2rem;
    border-radius: 10px;
    box-shadow: var(--shadow);
    width: 100%;
    max-width: 500px;
    margin: 1rem;
    position: relative;
}

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

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

#theme-toggle {
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--text-color);
}

.password-display {
    display: flex;
    gap: 0.5rem;
    margin-bottom: 1.5rem;
}

#password {
    flex: 1;
    padding: 0.75rem;
    font-size: 1rem;
    border: 1px solid var(--border-color);
    border-radius: 5px;
    background: var(--bg-color);
    color: var(--text-color);
}

#copy-btn {
    padding: 0.75rem 1rem;
    background: var(--primary-color);
    color: #fff;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    transition: background 0.2s;
}

#copy-btn:hover {
    background: #0056b3;
}

.options {
    display: flex;
    flex-direction: column;
    gap: 1rem;
    margin-bottom: 1.5rem;
}

.option {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.option label {
    font-size: 1rem;
    color: var(--text-color);
}

#length {
    width: 100%;
}

#length-value {
    font-weight: bold;
}

#generate-btn {
    width: 100%;
    padding: 0.75rem;
    background: var(--primary-color);
    color: #fff;
    border: none;
    border-radius: 5px;
    font-size: 1rem;
    cursor: pointer;
    transition: background 0.2s;
}

#generate-btn:hover {
    background: #0056b3;
}

.watermark {
    text-align: center;
    font-size: 0.9rem;
    color: var(--watermark-color);
    margin-top: 1.5rem;
    opacity: 0.7;
}

/* Responsive Design */
@media (max-width: 600px) {
    .container {
        padding: 1.5rem;
    }

    h1 {
        font-size: 1.5rem;
    }

    .password-display {
        flex-direction: column;
    }

    #password, #copy-btn {
        width: 100%;
    }

    .watermark {
        font-size: 0.8rem;
    }
}