:root {
    --bg-color: #f0f0f0;
    --container-bg: #ffffff;
    --text-color: #333333;
    --button-bg: #007bff;
    --button-text: #ffffff;
    --number-bg: #eeeeee;
    --shadow: 0 0 10px rgba(0, 0, 0, 0.1);
}

body.dark-theme {
    --bg-color: #121212;
    --container-bg: #1e1e1e;
    --text-color: #e0e0e0;
    --button-bg: #3700b3;
    --button-text: #ffffff;
    --number-bg: #333333;
    --shadow: 0 0 10px rgba(0, 0, 0, 0.5);
}

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

.container {
    text-align: center;
    background-color: var(--container-bg);
    padding: 2.5rem;
    border-radius: 15px;
    box-shadow: var(--shadow);
    max-width: 400px;
    width: 90%;
    transition: background-color 0.3s, box-shadow 0.3s;
}

h1 {
    margin-bottom: 2rem;
    font-size: 1.8rem;
}

.controls {
    display: flex;
    justify-content: flex-end;
    margin-bottom: 1rem;
}

#theme-toggle {
    background: none;
    border: 1px solid var(--text-color);
    color: var(--text-color);
    padding: 0.4rem 0.8rem;
    border-radius: 20px;
    cursor: pointer;
    font-size: 0.8rem;
    margin-top: 0;
}

button {
    padding: 0.8rem 1.5rem;
    font-size: 1.1rem;
    cursor: pointer;
    border: none;
    background-color: var(--button-bg);
    color: var(--button-text);
    border-radius: 8px;
    margin-top: 1.5rem;
    transition: background-color 0.3s, transform 0.1s;
    width: 100%;
}

button:active {
    transform: scale(0.98);
}

.numbers-container {
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    gap: 0.8rem;
    margin-top: 2.5rem;
    min-height: 50px;
}

.number {
    width: 45px;
    height: 45px;
    border-radius: 50%;
    background-color: var(--number-bg);
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 1.2rem;
    font-weight: bold;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
    animation: fadeIn 0.4s ease-out;
}

/* Form Styles */
.form-section {
    margin-top: 3rem;
    text-align: left;
}

hr {
    border: 0;
    border-top: 1px solid var(--text-color);
    opacity: 0.1;
    margin-bottom: 2rem;
}

h3 {
    margin-bottom: 1.5rem;
    font-size: 1.2rem;
    text-align: center;
}

.form-group {
    margin-bottom: 1rem;
}

input, textarea {
    width: 100%;
    padding: 0.8rem;
    border-radius: 8px;
    border: 1px solid var(--number-bg);
    background-color: var(--container-bg);
    color: var(--text-color);
    font-family: inherit;
    box-sizing: border-box;
    transition: border-color 0.3s;
}

input:focus, textarea:focus {
    outline: none;
    border-color: var(--button-bg);
}

textarea {
    resize: vertical;
    min-height: 100px;
}

.submit-btn {
    background-color: var(--button-bg);
    color: white;
    font-weight: bold;
    margin-top: 0.5rem;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}