:root {
    --bg-color: #f0f0f0;
    --container-bg: #fff;
    --text-color: #333;
    --btn-bg: #4CAF50;
    --btn-hover: #45a049;
    --number-bg: #f0f0f0;
    --shadow: rgba(0, 0, 0, 0.1);
}

body.dark-mode {
    --bg-color: #121212;
    --container-bg: #1e1e1e;
    --text-color: #e0e0e0;
    --btn-bg: #388E3C;
    --btn-hover: #2E7D32;
    --number-bg: #333;
    --shadow: 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;
    margin: 0;
    background-color: var(--bg-color);
    color: var(--text-color);
    transition: background-color 0.3s, color 0.3s;
}

.container {
    text-align: center;
    background-color: var(--container-bg);
    padding: 40px;
    border-radius: 15px;
    box-shadow: 0 10px 20px var(--shadow), 0 6px 6px var(--shadow);
    transition: background-color 0.3s, box-shadow 0.3s;
    position: relative;
    max-width: 400px;
    width: 90%;
}

.theme-switch-wrapper {
    position: absolute;
    top: 10px;
    right: 10px;
}

#theme-toggle {
    background: none;
    border: 1px solid var(--text-color);
    color: var(--text-color);
    padding: 5px 10px;
    border-radius: 20px;
    cursor: pointer;
    font-size: 12px;
    transition: all 0.3s;
}

#theme-toggle:hover {
    background-color: var(--text-color);
    color: var(--container-bg);
}

h1 {
    color: var(--text-color);
    margin-bottom: 30px;
}

#generate-btn {
    background-color: var(--btn-bg);
    color: white;
    padding: 15px 30px;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    font-size: 16px;
    transition: background-color 0.3s, box-shadow 0.3s;
    box-shadow: 0 4px 6px var(--shadow);
}

#generate-btn:hover {
    background-color: var(--btn-hover);
    box-shadow: 0 7px 14px var(--shadow);
}

#numbers-container {
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    gap: 15px;
    margin-top: 30px;
}

.number {
    width: 50px;
    height: 50px;
    border-radius: 50%;
    background-color: var(--number-bg);
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 20px;
    font-weight: bold;
    color: var(--text-color);
    box-shadow: inset 0 2px 4px var(--shadow);
    transition: background-color 0.3s, color 0.3s;
}

.separator {
    margin: 40px 0;
    border: 0;
    border-top: 1px solid var(--shadow);
}

.contact-form h2 {
    font-size: 1.2rem;
    margin-bottom: 20px;
    color: var(--text-color);
}

.input-group {
    margin-bottom: 15px;
}

.input-group input,
.input-group textarea {
    width: 100%;
    padding: 12px;
    border: 1px solid var(--shadow);
    border-radius: 6px;
    background-color: var(--number-bg);
    color: var(--text-color);
    font-family: inherit;
    box-sizing: border-box;
    outline: none;
    transition: border-color 0.3s;
}

.input-group input:focus,
.input-group textarea:focus {
    border-color: var(--btn-bg);
}

.input-group textarea {
    height: 80px;
    resize: vertical;
}

#submit-btn {
    width: 100%;
    background-color: var(--text-color);
    color: var(--container-bg);
    padding: 12px;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    font-size: 14px;
    font-weight: bold;
    transition: opacity 0.3s, transform 0.1s;
}

#submit-btn:hover {
    opacity: 0.9;
}

#submit-btn:active {
    transform: scale(0.98);
}