:root {
    --background-color: #F7F7F7;
    --text-color: #333333;
    --input-bg-color: #FFFFFF;
    --button-bg-color: #10A37F;
    --button-hover-bg-color: #0E8A6E;
    --container-bg-color: #FFFFFF;
    --border-color: #E0E0E0;
    --font-family: 'Roboto', sans-serif;
}

.light-mode {
    --background-color: #F7F7F7;
    --text-color: #333333;
    --input-bg-color: #FFFFFF;
    --button-bg-color: #10A37F;
    --button-hover-bg-color: #0E8A6E;
    --container-bg-color: #FFFFFF;
    --border-color: #E0E0E0;
}

.dark-mode {
    --background-color: #1E1E1E;
    --text-color: #FFFFFF;
    --input-bg-color: #2B2B2B;
    --button-bg-color: #10A37F;
    --button-hover-bg-color: #0E8A6E;
    --container-bg-color: #2B2B2B;
    --border-color: #444444;
}

body {
    font-family: var(--font-family);
    margin: 0;
    padding: 0;
    background-color: var(--background-color);
    color: var(--text-color);
    display: flex;
    flex-direction: column;
    min-height: 100vh;
    transition: background-color 0.3s, color 0.3s;
}

header {
    width: 100%;
    background-color: var(--button-bg-color);
    color: #fff;
    padding: 10px;
    text-align: center;
}

.header-button {
    background-color: var(--button-bg-color);
    color: var(--text-color);
    padding: 10px 20px;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    text-decoration: none;
    font-size: 16px;
    margin-top: 10px;
    transition: background-color 0.3s;
}

.header-button:hover {
    background-color: var(--button-hover-bg-color);
}

nav ul {
    list-style-type: none;
    padding: 0;
    display: flex;
    justify-content: center;
    margin: 10px 0;
}

nav ul li {
    margin: 0 10px;
}

nav ul li a {
    text-decoration: none;
    color: var(--text-color);
    font-weight: bold;
    transition: color 0.3s;
}

nav ul li a:hover {
    color: var(--button-bg-color);
}

.title {
    text-align: center;
    font-size: 2rem;
    margin: 20px 0;
    color: var(--button-bg-color);
}

.container {
    background-color: var(--container-bg-color);
    padding: 20px;
    border-radius: 10px;
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.1);
    width: 80%;
    max-width: 600px;
    margin: 20px auto;
    text-align: center;
    transition: background-color 0.3s, box-shadow 0.3s;
}

.container.dark-mode {
    box-shadow: 0 2px 5px rgba(255, 255, 255, 0.1);
}

.input-text, .output-text {
    width: 100%;
    min-height: 150px;
    margin-bottom: 20px;
    padding: 10px;
    border: 1px solid var(--border-color);
    border-radius: 5px;
    resize: none;
    font-size: 16px;
    background-color: var(--input-bg-color);
    color: var(--text-color);
    box-sizing: border-box;
    transition: background-color 0.3s, color 0.3s;
}

.action-button {
    padding: 10px 20px;
    background-color: var(--button-bg-color);
    color: #fff;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    transition: background-color 0.3s, transform 0.2s;
    margin: 10px;
    font-size: 16px;
}

.action-button:hover {
    background-color: var(--button-hover-bg-color);
    transform: scale(1.05);
}

.action-button:disabled {
    background-color: #666;
    cursor: not-allowed;
}

.button-group {
    display: flex;
    justify-content: center;
    gap: 10px;
}

.toggle-button {
    position: fixed;
    top: 10px;
    right: 10px;
    background-color: transparent;
    border: none;
    color: var(--text-color);
    font-size: 1.5rem;
    cursor: pointer;
    transition: color 0.3s, transform 0.2s;
}

.toggle-button:hover {
    color: var(--button-bg-color);
    transform: scale(1.1);
}

.invalid {
    border-color: red;
}

.credit {
    font-size: 10px;
    color: var(--text-color);
    margin-top: 10px;
}