:root {
    --primary-color: #3498db;
    --secondary-color: #2c3e50;
    --background-color: #ecf0f1;
    --widget-background: #ffffff;
    --text-color: #34495e;
    --light-gray: #bdc3c7;
    --border-radius: 8px;
    --shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: var(--background-color);
    color: var(--text-color);
    margin: 0;
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

.header {
    background-color: var(--secondary-color);
    color: white;
    padding: 1rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    box-shadow: var(--shadow);
}

.logo {
    font-size: 1.5rem;
    font-weight: bold;
}

.nav a {
    color: white;
    text-decoration: none;
    margin-left: 1.5rem;
    transition: color 0.3s;
}

.nav a:hover {
    color: var(--primary-color);
}

.main-container {
    display: flex;
    flex: 1;
}

.sidebar {
    background-color: var(--widget-background);
    width: 250px;
    padding: 2rem;
    box-shadow: var(--shadow);
}

.sidebar h2 {
    color: var(--secondary-color);
    margin-top: 0;
}

.tool-list {
    list-style: none;
    padding: 0;
}

.tool-list li a {
    display: block;
    padding: 0.75rem 1rem;
    text-decoration: none;
    color: var(--text-color);
    border-radius: var(--border-radius);
    transition: background-color 0.3s, color 0.3s;
}

.tool-list li.active a, .tool-list li a:hover {
    background-color: var(--primary-color);
    color: white;
}

.content {
    flex: 1;
    padding: 2rem;
}

.tool-container {
    background-color: var(--widget-background);
    padding: 2rem;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
}

.tool-container h1 {
    color: var(--secondary-color);
    margin-top: 0;
}

.tool-container p {
    line-height: 1.6;
    margin-bottom: 1.5rem;
}

textarea {
    width: 100%;
    height: 150px;
    padding: 1rem;
    border: 1px solid var(--light-gray);
    border-radius: var(--border-radius);
    margin-bottom: 1rem;
    font-family: 'Courier New', Courier, monospace;
    font-size: 1rem;
    resize: vertical;
    box-sizing: border-box;
}

.button-group {
    margin-bottom: 1.5rem;
}

button, .button {
    background-color: var(--primary-color);
    color: white;
    padding: 0.75rem 1.5rem;
    border: none;
    border-radius: var(--border-radius);
    cursor: pointer;
    text-decoration: none;
    display: inline-block;
    margin-right: 1rem;
    font-size: 1rem;
    transition: background-color 0.3s;
}

button:hover, .button:hover {
    background-color: #2980b9;
}

#pdfPreview {
    border: 1px solid var(--light-gray);
    border-radius: var(--border-radius);
    min-height: 600px;
}

#pdfPreview embed {
    width: 100%;
    height: 600px;
    border-radius: var(--border-radius);
}

.footer {
    background-color: var(--secondary-color);
    color: white;
    text-align: center;
    padding: 1rem;
    margin-top: auto;
}