body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    margin: 0;
    padding: 0;
    color: #333;
    background-color: #f5f5f5;
}

header {
    background-color: #2c3e50;
    color: white;
    padding: 1rem 0;
    text-align: center;
}

nav ul {
    list-style: none;
    padding: 0;
    display: flex;
    justify-content: center;
    background-color: #34495e;
    margin: 0;
}

nav li {
    margin: 0 1rem;
}

nav a {
    color: white;
    text-decoration: none;
    padding: 0.5rem 1rem;
    display: block;
}

nav a.active {
    background-color: #1abc9c;
    border-radius: 4px;
}

main {
    max-width: 1200px;
    margin: 2rem auto;
    padding: 0 1rem;
}

.content-section {
    display: none;
    background: white;
    padding: 2rem;
    border-radius: 5px;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
    margin-bottom: 2rem;
}

.content-section.active {
    display: block;
}

h1, h2, h3 {
    color: #2c3e50;
}

.code-example, .code-hint {
    background: #f8f9fa;
    border-left: 4px solid #1abc9c;
    padding: 1rem;
    margin: 1rem 0;
    overflow-x: auto;
}

pre {
    margin: 0;
}

.hint-button {
    background-color: #3498db;
    color: white;
    border: none;
    padding: 0.5rem 1rem;
    border-radius: 4px;
    cursor: pointer;
    margin: 1rem 0;
}

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

.code-hint {
    display: none;
}

.theory-block {
    background: #e8f4fc;
    padding: 1rem;
    border-radius: 5px;
    margin: 1rem 0;
}

.hint-note {
    font-style: italic;
    color: #7f8c8d;
}

footer {
    text-align: center;
    padding: 1rem;
    background-color: #2c3e50;
    color: white;
    position: fixed;
    bottom: 0;
    width: 100%;
}