* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    color: #333;
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;
    background-color: #f9f9f9;
}

header {
    text-align: center;
    margin-bottom: 40px;
    padding-bottom: 20px;
    border-bottom: 1px solid #ddd;
}

header h1 {
    margin-bottom: 20px;
    color: #2c3e50;
}

nav ul {
    list-style-type: none;
    display: flex;
    justify-content: center;
    gap: 20px;
}

nav a {
    text-decoration: none;
    color: #546e7a;
    padding: 10px 15px;
    border-radius: 4px;
    transition: all 0.3s ease;
    font-weight: 500;
}

nav a:hover {
    background-color: #e0e0e0;
}

nav a.active {
    background-color: #2c3e50;
    color: white;
}

.app-intro {
    margin-bottom: 30px;
    padding: 25px;
    background-color: #e8f4fd;
    border-radius: 8px;
    box-shadow: 0 2px 15px rgba(0, 0, 0, 0.05);
}

.app-info-container {
    display: flex;
    align-items: center;
    max-width: 900px;
    margin: 0 auto;
}

.app-logo {
    flex: 0 0 auto;
    margin-right: 25px;
}

.app-logo img {
    width: 100px;
    height: auto;
    border-radius: 15px;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

.app-description {
    flex: 1 1 auto;
}

.app-intro h2 {
    color: #1565c0;
    margin-bottom: 15px;
    border-bottom: none;
    text-align: left;
}

.app-intro p {
    margin-bottom: 10px;
    text-align: left;
}

@media (max-width: 600px) {
    .app-info-container {
        flex-direction: column;
        text-align: center;
    }
    
    .app-logo {
        margin-right: 0;
        margin-bottom: 20px;
    }
    
    .app-intro h2, .app-intro p {
        text-align: center;
    }
}

.content-section {
    display: none;
    background-color: white;
    padding: 30px;
    border-radius: 8px;
    box-shadow: 0 2px 15px rgba(0, 0, 0, 0.05);
}

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

h2 {
    margin-bottom: 25px;
    color: #2c3e50;
    padding-bottom: 10px;
    border-bottom: 2px solid #eaeaea;
}

h3 {
    margin-top: 25px;
    margin-bottom: 15px;
    color: #37474f;
}

p {
    margin-bottom: 15px;
}

ul {
    margin-left: 25px;
    margin-bottom: 20px;
}

footer {
    margin-top: 40px;
    text-align: center;
    padding-top: 20px;
    border-top: 1px solid #ddd;
    color: #7f8c8d;
    font-size: 0.9rem;
}

@media (max-width: 768px) {
    body {
        padding: 15px;
    }
    
    .content-section {
        padding: 20px;
    }
    
    nav ul {
        flex-direction: column;
        gap: 10px;
    }
}