* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: Arial, sans-serif;
}

body {
    background-color: #f9f9f9;
    color: #333;
    line-height: 1.6;
}

/* Header */
.header {
    background-color: #1a365d;
    color: white;
    padding: 30px 20px;
    text-align: center;
}

.header h1 {
    font-size: 2.5rem;
    margin-bottom: 5px;
}

/* Navbar */
.navbar {
    background-color: #2b6cb0;
    display: flex;
    justify-content: center;
    padding: 10px;
}

.navbar a {
    color: white;
    text-decoration: none;
    padding: 10px 20px;
    margin: 0 5px;
    font-weight: bold;
}

.navbar a:hover {
    background-color: #1a365d;
    border-radius: 4px;
}

.yt-link {
    background-color: #e53e3e !important;
    border-radius: 4px;
}

/* Main Layout */
.container {
    display: flex;
    max-width: 1200px;
    margin: 20px auto;
    padding: 0 20px;
    gap: 30px;
}

/* Left Content */
.main-content {
    flex: 3;
    background: white;
    padding: 20px;
    border-radius: 8px;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
}

.main-content h2 {
    color: #2b6cb0;
    margin-bottom: 10px;
    border-bottom: 2px solid #e2e8f0;
    padding-bottom: 10px;
}

/* PDF List Item */
.pdf-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    border: 1px solid #e2e8f0;
    padding: 20px;
    margin-top: 20px;
    border-radius: 8px;
    background-color: #fff;
    transition: box-shadow 0.3s;
}

.pdf-item:hover {
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
}

.pdf-details h3 {
    color: #2d3748;
    margin-bottom: 5px;
}

.meta-info {
    font-size: 0.9rem;
    color: #718096;
    font-weight: bold;
    margin-bottom: 8px;
}

.description {
    font-size: 0.95rem;
    color: #4a5568;
}

.pdf-action {
    text-align: center;
    min-width: 150px;
}

.price {
    display: block;
    font-size: 1.5rem;
    color: #e53e3e;
    font-weight: bold;
    margin-bottom: 10px;
}

.buy-btn {
    background-color: #38a169;
    color: white;
    text-decoration: none;
    padding: 10px 15px;
    border-radius: 5px;
    font-weight: bold;
    display: inline-block;
}

.buy-btn:hover {
    background-color: #2f855a;
}

/* Right Sidebar */
.sidebar {
    flex: 1;
}

.widget {
    background: white;
    padding: 20px;
    border-radius: 8px;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
    margin-bottom: 20px;
}

.widget h3 {
    color: #1a365d;
    margin-bottom: 15px;
    border-bottom: 2px solid #e2e8f0;
    padding-bottom: 5px;
}

.widget ul {
    list-style: none;
}

.widget ul li {
    margin-bottom: 10px;
}

.widget ul li a {
    color: #2b6cb0;
    text-decoration: none;
}

.widget ul li a:hover {
    text-decoration: underline;
}

/* Footer */
.footer {
    background-color: #1a365d;
    color: white;
    text-align: center;
    padding: 20px;
    margin-top: 40px;
}

/* Mobile Responsive */
@media (max-width: 768px) {
    .container {
        flex-direction: column;
    }
    .pdf-item {
        flex-direction: column;
        text-align: left;
    }
    .pdf-action {
        margin-top: 20px;
        text-align: left;
    }
    .navbar {
        flex-wrap: wrap;
    }
}