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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: #f0f0f0;
    display: flex;
    flex-direction: column;
    height: 100vh;
}

header {
    background-color: #2c3e50;
    color: white;
    padding: 0.5rem 1.5rem;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 1rem;
    flex-wrap: wrap;
}

h1 {
    font-size: 1.1rem;
    font-weight: 500;
    margin: 0;
}

.pdf-selector {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.pdf-selector label {
    font-size: 0.9rem;
    white-space: nowrap;
}

.pdf-selector select {
    padding: 0.4rem 0.8rem;
    border-radius: 4px;
    border: none;
    background-color: white;
    color: #2c3e50;
    font-size: 0.9rem;
    cursor: pointer;
    min-width: 200px;
}

.pdf-selector select:focus {
    outline: 2px solid #3498db;
}

.nav-btn {
    padding: 0.4rem 0.8rem;
    background-color: #27ae60;
    color: white;
    text-decoration: none;
    border: none;
    border-radius: 4px;
    font-size: 0.9rem;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    cursor: pointer;
    transition: background-color 0.3s ease;
    white-space: nowrap;
}

.nav-btn:hover {
    background-color: #229954;
}

.container {
    flex: 1;
    padding: 1rem;
    display: flex;
    justify-content: center;
    align-items: center;
    overflow: hidden;
}

.pdf-viewer {
    width: 100%;
    max-width: 2000px;
    height: 100%;
    border: 2px solid #ddd;
    border-radius: 8px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
    background-color: white;
    position: relative;
    transition: all 0.3s ease;
}

.pdf-viewer iframe {
    width: 100%;
    height: 100%;
    border: none;
    border-radius: 8px;
}

.download-btn {
    display: inline-block;
    padding: 1rem 2rem;
    background-color: #3498db;
    color: white;
    text-decoration: none;
    border-radius: 5px;
    font-size: 1rem;
    transition: background-color 0.3s ease;
    margin-top: 1rem;
}

.download-btn:hover {
    background-color: #2980b9;
}

.no-pdf {
    text-align: center;
    padding: 2rem 1rem;
    color: #666;
}

.no-pdf p {
    margin-bottom: 1rem;
    font-size: 1rem;
}

.no-pdf small {
    color: #999;
    display: block;
    margin-top: 0.5rem;
}

/* Mobile-specific styles */
@media (max-width: 768px) {
    .container {
        padding: 0.5rem;
    }

    header {
        padding: 0.5rem 1rem;
        flex-direction: column;
        align-items: flex-start;
    }

    h1 {
        font-size: 1rem;
    }

    .pdf-selector {
        width: 100%;
    }

    .pdf-selector select {
        flex: 1;
        min-width: auto;
    }

    .pdf-viewer {
        border-radius: 4px;
        border-width: 1px;
    }

    .no-pdf {
        padding: 1.5rem 1rem;
    }

    .download-btn {
        padding: 0.875rem 1.5rem;
        font-size: 0.95rem;
    }
}

/* Very small mobile devices */
@media (max-width: 480px) {
    .container {
        padding: 0.25rem;
    }

    header {
        padding: 0.5rem;
    }

    h1 {
        font-size: 0.9rem;
    }

    .pdf-selector label {
        font-size: 0.85rem;
    }

    .pdf-selector select {
        font-size: 0.85rem;
    }
}