.PDF {
    width: 40%;
    float: left;
    margin-bottom: 100%;
}
.toolbar {
    margin: 15px 0;
    display: flex;
    align-items: center;
    gap: 15px;
}
button {
    padding: 8px 12px;
    border: 1px solid #007bff;
    background-color: #007bff;
    color: white;
    border-radius: 4px;
    cursor: pointer;
    transition: background-color 0.2s;
}
button:hover { background-color: #0056b3; }
button:disabled {
    background-color: #ccc;
    border-color: #ccc;
    cursor: not-allowed;
}
.viewer-container {
    width: 80%;
    max-width: 100%;
    height: 75vh;
    border: 1px solid #ccc;
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
    overflow: auto; /* canvasが大きい場合にスクロールできるように */
}
#pdf-canvas {
    display: block;
    margin: 0 auto;
}