/* PDF kitap görüntüleyici */
#viewerContainer {
    width: 80%;
    height: 90vh;
    margin: auto;
    overflow: hidden;
    position: relative;
    background: #f2f2f2;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.2);
    display: flex;
    align-items: center;
    justify-content: center;
}

#viewerContainer canvas {
    transition: opacity 0.5s ease-in-out;
    max-width: 100%;
    max-height: 100%;
    display: block;
    margin: auto;
    width: 100% !important;
    height: auto !important;
}

.btns {
    text-align: center;
    margin-top: 10px;
}

.btns button {
    padding: 10px 20px;
    margin: 0 20px;
    font-size: 16px;
    cursor: pointer;
}

.flipbook {
    max-width: 100%;
}

.fullscreenbtn {
    margin-top: -4rem;
    position: relative;
    z-index: 1;
    float: left;
}

.spinner {
    display: inline-block;
    vertical-align: middle;
    width: 1em;
    height: 1em;
    border: 0.15em solid #ccc;
    border-top-color: #333;
    border-radius: 50%;
    animation: spin 1.2s linear infinite;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}