body, html {
    height: 100%;
    margin: 0;
    font-family: 'Lexend Deca', sans-serif;
}

#container {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
}

#book {
    position: relative;
    display: flex;
    width: 800px;
    height: 600px;
    background-color: white;
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.2);
    border-radius: 20px;
}

.overlay {
    position: absolute;
    top: 0;
    width: 50%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.5);
    pointer-events: none;
    display: none;
    border-radius: 20px 0 0 20px; /* Left overlay rounded left corners */
    z-index: 1;
}

#right-overlay {
    left: 50%;
    border-radius: 0 20px 20px 0; /* Right overlay rounded right corners */
}

.page {
    width: 50%;
    padding: 20px;
    box-sizing: border-box;
    overflow-y: auto;
    pointer-events: none;
}

.left-page {
    border-right: 1px solid #ddd;
}

img {
    max-width: 100%;
    height: auto;
    margin-bottom: 10px;
    pointer-events: none;
}

#toggle-mask {
  position: absolute;
  top: 10px;
  left: 10px;
  z-index: 2;
    font-family: 'Lexend Deca', sans-serif;
}

#height-controls {
    position: absolute;
    top: 50px;
    left: 10px;
    z-index: 2;
    display: flex;
    align-items: center;
}

#increase-height, #decrease-height {
    font-family: 'Lexend Deca', sans-serif;
    margin-left: 5px;
}

#opacity-controls {
    position: absolute;
    top: 90px;
    left: 10px;
    z-index: 2;
    display: flex;
    align-items: center;
}

#increase-opacity, #decrease-opacity {
    font-family: 'Lexend Deca', sans-serif;
    margin-left: 5px;
}