.viewer-section {
    display: flex;
    flex-direction: column;
    min-height: calc(100vh - 200px);
    background-color: #1a1a2e;
}

.viewer-toolbar {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0.5rem 1rem;
    background-color: #16213e;
    color: #ffffff;
    gap: 0.5rem;
    flex-wrap: wrap;
    min-height: 56px;
}

.viewer-toolbar-start,
.viewer-toolbar-end {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    flex-shrink: 0;
}

.viewer-toolbar-center {
    flex: 1;
    text-align: center;
    min-width: 0;
}

.viewer-title {
    font-size: 1rem;
    font-weight: 600;
    margin: 0;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    color: #ffffff;
}

.viewer-title-number {
    font-weight: 400;
    opacity: 0.8;
    margin-left: 0.25rem;
}

.viewer-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.375rem;
    padding: 0.5rem 0.75rem;
    min-height: 44px;
    min-width: 44px;
    border: 2px solid transparent;
    border-radius: 0.375rem;
    background-color: rgba(255, 255, 255, 0.1);
    color: #ffffff;
    font-size: 0.875rem;
    font-weight: 500;
    cursor: pointer;
    text-decoration: none;
    transition: background-color 0.2s ease, border-color 0.2s ease;
    white-space: nowrap;
}

.viewer-btn:hover {
    background-color: rgba(255, 255, 255, 0.2);
}

.viewer-btn:focus-visible {
    outline: 3px solid #60a5fa;
    outline-offset: 2px;
}

.viewer-btn-icon {
    width: 1.25rem;
    height: 1.25rem;
    flex-shrink: 0;
}

.viewer-zoom-group {
    display: inline-flex;
    align-items: center;
    gap: 0.25rem;
    background-color: rgba(255, 255, 255, 0.08);
    border-radius: 0.375rem;
    padding: 0.125rem;
}

.viewer-zoom-label {
    font-size: 0.75rem;
    font-weight: 500;
    color: #e2e8f0;
    min-width: 2.5rem;
    text-align: center;
    font-variant-numeric: tabular-nums;
    padding: 0 0.25rem;
}

#icon-sound-on,
#icon-sound-off {
    width: 1.25rem;
    height: 1.25rem;
}

.viewer-sound-group {
    display: inline-flex;
    align-items: center;
    gap: 0.25rem;
    background-color: rgba(255, 255, 255, 0.08);
    border-radius: 0.375rem;
    padding: 0.125rem;
}

.viewer-sound-select {
    appearance: none;
    -webkit-appearance: none;
    -moz-appearance: none;
    background-color: rgba(255, 255, 255, 0.15);
    color: #ffffff;
    border: 2px solid transparent;
    border-radius: 0.375rem;
    padding: 0.375rem 1.75rem 0.375rem 0.5rem;
    font-size: 0.75rem;
    font-weight: 500;
    cursor: pointer;
    min-height: 44px;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' fill='none' viewBox='0 0 24 24' stroke='white' stroke-width='2'%3E%3Cpath stroke-linecap='round' stroke-linejoin='round' d='M19 9l-7 7-7-7'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 0.25rem center;
    background-size: 1rem;
}

.viewer-sound-select:focus-visible {
    outline: 3px solid #60a5fa;
    outline-offset: 2px;
}

.viewer-sound-select option {
    background-color: #16213e;
    color: #ffffff;
    font-size: 0.875rem;
}

.viewer-btn--download {
    background-color: #2563eb;
}

.viewer-btn--download:hover {
    background-color: #1d4ed8;
}

.viewer-container {
    flex: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 1rem;
    position: relative;
    overflow: auto;
    min-height: 400px;
}

.viewer-loading {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 1rem;
    color: #e2e8f0;
    font-size: 1rem;
    position: absolute;
    inset: 0;
}

.viewer-loading[hidden] {
    display: none;
}

.viewer-spinner {
    width: 2.5rem;
    height: 2.5rem;
    border: 4px solid rgba(255, 255, 255, 0.2);
    border-top-color: #60a5fa;
    border-radius: 50%;
    animation: viewer-spin 0.8s linear infinite;
}

@keyframes viewer-spin {
    to {
        transform: rotate(360deg);
    }
}

.viewer-error {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 1rem;
    color: #fca5a5;
    text-align: center;
    padding: 2rem;
    position: absolute;
    inset: 0;
}

.viewer-error[hidden] {
    display: none;
}

.viewer-error-icon {
    width: 3rem;
    height: 3rem;
    color: #f87171;
}

.viewer-error-link {
    color: #60a5fa;
    text-decoration: underline;
    font-weight: 500;
    padding: 0.5rem 1rem;
    border-radius: 0.375rem;
    min-height: 44px;
    display: inline-flex;
    align-items: center;
}

.viewer-error-link:hover {
    color: #93bbfd;
}

.viewer-error-link:focus-visible {
    outline: 3px solid #60a5fa;
    outline-offset: 2px;
}

#flipbook,
.flipbook {
    width: 100%;
    height: 100%;
}

.stf__parent {
    position: relative !important;
    width: 100% !important;
    height: 100% !important;
    display: block !important;
}

.stf__wrapper {
    position: relative !important;
    width: 100% !important;
    height: 100% !important;
}

.stf__block {
    position: absolute !important;
    inset: 0 !important;
    width: 100% !important;
    height: 100% !important;
}

.flipbook-page {
    background: #ffffff;
    overflow: hidden;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.3);
}

.flipbook-page canvas {
    display: block;
    width: 100%;
    height: 100%;
}

.viewer-nav {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 1.5rem;
    padding: 0.75rem 1rem;
    background-color: #16213e;
    min-height: 64px;
}

.viewer-nav-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-height: 44px;
    min-width: 44px;
    padding: 0.5rem;
    border: 2px solid transparent;
    border-radius: 50%;
    background-color: rgba(255, 255, 255, 0.1);
    color: #ffffff;
    cursor: pointer;
    transition: background-color 0.2s ease, opacity 0.2s ease;
}

.viewer-nav-btn:hover:not(:disabled) {
    background-color: rgba(255, 255, 255, 0.25);
}

.viewer-nav-btn:focus-visible {
    outline: 3px solid #60a5fa;
    outline-offset: 2px;
}

.viewer-nav-btn:disabled {
    opacity: 0.3;
    cursor: not-allowed;
}

.viewer-nav-icon {
    width: 1.5rem;
    height: 1.5rem;
}

.viewer-page-info {
    color: #e2e8f0;
    font-size: 1rem;
    font-weight: 500;
    min-width: 5rem;
    text-align: center;
    font-variant-numeric: tabular-nums;
}

.viewer-page-current {
    font-weight: 700;
    color: #ffffff;
}

.viewer-noscript {
    text-align: center;
    padding: 3rem 1rem;
    color: #e2e8f0;
}

.viewer-noscript-link {
    display: inline-block;
    margin-top: 1rem;
    padding: 0.75rem 1.5rem;
    background-color: #2563eb;
    color: #ffffff;
    border-radius: 0.375rem;
    text-decoration: none;
    font-weight: 600;
    min-height: 44px;
}

.viewer-noscript-link:hover {
    background-color: #1d4ed8;
}

.viewer-noscript-link:focus-visible {
    outline: 3px solid #60a5fa;
    outline-offset: 2px;
}

.viewer-section:fullscreen {
    background-color: #1a1a2e;
}

.viewer-section:fullscreen .viewer-toolbar {
    padding-top: 0.75rem;
    padding-bottom: 0.75rem;
}

@media (max-width: 767px) {
    .viewer-toolbar {
        flex-direction: column;
        gap: 0.375rem;
        padding: 0.5rem;
    }

    .viewer-toolbar-center {
        order: -1;
    }

    .viewer-title {
        font-size: 0.875rem;
    }

    .viewer-btn-label {
        display: none;
    }

    .viewer-btn {
        padding: 0.5rem;
    }

    .viewer-nav {
        gap: 1rem;
        padding: 0.5rem;
    }

    .viewer-container {
        min-height: 300px;
        padding: 0.5rem;
    }
}

@media (prefers-reduced-motion: reduce) {
    .viewer-spinner {
        animation: none;
        border-top-color: #60a5fa;
        border-right-color: #60a5fa;
    }

    .viewer-btn,
    .viewer-nav-btn {
        transition: none;
    }
}

@media (prefers-contrast: more) {
    .viewer-toolbar,
    .viewer-nav {
        background-color: #000000;
        border-bottom: 2px solid #ffffff;
    }

    .viewer-btn,
    .viewer-nav-btn {
        border: 2px solid #ffffff;
    }

    .viewer-btn:focus-visible,
    .viewer-nav-btn:focus-visible {
        outline: 3px solid #ffff00;
        outline-offset: 2px;
    }
}