:root {
    --bg: #f4f5f7;
    --panel: #ffffff;
    --text: #1b1f23;
    --muted: #5a6470;
    --accent: #005a9c;
    --accent-strong: #00497f;
    --border: #d0d7de;
    --danger: #a22a2a;
    --shadow: 0 6px 18px rgba(16, 24, 40, 0.12);
}

*,
*::before,
*::after {
    box-sizing: border-box;
}

html,
body {
    height: 100%;
}

body {
    margin: 0;
    background: linear-gradient(180deg, #eef2f7 0%, var(--bg) 42%, #ebeef3 100%);
    color: var(--text);
    font-family: "IBM Plex Sans", "Segoe UI", Tahoma, sans-serif;
}

.app {
    min-height: 100dvh;
    display: grid;
    grid-template-rows: auto 1fr;
}

.toolbar {
    display: grid;
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: 0.5rem;
    align-items: center;
    padding: 0.75rem;
    border-bottom: 1px solid var(--border);
    background: rgba(255, 255, 255, 0.94);
    backdrop-filter: blur(8px);
    position: sticky;
    top: 0;
    z-index: 20;
}

.toolbar-group {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    min-width: 0;
    flex-wrap: wrap;
}

.page-group {
    justify-content: center;
}

.zoom-group {
    justify-content: center;
}

.view-group {
    justify-content: flex-end;
}

.btn {
    appearance: none;
    border: 1px solid var(--border);
    background: var(--panel);
    color: var(--text);
    border-radius: 0.6rem;
    padding: 0.55rem 0.85rem;
    font-size: 0.95rem;
    line-height: 1.2;
    cursor: pointer;
    box-shadow: 0 1px 2px rgba(16, 24, 40, 0.08);
}

.btn:hover:not(:disabled) {
    border-color: var(--accent);
}

.btn:focus-visible {
    outline: 3px solid rgba(0, 90, 156, 0.35);
    outline-offset: 2px;
}

.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.label {
    font-size: 0.92rem;
    color: var(--muted);
}

#pageSlider {
    width: min(320px, 55vw);
}

#pageInfo {
    min-width: 8.8rem;
    text-align: right;
    font-weight: 600;
}

.zoom-info {
    min-width: 4.5rem;
    text-align: center;
    font-weight: 600;
}

.toggle {
    display: inline-flex;
    align-items: center;
    gap: 0.45rem;
    border: 1px solid var(--border);
    border-radius: 0.6rem;
    background: var(--panel);
    padding: 0.42rem 0.7rem;
    user-select: none;
}

.toggle input {
    margin: 0;
}

.viewer-shell {
    position: relative;
    overflow: hidden;
    padding: 1rem;
    touch-action: none;
}

.mobile-quick-nav {
    display: none;
}

.canvas-wrap {
    height: 100%;
    display: grid;
    grid-template-columns: minmax(0, 1fr);
    gap: 1rem;
    align-items: center;
    justify-items: center;
}

body.is-two-page .canvas-wrap {
    grid-template-columns: repeat(2, minmax(0, 1fr));
}

.canvas-card {
    width: 100%;
    height: 100%;
    display: grid;
    place-items: center;
    border: 1px solid var(--border);
    border-radius: 0.8rem;
    background: radial-gradient(circle at top, #fff 0%, #fbfbfd 62%, #f6f8fb 100%);
    box-shadow: var(--shadow);
    overflow: auto;
}

.canvas-card canvas {
    display: block;
    max-width: 100%;
    max-height: 100%;
    background: #fff;
}

body:not(.is-two-page) #canvasRight {
    display: none;
}

body:not(.is-two-page) .canvas-wrap .canvas-card:last-child {
    display: none;
}

.status-overlay {
    position: absolute;
    inset: 0;
    display: none;
    place-items: center;
    z-index: 10;
    text-align: center;
    padding: 1.2rem;
    background: rgba(16, 24, 40, 0.2);
}

.status-overlay.is-visible {
    display: grid;
}

.status-overlay p {
    margin: 0;
    padding: 0.75rem 0.95rem;
    max-width: min(90vw, 560px);
    border: 1px solid rgba(255, 255, 255, 0.35);
    border-radius: 0.75rem;
    background: rgba(16, 24, 40, 0.7);
    color: #fff;
}

.status-overlay.error p {
    background: rgba(120, 20, 20, 0.82);
}

.spinner {
    width: 2.4rem;
    height: 2.4rem;
    border-radius: 50%;
    border: 4px solid rgba(255, 255, 255, 0.35);
    border-top-color: #ffffff;
    margin: 0 auto 0.8rem;
    animation: spin 0.9s linear infinite;
}

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

@media (max-width: 1023px) {
    body.mobile-controls-hidden .toolbar {
        display: none;
    }

    .toolbar {
        grid-template-columns: 1fr;
        position: static;
        margin: 0.4rem 0.4rem 0;
        border-radius: 0.8rem;
        border: 1px solid var(--border);
        box-shadow: var(--shadow);
    }

    .toolbar-group {
        justify-content: center;
    }

    .view-group {
        justify-content: center;
    }

    .btn {
        padding: 0.65rem 0.95rem;
        font-size: 1rem;
    }

    #pageSlider {
        width: min(95vw, 450px);
    }

    .viewer-shell {
        padding: 0.4rem;
    }

    .canvas-wrap {
        gap: 0.65rem;
    }

    .canvas-card {
        border-radius: 0.65rem;
    }

    .mobile-quick-nav {
        position: fixed;
        left: 0.4rem;
        right: 0.4rem;
        bottom: calc(env(safe-area-inset-bottom, 0px) + 0.35rem);
        z-index: 18;
        display: grid;
        grid-template-columns: auto auto 1fr auto;
        gap: 0.4rem;
        align-items: center;
        padding: 0.45rem;
        background: rgba(255, 255, 255, 0.94);
        border: 1px solid var(--border);
        border-radius: 0.78rem;
        box-shadow: var(--shadow);
        backdrop-filter: blur(8px);
    }

    .btn-mobile {
        min-height: 2.7rem;
        min-width: 2.9rem;
        padding: 0.55rem 0.7rem;
    }

    #mobilePageInfo {
        text-align: center;
        font-weight: 700;
        color: var(--text);
        white-space: nowrap;
        overflow: hidden;
        text-overflow: ellipsis;
        font-size: 0.95rem;
        padding: 0 0.25rem;
    }

    body.mobile-controls-hidden .mobile-quick-nav {
        background: rgba(255, 255, 255, 0.98);
    }
}