.noselect {
    -webkit-touch-callout: none;
    -webkit-user-select: none;
    -khtml-user-select: none;
    -moz-user-select: none;
    -ms-user-select: none;
    user-select: none;
}

:root {
    --header-height: 88px;
    --header-main-height: 88px;
}

.app-header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: auto;
    min-height: 45px;
    background-color: #ffffff;
    display: grid;
    grid-template-columns: 1fr;
    grid-template-rows: auto auto;
    align-items: start;
    padding-left: 24px;
    padding-right: 12px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.06);
    z-index: 1100;
}

.header-main-column {
    display: grid;
    grid-template-columns: 1fr auto 1fr;
    align-items: center;
    min-height: var(--header-main-height);
}

.header-expression-column {
    display: none;
    align-items: center;
    flex-direction: column;
    padding-top: 8px;
    padding-bottom: 8px;
    margin-top: 8px;
}

body.expression-tools-visible .header-expression-column {
    display: flex;
    justify-content: center;
    border-top: 1px solid #d1d1d6;
}

.header-image-hint {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    font-size: 14px;
    color: #3a3a3c;
    line-height: 1.5;
    margin-top: 6px;
    text-align: center;
}

#header-expression-actions #frac-expr {
    margin-right: 16px;
}

#header-expression-actions #sqrt-pref-expr {
    margin-right: 16px;
}

#header-expression-actions #union-expr {
    margin-right: 16px;
}

#header-expression-actions #sub-expr {
    margin-right: 16px;
}

.header-left,
.header-right {
    display: flex;
    align-items: center;
    gap: 16px;
}

.header-left {
    justify-self: start;
}

.header-right {
    justify-self: end;
}

@media (max-width: 980px) {
    .header-right #logout {
        display: none;
    }
}

@media (max-width: 900px) {
    .header-right #avatar-letters {
        display: none;
    }
}

.header-center {
    display: flex;
    align-items: center;
    justify-content: center;
    min-width: 0;
    justify-self: center;
    flex-direction: column;
    gap: 6px;
}

.header-center-top {
    display: flex;
    align-items: center;
    justify-content: center;
    min-width: 0;
}

.header-expression-actions {
    display: flex;
    flex-direction: row;
    align-items: center;
    justify-content: center;
    gap: 0;
    min-width: 0;
}

.header-expression-actions .action-icon {
    width: 24pt;
    height: 24pt;
}

.header-center-left,
.header-center-right {
    display: flex;
    align-items: center;
    min-width: 0;
}

.header-center-left {
    justify-content: flex-end;
    margin-right: 12px;
}

.header-center-right {
    justify-content: flex-start;
    margin-left: 12px;
}

.header-tools-block {
    display: flex;
    flex-direction: column;
    gap: 4px;
}

.header-tools-row {
    display: flex;
    flex-direction: row;
    align-items: center;
}

.header-zoom-controls {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 3px 3px;
    border: 1px solid #d1d1d6;
    border-radius: 8px;
    background-color: #ffffff;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

.header-zoom-controls button {
    min-width: 28px;
    height: 28px;
    border-radius: 6px;
    border: 1px solid #c7c7cc;
    background-color: #ffffff;
    cursor: pointer;
}

.header-zoom-controls button:hover {
    background-color: #f2f2f7;
}

.header-zoom-controls span {
    text-align: center;
    font-size: 13px;
    color: #555555;
}

/* Keep PDF and canvas zoom values fully separate in the UI */
#pdf-zoom-label {
    display: none;
}

#canvas-zoom-label {
    display: inline;
}

body.pdf-open #pdf-zoom-label {
    display: inline;
}

body.pdf-open #canvas-zoom-label {
    display: none;
}

.pdf-loading-overlay {
    position: fixed;
    top: var(--header-height);
    left: 0;
    right: 0;
    bottom: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    background: rgba(255, 255, 255, 0.72);
    backdrop-filter: blur(2px);
    z-index: 2000;
}

.pdf-loading-card {
    display: flex;
    flex-direction: row;
    align-items: center;
    gap: 10px;
    padding: 12px 14px;
    border-radius: 12px;
    border: 1px solid rgba(0, 0, 0, 0.08);
    background: #ffffff;
    box-shadow: 0 6px 20px rgba(0, 0, 0, 0.08);
}

.pdf-loading-label {
    font-size: 13px;
    color: #555555;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

.pdf-loading-spinner {
    width: 16px;
    height: 16px;
    border-radius: 999px;
    border: 2px solid rgba(0, 0, 0, 0.12);
    border-top-color: rgba(0, 0, 0, 0.45);
    animation: pdfLoadingSpin 0.8s linear infinite;
}

.marker-crop-loading-overlay {
    position: absolute;
    inset: 0;
    display: none;
    align-items: center;
    justify-content: center;
    background: rgba(255, 255, 255, 0.66);
    backdrop-filter: blur(2px);
    z-index: 1200;
}

.marker-crop-loading-overlay.active {
    display: flex;
}

.marker-crop-loading-card {
    display: flex;
    flex-direction: row;
    align-items: center;
    gap: 10px;
    padding: 12px 14px;
    border-radius: 12px;
    border: 1px solid rgba(0, 0, 0, 0.08);
    background: #ffffff;
    box-shadow: 0 6px 20px rgba(0, 0, 0, 0.08);
}

.marker-crop-loading-spinner {
    width: 18px;
    height: 18px;
    border-radius: 999px;
    border: 2px solid rgba(0, 0, 0, 0.12);
    border-top-color: rgba(0, 0, 0, 0.45);
    animation: pdfLoadingSpin 0.8s linear infinite;
}

@keyframes pdfLoadingSpin {
    from {
        transform: rotate(0deg);
    }
    to {
        transform: rotate(360deg);
    }
}

.collapse-icon {
    transform: rotate(90deg);
}

.header-icon-btn {
    width: 40px;
    height: 40px;
    border-radius: 20px;
    border: none;
    background-color: white;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    padding: 0;
}

.header-icon-btn img {
    width: 20px;
    height: 20px;
    transition: transform 0.1s ease;
}

.header-avatar {
    width: 36px;
    height: 36px;
    border-radius: 50%;
    background-color: #e2e2e2;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 14px;
    font-weight: 600;
    color: #555555;
}

body.sidebar-collapsed #sidebar-toggle-btn img {
    transform: rotate(270deg);
}

.container * {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
}

#expressionsCanvas * {
    font-family: 'sans-serif';
    font-style: italic;
}

.main {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    min-height: 100vh;
    background-color: #f5f5f7;
    padding: 15px;
    overflow-x: auto;
}

.container {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 20px;
    width: 100%;
    max-width: 1300px;
}

body.pdf-open .container {
    max-width: none;
}

body.pdf-open {
    overflow: hidden; /* prevent extra page scroll when PDF is full-screen */
}

body.pdf-open #keyboard {
    display: none;
}

body.pdf-open .main {
    justify-content: flex-start;
    height: 100vh;      /* full screen height */
    min-height: auto;
    padding-top: 0;
    padding-bottom: 0;
}

#canvas-layout {
    position: relative;
    display: grid;
    grid-template-columns: auto auto;
    grid-template-rows: auto auto;
    grid-template-areas:
        "canvas tools"
        "page tools";
    column-gap: 10px;
    row-gap: 10px;
    align-items: start;
}

#canvas-container {
    grid-area: canvas;
}

#page-controls {
    grid-area: page;
    justify-self: center;
    width: 794px;
    display: flex;
    align-items: center;
}

#tools-column {
    grid-area: tools;
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    gap: 8px;
}

#pdf-viewer-container {
    display: none;
    position: fixed;
    top: var(--header-height);
    left: 0;
    right: 0;
    bottom: 0;
    z-index: 999;
}

.pdf-viewer {
    display: flex;
    height: 100%;
}

.pdf-sidebar {
    width: 100px;
    min-width: 100px;
    background-color: #f5f5f7;
    border-right: 1px solid #d1d1d6;
    padding: 10px;
    overflow-y: auto;
}

.pdf-main {
    flex: 1;
    min-width: 0;
    background-color: #e5e5ea;
    display: flex;
    flex-direction: column;
}

.pdf-toolbar {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 8px 16px;
    background-color: #f5f5f7;
    border-bottom: 1px solid #d1d1d6;
    position: relative;
}

.pdf-toolbar button {
    min-width: 28px;
    height: 28px;
    border-radius: 4px;
    border: 1px solid #c7c7cc;
    background-color: #ffffff;
    cursor: pointer;
}

.pdf-toolbar button:hover {
    background-color: #f2f2f7;
}

.pdf-page-indicator {
    position: absolute;
    left: 16px;
    font-size: 13px;
    color: #555555;
}

#pdf-pages {
    flex: 1;
    overflow-y: auto;
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
    display: block;
    width: 100%;
    padding: 20px 0;
    gap: 16px;
}

#pdf-pages canvas {
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
    background-color: #ffffff;
}

.pdf-page-wrapper {
    position: relative;
    width: fit-content;
    margin: 0 auto;
}

.pdf-page-wrapper canvas {
    display: block;
}

.pdf-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none; /* will switch to auto when we start drawing */
}

#pdf-thumbnails {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

#pdf-thumbnails canvas {
    width: 100%;
    height: auto;
    cursor: pointer;
    box-shadow: 0 2px 6px rgba(0, 0, 0, 0.12);
    border: 2px solid transparent;
    box-sizing: border-box;
}

#pdf-thumbnails canvas.pdf-thumb-active {
    border-color: #007aff;
    box-shadow: 0 0 0 1px rgba(0, 122, 255, 0.4), 0 2px 6px rgba(0, 0, 0, 0.2);
}

.title {
    font-size: 24px;
    font-weight: 600;
    color: #1d1d1f;
}

#canvas-container {
    position: relative;
    width: 794px;
    min-height: 1123px;
    border: 1px solid #d1d1d6;
    border-radius: 12px;
    overflow: visible;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
    background-color: white;
}

#marker-back-button {
    position: fixed;
    top: calc(var(--header-height) + 12px);
    left: calc(50% - 397px - 40px);
    z-index: 1000;
}

#marker-back-button.marker-back-button {
    right: auto;
    width: 30px;
    height: var(--header-height);
    background-color: rgba(255, 255, 255, 0.92);
    border: 1px solid #d1d1d6;
    border-radius: 10px;
    z-index: 1200;
}

#marker-back-button.marker-back-button .pdf-marker-open {
    height: 100%;
    min-height: 0;
}

#marker-back-button.marker-back-button .pdf-marker-icon {
    transform: rotate(180deg) !important;
}

#expression-copy-button.expression-copy-button {
    position: absolute;
    z-index: 1000;
    width: 30px;
    display: none;
    cursor: pointer;
}

#expression-copy-button.expression-copy-button .pdf-marker-open {
    height: 100%;
    min-height: 0;
}

#expression-copy-button.expression-copy-button .pdf-marker-icon {
    transform: none !important;
}

#canvas {
    cursor: pointer;
    width: 100%;
}

.point {
    fill: rgba(100, 150, 255, 0.3);
    stroke: #000;
    stroke-width: 1px;
    r: 4px;
    cursor: pointer;
}

.point.active {
    fill: rgba(70, 120, 220, 0.5);
}

.point.attached {
    fill: rgba(255, 150, 100, 0.5);
}

.point.intersection {
    fill: rgba(255, 100, 100, 0.7);
}

.point-label {
    font-size: 14px;
    font-weight: 500;
    fill: #000;
    text-anchor: start;
    dominant-baseline: central;
    pointer-events: none;
    stroke: white;
    stroke-width: 3px;
    stroke-linejoin: round;
    paint-order: stroke;
    z-index: 99;
}

.point-index {
    font-size: 10px;
    baseline-shift: sub;
    stroke: white;
    stroke-width: 3px;
    stroke-linejoin: round;
    paint-order: stroke;
    z-index: 99;
}

.segment {
    stroke: black;
    stroke-width: 2px;
    cursor: pointer;
}

.segment.active {
    stroke: rgba(55, 55, 100, 0.5);
}

.segment-drag-area {
    stroke: transparent;
    stroke-width: 6px;
    cursor: move;
}

.temp-drawing-path {
    fill: none;
    stroke: var(--drawing-color, #000000);
    stroke-width: 1px;
    pointer-events: none;
}

.temp-angle-path {
    fill: none;
    stroke: red;
    stroke-width: 2px;
    pointer-events: none;
}

.angle-arc {
    fill: none;
    stroke: red;
    stroke-width: 2px;
    pointer-events: none;
}

.straight-angle {
    fill: none;
    stroke: red;
    stroke-width: 2px;
    pointer-events: none;
}

.angle-drag-area {
    fill: none;
    stroke: transparent;
    stroke-width: 6px;
    cursor: pointer;
}

.circle {
    fill: none;
    stroke: black;
    stroke-width: 2px;
    pointer-events: none;
}

.circle-drag-area {
    fill: none;
    stroke: transparent;
    stroke-width: 6px;
    cursor: pointer;
}

.temp-circle {
    fill: none;
    stroke: black;
    stroke-width: 2px;
    stroke-opacity: 0.5;
    pointer-events: none;
}

.controls {
    display: flex;
    gap: 12px;
    width: 100%;
    justify-content: center;
    padding: 12px;
    background-color: white;
    border-radius: 12px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
}

.control-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 10px 16px;
    background-color: #007AFF;
    color: white;
    border: none;
    border-radius: 8px;
    font-size: 16px;
    font-weight: 500;
    cursor: pointer;
    transition: background-color 0.2s;
}

.control-btn:disabled {
    background-color: #8E8E93;
    cursor: not-allowed;
}

.control-btn:not(:disabled):hover {
    background-color: #0056CC;
}

.control-btn.active {
    background-color: #0056CC;
}

.key {
    display: flex;
    align-items: center;
    justify-content: center;
    height: 44px;
    background-color: #FFFFFF;
    border: 1px solid #D1D1D6;
    border-radius: 8px;
    font-size: 18px;
    font-weight: 500;
    cursor: pointer;
    transition: background-color 0.1s;
    user-select: none;
}

.key:hover {
    background-color: #F2F2F7;
}

.key:active {
    background-color: #E5E5EA;
}

.marker-path {
    fill: none;
    stroke-linecap: round;
    stroke-linejoin: round;
}

.highlight-path {
    fill: none;
    stroke-linecap: round;
    stroke-linejoin: round;
}

.temp-erase-path {
    fill: none;
    stroke: #3700ff3e;
    stroke-width: 2px;
    pointer-events: none;
    opacity: 0.7;
    stroke-dasharray: 5, 5;
}

#canvas.erase-mode {
    cursor: url('data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" width="20" height="20" viewBox="0 0 20 20"><circle cx="10" cy="10" r="8" fill="none" stroke="black" stroke-width="2"/></svg>') 10 10, auto;
}

#controls-inline-wrapper {
    position: sticky;
    top: 0px;              /* under fixed header (60px) + 20px gap */
    display: inline-flex;
    align-items: flex-start;
    gap: 10px;              /* 10px between the two control blocks */
    pointer-events: auto;
    visibility: visible;
}

#controls-block {
    background-color: #e2e2e2;
    padding: 2pt;
    border-radius: 2pt;
}

.controls-hint {
    position: static;
    display: inline-flex;
    height: auto;
    background-color: rgba(255, 255, 255, 0.92);
    border: 1px solid #d1d1d6;
    border-radius: 2pt;
    box-shadow: 0 6px 16px rgba(0, 0, 0, 0.12);
    padding: 8px 10px;
    margin-top: 0px;
    max-width: none;
}

.controls-hint-text {
    font-size: 12px;
    line-height: 16px;
    color: #1d1d1f;
}

#highlight-controls-block {
    background-color: transparent;
    padding: 0;
    border-radius: 2pt;
}

#highlight-controls-block .highlight-controls-inner {
    display: flex;
    flex-direction: column;
    gap: 4px;
}

#highlight-controls-block .highlight-colors-row,
#highlight-controls-block .highlight-tools-row {
    display: flex;
    flex-direction: row;
    align-items: center;
}

#highlight-controls-block .highlight-colors-row {
    justify-content: end;
}

#highlight-controls-block .highlight-tools-row {
    justify-content: end;
}

.marker-width-control {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    margin-right: 10px;
    padding: 2px 6px;
    border: 1px solid #d1d1d6;
    border-radius: 10px;
    background-color: rgba(255, 255, 255, 0.92);
    width: 100px;
    box-sizing: border-box;
    visibility: hidden;
    opacity: 0;
    pointer-events: none;
}

body.marker-width-visible .marker-width-control {
    visibility: visible;
    opacity: 1;
    pointer-events: auto;
}

.marker-width-preview {
    width: 28px;
    height: 20px;
    border-radius: 8px;
    border: 1px solid #d1d1d6;
    background:
        linear-gradient(to bottom,
            transparent calc(50% - 1px),
            #1d1d1f calc(50% - 1px),
            #1d1d1f calc(50% + 1px),
            transparent calc(50% + 1px));
}

.marker-width-slider {
    width: 55px;
    accent-color: #007AFF;
}

.marker-width-value {
    min-width: 20px;
    text-align: right;
    font-size: 12px;
    color: #1d1d1f;
    display: none;
}

.flexed {
    display: flex;
}

.space-icon {
    width: 5pt;
}

.mode-icon {
    width: 28pt;
    height: 24pt;
    background-color: #ffffff;
    position: relative;
    border-radius: 2pt;
    border: 1pt solid #d1d1d6;
    margin: 1px;
    cursor: pointer;
}

.action-icon {
    width: 28pt;
    height: 24pt;
    background-color: transparent;
    position: relative;
    border-radius: 2pt;
    border: 1pt solid #d1d1d6;
    margin: 1px;
    cursor: pointer;
}

.color-icon {
    width: 26pt;
    height: 24pt;
    background-color: #ffffff;
    position: relative;
    border-radius: 2pt;
    border: 1pt solid #d1d1d6;
    margin: 2px;
    cursor: pointer;
}

.mode-icon img {
    position: absolute;
    left: 2pt;
    top: 2pt;
    width: 18pt;
    height: 18pt;
}

.action-icon img {
    position: absolute;
    left: 2pt;
    top: 2pt;
    width: 18pt;
    height: 18pt;
}

#lte-expr img {
    transform: scaleX(-1);
}

.action-icon img:active {
    position: absolute;
    left: 3pt;
    top: 3pt;
    width: 16pt;
    height: 16pt;
}

.circle {
    width: 14pt;
    height: 14pt;
    position: relative;
    left: 6pt;
    top: 6pt;
    border-radius: 7pt;
}

#black-color-picker {
    background-color: black;
}

#red-color-picker {
    background-color: #FF4E40;
}

#green-color-picker {
    background-color: #38E156;
}

#blue-color-picker {
    background-color: #FFFFFF;
    border: 1px solid #d1d1d6;
    box-sizing: border-box;
}

/* Стили для тултипов */
.tooltip {
    position: absolute;
    background-color: rgba(60, 60, 60, 0.9);
    color: #f0f0f0;
    padding: 1px 6px;
    border-radius: 6px;
    font-size: 12px;
    line-height: 1.3;
    white-space: nowrap;
    z-index: 1300;
    pointer-events: none;
    opacity: 0;
    transition: opacity 0.2s;
    text-align: center;
    line-height: 1.8;
}

.tooltip.show {
    opacity: 1;
}

.tooltip::after {
    position: absolute;
    border-width: 5px;
    border-style: solid;
}

/* Позиционирование тултипов для top-line */
.top-line .tooltip {
    bottom: 100%;
    left: 50%;
    transform: translateX(-50%);
    margin-bottom: 5px;
}

.top-line .tooltip::after {
    top: 100%;
    left: 50%;
    transform: translateX(-50%);
    border-color: rgba(60, 60, 60, 0.9) transparent transparent transparent;
}

/* Позиционирование тултипов для bottom-line */
.bottom-line .tooltip {
    top: 100%;
    left: 50%;
    transform: translateX(-50%);
    margin-top: 5px;
}

.bottom-line .tooltip::after {
    bottom: 100%;
    left: 50%;
    transform: translateX(-50%);
    border-color: transparent transparent rgba(60, 60, 60, 0.9) transparent;
}

/* Позиционирование тултипов для left-row */
.left-row .tooltip {
    right: 100%;
    top: 50%;
    transform: translateY(-50%);
    margin-right: 5px;
}

.left-row .tooltip::after {
    left: 100%;
    top: 50%;
    transform: translateY(-50%);
    border-color: transparent transparent transparent rgba(60, 60, 60, 0.9);
}

/* Позиционирование тултипов для right-row */
.right-row .tooltip {
    left: 100%;
    top: 50%;
    transform: translateY(-50%);
    margin-left: 5px;
}

.right-row .tooltip::after {
    right: 100%;
    top: 50%;
    transform: translateY(-50%);
    border-color: transparent rgba(60, 60, 60, 0.9) transparent transparent;
}

.icon-choosen {
    border-color: #b8b8bf;
    background-color: #e5e5ea;
}

.color-choosen {
    border-color: #b8b8bf;
    background-color: #e5e5ea;
}

.shortcut-tip {
    position: absolute;
    right: 2pt;
    top: 0;
    font-size: 7pt;
    color: rgba(32, 32, 42, 0.531);
}

.expression-actions {
    display: none;
}

.img-resize-handle {
    fill: #007bff;
    stroke: white;
    stroke-width: 2;
    cursor: pointer;
    opacity: 0.7;
}
.img-resize-handle:hover {
    opacity: 1;
    fill: #0056b3;
}
.resize-border {
    fill: none;
    stroke: #007bff;
    stroke-width: 2;
    stroke-dasharray: 5,5;
    pointer-events: none;
}

.pdf-selection-border {
    border: 2px dashed #007bff;
    box-sizing: border-box;
}

.pdf-selection-marker {
    position: absolute;
    right: 0;
    width: 30px;
    background-color: rgba(255, 255, 255, 0.92);
    border: 1px solid #d1d1d6;
    border-radius: 10px;
    box-shadow: 0 6px 16px rgba(0, 0, 0, 0.12);
    cursor: default;
    user-select: none;
    overflow: hidden;
}

.pdf-marker-open,
.pdf-marker-delete {
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 32px;
    cursor: pointer;
    transition: background-color 120ms ease, filter 120ms ease;
}

.pdf-marker-open {
    flex: 1 1 auto;
}

.pdf-marker-open:hover,
.pdf-marker-delete:hover {
    background-color: rgba(0, 0, 0, 0.05);
}

.pdf-marker-open:active,
.pdf-marker-delete:active {
    background-color: rgba(0, 0, 0, 0.09);
}

.pdf-marker-delete {
    flex: 0 0 32px;
    border-top: 1px solid #d1d1d6;
}

.pdf-marker-icon {
    width: 16px;
    height: 16px;
    opacity: 0.85;
    pointer-events: none;
}

.pdf-marker-open:hover .pdf-marker-icon,
.pdf-marker-delete:hover .pdf-marker-icon {
    opacity: 1;
}

#add-page-btn {
    width: 100%;
    height: 24px;
    cursor: pointer;
    border-radius: 12px;
    border: 1px solid #d1d1d6;
    background-color: rgba(255, 255, 255, 0.92);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
    color: #1c1c1e;
    font-size: 20px;
    font-weight: 600;
}

#add-page-btn:hover {
    background-color: rgba(255, 255, 255, 0.98);
}

#add-page-btn:active {
    transform: translateY(1px);
}

.reload-required-overlay {
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.35);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 2000;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

.reload-required-modal {
    width: min(420px, calc(100vw - 32px));
    background: #ffffff;
    border-radius: 14px;
    border: 1px solid #d1d1d6;
    box-shadow: 0 12px 30px rgba(0, 0, 0, 0.2);
    padding: 18px 18px 14px;
}

.reload-required-title {
    font-size: 16px;
    font-weight: 700;
    color: #111111;
    margin-bottom: 6px;
}

.reload-required-text {
    font-size: 14px;
    color: #555555;
    line-height: 1.35;
    margin-bottom: 14px;
}

.reload-required-actions {
    display: flex;
    justify-content: flex-end;
    gap: 10px;
}

.reload-required-btn {
    height: 34px;
    padding: 0 14px;
    border-radius: 10px;
    border: 1px solid #c7c7cc;
    background: #ffffff;
    cursor: pointer;
    font-size: 14px;
}

.reload-required-btn-primary {
    border-color: #ff3b30;
    background: #ff3b30;
    color: #ffffff;
}

/* Sidebar students row actions: keep add-items-block pinned to the right
   Override the generic `.container * { margin: 0; }` reset above */
#sidebar .add-items-block {
    margin-left: auto;
}

body.vk-open {
    padding-bottom: 300px;
}

#keyboard.vk-host {
    position: fixed;
    left: 0;
    right: 0;
    bottom: 0;
    z-index: 1800;
    pointer-events: none;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

#keyboard.vk-host .vk-sheet {
    pointer-events: auto;
    display: inline-block;
    width: fit-content;
    margin: 0 auto 8px;
    background: rgba(242, 242, 247, 0.95);
    border: 1px solid rgba(209, 209, 214, 0.9);
    border-radius: 18px;
    box-shadow: 0 18px 50px rgba(0, 0, 0, 0.25);
    overflow: hidden;
    transform: translateY(0);
    transition: transform 220ms ease, opacity 220ms ease;
    -webkit-backdrop-filter: blur(16px);
    backdrop-filter: blur(16px);
}

#keyboard.vk-host.vk-collapsed .vk-sheet {
    width: 84px;
    display: block;
    margin-left: auto;
    margin-right: auto;
    border-radius: 999px;
    margin-bottom: 10px;
    transform: translateY(0);
    opacity: 1;
}

#keyboard.vk-host .vk-header {
    padding: 8px 12px 10px;
    cursor: pointer;
    user-select: none;
}

#keyboard.vk-host .vk-grabber {
    width: 44px;
    height: 5px;
    border-radius: 999px;
    background: rgba(60, 60, 67, 0.28);
    margin: 0 auto 8px;
}

#keyboard.vk-host .vk-body {
    padding: 8px 10px 12px;
}

#keyboard.vk-host .vk-layout {
    display: flex;
    align-items: flex-start;
    justify-content: center;
    gap: 20px;
}

#keyboard.vk-host .vk-exprbar {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 6px;
    margin-bottom: 6px;
}

#keyboard.vk-host .vk-exprbar-icons {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 6px;
    margin-bottom: 18px;
}

#keyboard.vk-host .vk-exprbar-gap {
    width: 10px;
}

#keyboard.vk-host .vk-key-icon {
    width: 34px;
    min-width: 34px;
    max-width: 34px;
    flex: 0 0 34px;
    padding: 0;
}

#keyboard.vk-host .vk-key-icon-img {
    width: 24px;
    height: 24px;
    object-fit: contain;
    pointer-events: none;
}

#keyboard.vk-host .vk-main {
    display: flex;
    flex-direction: column;
    gap: 0;
    flex: 0 0 auto;
}

#keyboard.vk-host .vk-num {
    display: flex;
    flex-direction: column;
    gap: 0;
    flex: 0 0 auto;
}

#keyboard.vk-host .vk-numpad {
    display: flex;
    flex-direction: column;
    gap: 0;
    flex: 0 0 auto;
}

#keyboard.vk-host .vk-ops {
    display: flex;
    flex-direction: column;
    gap: 0;
    flex: 0 0 auto;
}

#keyboard.vk-host .vk-moves {
    display: flex;
    flex-direction: column;
    gap: 0;
    flex: 0 0 auto;
}

#keyboard.vk-host .vk-moves-grid {
    display: grid;
    grid-template-columns: repeat(3, 34px);
    grid-template-rows: repeat(3, 42px);
    column-gap: 6px;
    row-gap: 8px;
    align-items: center;
    justify-items: center;
}

#keyboard.vk-host .vk-move-spacer {
    width: 34px;
    height: 42px;
}

#keyboard.vk-host .vk-key-move {
    background: rgba(255, 255, 255, 0.92);
}

#keyboard.vk-host .vk-move-icon {
    width: 22px;
    height: 22px;
}

#keyboard.vk-host .vk-numpad-row {
    justify-content: flex-end;
}

#keyboard.vk-host .vk-key-numpad {
    width: 34px;
    min-width: 34px;
    max-width: 34px;
    flex: 0 0 34px;
}

/* Collapsed state: show only a small grabber pill */
#keyboard.vk-host.vk-collapsed {
    pointer-events: auto;
}

#keyboard.vk-host.vk-collapsed .vk-header {
    padding: 10px 0;
}

#keyboard.vk-host.vk-collapsed .vk-grabber {
    margin: 0 auto;
}

#keyboard.vk-host.vk-collapsed .vk-body {
    display: none;
}

#keyboard.vk-host {
    --vk-row-gap: 4px;
    --vk-row-inner-gap: 6px;
}

#keyboard.vk-host.vk-lang-ru {
    --vk-row-gap: 3px;
    --vk-row-inner-gap: 5px;
}

#keyboard.vk-host .vk-row {
    display: flex;
    justify-content: center;
    gap: var(--vk-row-gap);
    margin-bottom: 8px;
}

#keyboard.vk-host .vk-row-inner {
    display: flex;
    justify-content: center;
    gap: var(--vk-row-inner-gap);
}

#keyboard.vk-host .vk-row-bottom {
    margin-bottom: 2px;
}

#keyboard.vk-host .vk-key {
    height: 42px;
    width: 34px;
    min-width: 34px;
    max-width: 34px;
    flex: 0 0 34px;
    padding: 0;
    box-sizing: border-box;
    border-radius: 10px;
    border: 1px solid rgba(209, 209, 214, 0.9);
    background: rgba(255, 255, 255, 0.92);
    box-shadow: 0 1px 0 rgba(0, 0, 0, 0.06);
    font-size: 18px;
    font-weight: 500;
    color: #1c1c1e;
    cursor: pointer;
    user-select: none;
    transition: transform 60ms ease, background-color 60ms ease;
}

#keyboard.vk-host .vk-key:active {
    transform: translateY(1px);
    background: rgba(229, 229, 234, 0.95);
}

#keyboard.vk-host .vk-key-wide {
    width: 54px;
    min-width: 54px;
    max-width: 54px;
    flex: 0 0 54px;
    font-size: 16px;
    background: rgba(235, 235, 240, 0.95);
}

#keyboard.vk-host .vk-key-backspace {
    background: rgba(235, 235, 240, 0.95);
}

#keyboard.vk-host .vk-key-backspace-move {
    padding-right: 3px;
}

#keyboard.vk-host .vk-key-space {
    width: calc(34px * 4 + var(--vk-row-gap) * 3);
    min-width: calc(34px * 4 + var(--vk-row-gap) * 3);
    max-width: calc(34px * 4 + var(--vk-row-gap) * 3);
    flex: 0 0 calc(34px * 4 + var(--vk-row-gap) * 3);
    font-size: 16px;
    background: rgba(255, 255, 255, 0.92);
}

#keyboard.vk-host .vk-key-spacer {
    visibility: hidden;
    border: none;
    background: transparent;
    box-shadow: none;
    cursor: default;
    pointer-events: none;
}

#keyboard.vk-host.vk-shift .vk-key-shift {
    background: rgba(0, 122, 255, 0.92);
    border-color: rgba(0, 122, 255, 0.92);
    color: #ffffff;
}