* { margin: 0; padding: 0; box-sizing: border-box; }

:root {
    --win-face: #c0c0c0;
    --win-light: #ffffff;
    --win-mid: #dfdfdf;
    --win-shadow: #808080;
    --win-dark: #000000;
    --win-title: #000080;
    --win-title-inactive: #808080;
    --win-title-text: #ffffff;
    --win-desktop: #008080;
    --win-selection: #000080;
}

html, body {
    height: 100%;
    overflow: hidden;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    font-size: 13px;
    user-select: none;
    -webkit-user-select: none;
}

/* ---- DESKTOP ---- */
#desktop {
    position: fixed;
    inset: 0;
    bottom: 36px;
    background: var(--win-desktop);
    overflow: hidden;
}

.desktop-icons {
    display: flex;
    flex-direction: column;
    gap: 8px;
    padding: 12px;
    align-items: flex-start;
    flex-wrap: wrap;
    max-height: 100%;
    align-content: flex-start;
}

.desktop-icon {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 4px;
    padding: 4px 4px 6px;
    cursor: pointer;
    border: 1px solid transparent;
    width: 80px;
    -webkit-tap-highlight-color: transparent;
}

.desktop-icon:active,
.desktop-icon.selected {
    border: 1px dotted #fff;
}

.desktop-icon .icon-img {
    width: 40px;
    height: 40px;
    pointer-events: none;
}

.desktop-icon .icon-label {
    font-size: 12px;
    color: #fff;
    text-align: center;
    text-shadow: 1px 1px 1px #000;
    line-height: 1.2;
    max-width: 80px;
    word-wrap: break-word;
    pointer-events: none;
}

/* ---- WINDOWS ---- */
.win {
    position: absolute;
    background: var(--win-face);
    display: flex;
    flex-direction: column;
    border-top: 2px solid var(--win-light);
    border-left: 2px solid var(--win-light);
    border-right: 2px solid var(--win-dark);
    border-bottom: 2px solid var(--win-dark);
    box-shadow: inset 1px 1px 0 var(--win-mid), inset -1px -1px 0 var(--win-shadow);
    min-width: 240px;
    min-height: 120px;
}

.win.maximized {
    top: 0 !important;
    left: 0 !important;
    width: 100% !important;
    height: calc(100vh - 36px) !important;
    border: none;
    box-shadow: none;
}

.win.minimized {
    display: none;
}

/* Title Bar */
.title-bar {
    display: flex;
    align-items: center;
    gap: 4px;
    padding: 2px 3px;
    background: linear-gradient(90deg, var(--win-title), #1084d0);
    color: var(--win-title-text);
    flex-shrink: 0;
    cursor: default;
}

.win.inactive .title-bar {
    background: linear-gradient(90deg, var(--win-title-inactive), #b4b4b4);
}

.title-bar-icon {
    width: 16px;
    height: 16px;
    flex-shrink: 0;
}

.title-bar-text {
    flex: 1;
    font-size: 12px;
    font-weight: 700;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    padding-left: 2px;
    pointer-events: none;
}

.title-bar-controls {
    display: flex;
    gap: 2px;
    flex-shrink: 0;
}

.title-bar-controls button {
    width: 18px;
    height: 16px;
    background: var(--win-face);
    border-top: 1px solid var(--win-light);
    border-left: 1px solid var(--win-light);
    border-right: 1px solid var(--win-dark);
    border-bottom: 1px solid var(--win-dark);
    box-shadow: inset -1px -1px 0 var(--win-shadow);
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    font-size: 9px;
    font-weight: 700;
    color: #000;
    padding: 0;
    font-family: inherit;
    line-height: 1;
}

.title-bar-controls button:active {
    border-top: 1px solid var(--win-dark);
    border-left: 1px solid var(--win-dark);
    border-right: 1px solid var(--win-light);
    border-bottom: 1px solid var(--win-light);
    box-shadow: inset 1px 1px 0 var(--win-shadow);
    padding: 1px 0 0 1px;
}

/* Menu Bar */
.menu-bar {
    display: flex;
    gap: 0;
    padding: 1px 0;
    border-bottom: 1px solid var(--win-shadow);
    flex-shrink: 0;
}

.menu-bar span {
    padding: 2px 8px;
    font-size: 12px;
    color: #000;
    cursor: default;
}

.menu-bar span:hover {
    background: var(--win-selection);
    color: #fff;
}

/* Window Body */
.win-body {
    flex: 1;
    margin: 3px;
    overflow: auto;
    background: #fff;
    border-top: 1px solid var(--win-shadow);
    border-left: 1px solid var(--win-shadow);
    border-right: 1px solid var(--win-light);
    border-bottom: 1px solid var(--win-light);
    box-shadow: inset 1px 1px 0 var(--win-dark);
}

/* Status Bar */
.status-bar {
    display: flex;
    align-items: center;
    padding: 2px 4px;
    flex-shrink: 0;
}

.status-bar-field {
    flex: 1;
    padding: 1px 6px;
    font-size: 11px;
    color: #000;
    border-top: 1px solid var(--win-shadow);
    border-left: 1px solid var(--win-shadow);
    border-right: 1px solid var(--win-light);
    border-bottom: 1px solid var(--win-light);
}

/* ---- FOLDER VIEW ---- */
.folder-grid {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    padding: 12px;
    align-content: flex-start;
    min-height: 100%;
}

.folder-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 4px;
    padding: 6px 10px 8px;
    cursor: pointer;
    border: 1px solid transparent;
    width: 90px;
    -webkit-tap-highlight-color: transparent;
}

.folder-item:active,
.folder-item.selected {
    background: var(--win-selection);
    border: 1px dotted #000;
}

.folder-item:active .folder-item-label,
.folder-item.selected .folder-item-label {
    color: #fff;
}

.folder-item .icon-img {
    width: 32px;
    height: 32px;
    pointer-events: none;
}

.folder-item-label {
    font-size: 11px;
    color: #000;
    text-align: center;
    line-height: 1.2;
    word-wrap: break-word;
    pointer-events: none;
}

/* ---- NOTEPAD / ARTICLE VIEW ---- */
.notepad-body {
    padding: 8px 12px;
    font-family: 'Segoe UI', -apple-system, sans-serif;
    font-size: 15px;
    line-height: 1.65;
    color: #1a1a1a;
    cursor: text;
    user-select: text;
    -webkit-user-select: text;
}

.notepad-body h2 {
    font-size: 22px;
    font-weight: 700;
    margin: 36px 0 10px;
    color: #000;
    letter-spacing: -0.01em;
}

.notepad-body h2:first-child {
    margin-top: 8px;
}

.notepad-body h3 {
    font-size: 17px;
    font-weight: 700;
    margin: 28px 0 8px;
    color: #000;
}

.notepad-body p {
    margin-bottom: 12px;
}

.notepad-body strong {
    font-weight: 600;
    color: #000;
}

.notepad-body ul, .notepad-body ol {
    margin: 0 0 12px 20px;
}

.notepad-body li {
    margin-bottom: 6px;
}

.notepad-body code {
    font-family: 'Cascadia Mono', 'SF Mono', Consolas, monospace;
    font-size: 0.88em;
    background: #f0f0f0;
    padding: 1px 4px;
    border: 1px solid #ddd;
}

.notepad-body pre {
    background: #f8f8f8;
    border-top: 1px solid var(--win-shadow);
    border-left: 1px solid var(--win-shadow);
    border-right: 1px solid var(--win-light);
    border-bottom: 1px solid var(--win-light);
    padding: 12px 14px;
    margin: 16px 0;
    overflow-x: auto;
    font-family: 'Cascadia Mono', 'SF Mono', Consolas, monospace;
    font-size: 13px;
    line-height: 1.55;
    color: #1a1a1a;
}

.notepad-body pre code {
    background: none;
    border: none;
    padding: 0;
    font-size: inherit;
}

.notepad-body .svg-diagram {
    display: flex;
    justify-content: center;
    margin: 24px 0;
    padding: 20px 12px;
    overflow-x: auto;
}

.notepad-body .svg-diagram svg {
    width: 100%;
    height: auto;
    flex-shrink: 0;
}

.notepad-body .takeaways {
    margin: 32px 0 16px;
    padding-top: 16px;
    border-top: 1px solid #ccc;
}

/* ---- IMAGE VIEWER ---- */
.viewer-body {
    background: #0a0520;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 0;
    overflow: hidden;
}

.viewer-body svg {
    width: 100%;
    height: 100%;
    display: block;
}

.notepad-body .takeaways h3 {
    font-size: 14px;
    text-transform: uppercase;
    letter-spacing: 0.04em;
    color: #555;
    margin: 0 0 12px;
}

.notepad-body .takeaways ul {
    margin-left: 0;
    list-style: none;
}

.notepad-body .takeaways li {
    padding: 6px 0;
    border-bottom: 1px solid #eee;
}

.notepad-body .takeaways li:last-child {
    border-bottom: none;
}

/* ---- TASKBAR ---- */
#taskbar {
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    height: 36px;
    background: var(--win-face);
    border-top: 2px solid var(--win-light);
    display: flex;
    align-items: center;
    padding: 2px 4px;
    gap: 4px;
    z-index: 9999;
}

#start-btn {
    height: 28px;
    padding: 0 8px;
    font-size: 12px;
    font-weight: 700;
    font-family: inherit;
    background: var(--win-face);
    border-top: 2px solid var(--win-light);
    border-left: 2px solid var(--win-light);
    border-right: 2px solid var(--win-dark);
    border-bottom: 2px solid var(--win-dark);
    box-shadow: inset -1px -1px 0 var(--win-shadow);
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 4px;
    flex-shrink: 0;
}

#start-btn:active, #start-btn.active {
    border-top: 2px solid var(--win-dark);
    border-left: 2px solid var(--win-dark);
    border-right: 2px solid var(--win-light);
    border-bottom: 2px solid var(--win-light);
    box-shadow: inset 1px 1px 0 var(--win-shadow);
    padding: 1px 7px 0 9px;
}

#start-btn svg {
    width: 18px;
    height: 18px;
    pointer-events: none;
}

.taskbar-divider {
    width: 2px;
    height: 24px;
    border-left: 1px solid var(--win-shadow);
    border-right: 1px solid var(--win-light);
    flex-shrink: 0;
}

#taskbar-windows {
    flex: 1;
    display: flex;
    gap: 3px;
    overflow: hidden;
    min-width: 0;
}

.taskbar-btn {
    height: 26px;
    min-width: 0;
    max-width: 180px;
    flex: 1;
    padding: 0 8px;
    font-size: 12px;
    font-family: inherit;
    background: var(--win-face);
    border-top: 2px solid var(--win-light);
    border-left: 2px solid var(--win-light);
    border-right: 2px solid var(--win-dark);
    border-bottom: 2px solid var(--win-dark);
    box-shadow: inset -1px -1px 0 var(--win-shadow);
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 4px;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    text-align: left;
    color: #000;
}

.taskbar-btn.active {
    border-top: 2px solid var(--win-dark);
    border-left: 2px solid var(--win-dark);
    border-right: 2px solid var(--win-light);
    border-bottom: 2px solid var(--win-light);
    box-shadow: inset 1px 1px 0 var(--win-shadow);
    font-weight: 700;
    background: #fff;
}

.taskbar-btn .btn-text {
    overflow: hidden;
    text-overflow: ellipsis;
    pointer-events: none;
}

#tray {
    display: flex;
    align-items: center;
    padding: 0 8px;
    height: 24px;
    border-top: 1px solid var(--win-shadow);
    border-left: 1px solid var(--win-shadow);
    border-right: 1px solid var(--win-light);
    border-bottom: 1px solid var(--win-light);
    flex-shrink: 0;
}

#clock {
    font-size: 12px;
    color: #000;
    font-variant-numeric: tabular-nums;
}

/* ---- START MENU ---- */
#start-menu {
    position: fixed;
    bottom: 36px;
    left: 4px;
    width: 200px;
    background: var(--win-face);
    border-top: 2px solid var(--win-light);
    border-left: 2px solid var(--win-light);
    border-right: 2px solid var(--win-dark);
    border-bottom: 2px solid var(--win-dark);
    box-shadow: inset -1px -1px 0 var(--win-shadow);
    z-index: 10000;
    display: none;
    flex-direction: column;
}

#start-menu.open {
    display: flex;
}

.start-sidebar {
    position: absolute;
    left: 0;
    top: 0;
    bottom: 0;
    width: 24px;
    background: linear-gradient(to top, #000080, #1084d0);
    display: flex;
    align-items: flex-end;
    padding: 6px 0;
}

.start-sidebar span {
    color: #ccc;
    font-size: 11px;
    font-weight: 700;
    writing-mode: vertical-rl;
    transform: rotate(180deg);
    letter-spacing: 1px;
    padding: 4px;
}

.start-items {
    margin-left: 24px;
    padding: 4px 0;
}

.start-item {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 6px 12px;
    cursor: pointer;
    font-size: 12px;
    color: #000;
}

.start-item:hover {
    background: var(--win-selection);
    color: #fff;
}

.start-item .si-icon {
    font-size: 16px;
    width: 20px;
    text-align: center;
    pointer-events: none;
}

.start-divider {
    height: 1px;
    margin: 2px 4px 2px 28px;
    border-top: 1px solid var(--win-shadow);
    border-bottom: 1px solid var(--win-light);
}

/* ---- DIALOG ---- */
.dialog-overlay {
    position: fixed;
    inset: 0;
    background: transparent;
    z-index: 20000;
    display: flex;
    align-items: center;
    justify-content: center;
}

.dialog {
    background: var(--win-face);
    border-top: 2px solid var(--win-light);
    border-left: 2px solid var(--win-light);
    border-right: 2px solid var(--win-dark);
    border-bottom: 2px solid var(--win-dark);
    box-shadow: inset -1px -1px 0 var(--win-shadow);
    padding: 0;
    min-width: 280px;
    max-width: 380px;
}

.dialog .title-bar {
    cursor: default;
}

.dialog-body {
    padding: 20px 24px;
    display: flex;
    align-items: flex-start;
    gap: 16px;
}

.dialog-icon {
    font-size: 32px;
    flex-shrink: 0;
    line-height: 1;
}

.dialog-text {
    font-size: 13px;
    line-height: 1.45;
    color: #000;
}

.dialog-text strong {
    display: block;
    margin-bottom: 6px;
    font-size: 13px;
}

.dialog-actions {
    display: flex;
    justify-content: center;
    padding: 0 24px 16px;
    gap: 8px;
}

.dialog-actions button {
    min-width: 80px;
    height: 26px;
    font-size: 12px;
    font-family: inherit;
    background: var(--win-face);
    border-top: 2px solid var(--win-light);
    border-left: 2px solid var(--win-light);
    border-right: 2px solid var(--win-dark);
    border-bottom: 2px solid var(--win-dark);
    box-shadow: inset -1px -1px 0 var(--win-shadow);
    cursor: pointer;
    color: #000;
}

.dialog-actions button:active {
    border-top: 2px solid var(--win-dark);
    border-left: 2px solid var(--win-dark);
    border-right: 2px solid var(--win-light);
    border-bottom: 2px solid var(--win-light);
    box-shadow: inset 1px 1px 0 var(--win-shadow);
}

.dialog-actions button:focus-visible {
    outline: 1px dotted #000;
    outline-offset: -4px;
}

/* ---- RESPONSIVE ---- */
@media (max-width: 600px) {
    .desktop-icons {
        flex-direction: row;
        flex-wrap: wrap;
        justify-content: center;
        padding: 16px 8px;
        gap: 4px;
        max-height: none;
    }

    .desktop-icon {
        min-width: 80px;
    }

    .win:not(.maximized) {
        left: 2px !important;
        top: 2px !important;
        width: calc(100% - 4px) !important;
        height: calc(100vh - 40px) !important;
    }

    .folder-grid {
        justify-content: center;
    }

    .notepad-body {
        font-size: 15px;
        padding: 8px 10px;
    }

    .notepad-body h2 {
        font-size: 19px;
    }

    .notepad-body h3 {
        font-size: 16px;
    }

    .notepad-body .diagram {
        font-size: 10px;
        padding: 10px;
    }

    .taskbar-btn {
        max-width: 120px;
    }
}

@media (min-width: 601px) and (max-width: 900px) {
    .win:not(.maximized) {
        max-width: calc(100% - 20px);
        max-height: calc(100vh - 56px);
    }
}

/* ===== Reduction: reading pages, PDF viewer, knowledge graph ===== */
.reading-note {
    font-style: italic;
    color: #5a5a5a;
    background: #f3f1ea;
    padding: 8px 10px;
    margin: 10px 0 16px;
    font-size: 13px;
}
.poem-sub { font-style: italic; color: #555; margin-top: -6px; }
.poem { font-family: Georgia, "Times New Roman", serif; }
.poem p { line-height: 1.55; margin: 0 0 16px; }

/* PDF viewer */
.pdf-body { padding: 0 !important; overflow: hidden; }
.pdf-frame { width: 100%; height: 100%; border: 0; display: block; background: #525659; }

/* Knowledge graph */
.kg-body { padding: 0 !important; overflow: hidden; position: relative; background: #0f1420; }
.kg-root { position: absolute; inset: 0; }
.kg-svg { width: 100%; height: 100%; display: block; background: #0f1420; cursor: grab; touch-action: none; }
.kg-svg:active { cursor: grabbing; }
.kg-edge { stroke: #39425a; stroke-width: 1.5; }
.kg-edge.hot { stroke: #d7ddec; stroke-width: 2.5; }
.kg-node { cursor: pointer; }
.kg-node circle { stroke: #e8ecf5; stroke-opacity: 0.22; transition: stroke-opacity 0.12s; }
.kg-node:hover circle { stroke-opacity: 0.7; }
.kg-node.sel circle { stroke: #ffffff; stroke-opacity: 1; }
.kg-node.dim { opacity: 0.22; }
.kg-label {
    fill: #cdd4e3;
    font-size: 12px;
    font-family: -apple-system, "Segoe UI", Tahoma, sans-serif;
    pointer-events: none;
    paint-order: stroke;
    stroke: #0f1420;
    stroke-width: 3px;
    stroke-linejoin: round;
}
.kg-legend {
    position: absolute; top: 8px; left: 10px;
    display: flex; flex-wrap: wrap; gap: 5px 12px; max-width: 62%;
    font: 11px -apple-system, "Segoe UI", sans-serif; color: #cdd4e3;
    pointer-events: none;
}
.kg-leg i { display: inline-block; width: 10px; height: 10px; border-radius: 50%; margin-right: 4px; vertical-align: middle; }
.kg-panel {
    position: absolute; right: 10px; bottom: 10px; width: 244px;
    background: rgba(18, 24, 38, 0.93); border: 1px solid #39425a;
    padding: 10px 12px; color: #dfe4ef;
    font: 13px/1.5 -apple-system, "Segoe UI", Tahoma, sans-serif;
}
.kg-panel-title { font-weight: 700; margin-bottom: 4px; }
.kg-panel-link { color: #7fb0ff; display: inline-block; margin-top: 8px; cursor: pointer; text-decoration: none; }
.kg-panel-link:hover { text-decoration: underline; }
@media (max-width: 600px) {
    .kg-panel { width: 180px; font-size: 12px; }
    .kg-legend { max-width: 100%; font-size: 10px; }
}