/* ==========================================================================
   LAYOUT.CSS - Grid, Panes, Work Area, Zen Mode
   ========================================================================== */

:root {
    --pane-bg:
        radial-gradient(circle at 16% 16%, color-mix(in srgb, var(--amb-c1, #60a5fa66) 32%, transparent) 0%, transparent 46%),
        radial-gradient(circle at 88% 10%, color-mix(in srgb, var(--amb-c2, #f472b699) 30%, transparent) 0%, transparent 46%),
        linear-gradient(165deg, var(--app-surface, #1c232b) 0%, var(--app-surface-strong, #14181e) 100%);
    --pane-bg-elevated: linear-gradient(165deg,
            color-mix(in srgb, var(--card-bg, rgba(15, 23, 42, 0.6)) 68%, #20262e 32%) 0%,
            color-mix(in srgb, var(--card-bg, rgba(15, 23, 42, 0.6)) 84%, #13181e 16%) 100%);
}

/* --- Layout Grid --- */
#work-area {
    display: grid;
    grid-template-columns: 1fr;
    height: 100%;
    width: 100%;
    position: relative;
    overflow: hidden;
    transition: grid-template-columns 0.3s cubic-bezier(0.25, 1, 0.5, 1);
}

#work-area.split-view {
    grid-template-columns: 1fr auto 1fr;
}

body.panel-reorder-ready #quiz-pane>h1,
body.panel-reorder-ready #controls-bar,
body.panel-reorder-ready #pdf-header,
body.panel-reorder-ready #ai-header {
    cursor: grab;
}

body.panel-reorder-dragging #work-area {
    cursor: grabbing;
}

body.panel-reorder-dragging #quiz-pane>h1,
body.panel-reorder-dragging #controls-bar,
body.panel-reorder-dragging #pdf-header,
body.panel-reorder-dragging #ai-header {
    cursor: grabbing !important;
}

#work-area #quiz-pane.panel-reorder-source,
#work-area #pdf-pane.panel-reorder-source,
#work-area #ai-pane.panel-reorder-source {
    opacity: 0.46;
    filter: saturate(0.7) contrast(0.94);
}

#work-area #quiz-pane.panel-reorder-target,
#work-area #pdf-pane.panel-reorder-target,
#work-area #ai-pane.panel-reorder-target {
    outline: 2px dashed color-mix(in srgb, var(--g1, #60a5fa) 56%, var(--g2, #f472b6) 44%);
    outline-offset: -2px;
    box-shadow:
        inset 0 0 0 999px color-mix(in srgb, var(--g1, #60a5fa) 14%, transparent),
        0 0 18px color-mix(in srgb, var(--g2, #f472b6) 34%, transparent);
}

.panel-reorder-panel-ghost {
    position: fixed;
    left: 0;
    top: 0;
    transform: translate(-9999px, -9999px);
    pointer-events: none;
    z-index: 20050;
    display: flex;
    flex-direction: column;
    overflow: hidden;
    opacity: 0.58;
    filter: saturate(0.86);
    box-shadow: 0 14px 36px rgba(2, 6, 23, 0.52);
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
    border: 1px solid color-mix(in srgb, var(--g1, #60a5fa) 46%, rgba(255, 255, 255, 0.2) 54%);
}

.panel-reorder-panel-ghost .panel-reorder-ghost-header {
    min-height: 34px;
    padding: 6px 10px;
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 0.82rem;
    font-weight: 700;
    color: var(--text-q, #f8fafc);
    border-bottom: 1px solid color-mix(in srgb, var(--bd, rgba(148, 163, 184, 0.26)) 76%, transparent 24%);
}

.panel-reorder-panel-ghost .panel-reorder-ghost-header * {
    pointer-events: none !important;
}

.panel-reorder-ghost-label {
    min-height: 34px;
    padding: 6px 10px;
    display: flex;
    align-items: center;
    font-size: 0.82rem;
    font-weight: 700;
    color: var(--text-q, #f8fafc);
    border-bottom: 1px solid color-mix(in srgb, var(--bd, rgba(148, 163, 184, 0.26)) 76%, transparent 24%);
}

.panel-reorder-ghost-body {
    flex: 1 1 auto;
    background:
        linear-gradient(165deg,
            color-mix(in srgb, var(--card-bg, rgba(15, 23, 42, 0.6)) 72%, #20262e 28%) 0%,
            color-mix(in srgb, var(--card-bg, rgba(15, 23, 42, 0.6)) 84%, #141a20 16%) 100%);
}

/* --- Panel Resize Handles --- */
.panel-resize-handle {
    display: none;
    width: 1px;
    cursor: col-resize;
    background: rgba(255, 255, 255, 0.15);
    position: relative;
    z-index: 100;
    transition: all 0.15s ease;
}

.panel-resize-handle:hover,
.panel-resize-handle.dragging {
    width: 8px;
    background: var(--g);
    box-shadow: 0 0 10px rgba(167, 139, 250, 0.5);
}

/* Prevent iframes from capturing mouse during resize */
body.resizing-panels iframe {
    pointer-events: none;
}

/* Show resize handles in split view */
#work-area.split-view #resize-quiz-pdf {
    display: block;
}

/* Show appropriate handle in trio view */
#work-area.trio-view #resize-quiz-pdf,
#work-area.trio-view #resize-pdf-ai {
    display: block;
}

/* Show resize handle in split-view-ai */
#work-area.split-view-ai #resize-pdf-ai {
    display: block;
}

/* --- Border Mode --- */
#work-area.bordered-mode.split-view {
    padding: 6px;
    gap: 6px;
    background: var(--pane-bg-elevated);
}

#work-area.bordered-mode.split-view #quiz-pane,
#work-area.bordered-mode.split-view #pdf-pane {
    border: 3px solid transparent;
    border-radius: 12px;
    background: linear-gradient(color-mix(in srgb, var(--card-bg, rgba(15, 23, 42, 0.6)) 74%, #20262e 26%), color-mix(in srgb, var(--card-bg, rgba(15, 23, 42, 0.6)) 84%, #141a20 16%)) padding-box, var(--border-g, var(--g)) border-box;
    box-shadow: 0 0 15px rgba(0, 0, 0, 0.5);
    transition: filter 2s ease, border-color 0.3s ease;
}

#work-area.bordered-mode.split-view #quiz-pane {
    border-right: 3px solid transparent;
}

#work-area.bordered-mode.split-view #pdf-pane {
    border-left: 3px solid transparent;
}

/* --- Quiz Pane --- */
#quiz-pane {
    padding: 1.5rem;
    overflow-y: auto;
    display: flex;
    flex-direction: column;
    align-items: center;
    border-right: 1px solid transparent;
    position: relative;
    height: 100%;
    width: 100%;
    -ms-overflow-style: none;
    scrollbar-width: none;
    transition: padding 0.3s ease;
    background: var(--pane-bg);
}

#work-area.split-view #quiz-pane {
    border-right: 1px solid var(--bd);
    align-items: center;
    padding: 1rem;
}

#quiz-pane::-webkit-scrollbar {
    display: none;
}

/* --- PDF Pane --- */
#pdf-pane {
    display: none;
    background: var(--pane-bg-elevated);
    flex-direction: column;
    position: relative;
    --pdf-header-height: 36px;
    height: 100%;
    border-left: 1px solid var(--app-border, rgba(148, 163, 184, 0.25));
    overflow: hidden;
    container-type: inline-size;
}

#work-area.split-view #pdf-pane {
    display: flex;
}

/* --- Trio View (3 Columns) --- */
#work-area.trio-view {
    grid-template-columns: 1fr auto 1fr auto 1fr;
}

#work-area.trio-view #pdf-pane,
#work-area.trio-view #ai-pane {
    display: flex;
    min-width: 0;
    overflow: hidden;
}

/* Split View with AI (Quiz + AI, no PDF) */
#work-area.split-view-ai {
    grid-template-columns: 1fr auto 1fr;
}

#work-area.split-view-ai #ai-pane {
    display: flex;
}

#work-area.split-view-ai #pdf-pane {
    display: none;
}

/* Border Mode for split-view-ai (Quiz + AI) */
#work-area.bordered-mode.split-view-ai {
    padding: 6px;
    gap: 6px;
    background: var(--pane-bg-elevated);
}

#work-area.bordered-mode.split-view-ai #quiz-pane,
#work-area.bordered-mode.split-view-ai #ai-pane {
    border: 3px solid transparent;
    border-radius: 12px;
    background: linear-gradient(color-mix(in srgb, var(--card-bg, rgba(15, 23, 42, 0.6)) 74%, #20262e 26%), color-mix(in srgb, var(--card-bg, rgba(15, 23, 42, 0.6)) 84%, #141a20 16%)) padding-box, var(--border-g, var(--g)) border-box;
    box-shadow: 0 0 15px rgba(0, 0, 0, 0.5);
    transition: filter 2s ease, border-color 0.3s ease;
}

#work-area.bordered-mode.split-view-ai #quiz-pane {
    border-right: 3px solid transparent;
}

#work-area.bordered-mode.split-view-ai #ai-pane {
    border-left: 3px solid transparent;
}

/* Quiz card in trio mode - smaller to fit 1/3 width */
#work-area.trio-view #quiz-card:not(.is-floating) {
    width: 95%;
    max-width: 100%;
    padding: 1.5rem;
    margin: 0 auto;
}

#work-area.trio-view #quiz-pane {
    padding: 0.5rem;
}

/* Hide some controls in trio mode to save space */
#work-area.trio-view .question-text {
    font-size: clamp(1.18rem, 1.02rem + 0.36vw, 1.38rem);
}

#work-area.trio-view .choice {
    padding: 0.8rem 1rem;
    font-size: 0.95rem;
}

/* Small header bar above the PDF iframe */
#pdf-header {
    display: flex;
    align-items: center;
    gap: 6px;
    padding: 5px 8px 5px calc(8px + var(--fullscreen-clearance-left, 0px));
    background: color-mix(in srgb, var(--card-bg, rgba(15, 23, 42, 0.6)) 84%, #161b22 16%);
    border-bottom: 1px solid var(--app-border, rgba(148, 163, 184, 0.25));
    flex-shrink: 0;
    position: relative;
    z-index: 3;
}

#pdf-header .header-buttons {
    display: flex;
    gap: 6px;
    align-items: center;
    margin-left: auto;
    flex: 0 0 auto;
}

#pdf-header button {
    width: 26px;
    height: 26px;
    padding: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 6px;
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid var(--g1, rgba(96, 165, 250, 0.3));
    font-size: 0.9rem;
    color: var(--g1, #60a5fa);
    cursor: pointer;
    transition: all 0.2s;
}

#pdf-header button:hover {
    background: rgba(96, 165, 250, 0.15);
    color: var(--g2, #a78bfa);
    border-color: var(--g2, #a78bfa);
}

/* PDF Title in header */
#pdf-title {
    font-size: 0.72rem;
    line-height: 1.1;
    flex: 0 0 clamp(110px, 38%, 340px);
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
    /* Theme-dynamic gradient text */
    background-image: var(--g);
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
    font-weight: 600;
}

#pdf-mini-toolbar {
    display: flex;
    align-items: center;
    gap: 3px;
    min-width: 0;
    flex: 1 1 auto;
    justify-content: flex-end;
    overflow-x: auto;
    scrollbar-width: none;
    -ms-overflow-style: none;
}

#pdf-mini-toolbar::-webkit-scrollbar {
    width: 0;
    height: 0;
    display: none;
}

#pdf-mini-toolbar .pdf-mini-btn {
    width: auto;
    min-width: 24px;
    height: 24px;
    padding: 0 6px;
    font-size: 0.68rem;
    font-weight: 600;
    line-height: 1;
    border-radius: 7px;
    white-space: nowrap;
    flex: 0 0 auto;
}

#pdf-mini-toolbar .pdf-mini-btn:disabled {
    opacity: 0.45;
    cursor: not-allowed;
}

#pdf-mini-toolbar .pdf-mini-btn.active {
    background: color-mix(in srgb, var(--g1, #60a5fa) 28%, rgba(255, 255, 255, 0.06));
    border-color: color-mix(in srgb, var(--g1, #60a5fa) 75%, rgba(255, 255, 255, 0.24));
    color: #e2e8f0;
}

#pdf-mini-toolbar .pdf-mini-readout {
    min-width: 46px;
    text-align: center;
    font-size: 0.68rem;
    font-weight: 700;
    color: #cbd5e1;
    font-variant-numeric: tabular-nums;
    flex: 0 0 auto;
    white-space: nowrap;
}

#pdf-page-indicator {
    min-width: 62px;
}

#pdf-zoom-label {
    min-width: 46px;
}

#pdf-mini-toolbar .pdf-mini-sep {
    width: 1px;
    height: 16px;
    background: rgba(148, 163, 184, 0.35);
    margin: 0 2px;
    border-radius: 999px;
}

#pdf-more-wrap {
    position: relative;
    display: flex;
    align-items: center;
}

#pdf-more-btn.active {
    background: color-mix(in srgb, var(--g1, #60a5fa) 24%, rgba(255, 255, 255, 0.08));
    border-color: color-mix(in srgb, var(--g2, #a78bfa) 74%, rgba(255, 255, 255, 0.25));
    color: #e2e8f0;
}

#pdf-more-menu {
    position: absolute;
    top: calc(100% + 6px);
    right: 0;
    z-index: 36;
    display: none;
    flex-direction: column;
    gap: 4px;
    padding: 7px;
    border-radius: 9px;
    border: 1px solid color-mix(in srgb, var(--g1, #60a5fa) 58%, rgba(255, 255, 255, 0.18));
    background: color-mix(in srgb, var(--card-bg, rgba(15, 23, 42, 0.92)) 92%, #060b14 8%);
    box-shadow: 0 14px 34px rgba(2, 6, 23, 0.55);
    min-width: 54px;
}

#pdf-more-menu.active {
    display: flex;
}

#pdf-more-menu .pdf-mini-btn {
    min-width: 40px;
    height: 24px;
    padding: 0 8px;
    justify-content: center;
    font-size: 0.7rem;
}

#pdfjs-host {
    position: absolute;
    left: 0;
    right: 0;
    bottom: 0;
    top: var(--pdf-header-height, 36px);
    min-height: 0;
    overflow: auto;
    scrollbar-width: none;
    -ms-overflow-style: none;
    padding: 2px 0 2px;
    background:
        radial-gradient(circle at 10% 0%, rgba(96, 165, 250, 0.08), transparent 42%),
        radial-gradient(circle at 90% 0%, rgba(244, 114, 182, 0.08), transparent 42%),
        color-mix(in srgb, var(--pane-bg-elevated, #0b1220) 92%, #020617 8%);
    outline: none;
}

#pdfjs-host::-webkit-scrollbar {
    width: 0;
    height: 0;
    display: none;
}

#pdfjs-pages {
    min-height: 100%;
    width: 100%;
}

#pdfjs-pages .page {
    margin: 0 auto 1px !important;
    border: 0 !important;
    border-radius: 4px;
    position: relative;
    isolation: isolate;
    overflow: hidden;
    box-shadow: 0 1px 4px rgba(2, 6, 23, 0.22);
    background: #fff;
}

/* Override built-in PDF.js viewer page chrome to keep slide gaps minimal. */
#pdfjs-pages.pdfViewer .page {
    margin: 0 auto 1px !important;
    border: 0 !important;
}

#pdfjs-pages .page.evidence-target-page {
    outline: 4px solid color-mix(in srgb, var(--g1, #60a5fa) 74%, #ffffff 26%);
    outline-offset: -4px;
    z-index: 8;
    box-shadow:
        0 0 0 2px #ffffff,
        0 0 0 6px color-mix(in srgb, var(--g2, #f472b6) 76%, #0f172a 24%),
        0 0 0 11px color-mix(in srgb, var(--g1, #60a5fa) 52%, transparent),
        0 0 34px color-mix(in srgb, var(--g2, #f472b6) 56%, transparent),
        0 1px 4px rgba(2, 6, 23, 0.22);
    filter: saturate(1.22) contrast(1.08);
}

#pdfjs-pages .page.evidence-target-page::after {
    content: '';
    position: absolute;
    inset: 0;
    pointer-events: none;
    border: 3px solid color-mix(in srgb, #ffffff 72%, var(--g2, #f472b6) 28%);
    border-radius: inherit;
}

#pdfjs-pages .page.evidence-target-page > .canvasWrapper {
    box-shadow: inset 9px 0 0 color-mix(in srgb, var(--g1, #60a5fa) 72%, var(--g2, #f472b6) 28%);
}

#pdfjs-pages .page canvas {
    display: block;
}

#pdfjs-pages .textLayer {
    border-radius: inherit;
}

#pdf-pane.ai-mode #pdfjs-host {
    display: none;
}

/* AI Mode - Minimal floating buttons only, no header bar */
#pdf-pane.ai-mode #pdf-header {
    position: absolute;
    top: 8px;
    right: 8px;
    left: auto;
    padding: 0;
    background: transparent;
    border: none;
    z-index: 100;
    justify-content: flex-end;
}

#pdf-pane.ai-mode #pdf-title {
    display: none;
}

#pdf-pane.ai-mode #pdf-mini-toolbar {
    display: none;
}

#pdf-pane.ai-mode #pdf-more-wrap {
    display: none;
}

#pdf-pane.ai-mode #pdf-header button {
    background: color-mix(in srgb, var(--card-bg, rgba(15, 23, 42, 0.6)) 80%, #1a2028 20%);
    backdrop-filter: blur(8px);
    opacity: 0.6;
}

#pdf-pane.ai-mode #pdf-header button:hover {
    opacity: 1;
    background: color-mix(in srgb, var(--card-bg, rgba(15, 23, 42, 0.6)) 90%, #12161c 10%);
}

#pdf-frame {
    display: none;
    position: absolute;
    left: 0;
    right: 0;
    bottom: 0;
    top: var(--pdf-header-height, 36px);
    width: 100%;
    height: 100%;
    border: none;
    overflow: hidden;
    scrollbar-width: none;
    -ms-overflow-style: none;
}

#pdf-frame::-webkit-scrollbar {
    width: 0;
    height: 0;
    display: none;
}

#pdf-pane.ai-mode #pdf-frame {
    display: block;
    top: 0;
}

body.pdf-expanded-mode {
    overflow: hidden;
}

body.quiz-card-expanded-mode {
    overflow: hidden;
}

#pdf-pane.pdf-pane-expanded {
    position: fixed;
    inset: 10px;
    z-index: 12050;
    display: flex !important;
    border: 1px solid var(--app-border, rgba(148, 163, 184, 0.35));
    border-radius: 14px;
    box-shadow: 0 20px 70px rgba(2, 6, 23, 0.75);
    background: color-mix(in srgb, var(--pane-bg-elevated, #0b1220) 96%, #020617 4%);
}

#pdf-pane.pdf-pane-expanded #pdf-header {
    padding: 8px 12px;
}

#pdf-pane.pdf-pane-expanded #pdfjs-host {
    padding: 12px 14px 18px;
}

@container (max-width: 760px) {
    #pdf-title {
        flex-basis: clamp(96px, 34%, 240px);
        font-size: 0.68rem;
    }

    #pdf-mini-toolbar .pdf-mini-sep {
        display: none;
    }

    #pdf-mini-toolbar .pdf-mini-btn {
        min-width: 22px;
        height: 23px;
        padding: 0 5px;
        font-size: 0.64rem;
    }

    #pdf-mini-toolbar .pdf-mini-readout {
        min-width: 40px;
        font-size: 0.64rem;
    }
}

@container (max-width: 620px) {
    #pdf-title {
        flex-basis: clamp(82px, 30%, 190px);
        font-size: 0.64rem;
    }
}

body.pdf-expanded-mode .panel-resize-handle {
    opacity: 0;
    pointer-events: none;
}

body.quiz-card-expanded-mode .panel-resize-handle {
    opacity: 0;
    pointer-events: none;
}

/* --- Zen Mode Styles --- */
body.zen-active {
    background: #0a0a0a !important;
    min-height: 100vh;
}

body.zen-active::before {
    display: none;
}

body.zen-active #controls-bar,
body.zen-active h1,
body.zen-active #pdf-pane,
body.zen-active #shortcuts-btn,
body.zen-active #nav-row {
    display: none !important;
}

body.zen-active #work-area {
    grid-template-columns: 1fr !important;
    padding: 0 !important;
    min-height: 100vh;
    background: #0a0a0a !important;
}

body.zen-active #quiz-pane {
    border: none !important;
    padding: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 100vh;
    background: #0a0a0a !important;
}

body.zen-active #quiz-card {
    box-shadow: none !important;
    background: #0a0a0a !important;
    border: 1px solid #333;
    animation: none !important;
    width: 100%;
    max-width: 900px;
    margin: auto;
}

#exit-zen-btn {
    position: fixed;
    top: 20px;
    right: 20px;
    z-index: 5000;
    padding: 10px 20px;
    background: rgba(255, 255, 255, 0.1);
    border: 1px solid #333;
    border-radius: 30px;
    color: #666;
    cursor: pointer;
    display: none;
    font-weight: bold;
    transition: all 0.2s;
}

#exit-zen-btn:hover {
    background: #fff;
    color: #000;
}

body.zen-active #exit-zen-btn {
    display: block;
}

/* Welcome Mode */
body.welcome-mode #controls-bar,
body.welcome-mode h1 {
    display: none;
}

body.welcome-mode .search-wrapper {
    display: none;
}

body.welcome-mode #quiz-pane {
    justify-content: center;
}

/* --- AI Pane Styling (Mirrors PDF Pane) --- */
#ai-pane {
    display: none;
    background: var(--pane-bg-elevated);
    flex-direction: column;
    position: relative;
    height: 100%;
    border-left: 1px solid var(--app-border, rgba(148, 163, 184, 0.25));
    overflow: hidden;
}

#ai-pane iframe {
    flex: 1;
    border: none;
    width: 100%;
    height: 100%;
}

#ai-expl-view {
    display: none;
    flex: 1;
    overflow-y: auto;
    padding: 10px 12px;
    background: var(--pane-bg-elevated);
    scrollbar-width: none;
    -ms-overflow-style: none;
}

#ai-expl-view::-webkit-scrollbar {
    width: 0;
    height: 0;
    display: none;
}

#ai-expl-content {
    min-height: 100%;
    padding: 0;
    color: var(--text-main, #e2e8f0);
}

#ai-expl-content .ai-expl-meta {
    margin-bottom: 10px;
    color: #94a3b8;
    font-size: 0.78rem;
    line-height: 1.5;
}

#ai-expl-content .ai-formatted-response {
    font-size: 0.94rem;
    line-height: 1.65;
}

#ai-expl-content .ai-expl-empty {
    color: #94a3b8;
    font-size: 0.87rem;
    line-height: 1.6;
    padding: 6px 0;
}

#ai-expl-content .ai-expl-slide-card {
    position: relative;
    margin: 0 0 12px 0;
    padding: 14px 14px 12px;
    border-radius: 12px;
    border: 1px solid color-mix(in srgb, var(--g1, #60a5fa) 30%, rgba(148, 163, 184, 0.35));
    background: color-mix(in srgb, var(--card-bg, rgba(15, 23, 42, 0.6)) 88%, rgba(255, 255, 255, 0.04) 12%);
    cursor: text;
    transition: transform 0.2s ease, box-shadow 0.2s ease, border-color 0.2s ease, background 0.2s ease;
}

#ai-expl-content .ai-expl-slide-card:hover {
    transform: translateY(-1px);
    border-color: color-mix(in srgb, var(--g1, #60a5fa) 56%, rgba(255, 255, 255, 0.22));
    box-shadow: 0 10px 26px rgba(2, 6, 23, 0.32);
}

#ai-expl-content .ai-expl-slide-card .dd-section-header {
    margin-top: 0;
    padding-right: 84px;
}

#ai-expl-content .ai-expl-slide-card .dd-paragraph:last-child {
    margin-bottom: 0;
}

#ai-expl-content .ai-expl-slide-expand-btn {
    position: absolute;
    top: 10px;
    right: 10px;
    border: 1px solid color-mix(in srgb, var(--g1, #60a5fa) 56%, rgba(255, 255, 255, 0.2));
    border-radius: 999px;
    background: rgba(15, 23, 42, 0.56);
    color: #cbd5e1;
    font-size: 0.72rem;
    line-height: 1;
    padding: 5px 10px;
    cursor: pointer;
    user-select: none;
}

#ai-expl-content .ai-expl-slide-expand-btn:hover {
    background: color-mix(in srgb, var(--g1, #60a5fa) 16%, rgba(15, 23, 42, 0.84));
    color: #e2e8f0;
}

#ai-expl-content .ai-expl-slide-target {
    border-radius: 9px;
    border: 1px solid rgba(6, 10, 18, 0.86);
    box-shadow:
        0 0 0 2px rgba(6, 10, 18, 0.92),
        0 0 0 4px color-mix(in srgb, var(--g1, #60a5fa) 54%, rgba(6, 10, 18, 0.46)),
        0 0 20px rgba(2, 6, 23, 0.58);
    background: transparent;
    transition: box-shadow 0.25s ease, background 0.25s ease;
}

.ai-expl-slide-modal {
    position: fixed;
    inset: 0;
    display: none;
    align-items: center;
    justify-content: center;
    padding: 18px;
    background: rgba(2, 6, 23, 0.68);
    backdrop-filter: blur(4px);
    -webkit-backdrop-filter: blur(4px);
    z-index: 10020;
}

.ai-expl-slide-modal.active {
    display: flex;
}

.ai-expl-slide-modal-card {
    position: relative;
    width: min(1470px, 96vw);
    max-height: 90vh;
    display: flex;
    flex-direction: column;
    overflow: hidden;
    border-radius: 16px;
    border: 1px solid var(--bd, #334155);
    background: color-mix(in srgb, var(--card-bg, rgba(15, 23, 42, 0.96)) 94%, rgba(255, 255, 255, 0.06) 6%);
    box-shadow: 0 30px 80px rgba(0, 0, 0, 0.55);
    transform: scale(0.94);
    opacity: 0;
    transition: transform 0.18s ease, opacity 0.18s ease;
}

.ai-expl-slide-modal.active .ai-expl-slide-modal-card {
    transform: scale(1);
    opacity: 1;
}

.ai-expl-slide-modal-close {
    position: absolute;
    top: 12px;
    right: 12px;
    width: 51px;
    height: 51px;
    border-radius: 11px;
    border: 1px solid rgba(255, 255, 255, 0.2);
    background: rgba(2, 6, 23, 0.58);
    color: #e2e8f0;
    font-size: 1.875rem;
    line-height: 1;
    cursor: pointer;
    z-index: 2;
}

.ai-expl-slide-modal-close:hover {
    background: rgba(15, 23, 42, 0.9);
}

.ai-expl-slide-modal-content {
    flex: 1;
    min-height: 0;
    overflow: auto;
    padding: 1.875rem 2.1rem 2.025rem;
    scrollbar-width: none;
    -ms-overflow-style: none;
}

.ai-expl-slide-modal-content::-webkit-scrollbar {
    width: 0;
    height: 0;
    display: none;
}

.ai-expl-slide-modal-content .ai-expl-slide-card {
    margin: 0;
    cursor: default;
    font-size: 1.5rem;
    line-height: 1.68;
}

.ai-expl-slide-modal-content .ai-expl-slide-card:hover {
    transform: none;
    box-shadow: none;
}

.ai-expl-slide-modal-content .ai-expl-slide-card .dd-section-header {
    font-size: 1.74rem;
    padding-left: 18px;
    border-left-width: 4px;
}

.ai-expl-slide-modal-content .ai-expl-slide-card .dd-paragraph {
    padding-left: 1.65rem;
}

#ai-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 8px;
    padding: 6px 10px 6px calc(10px + var(--fullscreen-clearance-left, 0px));
    background: color-mix(in srgb, var(--card-bg, rgba(15, 23, 42, 0.6)) 84%, #161b22 16%);
    border-bottom: 1px solid var(--app-border, rgba(148, 163, 184, 0.25));
    flex-shrink: 0;
}

#ai-header .header-buttons {
    display: flex;
    gap: 6px;
    align-items: center;
    flex: 0 0 auto;
    margin-left: 8px;
    position: relative;
    z-index: 3;
}

#ai-header .ai-header-left {
    display: flex;
    align-items: center;
    gap: 8px;
    min-width: 0;
    flex: 1;
    overflow: hidden;
}

#ai-pane-mode-wrap {
    display: none;
    align-items: center;
    gap: 8px;
    min-width: 0;
    flex: 1 1 auto;
    max-width: 100%;
    overflow: hidden;
}

#work-area.trio-view #ai-pane-mode-wrap,
#work-area.split-view-ai #ai-pane-mode-wrap {
    display: inline-flex;
    flex: 1 1 auto;
    min-width: 0;
}

#ai-header button {
    width: 26px;
    height: 26px;
    padding: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 6px;
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid var(--g1, rgba(96, 165, 250, 0.3));
    font-size: 0.9rem;
    color: var(--g1, #60a5fa);
    cursor: pointer;
    transition: all 0.2s;
}

#ai-header button:hover {
    background: rgba(96, 165, 250, 0.15);
    color: var(--g2, #a78bfa);
    border-color: var(--g2, #a78bfa);
}

#ai-title {
    font-size: 0.8rem;
    max-width: 70%;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
    /* Theme-dynamic gradient text */
    background-image: var(--g);
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
    font-weight: 600;
}

#work-area.trio-view #ai-title,
#work-area.split-view-ai #ai-title {
    max-width: 42%;
}

#ai-pane-mode,
#ai-expl-pdf-select {
    max-width: 175px;
    min-width: 0;
    background: color-mix(in srgb, var(--card-bg, rgba(15, 23, 42, 0.6)) 80%, #1a2028 20%);
    border: 1px solid var(--g1, rgba(96, 165, 250, 0.3));
    border-radius: 6px;
    color: #cbd5e1;
    font-size: 0.76rem;
    line-height: 1.1;
    padding: 4px 8px;
}

#ai-expl-pdf-select {
    -ms-overflow-style: none;
    scrollbar-width: none;
}

#ai-expl-pdf-select::-webkit-scrollbar {
    width: 0;
    height: 0;
    display: none;
}

#work-area.trio-view #ai-pane-mode,
#work-area.split-view-ai #ai-pane-mode {
    flex: 0 1 140px;
    max-width: 140px;
}

#work-area.trio-view #ai-expl-pdf-select,
#work-area.split-view-ai #ai-expl-pdf-select {
    flex: 1 1 auto;
    max-width: none;
}

#ai-pane-mode:focus,
#ai-expl-pdf-select:focus {
    outline: none;
    border-color: var(--g2, #a78bfa);
}

/* Border Mode for Trio View */
#work-area.bordered-mode.trio-view {
    padding: 6px;
    gap: 6px;
    background: var(--pane-bg-elevated);
}

#work-area.bordered-mode.trio-view #quiz-pane,
#work-area.bordered-mode.trio-view #pdf-pane,
#work-area.bordered-mode.trio-view #ai-pane {
    border: 3px solid transparent;
    border-radius: 12px;
    background: linear-gradient(color-mix(in srgb, var(--card-bg, rgba(15, 23, 42, 0.6)) 74%, #20262e 26%), color-mix(in srgb, var(--card-bg, rgba(15, 23, 42, 0.6)) 84%, #141a20 16%)) padding-box, var(--border-g, var(--g)) border-box;
    box-shadow: 0 0 15px rgba(0, 0, 0, 0.5);
    transition: filter 2s ease, border-color 0.3s ease;
}

/* Zen Mode hides AI pane too */
body.zen-active #ai-pane {
    display: none !important;
}