/* ============ DB Slide Finder — GeeksforGeeks-inspired UI ============ */
:root {
  --green:        #2f8d46;
  --green-dark:   #1f7a38;
  --green-darker: #176b33;
  --green-tint:   #e9f7ef;
  --green-tint2:  #d8f3df;
  --ink:          #1f2328;
  --ink-soft:     #3d4650;
  --muted:        #6b7785;
  --muted-2:      #8a96a3;
  --border:       #e6e9ec;
  --border-2:     #eef1f4;
  --bg:           #f5f7f9;
  --bg-canvas:    #eceff2;
  --card:         #ffffff;
  --mark-bg:      #d8f3df;
  --mark-ink:     #146c30;
  --shadow-sm:    0 1px 2px rgba(16,24,40,.05);
  --shadow:       0 4px 14px rgba(16,24,40,.08);
  --shadow-lg:    0 10px 34px rgba(16,24,40,.12);
  --radius:       12px;
  --radius-sm:    9px;
  --sidebar-w:    300px;
  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --mono: "Cascadia Mono", "JetBrains Mono", ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
}

* { box-sizing: border-box; }
[hidden] { display: none !important; } /* beat author display rules (.loading etc.) */
html, body { height: 100%; }
body {
  margin: 0;
  font-family: var(--font);
  color: var(--ink);
  background: var(--bg);
  display: flex;
  flex-direction: column;
  overflow: hidden;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}
button { font-family: inherit; cursor: pointer; }
::selection { background: var(--green-tint2); }

/* ---------------- Header ---------------- */
.topbar {
  height: 60px;
  flex: 0 0 60px;
  background: #fff;
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 22px;
  z-index: 20;
  box-shadow: var(--shadow-sm);
}
.brand { display: flex; align-items: center; gap: 13px; }
.brand-mark {
  width: 40px; height: 40px;
  border-radius: 11px;
  background: linear-gradient(145deg, var(--green) 0%, var(--green-darker) 100%);
  color: #fff;
  display: grid; place-items: center;
  box-shadow: 0 4px 12px rgba(47,141,70,.32);
}
.brand-text h1 {
  font-size: 18px; font-weight: 700; margin: 0; letter-spacing: -.2px;
  color: var(--ink);
}
.brand-sub { font-size: 12px; color: var(--muted); font-weight: 500; }
.topbar-meta { display: flex; gap: 8px; }
.pill {
  font-size: 12px; font-weight: 600; color: var(--green-darker);
  background: var(--green-tint); border: 1px solid var(--green-tint2);
  padding: 5px 11px; border-radius: 999px; white-space: nowrap;
}

/* ---------------- Layout ---------------- */
.layout { flex: 1 1 auto; display: flex; min-height: 0; }

/* stealth: brand header stays hidden; sidebar toggles -> looks like a plain PDF viewer */
body.stealth .topbar { display: none; }
body.viewer-only .sidebar { display: none; }

/* ---------------- Sidebar ---------------- */
.sidebar {
  width: var(--sidebar-w);
  flex: 0 0 var(--sidebar-w);
  background: #fff;
  border-right: 1px solid var(--border);
  display: flex; flex-direction: column;
  min-height: 0;
}
.search-wrap { padding: 16px 16px 10px; border-bottom: 1px solid var(--border-2); }
.search-box {
  position: relative; display: flex; align-items: center;
  background: #fff;
  border: 1.6px solid var(--border);
  border-radius: var(--radius-sm);
  transition: border-color .15s, box-shadow .15s;
}
.search-box:focus-within {
  border-color: var(--green);
  box-shadow: 0 0 0 3.5px rgba(47,141,70,.14);
}
.search-icon { color: var(--muted-2); margin-left: 13px; flex: 0 0 auto; }
#q {
  flex: 1; border: 0; outline: 0; background: transparent;
  padding: 12px 10px; font-size: 14.5px; color: var(--ink);
  min-width: 0;
}
#q::placeholder { color: var(--muted-2); }
#q::-webkit-search-cancel-button { display: none; }
.clear-btn {
  border: 0; background: #eef1f4; color: var(--muted);
  width: 22px; height: 22px; border-radius: 50%; margin-right: 9px;
  font-size: 16px; line-height: 1; display: grid; place-items: center;
  transition: background .15s, color .15s;
}
.clear-btn:hover { background: #e2545410; color: #d4493f; background: #fbe7e5; }
.search-status {
  font-size: 12px; color: var(--muted); margin-top: 9px; padding-left: 3px;
  min-height: 15px;
}
.search-status b { color: var(--green-darker); font-weight: 700; }

/* ---- Ask AI ---- */
.ai-bar { display: flex; gap: 8px; margin-top: 10px; align-items: center; }
.ai-btn {
  display: inline-flex; align-items: center; gap: 6px;
  border: 0; border-radius: 8px; padding: 8px 13px;
  background: linear-gradient(135deg, var(--green) 0%, var(--green-darker) 100%);
  color: #fff; font-size: 13px; font-weight: 600; cursor: pointer;
  box-shadow: 0 2px 8px rgba(47, 141, 70, .28); transition: filter .14s, transform .05s;
}
.ai-btn:hover { filter: brightness(1.07); }
.ai-btn:active { transform: scale(.97); }
.ai-btn.busy { pointer-events: none; opacity: .65; }
.ai-provider {
  border: 1.4px solid var(--border); border-radius: 8px; padding: 7px 8px;
  font-size: 12.5px; font-weight: 600; color: var(--ink-soft); background: #fff;
  outline: 0; cursor: pointer; flex: 1; min-width: 0;
}
.ai-provider:focus { border-color: var(--green); }

.ai-panel { /* fills the sidebar as a clean "notes" document — no AI branding */
  flex: 1 1 auto; min-height: 0; display: flex; flex-direction: column;
  margin: 0; padding: 0; background: #fff; border: 0;
}
.nt-head {
  display: flex; align-items: center; gap: 8px; flex: 0 0 auto;
  padding: 10px 16px; border-bottom: 1px solid var(--border-2);
}
.nt-title { font-size: 13px; font-weight: 700; color: var(--ink-soft); }
.nt-head .ai-close { margin-left: auto; }
.nt-doc { flex: 1 1 auto; min-height: 0; overflow-y: auto; padding: 6px 16px 28px; }
.nt-q {
  font-size: 12.5px; font-weight: 700; color: var(--green-darker);
  margin: 16px 0 6px; padding-left: 9px; border-left: 3px solid var(--green);
}
.nt-q:first-child { margin-top: 6px; }
.nt-a { font-size: 13.5px; line-height: 1.62; color: var(--ink); }
.nt-a h4, .nt-a h5, .nt-a h6 { margin: 12px 0 5px; line-height: 1.3; color: var(--ink); }
.nt-a h4 { font-size: 15px; }
.nt-a h5 { font-size: 13.5px; }
.nt-a h6 { font-size: 12.5px; color: var(--ink-soft); }
.nt-a p { margin: 7px 0; }
.nt-a ul, .nt-a ol { margin: 7px 0; padding-left: 20px; }
.nt-a li { margin: 3px 0; }
.nt-a strong { font-weight: 700; }
.nt-a code { font-family: var(--mono); font-size: 12px; background: var(--bg); padding: 1px 5px; border-radius: 4px; color: var(--green-darker); }
.nt-a pre.nt-code { background: #1f2630; color: #e6edf3; border-radius: 8px; padding: 11px 13px; overflow-x: auto; margin: 9px 0; }
.nt-a pre.nt-code code { background: none; color: inherit; padding: 0; font-size: 12px; }
.nt-a blockquote { margin: 8px 0; padding: 4px 12px; border-left: 3px solid var(--border); color: var(--muted); }
.nt-a hr { border: none; border-top: 1px solid var(--border); margin: 10px 0; }
.nt-a table.nt-table { border-collapse: collapse; margin: 9px 0; font-size: 12.5px; width: 100%; }
.nt-a .nt-table th, .nt-a .nt-table td { border: 1px solid var(--border); padding: 4px 8px; text-align: left; vertical-align: top; }
.nt-a .nt-table th { background: var(--bg); font-weight: 700; }
.nt-ref { color: var(--green-darker); font-weight: 600; cursor: pointer; border-bottom: 1px dotted var(--green); }
.nt-ref:hover { background: var(--green-tint); }
.nt-caret {
  display: inline-block; width: 7px; height: 15px; vertical-align: -3px; margin-left: 1px;
  background: var(--green); border-radius: 1px; animation: ntblink 1s steps(2) infinite;
}
@keyframes ntblink { 0%, 50% { opacity: 1; } 50.01%, 100% { opacity: 0; } }
.ai-head { display: flex; align-items: center; gap: 8px; margin-bottom: 8px; }
.ai-badge { font-size: 11px; font-weight: 600; color: var(--muted); letter-spacing: .2px; }
.ai-time { font-size: 11px; color: var(--muted-2); font-weight: 600; }
.ai-close {
  margin-left: auto; border: 0; background: transparent; color: var(--muted-2);
  font-size: 18px; line-height: 1; cursor: pointer; width: 22px; height: 22px; border-radius: 6px;
}
.ai-close:hover { background: #eef1f4; color: var(--ink-soft); }
.ai-answer { font-size: 13.5px; line-height: 1.55; color: var(--ink); }
.ai-sources { margin-top: 10px; display: flex; flex-wrap: wrap; gap: 6px; align-items: center; }
.ai-sources-label { font-size: 11.5px; color: var(--muted); font-weight: 600; }
.ai-chip {
  border: 1px solid var(--border); background: var(--bg); color: var(--ink-soft);
  font-size: 11.5px; font-weight: 700; padding: 3px 9px; border-radius: 999px; cursor: pointer;
  transition: all .14s;
}
.ai-chip:hover { background: var(--green-tint); border-color: var(--green); color: var(--green-darker); }
.ai-loading { font-size: 13px; color: var(--ink-soft); display: flex; align-items: center; gap: 8px; }
.ai-dim { color: var(--muted-2); font-size: 12px; }
.ai-error { font-size: 13px; color: #b4322a; line-height: 1.5; }
.ai-spinner {
  width: 15px; height: 15px; border-radius: 50%; display: inline-block;
  border: 2.5px solid var(--green-tint2); border-top-color: var(--green);
  animation: spin .8s linear infinite;
}
/* discreet toast for stealth commands (model switch, controls toggle) */
.ai-toast {
  position: fixed; left: 50%; bottom: 20px; transform: translateX(-50%) translateY(8px);
  background: rgba(31, 35, 40, .92); color: #fff; font-size: 12.5px; font-weight: 600;
  padding: 7px 14px; border-radius: 999px; pointer-events: none; z-index: 100; opacity: 0;
  transition: opacity .18s, transform .18s; box-shadow: 0 6px 20px rgba(16, 24, 40, .28);
}
.ai-toast.show { opacity: 1; transform: translateX(-50%) translateY(0); }

/* example chips */
.examples {
  padding: 13px 16px; display: flex; flex-wrap: wrap; gap: 8px;
  align-items: center; border-bottom: 1px solid var(--border-2);
}
.ex-label { font-size: 12px; color: var(--muted); font-weight: 600; margin-right: 1px; }
.chip {
  border: 1px solid var(--border); background: #fff; color: var(--ink-soft);
  font-size: 12.5px; font-weight: 500;
  padding: 6px 12px; border-radius: 999px;
  transition: all .14s;
}
.chip:hover {
  border-color: var(--green); color: var(--green-darker);
  background: var(--green-tint); transform: translateY(-1px);
}

/* results */
.results { flex: 1; overflow-y: auto; padding: 12px 14px 28px; }
.result-card {
  position: relative; display: block; width: 100%; text-align: left;
  background: var(--card); border: 1px solid var(--border);
  border-radius: var(--radius-sm); padding: 13px 14px 13px 16px;
  margin-bottom: 10px; cursor: pointer;
  transition: border-color .14s, box-shadow .14s, transform .05s;
  overflow: hidden;
}
.result-card::before {
  content: ""; position: absolute; left: 0; top: 0; bottom: 0; width: 3px;
  background: transparent; transition: background .14s;
}
.result-card:hover { border-color: #cfd6dd; box-shadow: var(--shadow); }
.result-card.active { border-color: var(--green); background: #fbfffc; }
.result-card.active::before { background: var(--green); }
.rc-top { display: flex; align-items: center; gap: 8px; margin-bottom: 7px; }
.rc-page {
  font-size: 11.5px; font-weight: 700; color: #fff; background: var(--green);
  padding: 2.5px 8px; border-radius: 6px; letter-spacing: .2px;
}
.rc-lecture {
  font-size: 11.5px; font-weight: 600; color: var(--muted);
  background: var(--bg); border: 1px solid var(--border-2);
  padding: 2.5px 8px; border-radius: 6px;
  white-space: nowrap; overflow: hidden; text-overflow: ellipsis; max-width: 165px;
}
.rc-score {
  margin-left: auto; display: flex; align-items: center; gap: 6px;
  font-size: 10.5px; color: var(--muted-2); font-weight: 600;
}
.rc-bar { width: 42px; height: 5px; border-radius: 3px; background: #edf0f3; overflow: hidden; }
.rc-bar > i { display: block; height: 100%; background: linear-gradient(90deg, var(--green), var(--green-dark)); border-radius: 3px; }
.rc-title {
  font-size: 13.5px; font-weight: 600; color: var(--ink); line-height: 1.35;
  margin-bottom: 5px;
  display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; overflow: hidden;
}
.rc-snippet {
  font-size: 12.5px; color: var(--ink-soft); line-height: 1.5;
  display: -webkit-box; -webkit-line-clamp: 3; -webkit-box-orient: vertical; overflow: hidden;
}
.rc-snippet mark, .hl-pop mark {
  background: rgba(255, 221, 0, .55); color: var(--ink);
  border-radius: 3px; padding: 0 2px; font-weight: 700;
}

/* slide thumbnail (actual rendered slide) inside result cards */
.rc-thumb {
  position: relative; margin-top: 9px;
  border: 1px solid var(--border); border-radius: 7px; overflow: hidden;
  background: #fbfcfd; line-height: 0; aspect-ratio: 4 / 3;
}
.rc-thumb::after { /* shimmer until the slide renders */
  content: ""; position: absolute; inset: 0; z-index: 0;
  background: linear-gradient(110deg, #f1f4f6 30%, #e7ebee 50%, #f1f4f6 70%);
  background-size: 200% 100%; animation: shimmer 1.25s linear infinite;
}
.result-card.thumb-ready .rc-thumb::after,
.result-card.thumb-failed .rc-thumb::after { display: none; }
.result-card.thumb-failed .rc-thumb { aspect-ratio: auto; min-height: 0; border: 0; }
@keyframes shimmer { from { background-position: 200% 0; } to { background-position: -200% 0; } }
.rc-canvas { position: relative; z-index: 1; width: 100%; height: auto; display: block; }
.rc-hl { position: absolute; inset: 0; z-index: 2; pointer-events: none; }
/* yellow word-match highlight — shared by result thumbnails and the main viewer.
   Positioned with CSS % (normalized coords) so it never drifts at zoom. */
.hl-box {
  position: absolute; background: rgba(255, 221, 0, .45);
  mix-blend-mode: multiply; border-radius: 1.5px;
  box-shadow: 0 0 0 1px rgba(228, 170, 0, .38);
  pointer-events: none;
}

/* confidence cutoff: reveal the long tail */
.show-more {
  display: block; width: 100%; margin: 2px 0 16px;
  padding: 10px; border: 1px dashed #d3dae0; border-radius: 9px;
  background: #fff; color: var(--green-darker); font-size: 12.5px; font-weight: 600;
  transition: background .14s, border-color .14s;
}
.show-more:hover { background: var(--green-tint); border-color: var(--green); }

/* hide all hints: live-search helper text + example chips */
.search-status, .examples { display: none !important; }

/* pasted-image attachments (discreet) + question thumbnails in the notes */
.att-strip { display: flex; flex-wrap: wrap; gap: 6px; padding: 7px 2px 0; }
.att-strip[hidden] { display: none; }
.att-thumb { position: relative; display: inline-block; line-height: 0; }
.att-thumb img { height: 34px; width: auto; max-width: 64px; object-fit: cover; border-radius: 5px; border: 1px solid var(--border, #d8dee6); }
.att-x { position: absolute; top: -6px; right: -6px; width: 16px; height: 16px; padding: 0; border: none; border-radius: 50%; background: #41505f; color: #fff; font-size: 12px; line-height: 15px; text-align: center; cursor: pointer; }
.att-x:hover { background: #1f2a36; }
.att-file { position: relative; display: inline-flex; align-items: center; height: 34px; max-width: 200px; padding: 0 10px; border-radius: 5px;
  background: var(--green-tint, #eef6ef); border: 1px solid var(--border, #d8dee6); font-size: 12px; color: var(--ink-soft, #41505f); }
.att-file-name { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.nt-qimgs { display: flex; flex-wrap: wrap; gap: 6px; margin-top: 6px; }
.nt-qimg { max-height: 130px; max-width: 100%; border-radius: 6px; border: 1px solid var(--border, #d8dee6); }

/* Adobe-style page thumbnail panel (the sidebar = PDF page previews) */
.results { padding: 8px 9px 24px; }
.pg-thumb {
  display: block; width: 100%; text-align: center; cursor: pointer;
  background: transparent; border: 0; padding: 7px 5px 3px; margin: 0;
}
.pg-img {
  position: relative; border: 1px solid var(--border); border-radius: 4px; overflow: hidden;
  background: #fbfcfd; line-height: 0; aspect-ratio: 4 / 3; box-shadow: var(--shadow-sm);
  transition: border-color .12s, box-shadow .12s;
}
.pg-thumb:hover .pg-img { border-color: #c2cad2; }
.pg-thumb.active .pg-img { border-color: var(--green); box-shadow: 0 0 0 2px rgba(47, 141, 70, .35); }
.pg-img::after { /* shimmer until the page renders */
  content: ""; position: absolute; inset: 0; z-index: 0;
  background: linear-gradient(110deg, #f1f4f6 30%, #e7ebee 50%, #f1f4f6 70%);
  background-size: 200% 100%; animation: shimmer 1.25s linear infinite;
}
.pg-thumb.thumb-ready .pg-img::after, .pg-thumb.thumb-failed .pg-img::after { display: none; }
.pg-img .rc-canvas { position: relative; z-index: 1; width: 100%; height: auto; display: block; }
.pg-img .rc-hl { position: absolute; inset: 0; z-index: 2; pointer-events: none; }
.pg-num { font-size: 11px; color: var(--muted); font-weight: 600; margin-top: 4px; }
.pg-thumb.active .pg-num { color: var(--green-darker); }

/* rich result card (search mode): thumbnail with yellow matches + meta + snippet */
.pg-thumb.result {
  text-align: left; padding: 9px; margin-bottom: 9px;
  border: 1px solid var(--border); border-radius: 10px; background: #fff;
  transition: border-color .12s, box-shadow .12s;
}
.pg-thumb.result:hover { border-color: #cfd6dd; box-shadow: var(--shadow); }
.pg-thumb.result.active { border-color: var(--green); background: #fbfffc; }
.pg-thumb.result.active .pg-img { border-color: var(--green); box-shadow: none; }
.rc-meta { margin-top: 8px; }
.rc-meta .rc-top { display: flex; align-items: center; gap: 6px; margin-bottom: 6px; }
.rc-meta .rc-bar { margin-left: auto; width: 40px; height: 5px; border-radius: 3px; background: #edf0f3; overflow: hidden; flex: 0 0 auto; }
.rc-meta .rc-bar > i { display: block; height: 100%; background: linear-gradient(90deg, var(--green), var(--green-dark)); border-radius: 3px; }
.pg-thumb.result .rc-snippet {
  font-size: 12px; color: var(--ink-soft); line-height: 1.45;
  display: -webkit-box; -webkit-line-clamp: 3; -webkit-box-orient: vertical; overflow: hidden;
}

/* empty / no-results states */
.state-msg {
  text-align: center; color: var(--muted); padding: 40px 24px;
}
.state-msg .ico { color: #c4ccd4; margin-bottom: 14px; }
.state-msg h3 { margin: 0 0 6px; font-size: 15px; color: var(--ink-soft); font-weight: 600; }
.state-msg p { margin: 0; font-size: 13px; line-height: 1.5; }

/* ---------------- Viewer ---------------- */
.viewer { flex: 1; display: flex; flex-direction: column; min-width: 0; min-height: 0; background: var(--bg-canvas); }
.toolbar {
  height: 52px; flex: 0 0 52px;
  background: #fff; border-bottom: 1px solid var(--border);
  display: flex; align-items: center; gap: 12px; padding: 0 14px;
  z-index: 10;
}
.tb-group { display: flex; align-items: center; gap: 4px; }
.tb-right { margin-left: 0; gap: 6px; }
.tb-lecture {
  flex: 1; text-align: center; font-size: 13px; font-weight: 600;
  color: var(--ink-soft); white-space: nowrap; overflow: hidden; text-overflow: ellipsis;
  padding: 0 8px;
}
.tb-btn {
  border: 1px solid transparent; background: transparent; color: var(--ink-soft);
  width: 34px; height: 34px; border-radius: 8px; display: grid; place-items: center;
  transition: background .13s, color .13s;
}
.tb-btn:hover { background: var(--green-tint); color: var(--green-darker); }
.tb-btn:active { transform: scale(.94); }
.tb-btn[disabled] { opacity: .35; pointer-events: none; }
.tb-btn-text { width: auto; padding: 0 12px; font-size: 13px; font-weight: 600; }
.page-ctl { display: flex; align-items: center; gap: 5px; padding: 0 3px; }
#pageInput {
  width: 50px; text-align: center; border: 1.4px solid var(--border);
  border-radius: 7px; padding: 6px 4px; font-size: 13px; font-weight: 600;
  color: var(--ink); outline: 0; transition: border-color .14s, box-shadow .14s;
}
#pageInput:focus { border-color: var(--green); box-shadow: 0 0 0 3px rgba(47,141,70,.13); }
.page-total { font-size: 13px; color: var(--muted); font-weight: 500; }
.zoom-level { font-size: 12.5px; color: var(--muted); font-weight: 600; min-width: 40px; text-align: center; }
.lecture-select {
  border: 1.4px solid var(--border); border-radius: 7px; padding: 6px 8px;
  font-size: 12.5px; font-weight: 600; color: var(--ink-soft); background: #fff;
  outline: 0; max-width: 150px; cursor: pointer;
}
.lecture-select:focus { border-color: var(--green); }

/* canvas scroll area */
.canvas-scroll {
  flex: 1; overflow: auto; position: relative;
  display: flex; align-items: flex-start; justify-content: center;
  padding: 26px;
  background: var(--bg-canvas);
}
.page-wrap {
  position: relative; background: #fff; box-shadow: var(--shadow-lg);
  border-radius: 3px; line-height: 0;
}
#pdfCanvas { display: block; border-radius: 3px; }
.hl-layer { position: absolute; inset: 0; pointer-events: none; z-index: 2; }

/* loading + error */
.loading { position: absolute; inset: 0; display: grid; place-content: center; justify-items: center; gap: 14px; color: var(--muted); }
.loading p { margin: 0; font-size: 13.5px; font-weight: 500; }
.spinner {
  width: 38px; height: 38px; border-radius: 50%;
  border: 3.5px solid var(--green-tint2); border-top-color: var(--green);
  animation: spin .8s linear infinite;
}
@keyframes spin { to { transform: rotate(360deg); } }
.viewer-error {
  position: absolute; top: 50%; left: 50%; transform: translate(-50%, -50%);
  max-width: 440px; text-align: center; color: var(--muted);
  background: #fff; border: 1px solid var(--border); border-radius: var(--radius);
  padding: 26px 28px; box-shadow: var(--shadow);
}
.viewer-error h3 { color: var(--ink); margin: 0 0 8px; font-size: 16px; }
.viewer-error code { font-family: var(--mono); background: var(--bg); padding: 2px 6px; border-radius: 5px; font-size: 12px; color: var(--green-darker); }

/* ---------------- scrollbars ---------------- */
.results::-webkit-scrollbar, .canvas-scroll::-webkit-scrollbar { width: 11px; height: 11px; }
.results::-webkit-scrollbar-thumb, .canvas-scroll::-webkit-scrollbar-thumb {
  background: #cdd4db; border-radius: 8px; border: 3px solid transparent; background-clip: content-box;
}
.results::-webkit-scrollbar-thumb:hover, .canvas-scroll::-webkit-scrollbar-thumb:hover { background: #b3bcc6; background-clip: content-box; border: 3px solid transparent; }

/* ---------------- SQL sandbox ---------------- */
.sbx-backdrop { position: fixed; inset: 0; background: rgba(16, 24, 40, .28); z-index: 200; }
.sbx-panel {
  position: fixed; top: 0; right: 0; bottom: 0; width: min(660px, 94vw);
  background: #fff; z-index: 201; display: flex; flex-direction: column;
  box-shadow: -8px 0 34px rgba(16, 24, 40, .20); border-left: 1px solid var(--border);
}
.sbx-panel.sbx-drag { outline: 2.5px dashed var(--green); outline-offset: -8px; }
.sbx-head { display: flex; align-items: center; gap: 10px; padding: 11px 14px; border-bottom: 1px solid var(--border-2); }
.sbx-title { font-size: 14px; font-weight: 700; color: var(--ink); }
.sbx-engine { font-size: 11.5px; font-weight: 700; padding: 3px 9px; border-radius: 999px; cursor: pointer; user-select: none; }
.sbx-engine.ok { color: var(--green-darker); background: var(--green-tint); border: 1px solid var(--green-tint2); }
.sbx-engine.warn { color: #8a6d00; background: #fff7da; border: 1px solid #f0e3a8; }
.sbx-engine small { font-weight: 600; opacity: .82; }
.sbx-x { margin-left: auto; border: 0; background: transparent; color: var(--muted-2); font-size: 20px; line-height: 1; width: 26px; height: 26px; border-radius: 6px; }
.sbx-x:hover { background: #eef1f4; color: var(--ink-soft); }
.sbx-tools { display: flex; align-items: center; gap: 8px; padding: 9px 14px; border-bottom: 1px solid var(--border-2); flex-wrap: wrap; }
.sbx-btn { border: 0; border-radius: 8px; padding: 7px 13px; font-size: 12.5px; font-weight: 600; cursor: pointer;
  background: linear-gradient(135deg, var(--green), var(--green-darker)); color: #fff; }
.sbx-btn:hover { filter: brightness(1.06); }
.sbx-btn.sbx-ghost { background: #fff; color: var(--ink-soft); border: 1.4px solid var(--border); }
.sbx-btn.sbx-ghost:hover { border-color: var(--green); color: var(--green-darker); background: var(--green-tint); }
.sbx-file { display: inline-flex; align-items: center; }
.sbx-hint { font-size: 11.5px; color: var(--muted-2); margin-left: auto; }
.sbx-editor {
  flex: 0 0 auto; height: 33%; min-height: 110px; resize: vertical; border: 0; border-bottom: 1px solid var(--border-2);
  padding: 12px 14px; font-family: var(--mono); font-size: 13px; line-height: 1.5; color: var(--ink); outline: 0; background: #fcfdfe;
}
.sbx-results { flex: 1 1 auto; overflow: auto; padding: 12px 14px 24px; background: #fff; }
.sbx-empty, .sbx-dim { color: var(--muted-2); font-size: 12.5px; }
.sbx-ok { color: var(--green-darker); font-weight: 700; font-size: 13px; margin-bottom: 6px; }
.sbx-err { color: #b4322a; font-size: 12.5px; white-space: pre-wrap; background: #fdecea; border: 1px solid #f5c6c0; border-radius: 8px; padding: 9px 11px; font-family: var(--mono); }
.sbx-tablelist { font-size: 12px; color: var(--ink-soft); line-height: 1.8; }
.sbx-tablelist code { background: var(--bg); padding: 1px 6px; border-radius: 5px; color: var(--green-darker); font-family: var(--mono); }
.sbx-set { margin-bottom: 16px; }
.sbx-tablewrap { overflow: auto; border: 1px solid var(--border); border-radius: 8px; }
.sbx-table { border-collapse: collapse; font-size: 12.5px; width: 100%; }
.sbx-table th, .sbx-table td { border-bottom: 1px solid var(--border-2); border-right: 1px solid var(--border-2); padding: 5px 9px; text-align: left; white-space: nowrap; vertical-align: top; }
.sbx-table th { background: var(--bg); font-weight: 700; position: sticky; top: 0; }
.sbx-table tr:nth-child(even) td { background: #fbfcfd; }
.sbx-null { color: var(--muted-2); font-style: italic; }
.sbx-count { font-size: 11.5px; color: var(--muted); margin-top: 5px; }
.sbx-busy .sbx-run { opacity: .6; pointer-events: none; }

/* tutor answer: Run button under a generated SQL block + its inline result */
.nt-runbar { margin: -4px 0 9px; }
.nt-run { border: 1px solid var(--green-tint2); border-radius: 7px; padding: 5px 12px; font-size: 12px; font-weight: 700;
  cursor: pointer; background: var(--green-tint); color: var(--green-darker); }
.nt-run:hover { background: var(--green-tint2); }
.nt-run:disabled { opacity: .55; cursor: default; }
.nt-copy { background: #fff; color: var(--ink-soft); border-color: var(--border); margin-left: 6px; }
.nt-copy:hover { background: var(--green-tint); color: var(--green-darker); border-color: var(--green-tint2); }
.nt-sql-result { margin: 0 0 12px; }
.nt-sql-result .sbx-table { font-size: 12px; }
.nt-sql-result .sbx-tablewrap { max-height: 280px; }

/* ---------------- responsive ---------------- */
@media (max-width: 880px) {
  .layout { flex-direction: column; }
  .sidebar { width: 100%; flex: 0 0 auto; max-height: 46vh; border-right: 0; border-bottom: 1px solid var(--border); }
  .viewer { flex: 1 1 auto; }
  .tb-lecture { display: none; }
  :root { --sidebar-w: 100%; }
}