:root {
  --bg: #eef8fd;
  --bg-2: #f8fcff;
  --ink: #1f3142;
  --muted: #71899f;
  --blue: #2f91d5;
  --blue-dark: #1976b8;
  --blue-soft: #e3f3fc;
  --line: rgba(47, 145, 213, .22);
  --line-soft: rgba(47, 145, 213, .14);
  --danger: #e85d75;
  --paper: #ffffff;
  --shadow: 0 20px 50px rgba(38, 91, 130, .12);
}

* { box-sizing: border-box; }
html, body { width: 100%; height: 100%; margin: 0; overflow: hidden; }
body {
  font-family: "Segoe UI", Inter, system-ui, -apple-system, BlinkMacSystemFont, sans-serif;
  color: var(--ink);
  background:
    linear-gradient(90deg, rgba(47,145,213,.045) 1px, transparent 1px),
    linear-gradient(rgba(47,145,213,.045) 1px, transparent 1px),
    radial-gradient(circle at 10% 8%, rgba(47,145,213,.16), transparent 34%),
    radial-gradient(circle at 86% 8%, rgba(115,180,224,.14), transparent 30%),
    linear-gradient(135deg, var(--bg), var(--bg-2));
  background-size: 28px 28px, 28px 28px, auto, auto, auto;
}

button, input, label { font: inherit; }
button, label { user-select: none; }
button { cursor: pointer; }

.topbar {
  position: fixed;
  top: 14px;
  left: 18px;
  right: 18px;
  z-index: 10;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  pointer-events: none;
}

.brand,
.top-actions {
  pointer-events: auto;
  display: flex;
  align-items: center;
  border: 1px solid var(--line-soft);
  background: rgba(255,255,255,.82);
  box-shadow: 0 14px 34px rgba(38,91,130,.10);
  backdrop-filter: blur(12px);
}

.brand {
  min-height: 48px;
  gap: 10px;
  padding: 8px 14px 8px 9px;
  border-radius: 18px;
  color: var(--ink);
  text-decoration: none;
  font-weight: 850;
}

.brand-copy {
  display: grid;
  line-height: 1.05;
}

.brand-copy strong { font-size: 15px; }
.brand-copy small {
  color: var(--blue-dark);
  font-size: 11px;
  font-weight: 750;
  margin-top: 4px;
}

.brand img {
  width: 34px;
  height: 34px;
  border-radius: 11px;
}

.top-actions {
  gap: 8px;
  padding: 8px;
  border-radius: 20px;
}

.action {
  min-height: 38px;
  border: 1px solid var(--line);
  border-radius: 14px;
  background: rgba(255,255,255,.72);
  color: var(--ink);
  padding: 9px 13px;
  font-size: 14px;
  font-weight: 750;
  text-decoration: none;
  transition: background .15s ease, transform .15s ease, color .15s ease;
}

.action:hover { transform: translateY(-1px); background: var(--blue-soft); }
.action.primary {
  color: #fff;
  background: var(--blue);
  border-color: transparent;
  box-shadow: 0 12px 22px rgba(47,145,213,.24);
}
.action.primary:hover { background: var(--blue-dark); }

.board-shell {
  width: 100vw;
  height: 100vh;
  padding: 78px 16px 16px;
}

.board-surface {
  position: relative;
  width: 100%;
  height: 100%;
  overflow: auto;
  border: 1px solid rgba(47,145,213,.10);
  border-radius: 28px;
  background: rgba(255,255,255,.34);
  box-shadow: inset 0 0 0 1px rgba(255,255,255,.50);
}

.canvas-layout {
  min-width: 1480px;
  min-height: 720px;
  height: 100%;
  padding: 64px clamp(24px, 3vw, 54px) 94px;
  display: grid;
  grid-template-columns: minmax(680px, 1fr) minmax(680px, 1fr);
  align-items: start;
  justify-content: stretch;
  gap: clamp(24px, 3.2vw, 52px);
}

.floating-tools {
  position: absolute;
  left: 50%;
  bottom: 18px;
  z-index: 8;
  transform: translateX(-50%);
  display: flex;
  flex-direction: row;
  align-items: center;
  gap: 7px;
  padding: 8px;
  border: 1px solid var(--line-soft);
  border-radius: 20px;
  background: rgba(255,255,255,.86);
  box-shadow: 0 16px 34px rgba(38,91,130,.12);
  backdrop-filter: blur(12px);
}

.tool {
  width: 38px;
  height: 38px;
  border: 1px solid var(--line);
  border-radius: 13px;
  background: #fff;
  color: var(--blue-dark);
  font-size: 20px;
  font-weight: 850;
  line-height: 1;
}

.tool:hover,
.tool.active { background: var(--blue); color: #fff; border-color: transparent; }
.tool.danger { color: var(--danger); }
.tool.danger:hover { background: var(--danger); color: #fff; }
.select-tool {
  display: inline-flex;
  align-items: center;
  justify-content: center;
}
.select-icon {
  width: 20px;
  height: 22px;
  display: inline-block;
  background: currentColor;
  clip-path: polygon(12% 0, 82% 55%, 53% 59%, 70% 96%, 55% 100%, 39% 64%, 18% 86%);
}
.marker-tool {
  display: inline-flex;
  align-items: center;
  justify-content: center;
}
.marker-icon {
  width: 20px;
  height: 18px;
  display: inline-block;
  transform: rotate(-12deg);
  border-radius: 4px 4px 6px 6px;
  background: #f4a7c6;
  box-shadow: inset 0 0 0 2px currentColor;
}
.eraser-tool {
  display: inline-flex;
  align-items: center;
  justify-content: center;
}
.eraser-icon {
  position: relative;
  width: 22px;
  height: 15px;
  display: inline-block;
  transform: rotate(-18deg);
  border: 2px solid currentColor;
  border-radius: 5px;
  background: linear-gradient(90deg, currentColor 0 34%, #fff 34% 100%);
}
.eraser-icon::after {
  content: "";
  position: absolute;
  left: 4px;
  right: 4px;
  bottom: -6px;
  height: 2px;
  border-radius: 999px;
  background: currentColor;
  opacity: .35;
}

.color {
  width: 36px;
  height: 36px;
  padding: 0;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: #fff;
  overflow: hidden;
}
.color::-webkit-color-swatch-wrapper {
  padding: 0;
}
.color::-webkit-color-swatch {
  border: 3px solid #fff;
  border-radius: 999px;
}
.color::-moz-color-swatch {
  border: 3px solid #fff;
  border-radius: 999px;
}

.size {
  width: 92px;
  height: 22px;
  appearance: none;
  transform: none;
  margin: 0;
  background: transparent;
}
.size::-webkit-slider-runnable-track {
  height: 7px;
  border-radius: 999px;
  background: linear-gradient(90deg, var(--blue) 0 var(--size-progress, 20%), rgba(31,49,66,.72) var(--size-progress, 20%) 100%);
}
.size::-webkit-slider-thumb {
  appearance: none;
  width: 18px;
  height: 18px;
  margin-top: -5px;
  border: 3px solid #fff;
  border-radius: 999px;
  background: var(--blue);
  box-shadow: 0 4px 10px rgba(38,91,130,.22);
}
.size::-moz-range-track {
  height: 7px;
  border-radius: 999px;
  background: rgba(31,49,66,.72);
}
.size::-moz-range-progress {
  height: 7px;
  border-radius: 999px;
  background: var(--blue);
}
.size::-moz-range-thumb {
  width: 14px;
  height: 14px;
  border: 3px solid #fff;
  border-radius: 999px;
  background: var(--blue);
  box-shadow: 0 4px 10px rgba(38,91,130,.22);
}

.slide-object,
.notes-column { position: relative; }

.slide-object {
  border-radius: 22px;
}

.slide-top {
  width: fit-content;
  margin: 0 auto 10px;
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 6px;
  border: 1px solid var(--line-soft);
  border-radius: 999px;
  background: rgba(255,255,255,.82);
  color: var(--muted);
  font-size: 13px;
  font-weight: 800;
  box-shadow: 0 10px 24px rgba(38,91,130,.08);
}

.page-btn {
  width: 30px;
  height: 30px;
  border: 0;
  border-radius: 999px;
  background: var(--blue-soft);
  color: var(--blue-dark);
  font-size: 23px;
  line-height: 1;
}
.page-btn:hover { background: var(--blue); color: #fff; }

.slide-frame {
  position: relative;
  width: min(100%, 980px);
  aspect-ratio: var(--slide-ratio, 16 / 9);
  height: auto;
  border-radius: 10px;
  background: transparent;
}

.slide-frame canvas,
.note-sheet canvas {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  touch-action: none;
  user-select: none;
}

#slideBase {
  z-index: 1;
  background: #fff;
  border-radius: 8px;
  box-shadow: var(--shadow);
}

#slideInk {
  z-index: 2;
  cursor: crosshair;
  border-radius: 8px;
}

.notes-column {
  padding-top: 0;
}

.notes-tools {
  position: relative;
  z-index: 4;
  display: flex;
  flex-direction: row;
  align-items: center;
  justify-content: center;
  gap: 10px;
  width: min(100%, 980px);
  margin: 0 auto 10px;
}

.notes-tools[hidden] {
  display: none;
}

.note-tool {
  width: 44px;
  height: 44px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: rgba(255,255,255,.88);
  color: var(--blue-dark);
  font-size: 25px;
  font-weight: 900;
  line-height: 1;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 12px 24px rgba(38,91,130,.12);
  backdrop-filter: blur(10px);
}

.note-tool:hover {
  background: var(--blue);
  color: #fff;
  border-color: transparent;
}

.sheet-switcher {
  order: -1;
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 6px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: rgba(255,255,255,.88);
  color: var(--blue-dark);
  box-shadow: 0 12px 24px rgba(38,91,130,.12);
}

.sheet-arrow {
  width: 30px;
  height: 30px;
  border: 0;
  border-radius: 999px;
  background: var(--blue-soft);
  color: var(--blue-dark);
  font-size: 24px;
  line-height: 1;
}

.sheet-arrow:hover {
  background: var(--blue);
  color: #fff;
}

.sheet-arrow:disabled {
  opacity: .42;
  cursor: default;
}

#sheetCounter {
  min-width: 42px;
  text-align: center;
  color: var(--muted);
  font-size: 12px;
  font-weight: 850;
}

.book-icon {
  position: relative;
  width: 23px;
  height: 25px;
  display: inline-block;
}

.book-icon::before,
.book-icon::after {
  content: "";
  position: absolute;
  top: 2px;
  width: 11px;
  height: 20px;
  border: 2px solid currentColor;
  background: #fff;
}

.book-icon::before {
  left: 1px;
  border-radius: 5px 2px 2px 5px;
  transform: skewY(-6deg);
}

.book-icon::after {
  right: 1px;
  border-radius: 2px 5px 5px 2px;
  transform: skewY(6deg);
}

.note-tool:hover .book-icon::before,
.note-tool:hover .book-icon::after {
  background: rgba(255,255,255,.92);
}

.notes-stack {
  position: relative;
  width: min(100%, 980px);
  aspect-ratio: var(--slide-ratio, 16 / 9);
  height: auto;
}

.note-sheet {
  position: absolute;
  inset: 0;
  display: none;
  width: 100%;
  height: 100%;
  border: 1.5px solid rgba(47,145,213,.34);
  border-radius: 18px;
  background:
    linear-gradient(#fff 31px, rgba(47,145,213,.12) 32px),
    #fff;
  background-size: 100% 32px;
  box-shadow: 0 16px 36px rgba(38,91,130,.08);
}

.note-sheet.active-note {
  display: block;
}

.note-sheet.active-zone,
.slide-frame.active-zone {
  outline: 3px solid rgba(47,145,213,.16);
  outline-offset: 5px;
}

.note-ink {
  z-index: 2;
  cursor: crosshair;
  border-radius: 18px;
}

.selection-box {
  position: absolute;
  z-index: 7;
  border: 2px solid var(--blue);
  border-radius: 8px;
  box-shadow: 0 0 0 3px rgba(255,255,255,.72), 0 10px 24px rgba(38,91,130,.16);
  cursor: move;
  touch-action: none;
}

.selection-box.draft {
  background: rgba(47,145,213,.08);
  border-style: dashed;
}

.selection-preview {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  border-radius: 6px;
  pointer-events: none;
}

.selection-handle {
  position: absolute;
  width: 12px;
  height: 12px;
  border: 2px solid var(--blue);
  border-radius: 4px;
  background: #fff;
  box-shadow: 0 3px 8px rgba(38,91,130,.18);
}

.selection-handle.nw { left: -7px; top: -7px; cursor: nwse-resize; }
.selection-handle.ne { right: -7px; top: -7px; cursor: nesw-resize; }
.selection-handle.sw { left: -7px; bottom: -7px; cursor: nesw-resize; }
.selection-handle.se { right: -7px; bottom: -7px; cursor: nwse-resize; }

.selection-rotate {
  position: absolute;
  left: 50%;
  top: -34px;
  width: 15px;
  height: 15px;
  transform: translateX(-50%);
  border: 2px solid var(--blue);
  border-radius: 999px;
  background: #fff;
  box-shadow: 0 3px 8px rgba(38,91,130,.18);
  cursor: grab;
}

.selection-rotate::after {
  content: "";
  position: absolute;
  left: 50%;
  top: 13px;
  width: 2px;
  height: 20px;
  transform: translateX(-50%);
  background: var(--blue);
  opacity: .72;
}

.add-note-sheet {
  font-size: 28px;
  padding-bottom: 3px;
}

.modal {
  width: min(680px, 92vw);
  border: 0;
  border-radius: 24px;
  padding: 22px;
  color: var(--ink);
  background: rgba(255,255,255,.96);
  box-shadow: 0 30px 90px rgba(31,49,66,.25);
}
.modal::backdrop { background: rgba(31,49,66,.22); backdrop-filter: blur(3px); }
.modal-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 18px;
}
.modal h2 { margin: 0; font-size: 24px; letter-spacing: 0; }
.icon-close {
  width: 34px;
  height: 34px;
  border: 0;
  border-radius: 12px;
  background: var(--blue-soft);
  color: var(--blue-dark);
  font-size: 22px;
  line-height: 1;
}

.soft-link {
  margin-left: auto;
  border: 0;
  border-radius: 999px;
  background: var(--blue-soft);
  color: var(--blue-dark);
  padding: 8px 12px;
  font-size: 13px;
  font-weight: 850;
}

.soft-link:hover {
  background: var(--blue);
  color: #fff;
}

.library-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
}
.library-grid button {
  min-height: 82px;
  border: 1px solid var(--line);
  border-radius: 16px;
  background: #f7fbfe;
  color: var(--ink);
  font-weight: 800;
}
.library-grid button:hover { background: var(--blue-soft); }
.library-grid[hidden] {
  display: none;
}

.library-items {
  min-height: 188px;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
}

.library-items[hidden] {
  display: none;
}

.library-card {
  min-height: 118px;
  border: 1px solid var(--line);
  border-radius: 16px;
  background: #f7fbfe;
  overflow: hidden;
  display: grid;
  grid-template-rows: 1fr auto;
  padding: 0;
  text-align: left;
}

.library-card img {
  width: 100%;
  height: 92px;
  object-fit: contain;
  background:
    linear-gradient(45deg, #eef5fb 25%, transparent 25%),
    linear-gradient(-45deg, #eef5fb 25%, transparent 25%),
    linear-gradient(45deg, transparent 75%, #eef5fb 75%),
    linear-gradient(-45deg, transparent 75%, #eef5fb 75%),
    #ffffff;
  background-size: 18px 18px;
  background-position: 0 0, 0 9px, 9px -9px, -9px 0;
}

.library-card span {
  padding: 8px 10px;
  color: var(--muted);
  font-size: 12px;
  font-weight: 750;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.library-card:hover {
  background: var(--blue-soft);
}

.library-empty {
  grid-column: 1 / -1;
  min-height: 120px;
  border: 1px dashed var(--line);
  border-radius: 16px;
  display: grid;
  place-items: center;
  color: var(--muted);
  font-weight: 750;
}
.library-upload {
  margin-top: 18px;
  padding-top: 16px;
  border-top: 1px solid var(--line-soft);
  display: flex;
  align-items: center;
  gap: 14px;
}
.library-upload[hidden] {
  display: none;
}
.library-upload p {
  margin: 0;
  color: var(--muted);
  font-size: 13px;
  line-height: 1.35;
}

.ai-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 12px;
}
.ai-grid label {
  display: grid;
  gap: 6px;
  color: var(--muted);
  font-size: 13px;
  font-weight: 750;
}
.ai-grid input,
.ai-grid textarea,
.ai-grid select {
  min-height: 42px;
  border: 1px solid var(--line);
  border-radius: 14px;
  padding: 10px 12px;
  color: var(--ink);
  background: #fff;
  font: inherit;
}
.ai-grid textarea {
  min-height: 92px;
  resize: vertical;
  line-height: 1.35;
}
.ai-notes-field {
  grid-column: 1 / -1;
}
.checks {
  margin: 16px 0 0;
  padding: 0;
  border: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}
.checks label {
  padding: 8px 12px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: #f7fbfe;
  color: var(--ink);
  font-size: 13px;
  font-weight: 750;
}
.checks input { accent-color: var(--blue); }
.ai-footer {
  margin-top: 18px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
}
.ai-mode-note {
  color: var(--blue-dark);
  font-weight: 800;
  font-size: 13px;
}
.ai-status {
  min-height: 20px;
  margin: 12px 0 0;
  color: var(--muted);
  line-height: 1.4;
}

.toast {
  position: fixed;
  left: 50%;
  bottom: 22px;
  z-index: 20;
  transform: translate(-50%, 18px);
  opacity: 0;
  visibility: hidden;
  max-width: min(560px, 92vw);
  padding: 12px 16px;
  border: 1px solid var(--line);
  border-radius: 16px;
  background: rgba(255,255,255,.94);
  color: var(--ink);
  box-shadow: 0 16px 36px rgba(38,91,130,.12);
  transition: opacity .18s ease, transform .18s ease, visibility .18s ease;
}
.toast.show {
  opacity: 1;
  visibility: visible;
  transform: translate(-50%, 0);
}

@media (max-width: 980px) {
  html, body { overflow: auto; }
  .topbar {
    position: sticky;
    top: 0;
    left: 0;
    right: 0;
    padding: 10px;
    background: rgba(238,248,253,.9);
    align-items: flex-start;
    flex-direction: column;
  }
  .top-actions { flex-wrap: wrap; }
  .board-shell { height: auto; min-height: 100vh; padding: 10px; }
  .board-surface { overflow: auto; min-height: 820px; }
  .canvas-layout {
    min-width: 0;
    min-height: 0;
    padding: 86px 16px 96px;
    grid-template-columns: 1fr;
    justify-items: center;
  }
  .floating-tools { left: 16px; right: 16px; transform: none; overflow-x: auto; justify-content: center; }
  .slide-frame {
    width: min(92vw, 640px);
    aspect-ratio: var(--slide-ratio, 16 / 9);
    height: auto;
  }
  .notes-column { padding-top: 0; }
  .notes-tools {
    position: static;
    margin-bottom: 10px;
    flex-direction: row;
    justify-content: flex-end;
  }
  .notes-tools,
  .notes-stack { width: min(92vw, 620px); }
  .ai-grid, .library-grid { grid-template-columns: 1fr; }
  .library-upload { align-items: flex-start; flex-direction: column; }
}