:root {
  --bg: #efede8;
  --panel: #faf9f6;
  --ink: #1c1c1e;
  --ink-soft: #5c5a55;
  --muted: #9a978f;
  --line: rgba(20, 18, 12, 0.08);
  --dot: rgba(20, 18, 12, 0.13);
  --accent: #3b6cf6;
  --well: rgba(255, 255, 255, 0.42);
  --chip: rgba(20, 18, 12, 0.06);
  --shadow: 0 1px 2px rgba(20, 18, 12, 0.06), 0 8px 24px -10px rgba(20, 18, 12, 0.18);
  --shadow-lift: 0 2px 4px rgba(20, 18, 12, 0.08), 0 22px 44px -14px rgba(20, 18, 12, 0.32);

  --c0: #fbefb0;
  --c1: #fcdcc8;
  --c2: #d2ecd9;
  --c3: #d5e3fa;
  --c4: #e5dbfa;
  --c5: #f9d7e2;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0d0d0f;
    --panel: #151517;
    --ink: #ecebe8;
    --ink-soft: #b4b2ad;
    --muted: #6f6d68;
    --line: rgba(255, 255, 255, 0.07);
    --dot: rgba(255, 255, 255, 0.09);
    --accent: #7b9cff;
    --well: rgba(0, 0, 0, 0.18);
    --chip: rgba(255, 255, 255, 0.07);
    --shadow: 0 1px 2px rgba(0, 0, 0, 0.4), 0 10px 28px -10px rgba(0, 0, 0, 0.6);
    --shadow-lift: 0 2px 4px rgba(0, 0, 0, 0.5), 0 24px 48px -12px rgba(0, 0, 0, 0.8);

    --c0: #47402a;
    --c1: #4b3427;
    --c2: #263f2f;
    --c3: #26364d;
    --c4: #372d4e;
    --c5: #482b37;
  }
}

* { box-sizing: border-box; }

html, body { height: 100%; margin: 0; }

body {
  display: flex;
  flex-direction: column;
  gap: 14px;
  padding: 22px 24px 24px;
  background: var(--bg);
  color: var(--ink);
  font: 14px/1.4 Inter, ui-sans-serif, system-ui, -apple-system, "Segoe UI", sans-serif;
  -webkit-font-smoothing: antialiased;
  overflow: hidden;
}

button {
  font: inherit;
  color: inherit;
  background: none;
  border: 0;
  padding: 0;
  cursor: pointer;
}

svg { width: 16px; height: 16px; fill: none; stroke: currentColor; stroke-width: 1.6; stroke-linecap: round; stroke-linejoin: round; }

/* ---------- header ---------- */

.top {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 16px;
  padding: 0 6px;
  min-height: 40px;
}

.crumbs {
  display: flex;
  align-items: baseline;
  gap: 10px;
  min-width: 0;
  overflow: hidden;
  white-space: nowrap;
}

.crumbs h1 { margin: 0; font-size: 30px; font-weight: 700; letter-spacing: -0.035em; }

.crumbs .sep { color: var(--muted); font-size: 18px; }

.crumbs .crumb {
  font-size: 18px;
  font-weight: 600;
  letter-spacing: -0.015em;
  color: var(--ink-soft);
  overflow: hidden;
  text-overflow: ellipsis;
  max-width: 260px;
}

.crumbs .crumb:last-child { color: var(--ink); }
.crumbs button:hover { opacity: 0.7; }

.status { font-size: 12px; color: var(--muted); transition: opacity 0.4s; }

/* ---------- canvas ---------- */

.canvas {
  position: relative;
  flex: 1;
  min-height: 0;
  border-radius: 28px;
  background-color: color-mix(in srgb, var(--panel) 45%, var(--bg));
  border: 1px solid var(--line);
  box-shadow: 0 1px 0 rgba(255, 255, 255, 0.6) inset, 0 30px 60px -40px rgba(0, 0, 0, 0.25);
  overflow: hidden;
  touch-action: none;
  cursor: default;
}

.canvas.morphing { pointer-events: none; }

.world { position: absolute; }

.empty {
  position: absolute;
  inset: 0;
  display: grid;
  place-content: center;
  text-align: center;
  pointer-events: none;
  color: var(--muted);
}
.empty[hidden] { display: none; }
.empty-title { font-size: 20px; font-weight: 600; color: var(--ink-soft); letter-spacing: -0.02em; }
.empty-sub { margin-top: 4px; }

/* ---------- toolbar ---------- */

.toolbar {
  position: absolute;
  left: 50%;
  bottom: 18px;
  transform: translateX(-50%);
  display: flex;
  align-items: center;
  gap: 2px;
  padding: 5px;
  border-radius: 14px;
  background: var(--panel);
  border: 1px solid var(--line);
  box-shadow: var(--shadow);
}

.tb-btn {
  display: flex;
  align-items: center;
  gap: 6px;
  height: 32px;
  padding: 0 10px;
  border-radius: 9px;
  font-weight: 500;
  font-size: 13px;
  color: var(--ink-soft);
}
.tb-btn:hover { background: var(--chip); color: var(--ink); }
.tb-btn.primary { background: var(--ink); color: var(--panel); padding: 0 12px 0 10px; }
.tb-btn.primary:hover { opacity: 0.88; }
.tb-btn.icon { width: 32px; padding: 0; justify-content: center; }
.tb-btn.zoom { min-width: 52px; justify-content: center; font-variant-numeric: tabular-nums; }
.tb-btn[hidden], .tb-sep[hidden] { display: none; }
.tb-sep { width: 1px; height: 18px; background: var(--line); margin: 0 6px; }

/* ---------- boxes ---------- */

.box {
  position: absolute;
  display: flex;
  flex-direction: column;
  background: var(--c);
  border-radius: 14px;
  box-shadow: var(--shadow);
  transition: box-shadow 0.18s, opacity 0.25s;
}

.box.c0 { --c: var(--c0); }
.box.c1 { --c: var(--c1); }
.box.c2 { --c: var(--c2); }
.box.c3 { --c: var(--c3); }
.box.c4 { --c: var(--c4); }
.box.c5 { --c: var(--c5); }

.box.selected { box-shadow: 0 0 0 2px var(--accent), var(--shadow); }
.box.lifting { box-shadow: var(--shadow-lift); }
.box.selected.lifting { box-shadow: 0 0 0 2px var(--accent), var(--shadow-lift); }

.head {
  flex: none;
  display: flex;
  align-items: center;
  gap: 9px;
  height: 44px;
  padding: 0 8px 0 12px;
  cursor: grab;
  user-select: none;
  transition: opacity 0.25s;
}
.lifting > .head { cursor: grabbing; }

.check {
  flex: none;
  display: grid;
  place-items: center;
  width: 19px;
  height: 19px;
  border-radius: 6px;
  border: 1.5px solid color-mix(in srgb, var(--ink) 38%, transparent);
  color: transparent;
  transition: background 0.15s, border-color 0.15s, color 0.15s;
}
.check svg { width: 13px; height: 13px; stroke-width: 2.4; }
.check:hover { color: color-mix(in srgb, var(--ink) 35%, transparent); }
.box.done > .head > .check { background: var(--ink); border-color: var(--ink); color: var(--c); }

.title {
  flex: 1;
  min-width: 0;
  font-weight: 600;
  font-size: 14.5px;
  letter-spacing: -0.01em;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  outline: none;
  transition: opacity 0.2s;
}
.title:empty::before { content: "Untitled"; color: color-mix(in srgb, var(--ink) 35%, transparent); }
.title[contenteditable="true"] { cursor: text; text-overflow: clip; user-select: text; }

.box.done > .head > .title { text-decoration: line-through; text-decoration-thickness: 1.5px; opacity: 0.5; }
.box.done > .body { opacity: 0.5; }

.count {
  flex: none;
  font-size: 11.5px;
  font-weight: 600;
  font-variant-numeric: tabular-nums;
  padding: 2px 7px;
  border-radius: 99px;
  background: var(--chip);
  color: var(--ink-soft);
}
.count.all { background: var(--ink); color: var(--c); }

.actions {
  flex: none;
  display: flex;
  gap: 1px;
  opacity: 0;
  transition: opacity 0.15s;
}
.box:hover > .head > .actions,
.box.selected > .head > .actions { opacity: 1; }
.actions button {
  display: grid;
  place-items: center;
  width: 26px;
  height: 26px;
  border-radius: 7px;
  color: var(--ink-soft);
}
.actions button:hover { background: var(--chip); color: var(--ink); }
.actions button[data-act="del"]:hover { color: #d9473d; }
.actions svg { width: 15px; height: 15px; }

.body {
  position: relative;
  flex: 1;
  min-height: 0;
  margin: 0 8px 8px;
  border-radius: 9px;
  background-color: var(--well);
  background-image: radial-gradient(circle, var(--dot) 1px, transparent 1.2px);
  background-size: 24px 24px;
  background-position: 12px 12px;
  overflow: hidden;
  cursor: pointer;
  transition: opacity 0.2s;
}

.hint {
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
  font-size: 12px;
  color: color-mix(in srgb, var(--ink) 40%, transparent);
  pointer-events: none;
  opacity: 0;
  transition: opacity 0.2s;
  text-align: center;
  padding: 8px;
}
.box:hover > .body > .hint { opacity: 1; }

.resize {
  position: absolute;
  right: 0;
  bottom: 0;
  width: 18px;
  height: 18px;
  cursor: nwse-resize;
  opacity: 0;
  transition: opacity 0.15s;
  color: color-mix(in srgb, var(--ink) 45%, transparent);
}
.resize svg { position: absolute; right: 3px; bottom: 3px; width: 10px; height: 10px; stroke-width: 1.5; }
.box:hover > .resize, .box.selected > .resize { opacity: 1; }

/* ---------- level of detail ---------- */

/* Too small for contents: just the header, filling the box. */
.box.lod-title > .body,
.box.lod-title > .head > .count,
.box.lod-title > .head > .actions { display: none; }
.box.lod-title > .head { flex: 1; height: auto; min-height: 0; padding: 0 8px 0 10px; cursor: pointer; }

/* Too small for a title: a plain tile. */
.box.lod-bare { border-radius: 6px; cursor: pointer; }
.box.lod-bare > .head,
.box.lod-bare > .body { display: none; }
.box.lod-bare > .resize { width: 12px; height: 12px; }
.box.lod-bare > .resize svg { right: 2px; bottom: 2px; width: 7px; height: 7px; }

/* ---------- drag & drop between boxes ---------- */

.box.lifting { pointer-events: none; opacity: 0.94; }

.box.drop-target > .body {
  background: color-mix(in srgb, var(--accent) 14%, var(--well));
  box-shadow: inset 0 0 0 2px var(--accent);
}

.crumbs button.drop-target {
  color: var(--accent);
  text-decoration: underline;
  text-underline-offset: 4px;
}

/* ---------- walls of the current level ---------- */

/* Each level is its own space with the same grid; an opened box keeps its rim
   and well so it reads as the box you clicked, now filling the screen. */
.frame {
  border-radius: 9px;
  background-color: var(--c);
  background-image:
    radial-gradient(circle, var(--dot) 1px, transparent 1.2px),
    linear-gradient(var(--well), var(--well));
  background-size: 24px 24px, auto;
  background-position: 12px 12px, 0 0;
  box-shadow: 0 0 0 8px var(--c), var(--shadow);
}
.frame.board {
  --c: var(--panel);
  border-radius: 18px;
  background-image: radial-gradient(circle, var(--dot) 1px, transparent 1.2px);
  box-shadow: 0 0 0 1px var(--line), var(--shadow);
}
.frame.c0 { --c: var(--c0); }
.frame.c1 { --c: var(--c1); }
.frame.c2 { --c: var(--c2); }
.frame.c3 { --c: var(--c3); }
.frame.c4 { --c: var(--c4); }
.frame.c5 { --c: var(--c5); }

/* ---------- opening and closing ---------- */

.canvas.opening .world > .box:not(.lifted),
.canvas.closing .world > .box:not(.lifted),
.canvas.opening .box.lifted > .head,
.canvas.closing .box.lifted > .head { opacity: 0; }
.canvas.closing .world > .box { transition: none; }
.canvas.closing .box.lifted > .head { transition: none; }
.box.lifted { box-shadow: var(--shadow-lift); }