:root {
  color-scheme: light;
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background: #f5f3ee;
  color: #24231f;
  --surface: #fffdf8;
  --surface-strong: #ffffff;
  --line: #d9d5ca;
  --ink-soft: #6c685f;
  --accent: #2559c5;
  --accent-soft: #eaf0ff;
  --danger: #b42c2c;
  --chip-shadow: 0 4px 14px rgb(36 35 31 / 0.12);
}

* { box-sizing: border-box; }

body {
  margin: 0;
  min-height: 100dvh;
  background:
    radial-gradient(circle at top right, rgb(37 89 197 / 0.08), transparent 34rem),
    var(--surface);
}

button, input { font: inherit; }
button { touch-action: manipulation; }

.app-shell {
  width: min(100% - 24px, 960px);
  margin: 0 auto;
  padding: 18px 0 48px;
}

.topbar,
.section-heading-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

.topbar { margin-bottom: 14px; }

h1, h2, p { margin-top: 0; }
h1 { margin-bottom: 0; font-size: clamp(1.5rem, 5vw, 2.15rem); }
h2 { margin-bottom: 0; font-size: clamp(1.05rem, 3.7vw, 1.3rem); }

.eyebrow,
.section-kicker {
  margin-bottom: 4px;
  color: var(--ink-soft);
  font-size: 0.76rem;
  font-weight: 750;
  letter-spacing: 0.05em;
  text-transform: uppercase;
}

.companion-card,
.workspace-section,
.answer-card,
.debug-panel {
  border: 1px solid var(--line);
  border-radius: 18px;
  background: rgb(255 255 255 / 0.86);
  box-shadow: 0 12px 38px rgb(50 47 38 / 0.06);
}

.workspace-section,
.answer-card { padding: 16px; margin-top: 12px; }

.companion-card {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 12px 14px;
}

.companion-avatar {
  display: grid;
  place-items: center;
  flex: 0 0 auto;
  width: 48px;
  height: 48px;
  border-radius: 16px;
  background: #f3eadc;
  font-size: 1.7rem;
}

.companion-message { margin: 0; line-height: 1.5; }
.workspace-heading { align-items: flex-start; }
.selection-status { margin: 8px 0 0; color: var(--ink-soft); font-size: 0.82rem; }

.history-controls {
  display: flex;
  gap: 6px;
  flex: 0 0 auto;
}

.icon-button,
.chip-menu button,
.board-create-menu button,
.primary-button,
.secondary-button,
.submit-answer-button {
  min-height: 46px;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: #fff;
  color: inherit;
  font-weight: 750;
}

.icon-button {
  width: 48px;
  padding: 0;
  font-size: 1.35rem;
}

.icon-button:disabled,
.submit-answer-button:disabled { opacity: 0.35; }

.board {
  position: relative;
  overflow: hidden;
  min-height: 430px;
  margin-top: 10px;
  border: 2px dashed #cec9bd;
  border-radius: 16px;
  background:
    linear-gradient(#f5f3ee 1px, transparent 1px),
    linear-gradient(90deg, #f5f3ee 1px, transparent 1px),
    #fffefa;
  background-size: 24px 24px;
  touch-action: none;
}

.board:focus-visible { outline: 3px solid rgb(37 89 197 / 0.25); outline-offset: 3px; }

.problem-dock {
  position: absolute;
  z-index: 4;
  inset: 0 0 auto 0;
  padding: 14px 16px 12px;
  border-bottom: 1px solid var(--line);
  background: rgb(255 253 248 / 0.97);
  box-shadow: 0 8px 20px rgb(50 47 38 / 0.05);
}

.problem-prompt {
  margin: 4px 0 8px;
  font-weight: 700;
}

.problem-expression {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 1px;
  min-height: 46px;
  font-size: 1.32rem;
}

.source-token {
  user-select: none;
  -webkit-user-select: none;
  touch-action: none;
  min-width: 0;
  min-height: 40px;
  padding: 2px 6px;
  border: 0;
  border-radius: 9px;
  background: transparent;
  color: #24231f;
  font-weight: 800;
  line-height: 1;
  cursor: grab;
}

.source-token:active {
  background: var(--accent-soft);
  color: #173f98;
  cursor: grabbing;
}

.helper-text,
.gesture-help {
  margin: 9px 0 0;
  color: var(--ink-soft);
  font-size: 0.82rem;
  line-height: 1.55;
}

.board-empty {
  position: absolute;
  inset: auto 0 0;
  display: grid;
  place-items: center;
  margin: 0;
  padding: 24px;
  color: #989287;
  text-align: center;
  pointer-events: none;
}

.board-chip {
  position: absolute;
  z-index: 2;
  display: inline-grid;
  place-items: center;
  min-width: 62px;
  min-height: 48px;
  padding: 0 14px;
  user-select: none;
  -webkit-user-select: none;
  touch-action: none;
  border: 1px solid #c9c4b8;
  border-radius: 13px;
  background: var(--surface-strong);
  color: #24231f;
  font-weight: 750;
  line-height: 1;
  box-shadow: var(--chip-shadow);
  cursor: grab;
  transform: translate3d(0,0,0);
}

.board-chip.is-selected {
  border-color: var(--accent);
  box-shadow: 0 0 0 4px rgb(37 89 197 / 0.15), var(--chip-shadow);
}

.board-chip.is-dragging { cursor: grabbing; }

.answer-card {
  display: grid;
  gap: 10px;
}

.answer-label {
  margin-top: 4px;
  font-size: 0.86rem;
  font-weight: 700;
  color: var(--ink-soft);
}

.answer-input {
  width: 100%;
  min-height: 52px;
  border: 1px solid #bdb8ad;
  border-radius: 13px;
  padding: 0 14px;
  background: #fff;
  color: inherit;
  font-size: 1.05rem;
  font-weight: 700;
}

.answer-input:focus {
  outline: 3px solid rgb(37 89 197 / 0.18);
  border-color: var(--accent);
}

.board-actions {
  display: grid;
  gap: 8px;
  margin-top: 4px;
}

.submit-answer-button {
  width: 100%;
  min-height: 52px;
  border-color: var(--accent);
  background: var(--accent);
  color: #fff;
  font-size: 1rem;
}

.submission-status {
  margin: 0;
  color: var(--ink-soft);
  font-size: 0.8rem;
  text-align: center;
}

.drag-preview {
  position: fixed;
  z-index: 70;
  pointer-events: none;
  min-width: 62px;
  min-height: 48px;
  padding: 14px;
  border: 1px solid var(--accent);
  border-radius: 13px;
  background: #fff;
  font-weight: 750;
  box-shadow: 0 10px 30px rgb(36 35 31 / 0.2);
  transform: translate(-50%, -50%);
}

.chip-menu,
.board-create-menu {
  position: fixed;
  z-index: 80;
  padding: 7px;
  border: 1px solid var(--line);
  border-radius: 14px;
  background: #fff;
  box-shadow: 0 12px 35px rgb(36 35 31 / 0.2);
}

.chip-menu { display: flex; gap: 6px; }
.board-create-menu { display: grid; gap: 6px; min-width: 170px; }
.board-create-menu p { margin: 4px 8px 2px; color: var(--ink-soft); font-size: 0.78rem; font-weight: 700; }
.chip-menu[hidden],
.board-create-menu[hidden],
.drag-preview[hidden] { display: none; }
.chip-menu button,
.board-create-menu button { min-height: 40px; padding: 0 14px; }
.chip-menu .danger { color: var(--danger); }

.chip-dialog {
  width: min(92vw, 420px);
  border: 1px solid var(--line);
  border-radius: 18px;
  padding: 0;
  box-shadow: 0 30px 90px rgb(0 0 0 / 0.28);
}

.chip-dialog::backdrop { background: rgb(15 15 15 / 0.35); }
.chip-dialog form { padding: 20px; }
.chip-dialog h2 { margin-bottom: 16px; }
.chip-dialog label { display: block; margin-bottom: 7px; font-weight: 700; }
.chip-dialog input {
  width: 100%;
  min-height: 48px;
  border: 1px solid #bdb8ad;
  border-radius: 12px;
  padding: 0 12px;
  font-size: 1rem;
}
.dialog-actions { display: flex; justify-content: flex-end; gap: 8px; margin-top: 16px; }
.primary-button { border-color: var(--accent); background: var(--accent); color: #fff; padding: 0 16px; }
.secondary-button { padding: 0 16px; }

.debug-panel { margin-top: 12px; padding: 12px 14px; color: var(--ink-soft); }
.debug-panel summary { cursor: pointer; font-weight: 700; }
.debug-panel pre { max-height: 220px; overflow: auto; white-space: pre-wrap; font-size: 0.75rem; }

@media (min-width: 768px) {
  .app-shell { padding-top: 28px; }
  .workspace-section, .answer-card { padding: 20px; }
  .board { min-height: 540px; }
  .answer-card { grid-template-columns: 1fr; }
  .board-actions { grid-template-columns: minmax(220px, 360px) 1fr; align-items: center; }
  .submission-status { text-align: left; }
}