*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  --sidebar-width: 260px;
  --bg-sidebar: #18181b;
  --bg-main: #f4f4f5;
  --text: #fafafa;
  --text-muted: #a1a1aa;
  --border: #3f3f46;
  --input-bg: #27272a;
  --accent: #f97316;
  --accent-hover: #ea6c00;
  --btn-secondary: #3f3f46;
  --btn-secondary-hover: #52525b;
}

body {
  display: grid;
  grid-template-columns: var(--sidebar-width) 1fr;
  min-height: 100vh;
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', system-ui, sans-serif;
}

/* ── Sidebar ─────────────────────────────────── */

.sidebar {
  background: var(--bg-sidebar);
  color: var(--text);
  display: flex;
  flex-direction: column;
  padding: 2rem 1.5rem;
  gap: 2rem;
  position: sticky;
  top: 0;
  height: 100vh;
  overflow-y: auto;
}

.sidebar-header h1 {
  font-size: 1.25rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 0.3rem;
}

.sidebar-header .subtitle {
  font-size: 0.8125rem;
  color: var(--text-muted);
}

/* ── Form ────────────────────────────────────── */

form {
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
  flex: 1;
}

.fields {
  display: flex;
  flex-direction: column;
  gap: 0.875rem;
}

.field label {
  display: block;
  font-size: 0.6875rem;
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.07em;
  margin-bottom: 0.375rem;
}

.input-row {
  display: flex;
  align-items: center;
  background: var(--input-bg);
  border: 1px solid var(--border);
  border-radius: 6px;
  overflow: hidden;
  transition: border-color 0.15s;
}

.input-row:focus-within {
  border-color: var(--accent);
}

.input-row input {
  flex: 1;
  background: transparent;
  border: none;
  outline: none;
  color: var(--text);
  font-size: 0.9375rem;
  padding: 0.5rem 0.75rem;
  width: 100%;
  min-width: 0;
  -moz-appearance: textfield;
}

.input-row input::-webkit-outer-spin-button,
.input-row input::-webkit-inner-spin-button {
  -webkit-appearance: none;
}

.steppers {
  display: flex;
  flex-direction: column;
  border-left: 1px solid var(--border);
  flex-shrink: 0;
}

.stepper {
  flex: 1;
  background: transparent;
  border: none;
  color: var(--text-muted);
  cursor: pointer;
  padding: 0 0.5rem;
  font-size: 0.5rem;
  line-height: 1;
  transition: color 0.15s, background 0.15s;
}

.stepper:hover {
  color: var(--accent);
  background: rgba(255, 255, 255, 0.05);
}

.input-row .unit {
  padding: 0 0.75rem;
  color: var(--text-muted);
  font-size: 0.8125rem;
  border-left: 1px solid var(--border);
  line-height: 2.5rem;
  user-select: none;
  white-space: nowrap;
}

/* ── Toggle ──────────────────────────────────── */

.field-toggle {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: 0.25rem;
}

.field-toggle > label:first-child {
  margin-bottom: 0;
}

.toggle {
  position: relative;
  display: inline-block;
  width: 2.25rem;
  height: 1.25rem;
  cursor: pointer;
  flex-shrink: 0;
}

.toggle input {
  opacity: 0;
  width: 0;
  height: 0;
  position: absolute;
}

.toggle-track {
  position: absolute;
  inset: 0;
  background: var(--border);
  border-radius: 9999px;
  transition: background 0.2s;
}

.toggle-track::after {
  content: '';
  position: absolute;
  top: 3px;
  left: 3px;
  width: 14px;
  height: 14px;
  background: var(--text-muted);
  border-radius: 50%;
  transition: transform 0.2s, background 0.2s;
}

.toggle input:checked + .toggle-track {
  background: var(--accent);
}

.toggle input:checked + .toggle-track::after {
  transform: translateX(1rem);
  background: white;
}

.toggle input:focus-visible + .toggle-track {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

/* ── Buttons ─────────────────────────────────── */

.actions {
  display: flex;
  gap: 0.5rem;
}

.btn {
  flex: 1;
  padding: 0.6rem 1rem;
  font-size: 0.875rem;
  font-weight: 500;
  border: none;
  border-radius: 6px;
  cursor: pointer;
  transition: background 0.15s;
}

.btn-secondary {
  background: var(--btn-secondary);
  color: var(--text);
}

.btn-secondary:hover {
  background: var(--btn-secondary-hover);
}

.btn-primary {
  background: var(--accent);
  color: white;
}

.btn-primary:hover {
  background: var(--accent-hover);
}

/* ── Box type selector ───────────────────────── */

.box-type {
  display: flex;
  background: var(--input-bg);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 3px;
  gap: 3px;
}

.box-type-btn {
  flex: 1;
  cursor: pointer;
}

.box-type-btn input {
  display: none;
}

.box-type-btn span {
  display: block;
  text-align: center;
  padding: 0.4rem 0.5rem;
  border-radius: 4px;
  font-size: 0.8125rem;
  font-weight: 500;
  color: var(--text-muted);
  transition: background 0.15s, color 0.15s;
  user-select: none;
}

.box-type-btn input:checked + span {
  background: var(--accent);
  color: white;
}

.box-type-btn span:hover {
  color: var(--text);
}

.box-type-btn input:checked + span:hover {
  color: white;
}

.shipping-mode .no-shipping {
  display: none;
}

/* ── Work area ───────────────────────────────── */

.work-area-inputs {
  display: flex;
  align-items: center;
  gap: 0.375rem;
}

.work-area-input {
  flex: 1;
  min-width: 0;
  background: var(--input-bg);
  border: 1px solid var(--border);
  border-radius: 6px;
  color: var(--text);
  font-size: 0.9375rem;
  padding: 0.5rem 0.5rem;
  outline: none;
  text-align: center;
  -moz-appearance: textfield;
  transition: border-color 0.15s;
}

.work-area-input::-webkit-outer-spin-button,
.work-area-input::-webkit-inner-spin-button {
  -webkit-appearance: none;
}

.work-area-input:focus {
  border-color: var(--accent);
}

.work-area-sep {
  color: var(--text-muted);
  font-size: 0.875rem;
  flex-shrink: 0;
}

.work-area-unit {
  color: var(--text-muted);
  font-size: 0.8125rem;
  white-space: nowrap;
  flex-shrink: 0;
}

/* ── Material size ───────────────────────────── */

.material-size {
  background: var(--input-bg);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 0.75rem 1rem;
}

.material-size-label {
  font-size: 0.6875rem;
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.07em;
  margin-bottom: 0.375rem;
}

.material-size-value {
  font-size: 1rem;
  font-weight: 600;
  color: var(--text);
  letter-spacing: -0.01em;
}

.fit-indicator {
  font-size: 0.75rem;
  font-weight: 500;
  margin-top: 0.4rem;
  min-height: 1em;
}

.fit-indicator.fits   { color: #22c55e; }
.fit-indicator.exceeds { color: #ef4444; }

/* ── Footer ──────────────────────────────────── */

.sidebar-footer {
  font-size: 0.75rem;
  color: var(--text-muted);
  display: flex;
  flex-direction: column;
  gap: 0.3rem;
}

.sidebar-footer a {
  color: var(--text-muted);
  text-decoration: none;
  transition: color 0.15s;
}

.sidebar-footer a:hover {
  color: var(--text);
}

/* ── Canvas area ─────────────────────────────── */

.canvas-area {
  background: var(--bg-main);
  display: flex;
  align-items: flex-start;
  justify-content: center;
  padding: 2.5rem;
  overflow: auto;
  min-height: 100vh;
}

canvas {
  display: block;
  background: white;
  border-radius: 4px;
  box-shadow: 0 1px 3px rgba(0,0,0,0.08), 0 4px 16px rgba(0,0,0,0.08);
}