:root {
  --bg: #ffffff;
  --fg: #0e0e10;
  --muted: #6b7280;
  --border: #d9d9e3;
  --accent: #0d6efd;
  --good: #0a7c28;
  --bad: #b00020;
  --surface: #f7f7fb;
}

* { box-sizing: border-box; }

html, body {
  height: 100%;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  font: 16px/1.5 system-ui, -apple-system, Segoe UI, Roboto, Arial, sans-serif;
}

.container {
  max-width: 760px;
  margin: 2rem auto;
  padding: 0 1rem;
}

h1 {
  font-size: 1.6rem;
  margin: 0 0 1rem;
}

.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1rem;
}

.matrix-fieldset {
  border: none;
  margin: 0;
  padding: 0 0 1rem;
}

.matrix-wrap {
  display: inline-block;
  padding: .5rem .75rem;
  border: 1px solid var(--border);
  border-radius: 10px;
  background: #fff;
  position: relative;
}

.matrix {
  border-collapse: collapse;
}

.matrix td {
  padding: .4rem;
}

.matrix input[type="number"] {
  width: 5.5rem;
  padding: .5rem .6rem;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--bg);
}

.row {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 1rem;
  align-items: end;
}

.field label {
  display: inline-block;
  margin-bottom: .25rem;
  font-weight: 600;
}

.field .hint {
  display: block;
  margin-top: .25rem;
  color: var(--muted);
}

.actions {
  display: flex;
  gap: .5rem;
  justify-content: end;
}

.btn {
  padding: .6rem .9rem;
  border: 1px solid var(--border);
  background: #fff;
  color: var(--fg);
  border-radius: 10px;
  cursor: pointer;
}

.btn.primary {
  background: var(--accent);
  color: #fff;
  border-color: var(--accent);
}

.result {
  display: block;
  margin-top: 1rem;
  padding: .9rem;
  border-radius: 10px;
  background: #fff;
  border: 1px solid var(--border);
}

.ok { color: var(--good); font-weight: 700; }
.bad { color: var(--bad); font-weight: 700; }

/* Accessibility helper for visual-only placeholders */
.sr-only {
  position: absolute !important;
  height: 1px; width: 1px;
  overflow: hidden;
  clip: rect(1px, 1px, 1px, 1px);
  white-space: nowrap;
  border: 0; padding: 0; margin: -1px;
}

/* Mobile tweaks */
@media (max-width: 560px) {
  .matrix input[type="number"] {
    width: 4.5rem;
  }
}

.hidden { display: none !important; }

.grid-2 {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
}
@media (max-width: 720px) {
  .grid-2 { grid-template-columns: 1fr; }
}