:root {
  color-scheme: light;
  --bg: #f4f1ea;
  --card: #fffcf7;
  --ink: #1c1917;
  --muted: #57534e;
  --line: #e7e5e4;
  --accent: #1d4ed8;
  --accent-dark: #1e3a8a;
  --soft: #eff6ff;
  --danger: #9f1239;
  --ok: #166534;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--ink);
  font: 17px/1.45 system-ui, "Segoe UI", Roboto, sans-serif;
}

.app {
  max-width: 40rem;
  margin: 0 auto;
  padding: 1rem 1rem calc(1.5rem + env(safe-area-inset-bottom));
}

header.top h1 {
  font-size: 1.55rem;
  line-height: 1.2;
  margin: 0 0 0.25rem;
}

.meta, .instruction, .save-note, .status {
  color: var(--muted);
}

.instructions {
  padding-left: 1.2rem;
  margin: 0.5rem 0 1rem;
}

.sheet-section {
  margin: 1.5rem 0;
}

.sheet-section h2 {
  font-size: 1.2rem;
  margin: 0 0 0.35rem;
  display: flex;
  justify-content: space-between;
  gap: 0.75rem;
  align-items: baseline;
}

.sheet-section h2 span {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--muted);
}

.question, .part {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 14px;
  padding: 0.9rem 1rem 1rem;
  margin: 0.75rem 0;
}

.part { background: #fff; }

.qhead, .part-head {
  display: flex;
  justify-content: space-between;
  gap: 0.75rem;
  font-weight: 700;
  margin-bottom: 0.35rem;
}

.marks { color: var(--muted); font-weight: 600; font-size: 0.85rem; }

.choice {
  display: flex;
  gap: 0.75rem;
  align-items: flex-start;
  padding: 0.85rem 0.9rem;
  border: 1px solid var(--line);
  border-radius: 12px;
  margin: 0.5rem 0;
  background: #fff;
  cursor: pointer;
}

.choice:has(input:checked) {
  border-color: var(--accent);
  background: var(--soft);
}

.choice input {
  width: 1.3rem;
  height: 1.3rem;
  margin-top: 0.15rem;
  accent-color: var(--accent);
}

textarea, input[type="text"] {
  width: 100%;
  font: inherit;
  padding: 0.75rem;
  border-radius: 12px;
  border: 1px solid #d6d3d1;
  background: #fff;
  color: var(--ink);
}

textarea { min-height: 4.5rem; resize: vertical; }

button, .file-btn {
  font: inherit;
  font-weight: 700;
  border: 0;
  border-radius: 12px;
  padding: 0.85rem 1rem;
  min-height: 48px;
  cursor: pointer;
}

.primary {
  background: var(--accent);
  color: white;
  width: 100%;
}

.primary:disabled { opacity: 0.6; }

.secondary {
  background: white;
  color: var(--accent-dark);
  border: 1px solid #bfdbfe;
}

.photo-actions, .bar {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  margin-top: 0.6rem;
}

.photo-preview {
  display: block;
  width: 100%;
  border-radius: 12px;
  border: 1px solid var(--line);
  background: white;
}

.figure {
  margin: 0.6rem 0;
  background: white;
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 0.4rem;
  overflow-x: auto;
}

.figure img, .figure object, .figure svg {
  width: 100%;
  height: auto;
  display: block;
}

.math { white-space: normal; }

.submit-bar {
  position: sticky;
  bottom: 0;
  padding: 0.75rem 0 calc(0.35rem + env(safe-area-inset-bottom));
  background: linear-gradient(transparent, var(--bg) 28%);
}

.card {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 16px;
  padding: 1.1rem;
}

.ok-title { color: var(--ok); margin-top: 0; }

.error { color: var(--danger); }

.missing { margin: 0.3rem 0; }

ul.plain { padding-left: 1.2rem; }