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

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--f-sans);
  font-size: var(--t-base);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

img, svg { max-width: 100%; }
[hidden] { display: none !important; }

/* --- typography --- */
h1, h2, h3, h4 { font-family: var(--f-serif); font-weight: 600; line-height: 1.15; margin: 0; letter-spacing: -0.015em; text-wrap: balance; }
h1 { font-size: var(--t-xl); }
h2 { font-size: var(--t-lg); }
h3 { font-size: var(--t-md); }
h4 { font-family: var(--f-sans); font-size: var(--t-base); letter-spacing: 0; }
p { margin: 0 0 var(--s-3); max-width: 68ch; }
.lede { font-size: var(--t-md); color: var(--muted); max-width: 62ch; }
.small { font-size: var(--t-sm); color: var(--muted); }
.mono { font-family: var(--f-mono); font-variant-numeric: tabular-nums; }
.eyebrow { font-family: var(--f-mono); font-size: var(--t-xs); letter-spacing: 0.14em; text-transform: uppercase; color: var(--muted); margin: 0 0 var(--s-2); }
a { color: var(--accent); text-underline-offset: 2px; }
a:hover { text-decoration-thickness: 2px; }
code { font-family: var(--f-mono); font-size: 0.9em; background: var(--sunken); padding: 1px 5px; border-radius: var(--r-sm); }
hr { border: none; border-top: 1px solid var(--rule); margin: var(--s-6) 0; }
ul, ol { margin: 0 0 var(--s-3); padding-left: 1.25em; }
li { margin-bottom: var(--s-1); max-width: 68ch; }

:focus-visible { outline: 2px solid var(--focus); outline-offset: 2px; border-radius: var(--r-sm); }

/* --- buttons: square-ish, never pills --- */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: var(--s-2);
  font: inherit; font-weight: 500; font-size: var(--t-base);
  padding: var(--s-2) var(--s-4); min-height: 38px;
  border: 1px solid var(--rule); border-radius: var(--r-md);
  background: var(--raised); color: var(--ink);
  cursor: pointer; text-decoration: none;
  transition: transform var(--motion-fast) var(--ease),
              background-color var(--motion-fast) var(--ease),
              border-color var(--motion-fast) var(--ease);
}
.btn:hover:not(:disabled) { border-color: var(--muted); }
.btn:active:not(:disabled) { transform: scale(0.97); }
.btn:disabled { opacity: 0.5; cursor: not-allowed; }
.btn-primary { background: var(--accent); border-color: var(--accent); color: var(--on-accent); }
.btn-primary:hover:not(:disabled) { filter: brightness(1.1); }
.btn-quiet { background: transparent; border-color: transparent; color: var(--muted); }
.btn-quiet:hover:not(:disabled) { background: var(--sunken); color: var(--ink); }
.btn-sm { min-height: 30px; padding: var(--s-1) var(--s-3); font-size: var(--t-sm); }
.btn-danger { color: var(--bad); border-color: var(--rule); }
.btn-danger:hover:not(:disabled) { border-color: var(--bad); background: var(--bad-wash); }

/* --- forms --- */
label { display: block; font-size: var(--t-sm); font-weight: 500; margin-bottom: var(--s-1); }
.field { margin-bottom: var(--s-4); }
.field-hint { font-size: var(--t-sm); color: var(--muted); margin: var(--s-1) 0 0; }
input[type="text"], input[type="email"], input[type="password"], input[type="date"],
input[type="number"], input[type="url"], select, textarea {
  width: 100%; font: inherit; font-size: var(--t-base); color: var(--ink);
  background: var(--raised); border: 1px solid var(--rule); border-radius: var(--r-md);
  padding: var(--s-2) var(--s-3); min-height: 38px;
}
textarea { min-height: 160px; resize: vertical; line-height: 1.6; }
input:disabled, textarea:disabled, select:disabled { background: var(--sunken); color: var(--muted); }
select { appearance: none; background-image: linear-gradient(45deg, transparent 50%, currentColor 50%), linear-gradient(135deg, currentColor 50%, transparent 50%); background-position: right 15px top 17px, right 10px top 17px; background-size: 5px 5px; background-repeat: no-repeat; padding-right: var(--s-6); }
.field-error { color: var(--bad); font-size: var(--t-sm); margin-top: var(--s-1); }
input[aria-invalid="true"], textarea[aria-invalid="true"] { border-color: var(--bad); }

/* --- surfaces --- */
.card { background: var(--raised); border: 1px solid var(--rule); border-radius: var(--r-lg); padding: var(--s-5); }
.card-tight { padding: var(--s-4); }

/* --- chips carry state, they are not decoration --- */
.chip {
  display: inline-block; font-family: var(--f-mono); font-size: var(--t-xs);
  font-weight: 600; letter-spacing: 0.08em; text-transform: uppercase;
  padding: 2px 9px; border-radius: var(--r-full); white-space: nowrap;
  background: var(--sunken); color: var(--muted);
}
.chip-good { background: var(--good-wash); color: var(--good); }
.chip-warn { background: var(--warn-wash); color: var(--warn); }
.chip-bad  { background: var(--bad-wash);  color: var(--bad); }
.chip-accent { background: var(--accent-wash); color: var(--accent); }

/* --- tables --- */
table { border-collapse: collapse; width: 100%; font-size: var(--t-base); }
th { font-family: var(--f-mono); font-size: var(--t-xs); letter-spacing: 0.1em; text-transform: uppercase;
     color: var(--muted); font-weight: 500; text-align: left; padding: var(--s-3) var(--s-4) var(--s-3) 0;
     border-bottom: 1px solid var(--rule); white-space: nowrap; }
td { padding: var(--s-3) var(--s-4) var(--s-3) 0; border-bottom: 1px solid var(--rule-soft); vertical-align: top; }
tr:last-child td { border-bottom: none; }
td.num, th.num { font-family: var(--f-mono); font-variant-numeric: tabular-nums; white-space: nowrap; }
.table-scroll { overflow-x: auto; }

/* --- note: one accent bar, used sparingly --- */
.note { border: 1px solid var(--rule); border-left: 3px solid var(--accent); background: var(--raised);
        padding: var(--s-4); border-radius: var(--r-md); font-size: var(--t-sm); margin: var(--s-4) 0; }
.note-warn { border-left-color: var(--warn); }
.note-bad { border-left-color: var(--bad); }
.note b { display: block; font-family: var(--f-mono); font-size: var(--t-xs); letter-spacing: 0.1em;
          text-transform: uppercase; margin-bottom: var(--s-2); color: var(--accent); }
.note-warn b { color: var(--warn); }
.note-bad b { color: var(--bad); }
.note p:last-child { margin-bottom: 0; }

/* --- folded detail: methodology folds, warnings do not --- */
details { border-top: 1px solid var(--rule-soft); padding: var(--s-2) 0; }
summary { cursor: pointer; font-size: var(--t-sm); color: var(--muted); list-style: none; padding: var(--s-1) 0; }
summary::-webkit-details-marker { display: none; }
summary::before { content: "+"; font-family: var(--f-mono); margin-right: var(--s-2); color: var(--accent); }
details[open] summary::before { content: "−"; }
details[open] summary { color: var(--ink); margin-bottom: var(--s-2); }

/* --- skeletons, not spinners: a skeleton says what shape is arriving --- */
.skeleton { background: var(--sunken); border-radius: var(--r-sm); height: 1em; }
.skeleton-line { height: 0.85em; margin-bottom: var(--s-2); }
.skeleton-line:nth-child(3n) { width: 72%; }
.skeleton-line:nth-child(3n+1) { width: 94%; }
.skeleton-block { height: 96px; border-radius: var(--r-md); }

/* --- empty states name which of the three things is true --- */
.empty { border: 1px dashed var(--rule); border-radius: var(--r-lg); padding: var(--s-6) var(--s-5);
         text-align: center; color: var(--muted); }
.empty h3 { font-family: var(--f-sans); font-size: var(--t-base); color: var(--ink); margin-bottom: var(--s-2); }
.empty p { margin: 0 auto var(--s-4); max-width: 44ch; font-size: var(--t-sm); }

/* --- layout helpers --- */
.wrap { max-width: 1120px; margin: 0 auto; padding: 0 var(--s-5); }
.wrap-narrow { max-width: 760px; margin: 0 auto; padding: 0 var(--s-5); }
.stack > * + * { margin-top: var(--s-4); }
.row { display: flex; gap: var(--s-3); align-items: center; }
.row-between { display: flex; gap: var(--s-3); align-items: center; justify-content: space-between; flex-wrap: wrap; }
.grid-2 { display: grid; grid-template-columns: repeat(2, 1fr); gap: var(--s-4); }
.grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: var(--s-4); }
.sr-only { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden;
           clip: rect(0 0 0 0); white-space: nowrap; border: 0; }

@media (max-width: 720px) {
  .grid-2, .grid-3 { grid-template-columns: 1fr; }
}

/* --- skip to content: first thing a keyboard reaches, invisible until focused */
.skip-link {
  position: absolute; left: var(--s-3); top: -100px; z-index: 100;
  background: var(--accent); color: var(--on-accent);
  padding: var(--s-2) var(--s-4); border-radius: var(--r-md);
  font-size: var(--t-sm); font-weight: 500; text-decoration: none;
  transition: top var(--motion) var(--ease);
}
.skip-link:focus { top: var(--s-3); }

/* --- entrance: a short, small rise. Enough to signal "this is new", not enough
   to make navigating the app feel slow. --- */
@keyframes rise {
  from { opacity: 0; transform: translateY(6px); }
  to   { opacity: 1; transform: none; }
}
.enter { animation: rise var(--motion-slow) var(--ease-out) both; }

/* Staggered only for short lists; a long list would finish late and read as lag. */
.enter-stagger > * { animation: rise var(--motion-slow) var(--ease-out) both; }
.enter-stagger > *:nth-child(1) { animation-delay: 0ms; }
.enter-stagger > *:nth-child(2) { animation-delay: 40ms; }
.enter-stagger > *:nth-child(3) { animation-delay: 80ms; }
.enter-stagger > *:nth-child(n+4) { animation-delay: 120ms; }

/* --- back to top: only appears once there is a page worth returning up --- */
.to-top {
  position: fixed; right: var(--s-5); bottom: var(--s-5); z-index: 30;
  width: 40px; height: 40px; display: grid; place-items: center;
  background: var(--raised); color: var(--muted);
  border: 1px solid var(--rule); border-radius: var(--r-md);
  box-shadow: var(--e-1); cursor: pointer;
  opacity: 0; pointer-events: none;
  transition: opacity var(--motion) var(--ease), transform var(--motion) var(--ease);
  transform: translateY(6px);
}
.to-top.is-visible { opacity: 1; pointer-events: auto; transform: none; }
.to-top:hover { color: var(--ink); border-color: var(--muted); }
.to-top:active { transform: scale(0.94); }

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
  .btn:active:not(:disabled) { transform: none; }
  .enter, .enter-stagger > * { animation: none; opacity: 1; transform: none; }
}

/* --- print: a marked commentary is something students take to a teacher --- */
@media print {
  .masthead, .to-top, .skip-link, #toast-host, .offline,
  .state-btns, .btn, form .field-hint, .sidebar { display: none !important; }
  body { background: #fff; color: #000; font-size: 11pt; }
  .card, .note { border: 1px solid #bbb; box-shadow: none; break-inside: avoid; }
  .criterion { break-inside: avoid; }
  .split { display: block; }
  a[href^="http"]::after { content: " (" attr(href) ")"; font-size: 9pt; color: #555; }
  .chip { border: 1px solid #999; }
  h1, h2, h3 { break-after: avoid; }
}

/* Touch sizing is gated on the pointer, not the viewport: a narrow desktop
   window is still driven by a mouse. This block is LAST because media queries
   add no specificity — anything after them would win. */
@media (pointer: coarse) {
  .btn { min-height: 44px; }
  .btn-sm { min-height: 40px; }
  .state-btn { min-height: 44px; min-width: 52px; }
  .pw-toggle { min-height: 40px; }
  .brand { display: inline-flex; align-items: center; min-height: 44px; }
  .nav a { min-height: 44px; display: inline-flex; align-items: center; }
  input[type="text"], input[type="email"], input[type="password"], input[type="date"],
  input[type="number"], input[type="url"], select { min-height: 44px; }
  summary { padding: var(--s-2) 0; }
}