/* Base: fonts, reset, type, focus, and the controls every screen uses.
   Components (shell, hero, tiles, progress, states) are in components.css,
   screen layouts in screens.css. Tokens only; no raw colours or sizes. */
@font-face {
  font-family: 'Figtree';
  src: url('../fonts/Figtree-VariableFont_wght.ttf') format('truetype');
  font-weight: 300 900; font-style: normal; font-display: block;
}
@font-face {
  font-family: 'Figtree';
  src: url('../fonts/Figtree-Italic-VariableFont_wght.ttf') format('truetype');
  font-weight: 300 900; font-style: italic; font-display: block;
}

*, *::before, *::after { box-sizing: border-box; }
html, body { margin: 0; }
html { scroll-padding-top: calc(var(--topbar-h) + var(--s-4)); }
body {
  font: var(--t-body); background: var(--canvas); color: var(--ink);
  min-width: 1200px;
  -webkit-font-smoothing: antialiased; text-rendering: optimizeLegibility;
  font-feature-settings: 'kern';
}
/* The teacher's screens are laptop-first: the 1200px minimum above. The
   student view (#/s/..., its top bar is .student-mode) works on a phone from
   360px wide, and so does any page that carries .phone-ready (the sign-in
   page): they lift the minimum. Their phone rules are in screens.css,
   "Student view on phones and tablets". */
body:has(.topbar.student-mode), body:has(.phone-ready) { min-width: 0; }
body.no-scroll { overflow: hidden; }
button, input, select, textarea { font: inherit; color: inherit; }
button { cursor: pointer; }
button:disabled { cursor: default; }
a { color: var(--primary); text-underline-offset: 3px; }
h1, h2, h3, h4, p { margin: 0; }
h1 { font: var(--t-h1); letter-spacing: -.01em; }
h2 { font: var(--t-h2); }
h3 { font: var(--t-h3); }
h4 { font: var(--t-label); }
b, strong { font-weight: var(--w-semibold); }
sup, sub { font-size: .72em; line-height: 0; }
img { max-width: 100%; }
::selection { background: var(--surface-mint); color: var(--green-900); }

:focus { outline: none; }
/* The focus ring wins over every component's own shadow (.btn-primary's
   lift, a card's hover): it is !important, and the ring itself comes from
   --focus-shadow, which a dark surface sets to --focus-ring-band
   (components.css, "focus on dark surfaces"). Never set box-shadow on a
   :focus-visible rule; set --focus-shadow on the container instead.
   tests/test_tokens_contrast.py guards this. */
:focus-visible { outline: none; box-shadow: var(--focus-shadow, var(--focus-ring)) !important; border-radius: var(--r-sm); }
h1:focus, [tabindex="-1"]:focus { box-shadow: none; }

.skip-link {
  position: fixed; top: var(--s-2); left: var(--s-2); z-index: 1000; transform: translateY(-200%);
  padding: var(--s-2) var(--s-4); border-radius: var(--r-md); background: var(--surface); color: var(--primary);
  font: var(--t-label); text-decoration: none; box-shadow: var(--e3);
}
.skip-link:focus, .skip-link:focus-visible { transform: none; }
.sr-only { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; }
.grow { flex-grow: 1; }
.muted { color: var(--muted); }
.strong { font-weight: var(--w-semibold); }
.num { font-variant-numeric: tabular-nums; }
.caption { font: var(--t-caption); color: var(--muted); }
.label { font: var(--t-label); }
.eyebrow { font: var(--t-label); letter-spacing: .06em; text-transform: uppercase; color: var(--muted); }
.error { color: var(--error-text); font: var(--t-body); }
.row { display: flex; align-items: center; gap: var(--s-3); }
.stack { display: flex; flex-direction: column; gap: var(--s-4); }

/* ---- buttons ---------------------------------------------------------- */
.btn {
  --btn-h: 44px;
  position: relative; display: inline-flex; align-items: center; justify-content: center; gap: var(--s-2);
  height: var(--btn-h); padding: 0 var(--s-5); border-radius: var(--r-md);
  border: 1px solid var(--control-line); background: var(--surface); color: var(--ink);
  font: var(--t-body); font-weight: var(--w-semibold); white-space: nowrap; text-decoration: none;
  transition: background var(--dur-1) var(--ease), border-color var(--dur-1) var(--ease),
    box-shadow var(--dur-1) var(--ease), transform var(--dur-1) var(--ease), color var(--dur-1) var(--ease);
}
.btn:hover:not(:disabled) { border-color: var(--primary); background: var(--surface-quiet); }
.btn:active:not(:disabled) { transform: translateY(1px); }
.btn:disabled, .btn[aria-disabled="true"] {
  background: var(--disabled-bg); color: var(--disabled-text); border-color: var(--disabled-bg); pointer-events: none;
}
.btn-primary { background: var(--primary); border-color: var(--primary); color: var(--on-primary); box-shadow: var(--e1); }
.btn-primary:hover:not(:disabled) { background: var(--primary-hover); border-color: var(--primary-hover); }
.btn-secondary, .btn-outline { color: var(--primary); border: 1.5px solid var(--primary); }
.btn-quiet, .btn-ghost { border-color: transparent; background: transparent; color: var(--primary); }
.btn-quiet:hover:not(:disabled) { background: var(--surface-quiet); border-color: transparent; }
.btn-danger { color: var(--error-text); }
.btn-danger:hover:not(:disabled) { border-color: var(--error); background: var(--error-bg); }
.btn-danger-solid { background: var(--error); border-color: var(--error); color: var(--white); }
.btn-danger-solid:hover:not(:disabled) { background: var(--error-text); border-color: var(--error-text); }  /* not .btn's pale hover: the text is white */
.btn-small { --btn-h: 34px; padding: 0 var(--s-3); font: var(--t-label); border-radius: var(--r-sm); }
.btn-big, .btn-lg { --btn-h: 52px; padding: 0 var(--s-6); font: var(--t-body-lg); font-weight: var(--w-semibold); border-radius: var(--r-md); }
.btn-block { width: 100%; }
.btn .kbd { font: var(--t-caption); opacity: .75; }

.icon-btn {
  display: inline-flex; align-items: center; justify-content: center; width: 40px; height: 40px;
  border: 1px solid var(--control-line); background: var(--surface); border-radius: var(--r-md);
  color: var(--ink); flex-shrink: 0; padding: 0; text-decoration: none;
  transition: background var(--dur-1) var(--ease), border-color var(--dur-1) var(--ease), color var(--dur-1) var(--ease);
}
.icon-btn:hover:not(:disabled) { border-color: var(--primary); color: var(--primary); background: var(--surface-quiet); }
.icon-btn:disabled { color: var(--disabled-text); background: var(--disabled-bg); border-color: var(--disabled-bg); }
.icon-btn.round { border-radius: var(--r-full); }
.icon-btn.bare { border-color: transparent; background: transparent; }
.icon-btn.bare:hover:not(:disabled) { background: var(--surface-quiet); }
.icon-btn.small { width: 32px; height: 32px; }
.icon-btn.big { width: 52px; height: 52px; }

/* back link (W2 screens still use it inside the page) */
.back {
  display: inline-flex; align-items: center; gap: var(--s-2); font: var(--t-body); font-weight: var(--w-semibold);
  color: var(--muted); text-decoration: none; border: 0; background: none; padding: var(--s-1) 0;
}
.back:hover { color: var(--primary); }

/* ---- form controls ---------------------------------------------------- */
.field { display: flex; flex-direction: column; gap: var(--s-2); min-width: 0; }
.field > span { font: var(--t-label); color: var(--muted); }
.input {
  height: 44px; padding: 0 var(--s-4); border-radius: var(--r-md); border: 1px solid var(--control-line);
  background: var(--surface); font: var(--t-body); width: 100%;
  transition: border-color var(--dur-1) var(--ease), box-shadow var(--dur-1) var(--ease);
}
.input:hover { border-color: var(--green-600); }
.input:focus { outline: none; border-color: var(--primary); box-shadow: 0 0 0 4px rgba(91, 210, 154, .35); }
.input.invalid, .input[aria-invalid="true"] { border-color: var(--error); }
.field > .field-error { display: inline-flex; align-items: center; gap: var(--s-1); font: var(--t-caption); color: var(--error-text); }
.search { position: relative; display: block; }
.search svg { position: absolute; left: var(--s-4); top: 50%; transform: translateY(-50%); color: var(--muted); pointer-events: none; }
.search .input { padding-left: 44px; }

/* ---- avatar ----------------------------------------------------------- */
.avatar {
  width: 40px; height: 40px; border-radius: var(--r-full); background: var(--surface-mint); color: var(--primary);
  display: inline-flex; align-items: center; justify-content: center; font: var(--t-label); font-size: 15px;
  flex-shrink: 0; letter-spacing: .02em;
}
.avatar.small { width: 32px; height: 32px; font-size: 13px; }
.avatar.big { width: 56px; height: 56px; font-size: 20px; }
.avatar.huge { width: 72px; height: 72px; font-size: 26px; font-weight: var(--w-medium); }
.avatar.solid { background: var(--primary); color: var(--on-primary); }
.avatar.fresh { background: var(--surface); border: 1.5px dashed var(--control-line); color: var(--muted); }
.on-band .avatar { background: var(--green-100); color: var(--green-800); }

/* ---- card ------------------------------------------------------------- */
.card {
  background: var(--surface); border: 1px solid var(--line-strong); border-radius: var(--r-lg);
  padding: var(--s-6); box-shadow: var(--e1);
}
.card.quiet { background: var(--surface-quiet); box-shadow: none; border-color: var(--line); }
.card.flush { padding: 0; overflow: hidden; }
.card h2 { font: var(--t-h3); }
.card h3 { font: var(--t-h3); }
.card-head { display: flex; align-items: center; gap: var(--s-3); margin-bottom: var(--s-4); }
.card-head h2, .card-head h3 { flex-grow: 1; }
a.card, button.card { color: inherit; text-decoration: none; text-align: left; transition: box-shadow var(--dur-2) var(--ease), border-color var(--dur-2) var(--ease), transform var(--dur-2) var(--ease); }
a.card:hover, button.card:hover { box-shadow: var(--e3); border-color: var(--green-300); transform: translateY(-1px); }

/* ---- chips, badges, counts -------------------------------------------- */
.chip {
  display: inline-flex; align-items: center; gap: var(--s-2); height: 36px; padding: 0 var(--s-4);
  border-radius: var(--r-full); border: 1px solid var(--control-line); background: var(--surface);
  font: var(--t-label); color: var(--ink);
}
.chip.small { height: 28px; padding: 0 var(--s-3); font: var(--t-caption); font-weight: var(--w-semibold); }
.chip.silly { border-color: var(--amber); background: var(--amber-bg); color: var(--amber-text); }
.chip.silly.on { background: var(--amber); border-color: var(--amber); color: var(--ink); }
.badge {
  display: inline-flex; align-items: center; justify-content: center; min-width: 22px; height: 22px; padding: 0 var(--s-2);
  border-radius: var(--r-full); font: var(--t-caption); font-weight: var(--w-semibold); font-variant-numeric: tabular-nums;
  background: var(--surface-mint); color: var(--green-800);
}
.badge.attention { background: var(--amber); color: var(--green-950); }
.badge.solid { background: var(--primary); color: var(--on-primary); }
.count-pill { display: inline-flex; min-width: 22px; height: 22px; padding: 0 var(--s-2); border-radius: var(--r-full); background: var(--surface-mint); color: var(--green-800); font: var(--t-caption); font-weight: var(--w-semibold); align-items: center; justify-content: center; }

/* ---- segmented control ------------------------------------------------- */
.seg { display: inline-flex; border: 1px solid var(--control-line); border-radius: var(--r-md); padding: 3px; gap: 3px; background: var(--surface); }
.seg button { border: 0; background: none; padding: 0 var(--s-4); height: 36px; font: var(--t-label); border-radius: var(--r-sm); white-space: nowrap; color: var(--muted); transition: background var(--dur-1) var(--ease), color var(--dur-1) var(--ease); }
.seg button:hover:not(:disabled):not([aria-pressed="true"]) { background: var(--surface-quiet); color: var(--ink); }
.seg button[aria-pressed="true"] { background: var(--primary); color: var(--on-primary); }
.seg.big button { height: 44px; padding: 0 var(--s-6); font: var(--t-body); font-weight: var(--w-semibold); }

/* ---- maths fragments (Typst SVG) -------------------------------------- */
.frag { display: block; max-width: 100%; height: auto; align-self: flex-start; }

/* loading placeholder kept for old markup; new code uses <Skeleton> */
.ghost { background: var(--track); border-radius: var(--r-lg); min-height: 120px; animation: shimmer 1.4s var(--ease) infinite; }
@keyframes shimmer { 50% { opacity: .55; } }
@keyframes spin { to { transform: rotate(360deg); } }
@keyframes rise { from { opacity: 0; transform: translateY(6px); } to { opacity: 1; transform: none; } }
@keyframes fade { from { opacity: 0; } to { opacity: 1; } }

/* the page heading takes focus after a navigation; it needs no ring */
/* headings and panels focused by script (tabindex -1) take no ring; a dialog keeps its lift */
:is(h1, h2, h3, [tabindex="-1"]):focus-visible { box-shadow: none !important; outline: none; }
.dialog[tabindex="-1"]:focus-visible { box-shadow: var(--e4) !important; }