/* Одна колонка шириной телефона: поля тетради слева, синяя ручка ученика, красная — учителя. */
:root {
  --paper: #f4f6fb;
  --sheet: #ffffff;
  --ink: #18213a;
  --muted: #66708a;
  --line: #dde3ef;
  --pen: #2346d6;
  --pen-soft: #e6ecff;
  --on-pen: #ffffff;
  --red: #d42a37;
  --red-soft: #fdeaec;
  --ok: #138a52;
  --ok-soft: #e3f5ec;
  --amber: #b26a00;
  --margin: #f2b8bd;
  --f-display: "Unbounded", "Golos Text", system-ui, sans-serif;
  --f-body: "Golos Text", system-ui, -apple-system, "Segoe UI", sans-serif;
  --f-hand: "Caveat", "Segoe Print", cursive;
  --f-mono: ui-monospace, "SF Mono", Menlo, Consolas, monospace;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --paper: #0f1320; --sheet: #171c2c; --ink: #e7eaf4; --muted: #9099b3; --line: #2a3148;
    --pen: #8aa2ff; --pen-soft: #232c4d; --on-pen: #0f1320; --red: #ff6b74; --red-soft: #3a1d24;
    --ok: #4fd18f; --ok-soft: #16301f; --amber: #f0b44c; --margin: #5a2b33; color-scheme: dark;
  }
}
:root[data-theme="dark"] {
    --paper: #0f1320; --sheet: #171c2c; --ink: #e7eaf4; --muted: #9099b3; --line: #2a3148;
    --pen: #8aa2ff; --pen-soft: #232c4d; --on-pen: #0f1320; --red: #ff6b74; --red-soft: #3a1d24;
    --ok: #4fd18f; --ok-soft: #16301f; --amber: #f0b44c; --margin: #5a2b33; color-scheme: dark;
}

* { box-sizing: border-box; }
html, body { margin: 0; }
body {
  background: var(--paper); color: var(--ink); font: 16px/1.5 var(--f-body);
  padding: env(safe-area-inset-top, 0px) max(16px, env(safe-area-inset-right, 0px)) 0 max(16px, env(safe-area-inset-left, 0px));
  -webkit-tap-highlight-color: transparent;
}
button { font: inherit; color: inherit; }
button:focus-visible, input:focus-visible, summary:focus-visible { outline: 2px solid var(--pen); outline-offset: 2px; }
.wrap { max-width: 560px; margin: 0 auto; padding-block: 18px 120px; display: flex; flex-direction: column; gap: 16px; }

/* Главная */
.eyebrow { font-size: 12px; letter-spacing: .08em; text-transform: uppercase; color: var(--muted); }
h1 { font: 700 22px/1.2 var(--f-display); margin: 4px 0 0; text-wrap: balance; }
.sub { margin: 4px 0 0; color: var(--muted); font-size: 14px; font-variant-numeric: tabular-nums; }
.rules { background: var(--sheet); border: 1px solid var(--line); border-radius: 14px; padding: 12px 14px; }
.rules summary { cursor: pointer; font-weight: 600; }
.rules[open] summary { margin-bottom: 8px; }
.rules h3 { font: 600 14px var(--f-display); margin: 12px 0 4px; }
.rules p { margin: 4px 0; font-size: 14px; }
.formula { font: 600 14px/1.7 var(--f-mono); white-space: pre-line; color: var(--ink); }
.list { display: flex; flex-direction: column; gap: 10px; }
.topic { display: flex; flex-direction: column; gap: 10px; }
.topic h2 { font: 700 17px/1.3 var(--f-display); margin: 10px 0 0; text-wrap: balance; }
.sub a { color: var(--pen); font-weight: 600; }
.ex-card { display: grid; grid-template-columns: auto 1fr auto; align-items: center; gap: 4px 14px; text-align: left; background: var(--sheet); border: 1px solid var(--line); border-radius: 14px; padding: 14px; cursor: pointer; }
.ex-num { grid-row: span 2; font: 700 22px var(--f-display); color: var(--pen); width: 1.6em; text-align: center; }
.ex-title { font-weight: 600; }
.ex-count { font-size: 13px; color: var(--muted); font-variant-numeric: tabular-nums; }
.ex-card .bar { grid-column: 2 / 4; }
.bar { height: 6px; background: var(--line); border-radius: 3px; overflow: hidden; display: flex; }
.bar i { height: 100%; background: var(--ok); }
.bar i.warn { background: var(--amber); }
.review { display: flex; justify-content: space-between; align-items: center; background: var(--red-soft); color: var(--red); border: 0; border-radius: 14px; padding: 14px; font-weight: 600; cursor: pointer; text-align: left; }
.review span { font: 600 22px var(--f-hand); }
.review.mix { background: var(--pen-soft); color: var(--pen); }

/* Упражнение */
.topbar { display: flex; align-items: center; gap: 10px; }
.back { border: 0; background: var(--sheet); border-radius: 10px; width: 40px; height: 40px; font-size: 20px; cursor: pointer; flex: none; }
.topbar .t { flex: 1; min-width: 0; }
.topbar .t b { display: block; font: 600 15px var(--f-display); }
.topbar .t span { font-size: 13px; color: var(--muted); font-variant-numeric: tabular-nums; }
.modes { display: grid; grid-template-columns: 1fr 1fr; background: var(--line); border-radius: 10px; padding: 3px; gap: 3px; flex: none; }
.modes button { border: 0; background: transparent; font-size: 13px; font-weight: 500; padding: 6px 10px; border-radius: 8px; cursor: pointer; }
.modes button[aria-pressed="true"] { background: var(--sheet); color: var(--pen); box-shadow: 0 1px 3px rgb(0 0 0 / .12); }
.dots { display: flex; flex-wrap: wrap; gap: 6px; }
.dot { width: 26px; height: 26px; border-radius: 50%; border: 1.5px solid var(--line); background: var(--sheet); font-size: 11px; color: var(--muted); cursor: pointer; padding: 0; font-variant-numeric: tabular-nums; }
.dot.ok { background: var(--ok); border-color: var(--ok); color: var(--on-pen); }
.dot.fixed { background: var(--amber); border-color: var(--amber); color: var(--on-pen); }
.dot.cur { border-color: var(--pen); border-width: 2.5px; color: var(--pen); font-weight: 700; }
.dot.cur.ok, .dot.cur.fixed { color: var(--on-pen); box-shadow: 0 0 0 2px var(--sheet), 0 0 0 4px var(--pen); }

.sheet { background: var(--sheet); border: 1px solid var(--line); border-radius: 16px; padding: 16px 16px 18px 30px; position: relative; display: flex; flex-direction: column; gap: 12px; }
.sheet::before { content: ""; position: absolute; left: 18px; top: 0; bottom: 0; width: 1.5px; background: var(--margin); }
.task { font-size: 13px; color: var(--muted); margin: 0; }
.from { font-size: 12px; color: var(--muted); }
.sent { font-size: 18px; line-height: 2.5; }
.num { color: var(--muted); margin-right: 4px; font-variant-numeric: tabular-nums; }

.slot { position: relative; display: inline-flex; align-items: center; gap: 6px; vertical-align: middle; line-height: 1.25; max-width: 100%; flex-wrap: wrap; }
.slot input { font: 18px var(--f-body); color: var(--pen); border: 0; border-bottom: 2px solid var(--pen); background: var(--pen-soft); border-radius: 6px 6px 0 0; padding: 4px 8px; width: 8.5em; max-width: 62vw; }
.slot input:focus { outline: none; background: var(--sheet); box-shadow: 0 0 0 2px var(--pen) inset; }
.verb { font-size: 15px; color: var(--muted); white-space: nowrap; }
.filled { color: var(--ok); font-weight: 600; background: var(--ok-soft); border-radius: 6px; padding: 2px 8px; }
.slot.bad input, .slot.bad .drop { border-color: var(--red); background: var(--red-soft); color: var(--red); }
.slot .ans { position: absolute; left: 4px; bottom: calc(100% - 4px); font: 600 21px/1 var(--f-hand); color: var(--red); white-space: nowrap; transform: rotate(-2deg); pointer-events: none; }

.drop { min-width: 6.5em; min-height: 38px; padding: 3px; border: 2px dashed var(--line); border-radius: 10px; display: inline-flex; flex-wrap: wrap; gap: 4px; align-items: center; cursor: pointer; background: transparent; }
.drop.active { border-color: var(--pen); background: var(--pen-soft); }
.drop.hover { border-style: solid; }
.tile { font: 500 16px var(--f-body); border: 1px solid var(--line); background: var(--sheet); color: var(--ink); border-radius: 9px; padding: 7px 12px; cursor: grab; touch-action: none; user-select: none; box-shadow: 0 2px 0 var(--line); }
.drop .tile { padding: 4px 9px; box-shadow: none; color: var(--pen); }
.tile.ghost { position: fixed; z-index: 50; pointer-events: none; box-shadow: 0 8px 20px rgb(0 0 0 / .25); }
.bank { display: flex; flex-wrap: wrap; gap: 8px; min-height: 40px; }
.bank-label { font-size: 12px; color: var(--muted); margin-bottom: -4px; }

.fb { border-radius: 12px; padding: 10px 12px; font-size: 15px; display: flex; flex-direction: column; gap: 8px; }
.fb.ok { background: var(--ok-soft); color: var(--ok); font-weight: 600; }
.fb.bad { background: var(--red-soft); }
.why { color: var(--red); font-weight: 600; }
.why span { color: var(--ink); font-weight: 400; }
.why small { display: block; color: var(--muted); font-weight: 500; font-size: 12px; }
.ladder { display: flex; gap: 6px; flex-wrap: wrap; }
.ladder button { border: 1px solid var(--line); background: var(--sheet); border-radius: 9px; padding: 6px 11px; font-size: 13px; font-weight: 500; cursor: pointer; }
.ladder button:disabled { opacity: .4; cursor: default; }
.book { background: var(--sheet); border-left: 3px solid var(--pen); border-radius: 0 9px 9px 0; padding: 8px 10px; font-size: 14px; }
.book small { display: block; color: var(--muted); font-size: 12px; }

.bottom { position: fixed; left: 0; right: 0; bottom: 0; z-index: 20; background: linear-gradient(transparent, var(--paper) 30%); padding: 22px max(16px, env(safe-area-inset-right, 0px)) calc(14px + env(safe-area-inset-bottom, 0px)) max(16px, env(safe-area-inset-left, 0px)); }
.bottom .row { max-width: 560px; margin: 0 auto; display: flex; gap: 8px; }
.main-btn { flex: 1; border: 0; border-radius: 14px; padding: 15px; font-size: 17px; font-weight: 600; background: var(--pen); color: var(--on-pen); cursor: pointer; }
.main-btn.go { background: var(--ok); }
.ghost-btn:disabled { opacity: .5; }
.ghost-btn { border: 1px solid var(--line); background: var(--sheet); border-radius: 14px; padding: 15px 16px; cursor: pointer; font-weight: 500; }

/* Итоги */
.result { text-align: center; padding: 10px 0; }
.result .big { font: 700 44px var(--f-display); color: var(--ok); font-variant-numeric: tabular-nums; }
.mistakes { display: flex; flex-direction: column; gap: 8px; }
.mistake { background: var(--sheet); border: 1px solid var(--line); border-radius: 12px; padding: 10px 12px; font-size: 15px; }
.mistake mark { background: none; color: var(--ok); font-weight: 600; }
.actions { display: flex; flex-direction: column; gap: 8px; }

.toast { position: fixed; left: 50%; bottom: calc(96px + env(safe-area-inset-bottom, 0px)); transform: translateX(-50%); background: var(--ink); color: var(--paper); padding: 8px 14px; border-radius: 10px; font-size: 14px; z-index: 60; }

@media (prefers-reduced-motion: no-preference) {
  .fb, .book { animation: rise .18s ease-out; }
  @keyframes rise { from { opacity: 0; transform: translateY(4px); } }
}