:root {
  --page: var(--tg-theme-secondary-bg-color, #eef1f7);
  --card: var(--tg-theme-section-bg-color, var(--tg-theme-bg-color, #ffffff));
  --text: var(--tg-theme-text-color, #151a23);
  --hint: var(--tg-theme-hint-color, #7a8394);
  --accent: var(--tg-theme-button-color, #3d6df2);
  --accent-text: var(--tg-theme-button-text-color, #ffffff);
  --danger: var(--tg-theme-destructive-text-color, #e5484d);
  --ok: #1f9d63;
  --line: color-mix(in srgb, var(--hint) 22%, transparent);
  --soft: color-mix(in srgb, var(--accent) 12%, transparent);
  --radius: 18px;
  --math: "Cambria Math", "STIX Two Math", "Latin Modern Math", "Times New Roman", serif;
  color-scheme: light dark;
}

@media (prefers-color-scheme: dark) {
  :root {
    --page: var(--tg-theme-secondary-bg-color, #0f1218);
    --card: var(--tg-theme-section-bg-color, var(--tg-theme-bg-color, #1a1f29));
    --text: var(--tg-theme-text-color, #eef1f6);
    --hint: var(--tg-theme-hint-color, #8b94a6);
    --accent: var(--tg-theme-button-color, #5b86ff);
  }
}

* { box-sizing: border-box; -webkit-tap-highlight-color: transparent; }
[hidden] { display: none !important; }

html, body {
  margin: 0;
  background: var(--page);
  color: var(--text);
  font: 16px/1.45 -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
}

.app {
  max-width: 560px;
  margin: 0 auto;
  padding: 18px 16px calc(96px + env(safe-area-inset-bottom));
  min-height: 100vh;
}

.app.no-tabs { padding-bottom: calc(24px + env(safe-area-inset-bottom)); }

h1 { font-size: 26px; line-height: 1.2; margin: 6px 0 4px; letter-spacing: -0.02em; }
h2 { font-size: 21px; line-height: 1.25; margin: 0; letter-spacing: -0.01em; }
h3 { font-size: 13px; text-transform: uppercase; letter-spacing: 0.06em; color: var(--hint); margin: 26px 4px 10px; font-weight: 600; }
p { margin: 0; }
.hint { color: var(--hint); font-size: 14px; }
.screen { animation: enter .22s ease both; }
@keyframes enter { from { opacity: 0; transform: translateY(8px); } to { opacity: 1; transform: none; } }

/* segmented control */
.segment {
  display: grid; grid-auto-flow: column; grid-auto-columns: 1fr;
  background: var(--card); border-radius: 14px; padding: 4px; gap: 4px; margin: 18px 0 4px;
}
.segment button {
  border: 0; background: transparent; color: var(--text); font: inherit; font-weight: 600;
  padding: 10px 0; border-radius: 10px; cursor: pointer; transition: background .15s, color .15s;
}
.segment button.on { background: var(--accent); color: var(--accent-text); }

/* lists */
.list { background: var(--card); border-radius: var(--radius); overflow: hidden; }
.row {
  display: flex; align-items: center; gap: 14px; width: 100%; padding: 13px 16px;
  border: 0; background: transparent; color: inherit; font: inherit; text-align: left; cursor: pointer;
}
.row + .row { border-top: 1px solid var(--line); }
.row:active { background: var(--soft); }
.row .body { flex: 1; min-width: 0; }
.row .title { font-weight: 600; }
.row .sub { color: var(--hint); font-size: 14px; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.row .sub.math { font-family: var(--math); font-size: 15px; }
.chev { color: var(--hint); font-size: 20px; }
.badge {
  flex: none; width: 40px; height: 40px; border-radius: 12px; display: grid; place-items: center;
  font-weight: 700; font-size: 17px; color: #fff;
}
.count { color: var(--hint); font-size: 14px; font-variant-numeric: tabular-nums; }

.hero-row {
  display: flex; align-items: center; gap: 14px; width: 100%; padding: 16px; margin: 14px 0 0;
  border: 0; border-radius: var(--radius); cursor: pointer; font: inherit; text-align: left;
  background: linear-gradient(135deg, var(--accent), color-mix(in srgb, var(--accent) 60%, #8a5cff));
  color: #fff;
}
.hero-row .title { font-weight: 700; }
.hero-row .sub { opacity: .85; font-size: 14px; }
.hero-row .body { flex: 1; }

/* buttons */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 8px;
  border: 0; border-radius: 14px; padding: 14px 18px; font: inherit; font-weight: 600;
  cursor: pointer; background: var(--soft); color: var(--accent); transition: transform .08s, opacity .15s;
}
.btn:active { transform: scale(.97); }
.btn:disabled { opacity: .45; cursor: default; transform: none; }
.btn.primary { background: var(--accent); color: var(--accent-text); }
.btn.ok { background: var(--ok); color: #fff; }
.btn.bad { background: color-mix(in srgb, var(--danger) 14%, transparent); color: var(--danger); }
.btn.danger { background: transparent; color: var(--danger); }
.btn.block { width: 100%; }
.btn.small { padding: 8px 12px; font-size: 14px; border-radius: 10px; }
.actions { display: grid; grid-auto-flow: column; grid-auto-columns: 1fr; gap: 10px; margin-top: 16px; }
.stack { display: grid; gap: 10px; margin-top: 16px; }

.back {
  border: 0; background: none; color: var(--accent); font: inherit; padding: 4px 0; margin-bottom: 6px; cursor: pointer;
}

/* mode cards */
.modes { display: grid; gap: 12px; margin-top: 18px; }
.mode {
  display: flex; gap: 16px; align-items: center; padding: 18px; border-radius: var(--radius);
  background: var(--card); border: 0; color: inherit; font: inherit; text-align: left; cursor: pointer;
}
.mode:disabled { opacity: .5; cursor: default; }
.mode .icon { font-size: 30px; width: 54px; height: 54px; border-radius: 16px; display: grid; place-items: center; background: var(--soft); flex: none; }
.mode .title { font-weight: 700; font-size: 17px; }

/* quiz */
.quiz-top { display: flex; align-items: center; gap: 12px; margin: 4px 0 18px; }
.progress { flex: 1; height: 8px; border-radius: 8px; background: var(--line); overflow: hidden; }
.progress i { display: block; height: 100%; background: var(--accent); border-radius: 8px; transition: width .3s ease; }
.quiz-top .count { min-width: 44px; text-align: right; }
.close { border: 0; background: var(--card); color: var(--hint); width: 34px; height: 34px; border-radius: 50%; font-size: 18px; cursor: pointer; }

.qcard { background: var(--card); border-radius: 22px; padding: 26px 20px; text-align: center; box-shadow: 0 8px 30px rgba(0,0,0,.05); }
.qlabel { color: var(--hint); font-size: 13px; text-transform: uppercase; letter-spacing: .07em; margin-bottom: 10px; }
.variant {
  display: inline-block; margin-top: 10px; padding: 5px 12px; border-radius: 999px;
  background: var(--soft); color: var(--accent); font-size: 14px; font-weight: 600;
}
.formula {
  font-family: var(--math); font-size: 30px; line-height: 1.3; margin: 18px 0 6px; word-break: break-word;
}
.reveal { animation: pop .28s cubic-bezier(.2,.9,.3,1.3) both; }
@keyframes pop { from { opacity: 0; transform: scale(.92); } to { opacity: 1; transform: none; } }

.legend { margin: 14px 0 0; padding: 0; list-style: none; text-align: left; }
.legend li { padding: 7px 0; border-top: 1px solid var(--line); font-size: 15px; }
.legend b { font-family: var(--math); font-size: 17px; font-weight: 600; margin-right: 4px; }
.note { margin-top: 14px; padding: 10px 12px; border-radius: 12px; background: var(--soft); font-size: 14px; text-align: left; }

.options { display: grid; gap: 10px; margin-top: 16px; }
.opt {
  border: 2px solid transparent; background: var(--card); color: var(--text); border-radius: 16px;
  padding: 16px; font-family: var(--math); font-size: 20px; cursor: pointer; transition: border-color .15s, background .15s, transform .08s;
}
.opt:active { transform: scale(.98); }
.opt:disabled { cursor: default; transform: none; }
.opt.right { border-color: var(--ok); background: color-mix(in srgb, var(--ok) 14%, var(--card)); }
.opt.wrong { border-color: var(--danger); background: color-mix(in srgb, var(--danger) 12%, var(--card)); }
.opt.dim { opacity: .5; }

.verdict { font-weight: 700; font-size: 18px; margin-top: 18px; text-align: center; }
.verdict.ok { color: var(--ok); }
.verdict.bad { color: var(--danger); }

/* result */
.result { text-align: center; padding-top: 30px; }
.ring { width: 170px; height: 170px; margin: 0 auto 18px; }
.ring circle { fill: none; stroke-width: 14; }
.ring .track { stroke: var(--line); }
.ring .bar { stroke: var(--accent); stroke-linecap: round; transform: rotate(-90deg); transform-origin: center; transition: stroke-dashoffset .8s ease; }
.ring text { fill: var(--text); font-size: 34px; font-weight: 700; text-anchor: middle; dominant-baseline: central; }

/* stats */
.stat { padding: 14px 16px; }
.stat + .stat { border-top: 1px solid var(--line); }
.stat .top { display: flex; justify-content: space-between; gap: 10px; margin-bottom: 8px; }
.stat .pct { font-weight: 700; font-variant-numeric: tabular-nums; }
.bar { height: 8px; border-radius: 8px; background: var(--line); overflow: hidden; }
.bar i { display: block; height: 100%; border-radius: 8px; }

/* forms */
.field { display: grid; gap: 6px; margin-top: 14px; }
.field span { font-size: 14px; color: var(--hint); font-weight: 600; }
input, textarea {
  width: 100%; border: 1px solid var(--line); background: var(--card); color: var(--text);
  border-radius: 12px; padding: 12px 14px; font: inherit; outline: none;
}
input:focus, textarea:focus { border-color: var(--accent); }
textarea { min-height: 110px; resize: vertical; }
input.math { font-family: var(--math); font-size: 20px; }
.symbols { display: flex; flex-wrap: wrap; gap: 6px; margin-top: 6px; }
.symbols button {
  min-width: 38px; height: 36px; border: 0; border-radius: 10px; background: var(--card); color: var(--text);
  font-family: var(--math); font-size: 17px; cursor: pointer;
}
.symbols button:active { background: var(--soft); }
.preview { font-family: var(--math); font-size: 24px; text-align: center; padding: 14px; background: var(--card); border-radius: 14px; min-height: 60px; }

.head { display: flex; align-items: flex-start; justify-content: space-between; gap: 12px; }
.empty { text-align: center; padding: 40px 20px; color: var(--hint); }
.empty .big { font-size: 44px; margin-bottom: 10px; }

/* panel: requests and statuses */
.req { padding: 14px 16px; }
.req + .req { border-top: 1px solid var(--line); }
.req .title { font-weight: 600; }
.req .sub { color: var(--hint); font-size: 14px; }
.req .actions { margin-top: 10px; }
.pill { display: inline-block; margin-top: 10px; padding: 4px 12px; border-radius: 999px; font-size: 13px; font-weight: 600; }
.pill.approved { background: color-mix(in srgb, var(--ok) 15%, transparent); color: var(--ok); }
.pill.pending { background: color-mix(in srgb, #f59e0b 18%, transparent); color: #c27c00; }
.pill.rejected { background: color-mix(in srgb, var(--danger) 14%, transparent); color: var(--danger); }

/* tabs */
.tabs {
  position: fixed; left: 0; right: 0; bottom: 0; display: flex; justify-content: center;
  background: color-mix(in srgb, var(--card) 88%, transparent); backdrop-filter: blur(14px);
  border-top: 1px solid var(--line); padding: 6px 8px calc(6px + env(safe-area-inset-bottom));
}
.tabs button {
  flex: 1; max-width: 180px; border: 0; background: none; color: var(--hint); font: inherit; font-size: 12px;
  display: grid; gap: 2px; justify-items: center; padding: 6px 0; cursor: pointer; font-weight: 600;
}
.tabs button .i { font-size: 22px; line-height: 1; filter: grayscale(1); opacity: .7; }
.tabs button.on { color: var(--accent); }
.tabs button.on .i { filter: none; opacity: 1; }

.toast {
  position: fixed; left: 50%; bottom: calc(90px + env(safe-area-inset-bottom)); transform: translateX(-50%);
  background: #1d2330; color: #fff; padding: 11px 16px; border-radius: 12px; font-size: 14px;
  max-width: calc(100% - 32px); box-shadow: 0 8px 24px rgba(0,0,0,.2); animation: enter .2s ease both; z-index: 10;
}

.loader { width: 34px; height: 34px; margin: 120px auto; border-radius: 50%; border: 3px solid var(--line); border-top-color: var(--accent); animation: spin .8s linear infinite; }
@keyframes spin { to { transform: rotate(360deg); } }

@media (prefers-reduced-motion: reduce) { * { animation: none !important; transition: none !important; } }

/* --- v2 additions --- */
.opt.text { font-family: inherit; font-size: 17px; text-align: left; }
.qtext { font-size: 19px; font-weight: 600; line-height: 1.35; }
.qexpr { font-family: var(--math); font-size: 28px; margin-top: 14px; word-break: break-word; }
.steps { color: var(--hint); font-size: 13px; font-weight: 600; margin-bottom: 4px; }

.choice { display: grid; gap: 10px; margin-top: 16px; }
.choice button {
  display: flex; gap: 14px; align-items: center; padding: 16px; border-radius: 16px; border: 2px solid transparent;
  background: var(--card); color: inherit; font: inherit; text-align: left; cursor: pointer;
}
.choice button.on { border-color: var(--accent); background: var(--soft); }
.choice .icon { font-size: 26px; }
.choice .title { font-weight: 700; }

.grades { display: grid; grid-template-columns: repeat(5, 1fr); gap: 8px; margin-top: 16px; }
.grades button {
  padding: 18px 0; border-radius: 14px; border: 2px solid transparent; background: var(--card); color: inherit;
  font: inherit; font-size: 20px; font-weight: 700; cursor: pointer;
}
.grades button.on { border-color: var(--accent); background: var(--soft); color: var(--accent); }

.check { display: flex; align-items: center; gap: 12px; width: 100%; padding: 13px 16px; cursor: pointer; }
.check + .check { border-top: 1px solid var(--line); }
.check input { width: 22px; height: 22px; flex: none; accent-color: var(--accent); margin: 0; }
.check .body { flex: 1; min-width: 0; }
.check .sub { color: var(--hint); font-size: 13px; }
.check .sub.math { font-family: var(--math); font-size: 15px; }
.group-title { font-size: 13px; color: var(--hint); font-weight: 600; margin: 18px 4px 8px; }

.chips { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 8px; }
.chips button {
  padding: 8px 14px; border-radius: 999px; border: 0; background: var(--card); color: var(--text);
  font: inherit; font-size: 15px; cursor: pointer;
}
.chips button.on { background: var(--accent); color: var(--accent-text); }

select {
  width: 100%; border: 1px solid var(--line); background: var(--card); color: var(--text);
  border-radius: 12px; padding: 12px 14px; font: inherit;
}
.toggle { display: flex; align-items: center; justify-content: space-between; gap: 12px; margin-top: 14px; }
.toggle input { width: 22px; height: 22px; accent-color: var(--accent); flex: none; }

.cardbox { background: var(--card); border-radius: 22px; padding: 22px 20px; box-shadow: 0 8px 30px rgba(0,0,0,.05); }
.cardbox .crumb { color: var(--hint); font-size: 13px; }
.cardbox h2 { margin-top: 6px; }
.cardbox .formula { text-align: center; }
.cardbox img { width: 100%; border-radius: 14px; margin-top: 14px; }
.comps { width: 100%; border-collapse: collapse; margin-top: 12px; font-size: 15px; }
.comps td { padding: 8px 6px; border-top: 1px solid var(--line); vertical-align: top; }
.comps td:first-child { font-family: var(--math); font-size: 18px; font-weight: 600; white-space: nowrap; }
.comps td:last-child { color: var(--hint); white-space: nowrap; text-align: right; }
.cardbox .note { white-space: pre-line; }

.tiles { display: grid; grid-template-columns: repeat(3, 1fr); gap: 10px; margin-top: 12px; }
.tile { background: var(--card); border-radius: 16px; padding: 12px; text-align: center; }
.tile b { display: block; font-size: 22px; font-variant-numeric: tabular-nums; }
.tile span { color: var(--hint); font-size: 12px; }

.track { background: var(--card); border-radius: var(--radius); padding: 16px; margin-top: 14px; }
.track .title { font-weight: 700; font-size: 17px; }
.track .sub { color: var(--hint); font-size: 14px; margin-top: 2px; }
.track .stack { margin-top: 12px; }

.days { display: flex; align-items: flex-end; gap: 4px; height: 90px; padding: 12px 12px 0; }
.days div { flex: 1; display: flex; flex-direction: column; justify-content: flex-end; height: 100%; gap: 2px; }
.days i { display: block; border-radius: 4px 4px 0 0; background: var(--accent); min-height: 2px; }
.days i.bad { background: color-mix(in srgb, var(--danger) 60%, transparent); border-radius: 0; }
.days-labels { display: flex; gap: 4px; padding: 4px 12px 12px; color: var(--hint); font-size: 10px; }
.days-labels span { flex: 1; text-align: center; }

.codebox { text-align: center; padding: 22px; background: var(--card); border-radius: 22px; margin-top: 16px; }
.codebox .code { font-family: ui-monospace, Consolas, monospace; font-size: 36px; font-weight: 700; letter-spacing: .2em; margin: 8px 0; }
.codebox .link { word-break: break-all; font-size: 14px; color: var(--hint); }

.warn { color: #c27c00; }
.okc { color: var(--ok); }
.badc { color: var(--danger); }
.comp-row { display: grid; grid-template-columns: 80px 1fr 80px 34px; gap: 6px; margin-top: 6px; }
.comp-row input { padding: 10px; }
.comp-row button { border: 0; background: none; color: var(--danger); font-size: 20px; cursor: pointer; }
.search { margin-top: 14px; }
.preview-q { padding: 12px 16px; }
.preview-q + .preview-q { border-top: 1px solid var(--line); }
.preview-q ol { margin: 6px 0 0; padding-left: 20px; }
.preview-q li.right { color: var(--ok); font-weight: 600; }
.login { text-align: center; padding-top: 60px; }
.login .big { font-size: 56px; }
sub { font-size: .62em; vertical-align: -.25em; line-height: 0; }

/* --- v2.1: home, streaks, animations --- */
.today { display: flex; gap: 14px; align-items: center; background: var(--card); border-radius: var(--radius); padding: 14px 16px; margin-top: 16px; }
.today .body { flex: 1; min-width: 0; }
.today .title { font-weight: 700; }
.today .sub { color: var(--hint); font-size: 14px; margin-bottom: 8px; }
.fire { font-size: 30px; display: grid; justify-items: center; line-height: 1; min-width: 48px; }
.fire b { font-size: 16px; margin-top: 2px; }
.fire.off { filter: grayscale(1); opacity: .5; }
.hero-row.big { padding: 20px 18px; box-shadow: 0 10px 28px color-mix(in srgb, var(--accent) 35%, transparent); }
.hero-row.big .icon { font-size: 32px; width: 54px; height: 54px; display: grid; place-items: center; border-radius: 16px; background: rgba(255,255,255,.18); flex: none; }
.hero-row.big .title { font-size: 18px; }
.meter { display: flex; height: 10px; border-radius: 10px; background: var(--line); overflow: hidden; margin-top: 12px; }
.meter i { display: block; height: 100%; transition: width .5s ease; }
.m-ok { background: var(--ok); }
.m-act { background: var(--accent); }
.legend-row { display: flex; flex-wrap: wrap; gap: 4px 14px; margin-top: 8px; font-size: 13px; color: var(--hint); }
.legend-row i { display: inline-block; width: 9px; height: 9px; border-radius: 50%; margin-right: 5px; background: var(--line); }
.legend-row i.m-ok { background: var(--ok); }
.legend-row i.m-act { background: var(--accent); }
.mini-actions { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 12px; }
.mini-actions .btn { flex: 1 1 auto; }
.quiz-stats { display: flex; gap: 8px; margin: -8px 0 12px; min-height: 26px; }
.chip { padding: 3px 10px; border-radius: 999px; background: var(--card); font-size: 14px; font-weight: 700; }
.fire-chip { background: color-mix(in srgb, #f97316 18%, var(--card)); color: #ea580c; animation: pop .3s ease both; }
.qlabel { font-weight: 600; }
.opt.pop { animation: pop .35s cubic-bezier(.2,.9,.3,1.4) both; }
.opt.shake { animation: shake .4s ease both; }
@keyframes shake { 20%, 60% { transform: translateX(-7px); } 40%, 80% { transform: translateX(7px); } }
.burst { position: relative; height: 0; }
.burst span { position: absolute; left: 50%; top: 80px; font-size: 26px; opacity: 0; animation: fly 1.3s ease-out forwards; }
@keyframes fly { 0% { opacity: 1; transform: translate(-50%, 0) scale(.4); } 100% { opacity: 0; transform: translate(calc(-50% + var(--x)), var(--y)) scale(1.2) rotate(30deg); } }

/* --- v3: tablet and desktop --- */
/* Tablet: wider column, two-column grids for cards and answer options. */
@media (min-width: 700px) {
  .app { max-width: 780px; padding: 28px 28px calc(110px + env(safe-area-inset-bottom)); }
  h1 { font-size: 30px; }
  .modes, .choice, .options { grid-template-columns: 1fr 1fr; }
  .options .opt.text { grid-column: 1 / -1; }
  .qcard, .cardbox { padding: 34px 32px; }
  .formula { font-size: 34px; }
  .qexpr { font-size: 32px; }
  .tabs button { max-width: 200px; font-size: 13px; }
  .row:hover, .mode:hover, .choice button:hover, .opt:not(:disabled):hover { background: color-mix(in srgb, var(--accent) 7%, var(--card)); }
}

/* Desktop: tabs become a sidebar, content gets a wide centered column. */
@media (min-width: 1000px) {
  .tabs {
    top: 0; right: auto; width: 230px; flex-direction: column; justify-content: flex-start; gap: 4px;
    padding: 28px 14px; border-top: 0; border-right: 1px solid var(--line);
  }
  .tabs::before { content: "🧲 Физформула"; font-weight: 700; font-size: 18px; padding: 0 12px 18px; }
  .tabs button {
    flex: none; max-width: none; display: flex; align-items: center; gap: 12px;
    padding: 11px 12px; border-radius: 12px; font-size: 15px; text-align: left;
  }
  .tabs button:hover { background: var(--soft); }
  .tabs button.on { background: var(--soft); }
  .app { max-width: 1000px; padding: 40px 48px 48px; }
  .app:not(.no-tabs) { margin-left: 230px; max-width: none; }
  .app:not(.no-tabs) > .screen { max-width: 980px; margin: 0 auto; }
  h1 { font-size: 34px; }
  .modes { grid-template-columns: repeat(3, 1fr); }
  .mode { flex-direction: column; align-items: flex-start; }
  /* Single-card screens (cards, quiz, result) read better in a narrower column. */
  .app > .screen:has(.qcard, .cardbox, .result) { max-width: 760px; }
  .app > .screen:has(> .empty), .app > .screen:has(.login) { max-width: 560px; }
  .toast { bottom: 28px; }
  .days { height: 140px; }
}