/* Банк заданий — стиль «Тетрадь» */
:root{
  --bz-ink:#1C2433; --bz-muted:#56617A; --bz-blue:#1F4FB8; --bz-blue-d:#163A88; --bz-red:#C7403B;
  --bz-line:#D5DCE6; --bz-paper:#FCFBF7; --bz-cell:#E3E9F2; --bz-white:#FFFFFF;
  --bz-ok:#1C7A46; --bz-ok-bg:#E8F6EE; --bz-bad:#B3261E; --bz-bad-bg:#FDEDEC;
}
body.bz{margin:0;color:var(--bz-ink);font-family:'Golos Text',system-ui,sans-serif;font-size:16px;line-height:1.5;
  background-color:var(--bz-paper);
  background-image:linear-gradient(var(--bz-cell) 1px,transparent 1px),linear-gradient(90deg,var(--bz-cell) 1px,transparent 1px);
  background-size:22px 22px}
.bz *,.bz *::before,.bz *::after{box-sizing:border-box}
.bz a{color:var(--bz-blue)}
.bz a:hover{color:var(--bz-blue-d)}
.bz-wrap{max-width:1200px;margin:0 auto;padding:0 20px}
.bz-hand{font-family:Caveat,'Comic Sans MS',cursive;font-weight:700}
.bz-red{color:var(--bz-red)}
.bz-muted{color:var(--bz-muted);font-size:14px}

/* шапка */
.bz-top{background:var(--bz-white);border-bottom:2px solid var(--bz-blue)}
.bz-top-in{display:flex;flex-wrap:wrap;align-items:center;gap:10px 28px;padding-top:12px;padding-bottom:12px}
.bz-logo{font-family:Caveat,cursive;font-size:30px;font-weight:700;text-decoration:none;color:var(--bz-blue)!important;line-height:1.1}
.bz-subjects{display:flex;flex-wrap:wrap;gap:4px 18px}
.bz-subjects a{text-decoration:none;color:var(--bz-ink);font-weight:500;padding:6px 0;border-bottom:2px solid transparent}
.bz-subjects a.is-active,.bz-subjects a:hover{color:var(--bz-blue);border-bottom-color:var(--bz-red)}

.bz-main{padding-top:20px;padding-bottom:48px}
.bz-crumbs{font-size:14px;color:var(--bz-muted);margin-bottom:14px}
.bz-crumbs a{color:var(--bz-muted);text-decoration:none}
.bz-crumbs a:hover{color:var(--bz-blue);text-decoration:underline}

.bz-cols{display:flex;flex-wrap:wrap;gap:22px;align-items:flex-start}
.bz-col-main{flex:999 1 560px;min-width:0;display:flex;flex-direction:column;gap:14px}
.bz-side{flex:1 1 270px;min-width:0;display:flex;flex-direction:column;gap:14px}

.bz-card{background:var(--bz-white);border:1px solid var(--bz-line);padding:20px 22px}
.bz-task{border-left:3px solid var(--bz-red);display:flex;flex-direction:column;gap:14px;padding:24px 26px}
.bz-task-head{display:flex;flex-wrap:wrap;justify-content:space-between;align-items:baseline;gap:6px 14px}
.bz-h1{margin:0;font-size:26px;line-height:1.2;font-weight:700}
.bz-h1 .bz-hand{color:var(--bz-blue);font-size:1.1em;font-weight:700}
.bz-h2{margin:0 0 10px;font-size:20px;font-weight:600}
.bz-h2 a{text-decoration:none;color:var(--bz-ink)}
.bz-h2 a:hover{color:var(--bz-blue)}
.bz-cond{font-size:18px;line-height:1.65}
.bz-cond p{margin:0 0 10px}
/* только рисунки к задачам: svg внутри формул KaTeX (корни, дроби) трогать нельзя */
.bz-cond img,.bz-cond figure > svg{max-width:100%;height:auto}
.bz-cond figure{margin:6px 0}
.bz-cond figcaption{font-size:13px;color:var(--bz-muted)}

/* ответ */
.bz-answer{display:flex;flex-wrap:wrap;align-items:center;gap:10px}
.bz-label{font-size:26px;color:var(--bz-blue)}
.bz-answer input{font:inherit;font-size:17px;width:190px;min-height:46px;padding:0 12px;border:0;border-bottom:2px solid var(--bz-blue);background:#F4F7FC;color:var(--bz-ink)}
.bz-answer input:focus{outline:2px solid var(--bz-blue);outline-offset:2px}
.bz-answer.is-ok input{border-bottom-color:var(--bz-ok);background:var(--bz-ok-bg)}
.bz-answer.is-bad input{border-bottom-color:var(--bz-bad);background:var(--bz-bad-bg)}
.bz-result{font-family:Caveat,cursive;font-size:24px;font-weight:700}
.bz-answer.is-ok .bz-result{color:var(--bz-ok)}
.bz-answer.is-bad .bz-result{color:var(--bz-bad)}

.bz-btn,.bz-btn-outline{display:inline-flex;align-items:center;justify-content:center;gap:6px;min-height:46px;padding:0 20px;font:inherit;font-size:16px;font-weight:600;text-decoration:none;cursor:pointer;border:1px solid var(--bz-blue)}
.bz-btn{background:var(--bz-blue);color:#fff!important}
.bz-btn:hover{background:var(--bz-blue-d)}
.bz-btn-outline{background:var(--bz-white);color:var(--bz-blue)!important}
.bz-btn-outline:hover{background:#EEF3FC}
.bz-btn-block{width:100%}
.bz-btn-lg{min-height:52px;padding:0 28px;font-size:17px}
.bz-btn:focus-visible,.bz-btn-outline:focus-visible,.bz-acc-btn:focus-visible,.bz-explain-btn:focus-visible,.bz-nums a:focus-visible{outline:2px solid var(--bz-red);outline-offset:2px}
.bz-link{background:none;border:0;padding:0;font:inherit;color:var(--bz-blue);text-decoration:underline;cursor:pointer}

/* аккордеоны */
.bz-acc-btn{width:100%;min-height:48px;padding:0 16px;display:flex;justify-content:space-between;align-items:center;font:inherit;font-weight:600;color:var(--bz-blue);background:transparent;border:1px dashed #9AA8BD;cursor:pointer;text-align:left}
.bz-acc-panel{padding:12px 16px;border:1px dashed #9AA8BD;border-top:0;font-family:Caveat,cursive;font-size:28px;color:var(--bz-blue)}
.bz-explain{padding:0}
.bz-explain-btn{width:100%;display:flex;justify-content:space-between;align-items:center;gap:12px;padding:16px 22px;background:none;border:0;font:inherit;text-align:left;cursor:pointer;color:var(--bz-ink)}
.bz-explain-btn > span:first-child{display:flex;flex-direction:column}
.bz-explain-btn .bz-hand{font-size:22px;line-height:1}
.bz-explain-title{font-size:19px;font-weight:600}
.bz-sq{flex:0 0 44px;width:44px;height:44px;display:flex;align-items:center;justify-content:center;border:1px solid var(--bz-blue);color:var(--bz-blue);font-size:22px}
.bz-explain-btn[aria-expanded="true"] .bz-sq{background:var(--bz-blue);color:#fff}
.bz-explain-body{padding:0 22px 20px;font-size:17px;line-height:1.7}
.bz-explain-body p{margin:0 0 8px}
.bz-explain-body ol,.bz-explain-body ul{margin:0 0 8px;padding-left:22px}

.bz-pager{display:flex;justify-content:space-between;gap:10px;flex-wrap:wrap}

/* сайдбар */
.bz-side-card{display:flex;flex-direction:column;gap:12px}
.bz-side-head{font-size:13px;font-weight:600;color:var(--bz-muted);letter-spacing:.02em}
.bz-side-title{font-size:26px;line-height:1}
.bz-side-card p{margin:0}
.bz-nums{display:grid;grid-template-columns:repeat(5,minmax(0,1fr));gap:6px}
.bz-nums a{display:flex;align-items:center;justify-content:center;height:42px;text-decoration:none;font-size:14px;border:1px solid var(--bz-line);color:var(--bz-ink);background:#fff}
.bz-nums a:hover{border-color:var(--bz-blue)}
.bz-nums a.is-ok{border-color:#9CCFB2;background:var(--bz-ok-bg);color:var(--bz-ok)}
.bz-nums a.is-bad{border-color:#F0B9B4;background:var(--bz-bad-bg);color:var(--bz-bad)}
.bz-nums a.is-current{background:var(--bz-blue);border-color:var(--bz-blue);color:#fff;font-weight:700}

/* списки */
.bz-rows{display:flex;flex-direction:column}
.bz-row{display:flex;gap:14px;align-items:flex-start;padding:12px 4px;border-top:1px solid #EDF0F5;text-decoration:none;color:var(--bz-ink)!important}
.bz-row:first-child{border-top:0}
.bz-row:hover{background:#F6F8FC}
.bz-row-n{flex:0 0 38px;height:38px;display:flex;align-items:center;justify-content:center;border:1px solid var(--bz-line);font-weight:600}
.bz-row.is-ok .bz-row-n{background:var(--bz-ok-bg);color:var(--bz-ok);border-color:#9CCFB2}
.bz-row.is-bad .bz-row-n{background:var(--bz-bad-bg);color:var(--bz-bad);border-color:#F0B9B4}
.bz-row-t{padding-top:7px}
.bz-lines{display:grid;grid-template-columns:repeat(auto-fill,minmax(260px,1fr));gap:12px}
.bz-line{display:flex;gap:14px;align-items:center;text-decoration:none;color:var(--bz-ink)!important}
.bz-line:hover{border-color:var(--bz-blue)}
.bz-line-n{flex:0 0 52px;height:52px;display:flex;align-items:center;justify-content:center;background:var(--bz-blue);color:#fff;font-size:24px;font-weight:700}
.bz-line-body{display:flex;flex-direction:column}
.bz-line-title{font-weight:600}

/* главная */
.bz-hero{padding:18px 0 22px}
.bz-hero-title{margin:0;font-size:clamp(30px,4vw,44px);line-height:1.1}
.bz-hero-title .bz-hand{color:var(--bz-blue)}
.bz-hero-sub{font-size:17px;max-width:640px;margin:10px 0 0}
.bz-subject-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(300px,1fr));gap:14px}
.bz-subject{border-left:3px solid var(--bz-red)}
.bz-subject-cta{display:flex;flex-direction:column;gap:10px;align-items:flex-start}
.bz-subject-cta p{margin:0}
.bz-subject-cta .bz-h2{font-size:28px;margin:0}
.bz-chips{display:flex;flex-wrap:wrap;gap:6px}
.bz-chip{display:inline-flex;align-items:center;min-height:38px;padding:0 12px;border:1px solid var(--bz-line);text-decoration:none;color:var(--bz-ink)!important;background:#fff;font-size:14px}
.bz-chip:hover,.bz-chip.is-active{border-color:var(--bz-blue);color:var(--bz-blue)!important;background:#EEF3FC}

/* конструктор */
.bz-builder{display:flex;flex-direction:column;gap:18px;border-left:3px solid var(--bz-red)}
.bz-fs{border:0;padding:0;margin:0;display:flex;flex-direction:column;gap:10px}
.bz-fs legend{font-weight:600;margin-bottom:8px}
.bz-pick{display:flex;flex-direction:column;gap:6px}
.bz-pick-item{display:flex;gap:10px;align-items:flex-start;padding:10px 12px;border:1px solid var(--bz-line);cursor:pointer}
.bz-pick-item input{width:20px;height:20px;margin-top:2px;accent-color:var(--bz-blue)}
.bz-pick-tools{font-size:14px}
.bz-select{font:inherit;min-height:44px;padding:0 10px;border:1px solid var(--bz-line);background:#fff;width:120px}
.bz-variant{display:flex;flex-direction:column;gap:14px;max-width:880px}
.bz-variant-head{display:flex;flex-wrap:wrap;gap:12px;justify-content:space-between;align-items:flex-start}
.bz-variant-head p{margin:6px 0 0}
.bz-variant-actions{display:flex;gap:8px;flex-wrap:wrap}
.bz-variant-foot{display:flex;flex-wrap:wrap;gap:16px;align-items:center}
.bz-score{font-size:18px}
.bz-score b{font-family:Caveat,cursive;font-size:34px;color:var(--bz-blue)}
.bz-right{font-size:15px;color:var(--bz-muted)}

.bz-foot{border-top:1px solid var(--bz-line);background:#fff;padding:18px 0;font-size:14px;color:var(--bz-muted)}

@media (max-width:640px){
  .bz-task{padding:18px 16px}
  .bz-h1{font-size:22px}
  .bz-cond{font-size:17px}
  .bz-answer input{flex:1;min-width:0;width:auto}
  .bz-answer .bz-btn{flex:1 0 100%}
  .bz-explain-btn{padding:14px 16px}
  .bz-explain-body{padding:0 16px 16px}
}