:root{
    --bg:#eef1f5;
    --surface:#ffffff;
    --ink:#33404d;
    --ink-soft:#71808f;
    --line:#e3e8ef;
    --accent:#5b8aa6;
    --plus:#7ba894;
    --plus-bg:#e9f1ed;
    --minus:#6f97bd;
    --minus-bg:#e8eef5;
    --gange:#9384bf;
    --gange-bg:#ece9f4;
    --division:#cf9572;
    --division-bg:#f5ece4;
    --good:#5a9d77;
    --bad:#cf7b6f;
    --grid:#c2d2e3;
    --paper:#fdfdfa;
  }
  *{box-sizing:border-box;margin:0;padding:0;}
  html,body{height:100%;}
  body{
    font-family:'Nunito',-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;
    background:var(--bg);
    color:var(--ink);
    line-height:1.55;
    -webkit-font-smoothing:antialiased;
  }
  .wrap{max-width:760px;margin:0 auto;padding:24px 20px 64px;}

  /* Header */
  header.site{
    padding:6px 4px 22px;
  }
  .brand{
    display:inline-flex;align-items:center;gap:12px;
    padding:6px;margin:-6px;border-radius:14px;
    cursor:pointer;
    transition:background .12s ease, transform .08s ease;
  }
  .brand:hover{ background:rgba(91,138,166,.09); }
  .brand:active{ transform:scale(.99); }
  .brand:focus-visible{ outline:3px solid var(--accent); outline-offset:2px; }
  .logo-mark{
    width:42px;height:42px;flex:none;
  }
  .site h1{
    font-size:1.5rem;font-weight:800;letter-spacing:-.01em;
  }
  .site .tag{
    font-size:.9rem;color:var(--ink-soft);font-weight:600;
  }

  /* Cards */
  .card{
    background:var(--surface);
    border:1px solid var(--line);
    border-radius:16px;
    padding:22px;
  }
  .intro{margin-bottom:20px;}
  .intro p{color:var(--ink-soft);font-weight:600;}
  .intro h2{font-size:1.3rem;margin-bottom:6px;}

  /* Operation grid */
  .op-grid{
    display:grid;grid-template-columns:1fr 1fr;gap:14px;
  }
  .op-card{
    background:var(--surface);
    border:1px solid var(--line);
    border-radius:16px;
    padding:20px;
    cursor:pointer;
    text-align:left;
    font-family:inherit;
    transition:transform .12s ease, box-shadow .12s ease;
    display:flex;flex-direction:column;gap:4px;
  }
  .op-card:hover{transform:translateY(-3px);box-shadow:0 8px 20px rgba(51,64,77,.08);}
  .op-card:focus-visible{outline:3px solid var(--accent);outline-offset:2px;}
  .op-badge{
    width:52px;height:52px;border-radius:14px;
    display:flex;align-items:center;justify-content:center;
    font-size:1.9rem;font-weight:800;color:#fff;margin-bottom:8px;
  }
  .op-card .op-name{font-size:1.2rem;font-weight:800;}
  .op-card .op-desc{font-size:.9rem;color:var(--ink-soft);font-weight:600;}
  .op-card .op-progress{
    margin-top:10px;font-size:.82rem;font-weight:700;color:var(--ink-soft);
  }

  /* Buttons */
  .btn{
    font-family:inherit;font-weight:700;font-size:1rem;
    border:none;border-radius:12px;padding:12px 20px;
    cursor:pointer;transition:filter .12s ease, transform .08s ease;
    color:#fff;background:var(--accent);
  }
  .btn:hover{filter:brightness(1.06);}
  .btn:active{transform:scale(.98);}
  .btn:focus-visible{outline:3px solid var(--ink);outline-offset:2px;}
  .btn.ghost{
    background:transparent;color:var(--ink-soft);
    border:1px solid var(--line);
  }
  .btn.ghost:hover{background:#f4f6f9;filter:none;}
  .btn.block{width:100%;}
  .btn[disabled]{opacity:.45;cursor:not-allowed;}

  .back{
    background:none;border:none;font-family:inherit;font-weight:700;
    color:var(--ink-soft);cursor:pointer;font-size:.95rem;
    padding:6px 0;margin-bottom:14px;display:inline-flex;align-items:center;gap:6px;
  }
  .back:hover{color:var(--ink);}

  /* Operation menu */
  .op-head{
    display:flex;align-items:center;gap:14px;margin-bottom:20px;
  }
  .op-head .op-badge{margin-bottom:0;}
  .op-head h2{font-size:1.5rem;}
  .op-head .sub{color:var(--ink-soft);font-weight:600;font-size:.92rem;}
  .choice-grid{display:grid;grid-template-columns:1fr 1fr;gap:14px;}
  .choice{
    background:var(--surface);border:1px solid var(--line);
    border-radius:16px;padding:22px;cursor:pointer;font-family:inherit;
    text-align:left;transition:transform .12s ease, box-shadow .12s ease;
  }
  .choice:hover{transform:translateY(-3px);box-shadow:0 8px 20px rgba(51,64,77,.08);}
  .choice:focus-visible{outline:3px solid var(--accent);outline-offset:2px;}
  .choice .ico{font-size:1.7rem;margin-bottom:8px;}
  .choice h3{font-size:1.1rem;margin-bottom:4px;}
  .choice p{font-size:.88rem;color:var(--ink-soft);font-weight:600;}

  /* Section headings */
  h2.section{font-size:1.35rem;margin-bottom:4px;}
  .lead{color:var(--ink-soft);font-weight:600;margin-bottom:18px;}

  .panel{margin-bottom:18px;}
  .panel h3{font-size:1.05rem;margin-bottom:10px;}
  .steps-list{list-style:none;counter-reset:s;}
  .steps-list li{
    position:relative;padding:8px 0 8px 40px;
    border-bottom:1px solid var(--line);font-weight:600;
  }
  .steps-list li:last-child{border-bottom:none;}
  .steps-list li::before{
    counter-increment:s;content:counter(s);
    position:absolute;left:0;top:8px;
    width:26px;height:26px;border-radius:8px;
    background:var(--op-bg);color:var(--op);
    display:flex;align-items:center;justify-content:center;
    font-weight:800;font-size:.85rem;
  }

  .tip{
    background:var(--op-bg);border-radius:14px;padding:16px 18px;
    border:1px solid var(--line);
  }
  .tip h3{display:flex;align-items:center;gap:8px;}
  .tip p{font-weight:600;margin-top:6px;}

  /* Worked example / calc board */
  .example{
    border:1px solid var(--line);border-radius:14px;padding:20px;
    text-align:center;
  }
  .example .ex-title{font-weight:800;font-size:1.05rem;margin-bottom:14px;}
  .board-area{
    min-height:170px;display:flex;align-items:center;justify-content:center;
    padding:10px 0 16px;
  }
  table.calc{border-collapse:collapse;margin:0 auto;}
  table.calc td{
    width:46px;height:46px;text-align:center;
    font-size:1.8rem;font-weight:700;font-variant-numeric:tabular-nums;
    padding:0;
    border:1px solid var(--grid);
    background:var(--paper);
  }
  table.calc td.op-col{
    color:var(--op);font-weight:800;font-size:1.5rem;
  }
  table.calc tr.carry-row td{
    font-size:1rem;font-weight:800;color:var(--op);
    vertical-align:top;padding-top:4px;
  }
  table.calc tr.result-row td{
    border-top:3px solid var(--ink);
  }
  table.calc td.hl{
    background:var(--op-bg);
  }
  table.calc td.mul-label{
    border:none;background:none;
  }
  .carry-tag{
    display:inline-block;
    font-size:1rem;font-weight:800;
    color:var(--op);
  }
  .mul-label{
    font-size:.82rem;font-weight:700;
    color:var(--ink-soft);
    text-align:left;
    padding-left:10px;
    white-space:nowrap;
  }
  /* decimalkomma */
  table.calc td.comma-after{position:relative;}
  table.calc td.comma-after::after{
    content:",";
    position:absolute;right:-4px;bottom:6px;
    font-size:1.7rem;font-weight:800;color:var(--ink);z-index:2;
  }
  table.divtable td.dv-comma{position:relative;}
  table.divtable td.dv-comma::after{
    content:",";
    position:absolute;right:-3px;bottom:3px;
    font-size:1.35rem;font-weight:800;color:var(--ink);z-index:2;
  }
  /* minus: låne-markering */
  table.calc td.subtop{
    position:relative;
    vertical-align:middle;
    overflow:visible;
  }
  .subtop .digit{
    position:relative;
    display:inline-block;
    line-height:1;
  }
  .subtop .digit.struck{
    color:#9aa6b2;
  }
  .subtop .digit.struck::after{
    content:"";
    position:absolute;
    left:-5px;right:-5px;
    top:48%;
    border-top:3px solid var(--minus);
    transform:rotate(-16deg);
  }
  .subtop .ann-borrow{
    font-size:.82rem;
    font-weight:800;
    color:var(--minus);
    position:relative;
    top:-.62em;
    margin-right:-1px;
  }
  .subtop .ann-above{
    position:absolute;
    top:1px;left:50%;
    transform:translateX(-50%);
    font-size:1rem;
    font-weight:800;
    color:var(--minus);
    line-height:1;
  }
  /* division — trappedivision */
  table.divtable{
    border-collapse:collapse;margin:0 auto;
  }
  table.divtable td{
    width:44px;height:44px;text-align:center;padding:0;
    font-size:1.55rem;font-weight:700;font-variant-numeric:tabular-nums;
    border:1px solid var(--grid);
    background:var(--paper);
  }
  table.divtable td.dv-pad{ border:none;background:none; }
  table.divtable td.dv-dig{font-weight:800;}
  table.divtable td.dv-prod{color:var(--ink-soft);}
  table.divtable td.dv-rem{color:var(--op);font-weight:800;}
  table.divtable td.dv-bring{color:var(--op);font-weight:700;}
  table.divtable td.dv-bring::before{
    content:"↓";font-size:.62em;opacity:.7;margin-right:1px;
  }
  table.divtable td.dv-line{border-top:3px solid var(--ink);}
  table.divtable td.dv-tail{
    width:auto;text-align:left;white-space:nowrap;
    font-size:1.4rem;font-weight:800;padding-left:10px;
    border:none;background:none;
  }
  .divtable .qd{display:inline-block;min-width:24px;text-align:center;}
  .divtable .qd-off{color:var(--line);}
  .div-rest{margin-top:12px;font-size:1rem;font-weight:700;color:var(--ink-soft);}

  .caption{
    background:var(--op-bg);border-radius:12px;padding:14px 16px;
    font-weight:700;min-height:58px;display:flex;align-items:center;
    justify-content:center;text-align:center;
  }
  .stepper-controls{
    display:flex;justify-content:space-between;align-items:center;
    margin-top:14px;gap:10px;
  }
  .step-count{font-weight:700;color:var(--ink-soft);font-size:.9rem;}

  /* Practice */
  .level-row{display:flex;gap:8px;margin-bottom:18px;flex-wrap:wrap;}
  .level-btn{
    flex:1;min-width:90px;font-family:inherit;font-weight:700;font-size:.92rem;
    border:1px solid var(--line);background:var(--surface);color:var(--ink-soft);
    border-radius:10px;padding:9px 8px;cursor:pointer;transition:all .12s ease;
  }
  .level-btn:hover{border-color:var(--op);}
  .level-btn.active{
    background:var(--op);color:#fff;border-color:var(--op);
  }
  .level-btn:focus-visible{outline:3px solid var(--accent);outline-offset:2px;}

  .stat-row{
    display:flex;gap:10px;margin-bottom:16px;
  }
  .stat{
    flex:1;background:var(--surface);border:1px solid var(--line);
    border-radius:12px;padding:10px;text-align:center;
  }
  .stat .num{font-size:1.5rem;font-weight:800;color:var(--op);}
  .stat .lbl{font-size:.78rem;font-weight:700;color:var(--ink-soft);text-transform:uppercase;letter-spacing:.03em;}
  .stars{font-size:1.1rem;letter-spacing:2px;}

  .problem{
    text-align:center;padding:14px 0 6px;
  }
  .problem .q{
    font-size:2.6rem;font-weight:800;font-variant-numeric:tabular-nums;
    display:flex;align-items:center;justify-content:center;gap:14px;flex-wrap:wrap;
  }
  .problem .q .opsign{color:var(--op);}
  .answer-row{
    display:flex;gap:10px;justify-content:center;align-items:center;
    margin-top:18px;flex-wrap:wrap;
  }
  input.answer{
    font-family:inherit;font-size:1.6rem;font-weight:800;
    width:120px;text-align:center;
    border:2px solid var(--line);border-radius:12px;padding:8px 10px;
    color:var(--ink);
  }
  input.answer:focus{outline:none;border-color:var(--op);}
  input.answer.small{width:90px;}
  .answer-row .field-label{
    font-weight:700;color:var(--ink-soft);font-size:.95rem;
  }
  .dec-hint{
    text-align:center;font-size:.85rem;font-weight:700;
    color:var(--ink-soft);margin-top:10px;
  }
  .feedback{
    margin-top:16px;text-align:center;font-weight:800;font-size:1.05rem;
    min-height:28px;
  }
  .feedback.good{color:var(--good);}
  .feedback.bad{color:var(--bad);}
  .practice-actions{
    display:flex;gap:10px;justify-content:center;margin-top:14px;flex-wrap:wrap;
  }

  .solution{
    margin-top:16px;border:1px solid var(--line);border-radius:12px;
    padding:16px;background:#fafbfc;
  }
  .solution h4{font-size:1rem;margin-bottom:12px;}
  .solution ol{list-style:none;counter-reset:sol;}
  .solution ol li{
    position:relative;padding:7px 0 7px 34px;font-weight:600;
    border-bottom:1px solid var(--line);
  }
  .solution ol li:last-child{border-bottom:none;}
  .solution ol li::before{
    counter-increment:sol;content:counter(sol);
    position:absolute;left:0;top:7px;width:24px;height:24px;
    border-radius:7px;background:var(--op-bg);color:var(--op);
    display:flex;align-items:center;justify-content:center;font-weight:800;font-size:.8rem;
  }
  .solution .sol-board{margin:6px 0 14px;}

  footer.site{
    text-align:center;color:var(--ink-soft);font-size:.82rem;
    font-weight:600;padding-top:32px;
  }

  @media(max-width:560px){
    .op-grid,.choice-grid{grid-template-columns:1fr;}
    .problem .q{font-size:2.1rem;}
    table.calc td{width:40px;height:40px;font-size:1.5rem;}
    table.divtable td{width:37px;height:37px;font-size:1.3rem;}
    table.divtable td.dv-tail{font-size:1.15rem;}
    .mul-label{font-size:.72rem;padding-left:5px;}
  }