/* ==========================================================
   Global design system — KidsSheets
   Sections: tokens · base · layout · header · buttons · cards
   forms · tool layout · content · footer · utilities · print
   ========================================================== */
:root{
  --bg:#FDFBF7;--surface:#fff;--ink:#1E293B;--muted:#556275;--line:#E8E4DA;
  --blue:#2563EB;--blue-d:#1D4ED8;--blue-soft:#EFF6FF;--blue-line:#BFDBFE;
  --yellow:#FBBF24;--mint:#10B981;--mint-soft:#ECFDF5;--rose:#E11D48;--rose-soft:#FFF1F2;--amber-soft:#FFFBEB;
  --rb:linear-gradient(90deg,#EF4444,#F97316,#FACC15,#22C55E,#3B82F6,#8B5CF6);
  --r:14px;--r-lg:20px;--shadow:0 4px 18px rgba(30,41,59,.07);--shadow-lg:0 12px 34px rgba(30,41,59,.12);
  --s1:.25rem;--s2:.5rem;--s3:.75rem;--s4:1rem;--s5:1.5rem;--s6:2rem;--s7:3rem;--s8:4.5rem;
  --font:ui-rounded,"SF Pro Rounded","Nunito","Segoe UI",system-ui,-apple-system,Roboto,"Helvetica Neue",Arial,sans-serif;
  --max:1180px;
}
*,*::before,*::after{box-sizing:border-box}
html{-webkit-text-size-adjust:100%;scroll-behavior:smooth}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}*{transition:none!important;animation:none!important}}
body{margin:0;background:var(--bg);color:var(--ink);font-family:var(--font);font-size:1rem;line-height:1.65}
img,svg,canvas{max-width:100%}
h1,h2,h3,h4{line-height:1.2;margin:0 0 var(--s3);font-weight:800;letter-spacing:-.01em}
h1{font-size:clamp(1.85rem,5vw,2.9rem)}h2{font-size:clamp(1.45rem,3.4vw,2rem)}h3{font-size:1.2rem}
p{margin:0 0 var(--s4)}a{color:var(--blue)}a:hover{color:var(--blue-d)}
:focus-visible{outline:3px solid #F59E0B;outline-offset:2px;border-radius:6px}
.sr-only{position:absolute;width:1px;height:1px;overflow:hidden;clip:rect(0 0 0 0);white-space:nowrap}
.skip{position:absolute;left:-999px;top:0;background:var(--ink);color:#fff;padding:.6rem 1rem;z-index:100;border-radius:0 0 8px 0}
.skip:focus{left:0}
.container{width:100%;max-width:var(--max);margin:0 auto;padding:0 var(--s4)}
.section{padding:var(--s7) 0}.section-tight{padding:var(--s5) 0}
.center{text-align:center}.muted{color:var(--muted)}.small{font-size:.875rem}
.rainbow-text{background:var(--rb);-webkit-background-clip:text;background-clip:text;color:transparent;-webkit-text-fill-color:transparent}
.rainbow-bar{height:5px;background:var(--rb)}

/* header */
.site-header{background:var(--surface);border-bottom:1px solid var(--line);position:sticky;top:0;z-index:50}
.header-row{display:flex;align-items:center;gap:var(--s4);min-height:64px}
.brand{display:flex;align-items:center;gap:.6rem;text-decoration:none;color:var(--ink);flex-shrink:0}
.brand-mark{width:40px;height:40px;border-radius:12px;background:var(--blue-soft);display:grid;place-items:center;font-size:1.3rem}
.brand-name{font-weight:900;font-size:1.25rem;line-height:1.1;display:block}
.brand-tag{display:block;font-size:.7rem;color:var(--muted);font-weight:600}
.nav{display:none;margin-left:auto;align-items:center;gap:.15rem}
.nav a,.nav button.nav-link{font:inherit;font-weight:700;font-size:.95rem;color:var(--ink);text-decoration:none;padding:.55rem .8rem;border-radius:10px;background:none;border:0;cursor:pointer}
.nav a:hover,.nav button.nav-link:hover,.nav a[aria-current="page"]{background:var(--blue-soft);color:var(--blue)}
.has-menu{position:relative}
.menu{display:none;position:absolute;right:0;top:100%;min-width:220px;background:var(--surface);border:1px solid var(--line);border-radius:var(--r);box-shadow:var(--shadow-lg);padding:.4rem;z-index:60}
.menu.open{display:block}.menu a{display:block}
.header-cta{display:none}
.nav-toggle{margin-left:auto;background:none;border:2px solid var(--line);border-radius:12px;width:46px;height:46px;display:grid;place-items:center;cursor:pointer;color:var(--ink)}
.nav-toggle span,.nav-toggle span::before,.nav-toggle span::after{display:block;width:20px;height:2.5px;background:currentColor;border-radius:2px;position:relative;content:""}
.nav-toggle span::before{position:absolute;top:-6px}.nav-toggle span::after{position:absolute;top:6px}
.mobile-nav{display:none;border-top:1px solid var(--line);background:var(--surface);padding:var(--s3) var(--s4) var(--s5)}
.mobile-nav.open{display:block}
.mobile-nav a{display:block;padding:.8rem .5rem;font-weight:700;text-decoration:none;color:var(--ink);border-bottom:1px solid var(--line)}
.mobile-nav .group{font-size:.75rem;text-transform:uppercase;letter-spacing:.06em;color:var(--muted);font-weight:800;margin:var(--s4) 0 0}
.mobile-nav .btn{margin-top:var(--s4);width:100%;color:#fff}
@media(min-width:980px){.nav{display:flex}.header-cta{display:inline-flex;margin-left:var(--s3)}.nav-toggle,.mobile-nav{display:none!important}}

/* buttons */
.btn{display:inline-flex;align-items:center;justify-content:center;gap:.5rem;font:inherit;font-weight:800;font-size:1rem;line-height:1.2;text-decoration:none;text-align:center;padding:.8rem 1.25rem;border-radius:12px;border:2px solid transparent;cursor:pointer;background:var(--blue);color:#fff;transition:background .15s,transform .05s}
.btn:hover{background:var(--blue-d);color:#fff}.btn:active{transform:translateY(1px)}
.btn-secondary{background:var(--surface);color:var(--blue);border-color:var(--blue-line)}.btn-secondary:hover{background:var(--blue-soft);color:var(--blue-d)}
.btn-success{background:#047857}.btn-success:hover{background:#065F46}
.btn-ghost{background:none;color:var(--muted);border-color:transparent;font-weight:700}.btn-ghost:hover{background:#F1F5F9;color:var(--ink)}
.btn-block{width:100%}.btn-lg{padding:1rem 1.6rem;font-size:1.1rem}
.btn[disabled]{opacity:.5;cursor:not-allowed}

/* cards / grids */
.card{background:var(--surface);border:1px solid var(--line);border-radius:var(--r-lg);box-shadow:var(--shadow);padding:var(--s5)}
.card-link{display:block;text-decoration:none;color:inherit;transition:transform .12s,box-shadow .12s,border-color .12s}
.card-link:hover{transform:translateY(-2px);box-shadow:var(--shadow-lg);border-color:var(--blue-line);color:inherit}
.card-link h3{margin-bottom:.35rem;color:var(--ink)}.card-link p{margin:0;color:var(--muted);font-size:.95rem}
.card-icon{width:48px;height:48px;border-radius:14px;display:grid;place-items:center;font-size:1.6rem;margin-bottom:var(--s3);background:var(--blue-soft)}
.grid{display:grid;gap:var(--s4)}
.grid-2,.grid-3,.grid-4{grid-template-columns:1fr}
@media(min-width:620px){.grid-2,.grid-3,.grid-4{grid-template-columns:repeat(2,1fr)}}
@media(min-width:960px){.grid-3{grid-template-columns:repeat(3,1fr)}.grid-4{grid-template-columns:repeat(4,1fr)}}
.badge{display:inline-block;background:var(--amber-soft);color:#92400E;border:1px solid #FDE68A;border-radius:999px;padding:.25rem .8rem;font-size:.78rem;font-weight:800}
.tag-free{background:var(--mint-soft);color:#047857;border-color:#A7F3D0}
.steps{counter-reset:s;display:grid;gap:var(--s4)}
.step{position:relative;padding-left:3.4rem}
.step::before{counter-increment:s;content:counter(s);position:absolute;left:0;top:0;width:2.5rem;height:2.5rem;border-radius:50%;background:var(--blue);color:#fff;font-weight:900;display:grid;place-items:center}
.step h3{margin-bottom:.2rem}.step p{margin:0;color:var(--muted)}
.check-list{list-style:none;margin:0;padding:0;display:grid;gap:.6rem}
.check-list li{padding-left:1.8rem;position:relative}.check-list li::before{content:"✓";position:absolute;left:0;color:#047857;font-weight:900}

/* hero */
.hero{background:linear-gradient(180deg,#F0F7FF,var(--bg));padding:var(--s7) 0 var(--s6);text-align:center}
.hero p.lead{font-size:1.15rem;color:var(--muted);max-width:44rem;margin:0 auto var(--s5)}
.hero .actions{display:flex;flex-wrap:wrap;gap:var(--s3);justify-content:center}
.page-head{padding:var(--s5) 0 var(--s4)}
.page-head p.lead{color:var(--muted);font-size:1.05rem;max-width:46rem;margin:0}
.breadcrumbs{font-size:.85rem;color:var(--muted);padding:var(--s3) 0 0}
.breadcrumbs ol{list-style:none;display:flex;flex-wrap:wrap;gap:.35rem;margin:0;padding:0}
.breadcrumbs li+li::before{content:"›";margin-right:.35rem;color:#94A3B8}
.breadcrumbs a{color:var(--muted)}

/* forms */
.field{margin-bottom:var(--s4)}
.field>label,.field>.label{display:block;font-weight:800;font-size:.9rem;margin-bottom:.35rem}
.hint{display:block;font-size:.8rem;color:var(--muted);margin-top:.3rem;font-weight:500}
input[type=text],input[type=number],select,textarea{width:100%;font:inherit;font-size:1rem;color:var(--ink);background:#fff;border:2px solid #CBD5E1;border-radius:12px;padding:.65rem .8rem}
textarea{resize:vertical;min-height:5.2rem}
input:focus,select:focus,textarea:focus{border-color:var(--blue);outline:none;box-shadow:0 0 0 3px rgba(37,99,235,.18)}
input[aria-invalid=true],textarea[aria-invalid=true]{border-color:var(--rose)}
input[type=range]{width:100%;accent-color:var(--blue);height:1.8rem}
.row2{display:grid;grid-template-columns:1fr 1fr;gap:var(--s3)}
.switch{display:flex;align-items:center;justify-content:space-between;gap:var(--s3);padding:.7rem .85rem;border-radius:12px;background:var(--blue-soft);margin-bottom:var(--s3);cursor:pointer}
.switch b{display:block;font-size:.92rem}.switch small{display:block;color:var(--muted);font-size:.78rem}
.switch input{width:1.3rem;height:1.3rem;accent-color:var(--blue);flex-shrink:0}
.seg{display:grid;grid-auto-flow:column;grid-auto-columns:1fr;gap:.4rem}
.seg button,.chip{font:inherit;font-weight:700;font-size:.88rem;padding:.55rem .4rem;border-radius:11px;border:2px solid #CBD5E1;background:#fff;color:var(--ink);cursor:pointer}
.seg button[aria-pressed=true],.chip[aria-pressed=true]{background:var(--blue-soft);border-color:var(--blue);color:var(--blue-d)}
.seg button:hover,.chip:hover{border-color:var(--blue-line)}
.chips{display:flex;flex-wrap:wrap;gap:.35rem}.chip{min-width:2.4rem;padding:.4rem .5rem}
.panel{background:var(--amber-soft);border:1px solid #FDE68A;border-radius:14px;padding:var(--s3);margin-bottom:var(--s4)}
.panel>b{display:block;margin-bottom:.5rem}
.alert{border-radius:12px;padding:.75rem 1rem;font-weight:700;margin:0 0 var(--s3);font-size:.92rem}
.alert[hidden]{display:none}
.alert.error{background:var(--rose-soft);color:#9F1239;border:1px solid #FECDD3}
.alert.info{background:var(--blue-soft);color:#1E3A8A;border:1px solid var(--blue-line)}
.alert.ok{background:var(--mint-soft);color:#065F46;border:1px solid #A7F3D0}

/* tool layout */
.tool{display:grid;gap:var(--s5);align-items:start;padding-bottom:var(--s6)}
.tool-controls{padding:var(--s4)}
.tool-controls h2{font-size:1.25rem;display:flex;justify-content:space-between;align-items:center;gap:var(--s3)}
.tool-actions{display:grid;gap:.6rem;margin-top:var(--s4)}
.tool-actions .two{display:grid;grid-template-columns:1fr 1fr;gap:.6rem}
.tool-preview{padding:var(--s4)}
.preview-bar{display:flex;justify-content:space-between;align-items:center;gap:var(--s3);flex-wrap:wrap;margin-bottom:var(--s3)}
.preview-bar h2{font-size:1.25rem;margin:0}
.paper-wrap{background:#E8EDF3;border-radius:16px;padding:clamp(.5rem,2vw,1.25rem)}
.paper{max-width:600px;margin:0 auto;background:#fff;padding:6px;box-shadow:0 10px 35px rgba(0,0,0,.16)}
.paper canvas{display:block;width:100%;height:auto}
.pager{display:none;align-items:center;justify-content:center;gap:var(--s3);margin-top:var(--s3)}
.pager button{font:inherit;font-weight:700;padding:.5rem .9rem;border-radius:11px;border:2px solid #CBD5E1;background:#fff;cursor:pointer}
.pager button:disabled{opacity:.4;cursor:not-allowed}
.preview-note{margin:var(--s3) 0 0;font-size:.85rem;color:var(--muted);text-align:center}
@media(min-width:980px){.tool{grid-template-columns:350px minmax(0,1fr)}.tool-preview{position:sticky;top:78px}}

/* content */
.prose{max-width:46rem}
.prose h2{margin-top:var(--s6)}.prose h3{margin-top:var(--s5)}
.prose ul,.prose ol{padding-left:1.3rem;margin:0 0 var(--s4)}.prose li{margin:.3rem 0}
.prose a{text-decoration:underline}
.content-card{max-width:none}
.faq details{border-bottom:1px solid var(--line);padding:.2rem 0}
.faq summary{cursor:pointer;font-weight:800;padding:.9rem 0;list-style:none;display:flex;justify-content:space-between;gap:var(--s3)}
.faq summary::-webkit-details-marker{display:none}.faq summary::after{content:"+";font-size:1.3rem;line-height:1;color:var(--blue)}
.faq details[open] summary::after{content:"–"}.faq details p{color:var(--muted);margin:0 0 var(--s4)}
.related a{display:block;text-decoration:none}
.link-list{list-style:none;margin:0;padding:0;display:grid;gap:.5rem}
.link-list a{font-weight:700}

/* footer */
.site-footer{background:var(--surface);border-top:1px solid var(--line);margin-top:var(--s7);padding:var(--s7) 0 var(--s5)}
.footer-grid{display:grid;gap:var(--s5);grid-template-columns:1fr}
@media(min-width:760px){.footer-grid{grid-template-columns:1.4fr 1fr 1fr 1fr}}
.site-footer h2{font-size:.85rem;text-transform:uppercase;letter-spacing:.07em;color:var(--muted);margin-bottom:var(--s3)}
.site-footer ul{list-style:none;margin:0;padding:0;display:grid;gap:.45rem}
.site-footer a{color:var(--ink);text-decoration:none;font-weight:600;font-size:.95rem}.site-footer a:hover{color:var(--blue);text-decoration:underline}
.footer-bottom{border-top:1px solid var(--line);margin-top:var(--s5);padding-top:var(--s4);font-size:.85rem;color:var(--muted);display:flex;flex-wrap:wrap;justify-content:space-between;gap:var(--s3)}

/* print: the worksheet only */
@media print{
  @page{margin:0}
  body{background:#fff}
  .site-header,.site-footer,.breadcrumbs,.skip,.tool-controls,.preview-bar,.pager,.preview-note,.page-head,.section,.alert,.mobile-nav{display:none!important}
  .tool,.tool-preview,.paper-wrap,.paper,.container{display:block!important;padding:0!important;margin:0!important;border:0!important;box-shadow:0!important;background:#fff!important;max-width:none!important;position:static!important}
  .paper canvas{width:100%!important;height:auto!important;page-break-inside:avoid}
}