:root{
  --navy:#1B2A55;
  --ball:#E9F54A;
  --stitch:#D6263A;
  --grass:#2E7D46;
  --grass2:#358B4F;
  --board:#123524;
  --board-dark:#0A2217;
  --good:#1F9D55;
  --chalk:#FFFFFF;
}
*{box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
body{
  margin:0;
  font-family:"Baloo 2", ui-rounded, "Arial Rounded MT Bold", "Trebuchet MS", sans-serif;
  color:var(--navy);
  background:var(--grass) repeating-linear-gradient(90deg,var(--grass) 0 64px,var(--grass2) 64px 128px);
  min-height:100vh;
}
button{font:inherit;cursor:pointer;color:inherit}
:focus-visible{outline:4px solid var(--ball);outline-offset:3px}
[hidden]{display:none !important}
.wrap{max-width:1180px;margin:0 auto;padding:0 16px}
.skip{position:absolute;left:-999px;top:8px;background:#fff;padding:8px 12px;border-radius:8px;z-index:20}
.skip:focus{left:8px}

/* ---------- Top bar ---------- */
.topbar{background:var(--board);border-bottom:4px solid var(--board-dark);position:sticky;top:0;z-index:10}
.topbar-in{display:flex;align-items:center;justify-content:space-between;gap:12px;min-height:60px;padding-top:6px;padding-bottom:6px}
.brand{display:flex;align-items:center;gap:10px;white-space:nowrap;text-decoration:none;color:var(--ball);font-weight:800;font-size:clamp(18px,5vw,26px);line-height:1}
@media (max-width:380px){ .logo{width:28px;height:28px} .brand{gap:7px} .modes button{padding:5px 9px;font-size:14px} }
.brand small{font-size:.72em;font-weight:700;color:#CFE3D6}
.logo{width:34px;height:34px;flex:none}
.modes{display:flex;background:var(--board-dark);border-radius:12px;padding:3px}
.modes button{border:0;background:transparent;color:#CFE3D6;font-weight:700;font-size:15px;padding:5px 12px;border-radius:9px;white-space:nowrap}
.modes button[aria-selected="true"]{background:var(--ball);color:var(--navy)}

/* ---------- Layout ---------- */
.layout{display:grid;gap:16px;padding-top:16px;padding-bottom:28px}
@media (min-width:920px){
  .layout{grid-template-columns:300px minmax(0,1fr);gap:28px;align-items:start;padding-top:24px}
  .panel{position:sticky;top:88px}
}

/* ---------- Side panel ---------- */
.panel{color:#fff}
.intro{margin:0 0 12px;font-size:17px;line-height:1.4;max-width:42ch}
.filters{background:rgba(10,34,23,.55);border-radius:16px;border:2px solid rgba(255,255,255,.18)}
.filters summary{list-style:none;display:flex;justify-content:space-between;align-items:center;padding:10px 14px;font-weight:800;font-size:18px;cursor:pointer}
.filters summary::-webkit-details-marker{display:none}
.filters summary::after{content:"";width:10px;height:10px;border-right:3px solid #fff;border-bottom:3px solid #fff;transform:rotate(45deg);margin:-4px 4px 0 10px;transition:transform .2s}
.filters[open] summary::after{transform:rotate(-135deg);margin-top:4px}
.count{margin-left:auto;font-weight:500;font-size:15px;color:#CFE3D6}
.filters-body{padding:0 14px 14px}
.ptitle{font-size:15px;font-weight:700;margin:8px 0 6px;color:#CFE3D6}
.chips{display:flex;flex-wrap:wrap;gap:6px}
.chip{
  border:2px solid #fff;background:transparent;color:#fff;border-radius:999px;
  padding:3px 12px 3px 6px;font-weight:700;font-size:15px;display:inline-flex;align-items:center;gap:6px;min-height:36px;
}
.chip .dot{width:16px;height:16px;border-radius:50%;background:var(--c);border:2px solid #fff;flex:none}
.chip[aria-pressed="true"]{background:#fff;color:var(--navy)}
.levels{display:grid;grid-template-columns:repeat(3,1fr);gap:6px}
@media (min-width:920px){ .levels{grid-template-columns:1fr} }
.lvl-btn{
  border:2px solid #fff;background:transparent;color:#fff;border-radius:12px;padding:5px 10px;text-align:left;
  display:flex;flex-direction:column;line-height:1.15;
}
.lvl-btn b{display:flex;align-items:center;gap:3px;font-size:16px}
.lvl-btn b svg{width:14px;height:14px}
.lvl-btn small{font-size:13px;font-weight:500;opacity:.85}
.lvl-btn[aria-pressed="true"]{background:#fff;color:var(--navy)}
.tip{font-size:14px;line-height:1.4;margin:12px 0 0;color:#E4F0E8}
.panel-tools{display:flex;gap:8px;margin-top:10px;flex-wrap:wrap}
.tool{background:transparent;border:2px solid rgba(255,255,255,.7);color:#fff;border-radius:10px;padding:4px 12px;font-weight:700;font-size:15px;min-height:38px}
.tool:hover{background:rgba(255,255,255,.12)}

/* ---------- Scoreboard ---------- */
.board{display:flex;gap:8px;justify-content:flex-end;margin-bottom:12px}
.board div{background:var(--board);border:3px solid var(--board-dark);border-radius:10px;padding:2px 12px 0;text-align:center;min-width:86px}
.board span{display:block;font-size:28px;font-weight:800;color:var(--ball);font-variant-numeric:tabular-nums;line-height:1.1}
.board small{font-size:13px;color:#CFE3D6}

/* ---------- Card ---------- */
.stage{perspective:1600px;container-type:inline-size}
.card{display:grid;transition:transform .55s ease;transform-style:preserve-3d;position:relative;cursor:pointer}
.card.flipped{transform:rotateY(180deg);cursor:default}
.card.no-anim{transition:none}
.face{
  grid-area:1/1;backface-visibility:hidden;-webkit-backface-visibility:hidden;
  border-radius:22px;padding:18px 20px 20px;position:relative;overflow:hidden;min-height:420px;
  box-shadow:0 6px 0 rgba(0,0,0,.28);
}
.front{background:var(--ball)}
.back{background:#fff;transform:rotateY(180deg)}
.face > *:not(.stitch){position:relative;z-index:1}
.stitch{position:absolute;width:170px;height:170px;pointer-events:none;z-index:0}
.stitch.tl{top:-70px;left:-70px}
.stitch.br{bottom:-70px;right:-70px;transform:rotate(180deg)}
.back .stitch{opacity:.3}

.toprow{display:flex;justify-content:space-between;align-items:center;gap:8px;flex-wrap:wrap}
.tag{background:var(--c);color:#fff;border-radius:999px;padding:1px 14px;font-weight:700;font-size:15px}
.lvl{font-size:15px;font-weight:700;display:flex;align-items:center;gap:3px}
.lvl svg{width:16px;height:16px}
.q{font-size:clamp(21px,5vw,28px);line-height:1.25;font-weight:700;margin:14px 0;max-width:32ch}
.diagram{background:#fff;border-radius:14px;padding:6px 6px 2px;border:3px solid var(--navy);max-width:420px}
.diagram svg{display:block;width:100%;max-height:250px}
.legend{display:flex;gap:4px 12px;justify-content:center;font-size:14px;font-weight:700;padding:2px 0 4px;flex-wrap:wrap}
.legend span{display:inline-flex;align-items:center;gap:4px}
.legend svg{width:15px;height:15px}

.a-label{font-size:16px;font-weight:700;color:var(--stitch);margin:16px 0 0}
.a{font-size:clamp(23px,5.4vw,31px);font-weight:800;line-height:1.2;margin:2px 0 16px;max-width:30ch}
.back .diagram{margin-top:14px}
.why{font-size:19px;line-height:1.45;background:#F2F5FA;border-left:6px solid var(--c);padding:10px 14px;border-radius:0 12px 12px 0;max-width:44ch;margin:0}

/* Wide card: question beside the picture */
@container (min-width:620px){
  .face{padding:24px 28px 26px;min-height:400px}
  .front.has-d{display:grid;grid-template-columns:1fr minmax(260px,46%);grid-template-rows:auto 1fr;column-gap:24px;align-content:start}
  .front.has-d .toprow{grid-column:1 / -1}
  .front.has-d .q{align-self:center}
  .front.has-d .diagram{margin-top:14px}
  .back.has-d{display:grid;grid-template-columns:1fr minmax(240px,42%);grid-template-rows:auto 1fr;column-gap:24px;align-content:start}
  .back.has-d .toprow{grid-column:1 / -1}
  .back.has-d .diagram{margin-top:16px;align-self:start}
  .q{font-size:30px}
  .a{font-size:34px}
  .why{font-size:20px}
}

.done{text-align:center;padding-top:40px}
.done .big{font-size:72px;line-height:1;font-weight:800}
.done p{font-size:22px;font-weight:700;margin:10px auto;max-width:26ch}

/* ---------- Buttons ---------- */
.actions{display:flex;gap:10px;margin-top:18px;flex-wrap:wrap}
.btn{
  flex:1 1 140px;min-height:58px;border-radius:16px;border:0;font-size:21px;font-weight:800;
  box-shadow:0 4px 0 rgba(0,0,0,.28);
}
.btn:active{transform:translateY(2px);box-shadow:0 2px 0 rgba(0,0,0,.28)}
.btn-main{background:var(--stitch);color:#fff}
.btn-good{background:var(--good);color:#fff}
.btn-plain{background:#fff;color:var(--navy)}
.short{display:none}
@media (max-width:640px){ .short{display:inline} }
.keys{display:none;color:#E4F0E8;font-size:14px;text-align:center;margin:16px 0 0}
kbd{background:rgba(0,0,0,.3);border-radius:5px;padding:0 6px;font:inherit;font-weight:700}
@media (hover:hover) and (pointer:fine){ .keys{display:block} }

/* Phones: keep the buttons in reach */
@media (max-width:640px){
  .face{min-height:0}
  .card:not(.is-done) .face{min-height:380px}
  .actions{
    position:sticky;bottom:0;z-index:5;margin:14px -16px 0;padding:10px 16px calc(10px + env(safe-area-inset-bottom));
    background:rgba(18,53,36,.94);
  }
  .btn{min-height:54px;font-size:19px;flex-basis:100px}
  .intro{font-size:15px;margin-bottom:10px}
  .board{justify-content:stretch;margin-bottom:10px}
  .board div{flex:1;display:flex;align-items:baseline;justify-content:center;gap:6px;padding:3px 10px}
  .board span{font-size:22px}
  .diagram svg{max-height:210px}
  .long{display:none}
}

/* ---------- Study list ---------- */
.study-note{color:#fff;margin:0 0 12px;font-size:16px}
.study-grid{display:grid;align-items:start;grid-template-columns:repeat(auto-fill,minmax(290px,1fr));gap:12px}
.sitem{background:#fff;border-radius:16px;padding:14px 16px;border-top:8px solid var(--c);box-shadow:0 4px 0 rgba(0,0,0,.2);display:flex;flex-direction:column;gap:6px}
.sitem .toprow .tag{font-size:13px}
.sitem .lvl{font-size:13px}
.sitem .sq{font-weight:700;font-size:18px;line-height:1.3;margin:4px 0 0}
.sitem .sa{font-weight:800;font-size:18px;line-height:1.3;margin:0;color:var(--stitch)}
.sitem .sw{font-size:16px;line-height:1.4;margin:0}
.sitem .sd{width:150px;align-self:center;border:2px solid var(--navy);border-radius:10px;overflow:hidden;background:#fff}
.sitem .sd svg{display:block;width:100%}

/* ---------- About and footer ---------- */
.about{background:#fff;padding:28px 0 30px;border-top:6px solid var(--ball)}
.about h2{margin:0 0 14px;font-size:28px;line-height:1.1}
.about-cols{display:grid;gap:18px}
@media (min-width:760px){ .about-cols{grid-template-columns:repeat(3,1fr);gap:28px} }
.about h3{margin:0 0 4px;font-size:20px;color:var(--stitch)}
.about p{margin:0;font-size:17px;line-height:1.5;max-width:60ch}
.foot{background:var(--board);color:#CFE3D6;padding:18px 0 calc(18px + env(safe-area-inset-bottom));font-size:15px;line-height:1.45}
.foot p{margin:0 0 6px;max-width:70ch}

@media (prefers-reduced-motion:reduce){ .card{transition:none} .filters summary::after{transition:none} }

/* ---------- Print: fold-over cards ---------- */
#print-sheet{display:none}
@page{margin:0.4in}
@media print{
  body{background:#fff}
  .skip,.topbar,.layout,.about,.foot{display:none !important}
  #print-sheet{display:block;-webkit-print-color-adjust:exact;print-color-adjust:exact}
  .p-note{font-size:11pt;margin:0 auto .15in;width:7.3in;line-height:1.35}
  .pcard{
    display:grid;grid-template-columns:1fr 1fr;width:7.3in;height:2.4in;margin:0 auto .1in;
    border:1.5px dashed #888;break-inside:avoid;page-break-inside:avoid;
  }
  .pface{padding:.12in .16in;position:relative;overflow:hidden;display:flex;flex-direction:column}
  .pface.pfront{border-right:1.5px dotted #bbb;background:#FAFCD9}
  .pface .tag{font-size:9pt;padding:0 8px}
  .pface .lvl{font-size:9pt}
  .pface .lvl svg{width:10px;height:10px}
  .pface .q{font-size:12pt;margin:6px 0;line-height:1.25;max-width:none}
  .pface .pdiag{flex:1;min-height:0;display:flex;justify-content:center}
  .pface .pdiag svg{height:100%;max-height:1.35in;width:auto}
  .pface .a-label{font-size:9.5pt;margin:6px 0 0}
  .pface .a{font-size:13pt;margin:0 0 6px;max-width:none}
  .pface .why{font-size:10pt;line-height:1.35;padding:5px 8px;max-width:none}
  .pface.pback .pdiag{margin-top:4px}
}