/* Shared look for every lab page. Light only: these run on projectors and phones in class. */
:root{--bg:#FFFFFF;--soft:#F6F5F1;--card:#FFFFFF;--ink:#171A23;--muted:#5C6272;--line:#E3E1DA;
  --blue:#2F5FD0;--orange:#D9640B;--green:#2E8B57;--red:#C4452D;--gray:#9AA1B1;--radius:14px}
*{box-sizing:border-box}
html,body{margin:0;background:var(--bg);color:var(--ink);font-family:'Avenir Next','Segoe UI',Helvetica,Arial,sans-serif;-webkit-text-size-adjust:100%}
a{color:var(--blue)}
.wrap{max-width:1280px;margin:0 auto;padding:20px 24px 40px}
.narrow{max-width:560px;margin:0 auto;padding:20px 18px 40px}
h1{font-size:32px;margin:0 0 6px;letter-spacing:-.01em}
h2{font-size:22px;margin:0 0 8px}
.muted{color:var(--muted)}
.small{font-size:14px}
.card{background:var(--card);border:1px solid var(--line);border-radius:var(--radius);padding:18px 20px}
.soft{background:var(--soft);border-radius:var(--radius);padding:14px 18px}
.btn{font:inherit;font-size:18px;font-weight:700;border:none;border-radius:12px;padding:13px 20px;cursor:pointer;background:var(--ink);color:#fff;touch-action:manipulation}
.btn.alt{background:#fff;color:var(--ink);border:2px solid var(--ink)}
.btn.quiet{background:transparent;color:var(--muted);border:1.5px solid var(--line);font-size:15px;padding:8px 14px}
.btn:disabled{opacity:.4;cursor:default}
.btn.wide{width:100%}
input[type=text],input[type=password]{font:inherit;font-size:18px;padding:11px 12px;border:2px solid var(--line);border-radius:10px;width:100%}
input.code{font-size:32px;font-weight:800;letter-spacing:.2em;text-align:center;text-transform:uppercase}
label.field{display:block;margin:10px 0}
label.field span{display:block;font-size:14px;font-weight:700;color:var(--muted);margin-bottom:4px}
.row{display:flex;gap:10px;flex-wrap:wrap;align-items:center}
.err{color:var(--red);font-weight:600;min-height:1.3em}
.note{font-size:14px;color:var(--muted);line-height:1.4}
[hidden]{display:none !important}

/* teacher screen bar */
.labbar{display:flex;gap:22px;align-items:center;flex-wrap:wrap;border-bottom:1px solid var(--line);padding-bottom:14px;margin-bottom:16px}
.labbar .qr{width:170px;height:170px;flex:none;background:#fff}
.labbar .qr svg{width:100%;height:100%;display:block}
.labbar.compact .qr{width:84px;height:84px}
.labbar .join{font-size:22px;line-height:1.3}
.labbar .join b{font-size:46px;letter-spacing:.12em;display:block}
.labbar .count{margin-left:auto;text-align:right}
.labbar .count b{font-size:46px;display:block;line-height:1}
.labbar .tools{display:flex;gap:8px;flex-wrap:wrap;margin-top:8px}
.badge{display:inline-block;border-radius:999px;padding:3px 10px;font-size:13px;font-weight:800}
.badge.open{background:#E1F2E8;color:var(--green)}.badge.closed{background:#FBE7E1;color:var(--red)}

/* charts */
.chart svg{display:block;width:100%;height:auto}
.stat{border-radius:12px;padding:12px 16px;background:var(--soft)}
.stat .v{font-size:34px;font-weight:800;line-height:1.1}
.stat .l{font-size:14px;color:var(--muted);font-weight:700}