/* StudyNest Algebra Gold Standard additions — self-contained inside algebra/ */
:root{--alg-gold:#d6a91c;--alg-navy:#10233f;--alg-ink:#26364d;--alg-soft:#f6f8fc;--alg-green:#eaf8ef;--alg-red:#fff0f0}
.gold-discovery,.gold-think,.gold-practice,.gold-exam,.gold-summary,.interactive-lab{margin:28px 0;padding:24px;border-radius:20px;border:1px solid #dbe3ef;background:#fff;box-shadow:0 12px 30px rgba(16,35,63,.07)}
.gold-discovery{border-left:6px solid var(--alg-gold);background:linear-gradient(135deg,#fffdf4,#fff)}
.gold-think{border-left:6px solid #667eea}.gold-exam{border-left:6px solid #ef8f2f}.gold-summary{border-left:6px solid #2f9e63;background:var(--alg-green)}
.gold-practice .level{margin:16px 0;padding:16px;border-radius:14px;background:var(--alg-soft)}
.level h3{margin-top:0}.answer-reveal{margin-top:12px}.answer-reveal summary{cursor:pointer;font-weight:800;color:var(--alg-navy)}
.interactive-lab{background:linear-gradient(135deg,#f7f5ff,#fff)}.lab-controls{display:flex;gap:10px;flex-wrap:wrap;margin:14px 0}.lab-controls button{border:0;border-radius:999px;padding:11px 17px;font-weight:800;cursor:pointer;background:var(--alg-navy);color:#fff}.lab-controls button.secondary{background:#e8edf5;color:var(--alg-navy)}
.algebra-stage{min-height:150px;display:grid;place-items:center;padding:20px;border-radius:16px;background:#fff;border:2px dashed #ccd6e5}.equation-line{font-size:clamp(1.4rem,4vw,2.25rem);font-weight:900;color:var(--alg-navy);text-align:center}.step-output{margin-top:12px;min-height:28px;font-weight:750;color:var(--alg-ink)}
.factor-chip{display:inline-grid;place-items:center;min-width:52px;padding:10px;margin:5px;border-radius:12px;background:#eef2ff;font-weight:900}.factor-chip.active{background:#fff1b8;transform:translateY(-3px)}
.interval-line{position:relative;width:min(620px,95%);height:76px;margin:20px auto;border-bottom:4px solid var(--alg-navy)}.interval-line .tick{position:absolute;bottom:-11px;width:3px;height:22px;background:var(--alg-navy)}.interval-line .shade{position:absolute;bottom:-2px;height:10px;background:var(--alg-gold);border-radius:10px}.interval-line .dot{position:absolute;bottom:-10px;width:20px;height:20px;border-radius:50%;border:4px solid var(--alg-gold);background:#fff;z-index:2}.interval-line .dot.closed{background:var(--alg-gold)}
.feasible-grid{position:relative;width:min(500px,95%);aspect-ratio:1;background:linear-gradient(#edf1f7 1px,transparent 1px),linear-gradient(90deg,#edf1f7 1px,transparent 1px);background-size:10% 10%;border-left:4px solid var(--alg-navy);border-bottom:4px solid var(--alg-navy);overflow:hidden}.feasible-region{position:absolute;left:12%;bottom:8%;width:58%;height:48%;clip-path:polygon(0 100%,0 45%,48% 0,100% 35%,75% 100%);background:rgba(214,169,28,.35);border:3px solid var(--alg-gold)}
@media(max-width:650px){.gold-discovery,.gold-think,.gold-practice,.gold-exam,.gold-summary,.interactive-lab{padding:18px}.lab-controls button{width:100%}}