/* Delta-Sierra Mars R73 — scoped formula-parity cards. Only .r73-parity-lab/.r73-formula are affected. */
.r73-parity-lab{margin:2.5rem auto;padding:clamp(1rem,2.5vw,2rem);border:1px solid rgba(105,210,255,.28);border-radius:24px;background:linear-gradient(180deg,rgba(8,20,34,.97),rgba(10,27,43,.96));box-shadow:0 24px 60px rgba(0,0,0,.28);color:#f5f9fc;max-width:1100px}
.r73-parity-lab>h2{margin:0 0 .8rem;color:#fff;font-size:clamp(1.55rem,2.8vw,2.25rem);line-height:1.16;letter-spacing:-.02em}
.r73-parity-lab>p{max-width:78ch;color:#d7e5ef;line-height:1.7;margin:0 0 1.5rem}
.r73-formula{margin:1.35rem 0 1.7rem;padding:clamp(1rem,2vw,1.5rem);border:1px solid rgba(115,220,255,.28);border-radius:20px;background:linear-gradient(145deg,#0d2438 0%,#112d44 56%,#0b1d2d 100%);color:#f8fbfd;box-shadow:0 14px 36px rgba(0,0,0,.22);overflow:hidden}
.r73-formula h3{margin:.05rem 0 .9rem;color:#fff;font-size:clamp(1.18rem,2.2vw,1.55rem);line-height:1.25}
.r73-formula .formula-display{margin:.5rem 0 1rem;padding:.9rem 1rem;border:1px solid rgba(128,225,255,.38);border-radius:14px;background:#071522;color:#bfefff;font-family:ui-monospace,SFMono-Regular,Consolas,"Liberation Mono",monospace;font-size:clamp(.96rem,2vw,1.18rem);font-weight:700;line-height:1.45;overflow-wrap:anywhere;word-break:break-word;white-space:normal}
.r73-formula .academy-proof{display:grid;grid-template-columns:minmax(180px,240px) minmax(0,1fr);gap:0;margin:0;border:1px solid rgba(255,255,255,.10);border-radius:15px;overflow:hidden}
.r73-formula .academy-proof dt,.r73-formula .academy-proof dd{margin:0;padding:.78rem .9rem;border-bottom:1px solid rgba(255,255,255,.09);line-height:1.58}
.r73-formula .academy-proof dt{background:#0a1d2d;color:#aee9ff;font-weight:800}
.r73-formula .academy-proof dd{background:#132d43;color:#f1f7fb;min-width:0;overflow-wrap:anywhere}
.r73-formula .academy-proof dt:last-of-type,.r73-formula .academy-proof dd:last-child{border-bottom:0}
.r73-formula code{color:#fff;background:#06131f;border:1px solid rgba(137,224,255,.25);border-radius:8px;padding:.15rem .35rem;white-space:normal;overflow-wrap:anywhere}
.r73-formula .r73-calc-steps{display:grid;gap:.42rem;margin:.15rem 0}.r73-formula .r73-calc-steps p{margin:0}
.r73-formula .r73-practice{display:grid;gap:.8rem}.r73-formula .r73-practice p{margin:0}
.r73-formula .r73-guided-correction{padding:.75rem .85rem;border-left:4px solid #6fe4ff;background:rgba(80,205,255,.08);border-radius:10px}
.r73-formula details{border:1px solid rgba(127,220,255,.25);border-radius:10px;padding:.65rem .75rem;background:#0a1c2b}
.r73-formula summary{cursor:pointer;color:#c9f2ff;font-weight:800}
.r73-formula strong{color:#fff}
@media(max-width:696px){.r73-parity-lab{margin:1.4rem .45rem;padding:.85rem;border-radius:16px}.r73-formula{padding:.85rem;border-radius:15px}.r73-formula .academy-proof{display:block}.r73-formula .academy-proof dt{padding:.65rem .75rem;border-bottom:0}.r73-formula .academy-proof dd{padding:.72rem .75rem;border-bottom:1px solid rgba(255,255,255,.11)}.r73-formula .formula-display{font-size:.93rem;padding:.72rem .75rem}.r73-formula ol{padding-left:1.25rem}}
@media(max-width:390px){.r73-parity-lab{margin:1rem .2rem;padding:.68rem}.r73-formula{padding:.7rem}.r73-formula h3{font-size:1.08rem}.r73-formula .academy-proof dt,.r73-formula .academy-proof dd{font-size:.94rem}.r73-formula .formula-display{font-size:.88rem}}
@media print{.r73-parity-lab{background:#fff!important;color:#111!important;border:1px solid #aeb8bf;box-shadow:none;max-width:none}.r73-parity-lab>h2,.r73-formula h3,.r73-formula strong{color:#111!important}.r73-parity-lab>p{color:#222!important}.r73-formula{background:#fff!important;color:#111!important;border:1px solid #aeb8bf;box-shadow:none;break-inside:auto}.r73-formula .formula-display{background:#f2f5f7!important;color:#111!important;border-color:#aeb8bf}.r73-formula .academy-proof{display:block;border-color:#c7cdd2}.r73-formula .academy-proof dt{background:#edf2f5!important;color:#111!important;border-bottom:0;font-weight:800}.r73-formula .academy-proof dd{background:#fff!important;color:#111!important;border-bottom:1px solid #d4dade}.r73-formula code{background:#f5f5f5!important;color:#111!important;border-color:#bbb}.r73-formula details{background:#fff!important;color:#111!important}.r73-formula summary{color:#111!important}.r73-formula .r73-guided-correction{background:#f5fafc!important;border-left-color:#3b7f99;break-inside:avoid}.r73-formula h3,.r73-formula .formula-display,.r73-formula dt{break-after:avoid}.r73-formula p,.r73-formula li{orphans:3;widows:3}}