/* ── Content Sections Base ─────────────────────────── */
.cs{padding:4rem 0;border-top:1px solid var(--border-color)}
.cs-alt{background:var(--bg-secondary)}
.cs-inner{max-width:1100px;margin:0 auto;padding:0 1.5rem}
.cs-two-col{display:grid;grid-template-columns:1fr 1fr;gap:3rem;align-items:start}
.cs-reverse>:first-child{order:2}.cs-reverse>:last-child{order:1}
.cs-badge{display:inline-block;padding:3px 13px;background:var(--primary-100,#dbeafe);color:var(--primary-600,#2563eb);border-radius:100px;font-size:.72rem;font-weight:700;text-transform:uppercase;letter-spacing:.07em;margin-bottom:.75rem}
[data-theme=dark] .cs-badge{background:hsl(210,40%,18%);color:var(--primary-300,#93c5fd)}
.cs h2{font-size:clamp(1.35rem,3vw,1.85rem);font-weight:800;margin-bottom:.75rem}
.cs-text h2{margin-top:.25rem}
.cs-lead{font-size:1.02rem;line-height:1.82;color:var(--text-secondary);max-width:760px;margin-bottom:1.5rem}
.cs-note{font-size:.88rem;line-height:1.7;color:var(--text-tertiary);max-width:760px;margin-top:1.5rem}
.cs-text p{font-size:.93rem;line-height:1.8;color:var(--text-secondary);margin-bottom:.85rem}
p.cs-text{font-size:.93rem;line-height:1.8;color:var(--text-secondary);margin-bottom:.85rem}
.cs ol,.cs ul{padding-left:1.4rem;margin:.75rem 0 1rem}
.cs ol li,.cs ul li{font-size:.93rem;line-height:1.8;color:var(--text-secondary);margin-bottom:.6rem}
.cs ol li:last-child,.cs ul li:last-child{margin-bottom:0}
.cs-text a,.cs-note a{color:var(--primary-500,#3b82f6);text-decoration:underline;text-underline-offset:3px}

/* ── Section Headings h3 / h4 ─────────────────────── */
.cs h3{font-size:clamp(1.1rem,2.4vw,1.4rem);font-weight:700;color:var(--text-primary);margin:2rem 0 .75rem;padding-bottom:.45rem;border-bottom:2px solid var(--border-color);line-height:1.35}
.cs h4{font-size:clamp(.95rem,2vw,1.12rem);font-weight:700;color:var(--text-primary);margin:1.75rem 0 .6rem;line-height:1.35}

/* ── Tables ────────────────────────────────────────── */
.table-wrap{overflow-x:auto;-webkit-overflow-scrolling:touch;margin:1rem 0 1.25rem;border-radius:12px;border:1px solid var(--border-color);box-shadow:0 1px 3px rgba(0,0,0,.04)}
.cs table{width:100%;border-collapse:collapse;font-size:.88rem;line-height:1.5;min-width:480px}
.cs thead{position:sticky;top:0;z-index:1}
.cs thead th{background:var(--primary-500,#3b82f6);color:#fff;font-weight:700;font-size:.78rem;text-transform:uppercase;letter-spacing:.05em;padding:.7rem .85rem;text-align:left;white-space:nowrap;border:none}
.cs thead th:first-child{border-radius:11px 0 0 0}
.cs thead th:last-child{border-radius:0 11px 0 0}
[data-theme=dark] .cs thead th{background:hsl(217,50%,28%)}
.cs tbody td{padding:.6rem .85rem;color:var(--text-secondary);border-bottom:1px solid var(--border-color);white-space:nowrap}
.cs tbody tr:last-child td{border-bottom:none}
.cs tbody tr:nth-child(even){background:var(--bg-tertiary,hsl(210,20%,98%))}
[data-theme=dark] .cs tbody tr:nth-child(even){background:hsl(215,25%,14%)}
.cs tbody tr:hover{background:hsl(210,80%,96%);transition:background .15s}
[data-theme=dark] .cs tbody tr:hover{background:hsl(215,40%,18%)}
.cs tbody td:nth-last-child(-n+2){font-weight:600;color:var(--text-primary);font-variant-numeric:tabular-nums}

/* ── Formula Callout ───────────────────────────────── */
.formula-callout{background:var(--bg-tertiary);border-left:4px solid var(--primary-500,#3b82f6);border-radius:0 8px 8px 0;padding:.85rem 1.25rem;font-family:monospace;font-size:.95rem;color:var(--text-primary);margin:.75rem 0 1.1rem}
[data-theme=dark] .formula-callout{border-left-color:var(--primary-400,#60a5fa)}

/* ── Worked Example ────────────────────────────────── */
.worked-example{background:var(--bg-card);border:1px solid var(--border-color);border-radius:12px;padding:.9rem 1.2rem;margin:.75rem 0}
.we-label{font-size:.72rem;font-weight:700;text-transform:uppercase;letter-spacing:.06em;color:var(--text-tertiary);margin-bottom:4px}
.we-eq{font-family:monospace;font-size:.92rem;color:var(--text-secondary);margin-bottom:3px}
.we-result{font-size:1.08rem;font-weight:600;color:var(--text-primary)}
.we-metric{font-size:.88rem;color:var(--text-tertiary);font-weight:400}

/* ── Method / Warning Box ──────────────────────────── */
.method-box{background:hsl(210,100%,97%);border:1px solid hsl(210,60%,88%);border-radius:10px;padding:.85rem 1.1rem;font-size:.88rem;line-height:1.7;color:var(--text-secondary);margin:.75rem 0}
[data-theme=dark] .method-box{background:hsl(210,40%,12%);border-color:hsl(210,40%,22%)}

/* ── Shape Formula Picker ──────────────────────────── */
.sfp{margin:1.5rem 0}
.sfp-tabs{display:flex;flex-wrap:wrap;gap:8px;margin-bottom:.85rem}
.sfp-tab{padding:7px 18px;border:2px solid var(--border-color);border-radius:100px;background:var(--bg-card);color:var(--text-secondary);font-size:.85rem;font-weight:600;cursor:pointer;transition:all .18s;line-height:1}
.sfp-tab:hover{border-color:var(--primary-500,#3b82f6);color:var(--primary-500,#3b82f6)}
.sfp-tab.active{background:var(--primary-500,#3b82f6);border-color:var(--primary-500,#3b82f6);color:#fff}
.sfp-body{background:var(--bg-card);border:1px solid var(--border-color);border-radius:14px;padding:1.5rem;min-height:160px}
.sfp-layout{display:grid;grid-template-columns:1fr 1fr;gap:1.5rem;align-items:center}
.sfp-fig svg{width:100%;height:auto}
.sfp-eq{font-family:monospace;font-size:1.1rem;font-weight:800;color:var(--primary-500,#3b82f6);background:var(--bg-secondary);padding:8px 16px;border-radius:8px;display:inline-block;margin-bottom:.75rem}
[data-theme=dark] .sfp-eq{color:var(--primary-300,#93c5fd)}
.sfp-info p{font-size:.88rem;line-height:1.7;color:var(--text-secondary);margin-bottom:5px}
.sfp-eg{background:var(--bg-tertiary);border-radius:8px;padding:9px 13px;font-size:.86rem;color:var(--text-secondary);margin-top:.5rem}
.sfp-link{display:inline-block;margin-top:.75rem;font-size:.86rem;color:var(--primary-500,#3b82f6);font-weight:600;text-decoration:none}
.sfp-link:hover{text-decoration:underline}

/* ── Variable Legend ───────────────────────────────── */
.legend-strip{display:flex;flex-wrap:wrap;gap:7px;margin:1.5rem 0}
.ls-item{display:flex;align-items:center;gap:7px;padding:5px 13px;background:var(--bg-card);border:1px solid var(--border-color);border-radius:100px;font-size:.83rem;color:var(--text-secondary)}
.ls-sym{font-family:monospace;font-size:.95rem;font-weight:800;color:var(--primary-500,#3b82f6)}
[data-theme=dark] .ls-sym{color:var(--primary-300,#93c5fd)}

/* ── 3-Step Flow ───────────────────────────────────── */
.flow-steps{display:flex;align-items:stretch;justify-content:center;gap:0;margin:1.5rem 0;flex-wrap:wrap}
.flow-step{text-align:center;background:var(--bg-card);border:1px solid var(--border-color);border-radius:14px;padding:1.25rem 1rem;flex:1;min-width:170px;max-width:220px;box-shadow:var(--shadow-card)}
.flow-num{width:34px;height:34px;border-radius:50%;background:linear-gradient(135deg,#3b82f6,#0ea5e9);color:#fff;font-weight:800;font-size:1rem;display:flex;align-items:center;justify-content:center;margin:0 auto .5rem}
.flow-icon{font-size:1.5rem;margin-bottom:4px}
.flow-title{font-weight:700;font-size:.92rem;margin-bottom:5px}
.flow-desc{font-size:.8rem;color:var(--text-secondary);line-height:1.5;margin-bottom:7px}
.flow-eg{font-family:monospace;font-size:.8rem;background:var(--bg-secondary);border-radius:6px;padding:4px 9px;color:var(--text-secondary)}
.flow-arrow{font-size:1.5rem;color:var(--primary-500,#3b82f6);padding:0 .75rem;display:flex;align-items:center;flex-shrink:0}

/* ── Live Calc Widget ──────────────────────────────── */
.live-calc{background:linear-gradient(135deg,hsl(210,90%,97%),hsl(185,90%,97%));border:1px solid hsl(210,60%,88%);border-radius:16px;padding:1.5rem;box-shadow:var(--shadow-card)}
[data-theme=dark] .live-calc{background:hsl(210,40%,11%);border-color:hsl(210,40%,22%)}
.lc-title{font-size:.95rem;font-weight:700;margin-bottom:.85rem;color:var(--text-primary)}
.lc-inputs{display:grid;grid-template-columns:1fr 1fr 1fr;gap:.5rem;margin-bottom:.85rem}
.lc-inputs label{display:flex;flex-direction:column;gap:3px;font-size:.77rem;font-weight:600;color:var(--text-secondary)}
.lc-inputs input{padding:7px 9px;border:2px solid var(--border-color);border-radius:8px;font-size:.93rem;background:var(--bg-input,#fff);color:var(--text-primary);transition:border-color .18s;width:100%}
.lc-inputs input:focus{border-color:var(--primary-500,#3b82f6);outline:none}
.lc-formula{font-family:monospace;font-size:.85rem;color:var(--text-tertiary);margin-bottom:.85rem;padding:7px 12px;background:rgba(0,0,0,.04);border-radius:7px}
[data-theme=dark] .lc-formula{background:rgba(255,255,255,.05)}
.lc-result{text-align:center;padding:.5rem 0}
.lc-gal{font-size:2.5rem;font-weight:900;color:var(--primary-500,#3b82f6);line-height:1}
[data-theme=dark] .lc-gal{color:var(--primary-300,#93c5fd)}
.lc-unit{font-size:.8rem;color:var(--text-tertiary);margin-bottom:3px}
.lc-sub{font-size:.88rem;color:var(--text-secondary);margin-top:3px}

/* ── Diagram Wrappers ──────────────────────────────── */
.xsection-wrap,.kidney-wrap,.circle-wrap{display:flex;flex-direction:column;gap:.75rem;align-items:center}
.xsection-wrap svg,.kidney-wrap svg,.circle-wrap>svg{width:100%;height:auto;max-height:210px}
.circle-stats{display:flex;gap:.75rem;justify-content:center;flex-wrap:wrap}
.cstat{text-align:center;background:var(--bg-card);border:1px solid var(--border-color);border-radius:10px;padding:9px 16px}
.cstat span{display:block;font-size:1rem;font-weight:800;color:var(--primary-500,#3b82f6);line-height:1.2}
[data-theme=dark] .cstat span{color:var(--primary-300,#93c5fd)}
.cstat small{font-size:.72rem;color:var(--text-tertiary)}

/* ── PPM Cards ─────────────────────────────────────── */
.ppm-cards{display:grid;grid-template-columns:repeat(auto-fit,minmax(175px,1fr));gap:.85rem;margin:1.5rem 0}
.ppm-card{background:var(--bg-card);border:1px solid var(--border-color);border-radius:14px;padding:1.15rem;text-align:center;box-shadow:var(--shadow-card)}
.ppm-card--accent{border-color:var(--primary-500,#3b82f6);background:linear-gradient(135deg,hsl(210,90%,97%),#fff)}
[data-theme=dark] .ppm-card--accent{background:hsl(210,40%,12%)}
.ppm-val{font-size:1.9rem;font-weight:900;color:var(--primary-500,#3b82f6);line-height:1;margin-bottom:5px}
[data-theme=dark] .ppm-val{color:var(--primary-300,#93c5fd)}
.ppm-label{font-size:.82rem;font-weight:600;color:var(--text-primary);margin-bottom:3px}
.ppm-sub{font-size:.75rem;color:var(--text-tertiary)}

/* ── Volume Bar Chart ──────────────────────────────── */
.vol-bars{display:flex;flex-direction:column;gap:.85rem;margin:1.5rem 0;max-width:680px}
.vol-bar-row{display:grid;grid-template-columns:130px 1fr auto;align-items:center;gap:.85rem}
.vbr-label{font-size:.86rem;font-weight:600;color:var(--text-secondary)}
.vbr-track{background:var(--bg-tertiary);border-radius:100px;height:18px;overflow:hidden}
.vbr-fill{height:100%;border-radius:100px;width:0;transition:width 1.3s cubic-bezier(.17,.67,.36,1.05)}
.vbf--small{background:linear-gradient(90deg,#60a5fa,#38bdf8)}
.vbf--avg{background:linear-gradient(90deg,#3b82f6,#0ea5e9)}
.vbf--large{background:linear-gradient(90deg,#1d4ed8,#0284c7)}
.vbr-nums{font-size:.8rem;color:var(--text-secondary);white-space:nowrap}

/* ── Reference Sub-sections ────────────────────────── */
.sub-sections{display:grid;grid-template-columns:1fr 1fr;gap:2rem;margin-top:2.5rem}
.sub-sec{border-top:2px solid var(--border-color);padding-top:1.25rem}
.sub-sec h3{font-size:1.02rem;font-weight:700;margin-bottom:.75rem;color:var(--text-primary)}
.sub-sec p{font-size:.88rem;line-height:1.75;color:var(--text-secondary);margin-bottom:.5rem}
.sub-sec a{color:var(--primary-500,#3b82f6);text-decoration:underline;text-underline-offset:3px}
.sub-sec--olympic{grid-column:1/-1}
.olympic-wrap{display:grid;grid-template-columns:1fr auto;gap:2rem;align-items:start}
.olympic-visual{display:flex;align-items:flex-end;gap:.85rem}
.ov-col{display:flex;flex-direction:column;align-items:center;gap:5px}
.ov-bar{border-radius:6px 6px 0 0;width:56px}
.ov-bar--olympic{height:130px;background:linear-gradient(180deg,#3b82f6,#1d4ed8)}
.ov-bar--home{height:12px;background:linear-gradient(180deg,#60a5fa,#38bdf8)}
.ov-vs{font-size:.82rem;font-weight:700;color:var(--text-tertiary);align-self:center;padding-bottom:18px}
.ov-tag{font-size:.72rem;text-align:center;color:var(--text-secondary);line-height:1.4}

/* ── FAQ ───────────────────────────────────────────── */
.faq-list{display:flex;flex-direction:column;gap:16px;max-width:760px;margin:0}
.faq-item{background:var(--bg-card);border:1px solid var(--border-color);border-radius:12px;overflow:hidden}
.faq-q{padding:.9rem 1.25rem;font-size:.95rem;font-weight:600;cursor:pointer;list-style:none;display:flex;justify-content:space-between;align-items:center;color:var(--text-primary);transition:background .15s;text-align:left}
.faq-q h3{font-size:inherit;font-weight:inherit;color:inherit;margin:0;padding:0;line-height:inherit;text-align:left;flex:1}
.faq-q::-webkit-details-marker{display:none}
.faq-q::after{content:'+';font-size:1.35rem;font-weight:300;color:var(--text-tertiary);flex-shrink:0;margin-left:.85rem;transition:transform .2s}
.faq-item[open] .faq-q::after{transform:rotate(45deg)}
.faq-q:hover{background:var(--bg-tertiary)}
.faq-a{padding:0 1.25rem 1rem}
.faq-a p{font-size:.91rem;line-height:1.8;color:var(--text-secondary);margin:0}

/* ── Responsive ────────────────────────────────────── */
@media(max-width:880px){
  .cs-two-col{grid-template-columns:1fr}
  .cs-reverse>:first-child,.cs-reverse>:last-child{order:unset}
  .sfp-layout{grid-template-columns:1fr}
  .sub-sections{grid-template-columns:1fr}
  .olympic-wrap{grid-template-columns:1fr}
  .flow-steps{flex-direction:column;gap:.85rem}
  .flow-arrow{transform:rotate(90deg);padding:.25rem 0}
  .flow-step{max-width:100%}
}
@media(max-width:580px){
  .vol-bar-row{grid-template-columns:1fr;gap:3px}
  .lc-inputs{grid-template-columns:1fr}
  .ppm-cards{grid-template-columns:1fr 1fr}
}