/* ============================================================
   EngCalc Guides / Articles
   Archive grid, single-guide reading layout, dark mode, responsive
   ============================================================ */
.eca-page{--eca-blue:#2563EB;--eca-blue7:#1D4ED8;--eca-ink:#0F172A;--eca-body:#374151;--eca-muted:#6B7280;--eca-line:#E5E7EB;--eca-soft:#F3F4F6;--eca-bg:#FFFFFF;font-family:system-ui,-apple-system,'Segoe UI',Roboto,Helvetica,Arial,sans-serif;color:var(--eca-body);}
.eca-page *,.eca-page *::before,.eca-page *::after{box-sizing:border-box;}
.eca-container{max-width:1160px;margin:0 auto;padding:24px;}

/* breadcrumb */
.eca-breadcrumb{font-size:13px;margin-bottom:20px;}
.eca-breadcrumb ol{list-style:none;display:flex;flex-wrap:wrap;gap:6px;margin:0;padding:0;}
.eca-breadcrumb li{color:var(--eca-muted);}
.eca-breadcrumb li:not(:last-child)::after{content:'/';margin-left:6px;color:var(--eca-line);}
.eca-breadcrumb a{color:var(--eca-blue7);text-decoration:none;}
.eca-breadcrumb a:hover{text-decoration:underline;}

/* ---------- Archive ---------- */
.eca-archive-head{text-align:center;max-width:680px;margin:0 auto 28px;}
.eca-archive-head h1{font-size:34px;color:var(--eca-ink);margin:0 0 10px;letter-spacing:-.02em;}
.eca-archive-head p{font-size:16px;line-height:1.6;color:var(--eca-muted);margin:0;}
.eca-archive-tools{margin:0 0 26px;}
.eca-search{width:100%;max-width:440px;display:block;margin:0 auto 16px;padding:12px 16px;border:1px solid var(--eca-line);border-radius:12px;font-size:15px;background:var(--eca-soft);}
.eca-search:focus{outline:none;border-color:var(--eca-blue);background:#fff;}
.eca-cat-pills{display:flex;flex-wrap:wrap;gap:8px;justify-content:center;}
.eca-pill{padding:6px 14px;border-radius:999px;background:var(--eca-soft);color:var(--eca-body);font-size:13.5px;text-decoration:none;border:1px solid transparent;transition:background .15s,color .15s;}
.eca-pill:hover{background:#e5edff;color:var(--eca-blue7);}
.eca-pill.is-active{background:var(--eca-blue);color:#fff;}

.eca-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:22px;}
.eca-card{background:#fff;border:1px solid var(--eca-line);border-radius:16px;overflow:hidden;transition:transform .18s,box-shadow .18s,border-color .18s;}
.eca-card:hover{transform:translateY(-3px);box-shadow:0 18px 40px -20px rgba(15,23,42,.3);border-color:#dbe3ef;}
.eca-card-link{text-decoration:none;color:inherit;display:flex;flex-direction:column;height:100%;}
.eca-card-thumb{aspect-ratio:16/9;background:linear-gradient(120deg,#e0e7ff,#eff4ff);display:flex;align-items:center;justify-content:center;overflow:hidden;}
.eca-card-thumb img{width:100%;height:100%;object-fit:cover;}
.eca-card-thumb-ph{font-size:40px;color:#c7d2fe;}
.eca-card-body{padding:16px 18px 18px;display:flex;flex-direction:column;gap:8px;flex:1;}
.eca-card-cat{font-size:12px;font-weight:600;color:var(--eca-blue7);text-transform:uppercase;letter-spacing:.03em;}
.eca-card-title{font-size:17px;line-height:1.35;color:var(--eca-ink);margin:0;}
.eca-card-excerpt{font-size:14px;line-height:1.55;color:var(--eca-muted);margin:0;flex:1;}
.eca-card-meta{font-size:12.5px;color:var(--eca-muted);display:flex;gap:7px;align-items:center;margin-top:4px;}
.eca-dot{opacity:.5;}

.eca-noresults{text-align:center;color:var(--eca-muted);padding:40px 0;font-size:16px;}
.eca-pagination{display:flex;justify-content:center;gap:6px;margin-top:36px;flex-wrap:wrap;}
.eca-pagination .page-numbers{display:inline-flex;min-width:40px;height:40px;align-items:center;justify-content:center;padding:0 12px;border-radius:10px;background:var(--eca-soft);color:var(--eca-body);text-decoration:none;font-size:14px;}
.eca-pagination .page-numbers.current{background:var(--eca-blue);color:#fff;}
.eca-pagination .page-numbers:hover:not(.current){background:#e5edff;color:var(--eca-blue7);}

/* ---------- Single guide ---------- */
.eca-toolbar{display:flex;align-items:center;justify-content:space-between;gap:12px;padding:12px 0;border-top:1px solid var(--eca-line);border-bottom:1px solid var(--eca-line);margin-bottom:24px;flex-wrap:wrap;}
.eca-meta{font-size:13.5px;color:var(--eca-muted);display:flex;gap:8px;align-items:center;}
.eca-controls{display:flex;gap:6px;}
.eca-btn{width:38px;height:34px;border:1px solid var(--eca-line);background:#fff;border-radius:8px;cursor:pointer;font-size:13px;font-weight:600;color:var(--eca-body);display:inline-flex;align-items:center;justify-content:center;transition:background .15s,border-color .15s;}
.eca-btn:hover{background:var(--eca-soft);border-color:var(--eca-blue);color:var(--eca-blue7);}
.eca-title{font-size:clamp(26px,4vw,40px);line-height:1.2;color:var(--eca-ink);letter-spacing:-.02em;margin:0 0 20px;max-width:820px;}
.eca-hero{margin:0 0 28px;border-radius:16px;overflow:hidden;}
.eca-hero img{width:100%;height:auto;display:block;}

/* table of contents */
.eca-toc{background:var(--eca-soft);border:1px solid var(--eca-line);border-radius:14px;padding:18px 22px;margin:0 0 28px;max-width:820px;}
.eca-toc-title{font-weight:700;color:var(--eca-ink);margin:0 0 10px;font-size:14px;text-transform:uppercase;letter-spacing:.04em;}
.eca-toc ul{margin:0;padding:0 0 0 18px;}
.eca-toc li{margin:6px 0;}
.eca-toc a{color:var(--eca-blue7);text-decoration:none;font-size:14.5px;}
.eca-toc a:hover{text-decoration:underline;}

/* article body */
.eca-body{max-width:760px;font-size:var(--eca-fs,18px);line-height:1.75;color:var(--eca-body);}
.eca-body h2{font-size:1.5em;color:var(--eca-ink);margin:1.8em 0 .6em;line-height:1.3;scroll-margin-top:90px;}
.eca-body h3{font-size:1.2em;color:var(--eca-ink);margin:1.5em 0 .5em;}
.eca-body p{margin:0 0 1.1em;}
.eca-body ul,.eca-body ol{margin:0 0 1.2em;padding-left:1.4em;}
.eca-body li{margin:.4em 0;}
.eca-body a{color:var(--eca-blue7);text-decoration:underline;text-underline-offset:2px;}
.eca-body img{max-width:100%;height:auto;border-radius:12px;margin:1.2em 0;}
.eca-body table{width:100%;border-collapse:collapse;margin:1.4em 0;font-size:.92em;}
.eca-body th,.eca-body td{border:1px solid var(--eca-line);padding:10px 12px;text-align:left;}
.eca-body th{background:var(--eca-soft);font-weight:700;color:var(--eca-ink);}
.eca-body blockquote{border-left:4px solid var(--eca-blue);background:var(--eca-soft);margin:1.4em 0;padding:14px 18px;border-radius:0 10px 10px 0;}
.eca-body .eca-formula,.eca-body pre{background:#0f172a;color:#e2e8f0;padding:14px 18px;border-radius:10px;font-family:ui-monospace,'SF Mono',Menlo,monospace;font-size:.9em;overflow-x:auto;margin:1.2em 0;}

/* CTA to the calculator */
.eca-cta{margin:32px 0;max-width:820px;}
.eca-cta-inner{display:flex;align-items:center;justify-content:space-between;gap:20px;background:linear-gradient(120deg,#eff4ff,#e0e7ff);border:1px solid #dbe3ef;border-radius:16px;padding:22px 26px;flex-wrap:wrap;}
.eca-cta-kicker{font-size:12px;font-weight:700;text-transform:uppercase;letter-spacing:.05em;color:var(--eca-blue7);margin:0 0 2px;}
.eca-cta-title{font-size:19px;font-weight:800;color:var(--eca-ink);margin:0 0 4px;}
.eca-cta-text{font-size:14.5px;color:var(--eca-body);margin:0;max-width:44ch;}
.eca-cta-btn{background:var(--eca-blue);color:#fff;padding:12px 22px;border-radius:10px;text-decoration:none;font-weight:600;white-space:nowrap;transition:background .15s;}
.eca-cta-btn:hover{background:var(--eca-blue7);}

/* related cards */
.eca-related{margin:40px 0 0;max-width:820px;}
.eca-related h2{font-size:20px;color:var(--eca-ink);margin:0 0 16px;}
.eca-related-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:14px;}
.eca-related-card{display:flex;flex-direction:column;gap:5px;padding:14px 16px;border:1px solid var(--eca-line);border-radius:12px;text-decoration:none;transition:background .15s,border-color .15s;}
.eca-related-card:hover{background:var(--eca-soft);border-color:var(--eca-blue);}
.eca-rc-cat{font-size:11.5px;font-weight:600;text-transform:uppercase;letter-spacing:.03em;color:var(--eca-muted);}
.eca-rc-title{font-size:14.5px;font-weight:600;color:var(--eca-ink);line-height:1.35;}

/* ---------- Dark mode ---------- */
.eca-page.eca-dark{--eca-ink:#F1F5F9;--eca-body:#CBD5E1;--eca-muted:#94A3B8;--eca-line:#334155;--eca-soft:#1E293B;--eca-bg:#0F172A;background:#0F172A;}
.eca-page.eca-dark .eca-card,.eca-page.eca-dark .eca-btn,.eca-page.eca-dark .eca-search{background:#1E293B;}
.eca-page.eca-dark .eca-card-thumb{background:linear-gradient(120deg,#1e293b,#273449);}
.eca-page.eca-dark .eca-cta-inner{background:linear-gradient(120deg,#1e293b,#273449);border-color:#334155;}

/* ---------- Responsive ---------- */
@media(max-width:900px){.eca-grid{grid-template-columns:repeat(2,1fr);}.eca-related-grid{grid-template-columns:repeat(2,1fr);}}
@media(max-width:600px){.eca-grid{grid-template-columns:1fr;}.eca-related-grid{grid-template-columns:1fr;}.eca-container{padding:16px;}.eca-cta-inner{flex-direction:column;align-items:flex-start;}.eca-cta-btn{width:100%;text-align:center;}}
@media(prefers-reduced-motion:reduce){.eca-card{transition:none;}}