/* منصة أدوات فهد الهندسية - Mobile First، RTL */
:root{--bg:#f5f8fc;--surface:#fff;--surface2:#edf2f9;--text:#122438;--muted:#53667a;--primary:#0a64c0;--on-primary:#fff;--accent:#c76a00;--ok:#15803d;--bad:#c62828;--border:#d3deea;--c1:#0a64c0;--c2:#c76a00;--c3:#15803d;--c4:#c62828;--shadow:0 2px 10px rgba(16,40,70,.08)}
:root[data-theme=dark]{--bg:#0b1522;--surface:#132338;--surface2:#193049;--text:#e6eef7;--muted:#9db0c4;--primary:#4da3ff;--on-primary:#04121f;--accent:#fbbf24;--ok:#4ade80;--bad:#f87171;--border:#27405b;--c1:#4da3ff;--c2:#fbbf24;--c3:#4ade80;--c4:#f87171;--shadow:0 2px 12px rgba(0,0,0,.4)}
@media (prefers-color-scheme:dark){:root:not([data-theme=light]){--bg:#0b1522;--surface:#132338;--surface2:#193049;--text:#e6eef7;--muted:#9db0c4;--primary:#4da3ff;--on-primary:#04121f;--accent:#fbbf24;--ok:#4ade80;--bad:#f87171;--border:#27405b;--c1:#4da3ff;--c2:#fbbf24;--c3:#4ade80;--c4:#f87171;--shadow:0 2px 12px rgba(0,0,0,.4)}}
*{box-sizing:border-box}html{scroll-behavior:smooth}
body{margin:0;background:var(--bg);color:var(--text);font-family:"Segoe UI",Tahoma,"Noto Naskh Arabic","Noto Sans Arabic","Geeza Pro",Arial,sans-serif;line-height:1.9;font-size:17px}
a{color:var(--primary)}img,svg{max-width:100%}
.wrap{max-width:1040px;margin:0 auto;padding:0 16px}
:focus-visible{outline:3px solid var(--accent);outline-offset:2px}
header.site{background:var(--surface);border-bottom:1px solid var(--border);position:sticky;top:0;z-index:20}
header.site .wrap{display:flex;align-items:center;gap:10px;min-height:56px;flex-wrap:wrap;padding-top:4px;padding-bottom:4px}
.brand{font-weight:800;text-decoration:none;color:var(--text);display:flex;align-items:center;gap:8px;font-size:17px}
.brand svg{width:26px;height:26px;flex:none}
nav.main{display:flex;gap:4px;flex-wrap:wrap;margin-inline-start:auto;align-items:center}
nav.main a{padding:5px 10px;border-radius:8px;text-decoration:none;color:var(--muted);font-size:15px}
nav.main a:hover,nav.main a[aria-current=page]{background:var(--surface2);color:var(--text)}
#themeBtn{background:var(--surface2);border:1px solid var(--border);color:var(--text);border-radius:8px;padding:5px 10px;font:inherit;font-size:14px;cursor:pointer}
.crumbs{font-size:14px;color:var(--muted);padding:12px 0 0}.crumbs a{color:var(--muted)}
h1{font-size:clamp(25px,5vw,36px);line-height:1.4;margin:10px 0}
h2{font-size:clamp(21px,3.4vw,26px);margin:0 0 10px;line-height:1.5}h3{font-size:18px;margin:16px 0 4px}
.lead{color:var(--muted);font-size:18px;margin:0 0 10px}
.card{background:var(--surface);border:1px solid var(--border);border-radius:14px;padding:18px;margin:18px 0;box-shadow:var(--shadow)}
.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;padding:10px 18px;border-radius:10px;border:1px solid var(--primary);background:var(--primary);color:var(--on-primary);text-decoration:none;font:inherit;font-weight:700;font-size:16px;cursor:pointer;min-height:44px}
.btn.alt{background:transparent;color:var(--primary)}
.note{border-inline-start:4px solid var(--accent);background:var(--surface2);padding:10px 14px;border-radius:8px;margin:10px 0;font-size:15.5px}
.note.bad{border-color:var(--bad)}
.badges{display:flex;gap:8px;flex-wrap:wrap;margin:6px 0}.badge{font-size:13px;padding:2px 10px;border-radius:99px;background:var(--surface2);border:1px solid var(--border);color:var(--muted)}
ul.uses{padding-inline-start:22px;margin:6px 0}
.eqs{display:grid;gap:8px;margin:8px 0}.eq{direction:ltr;text-align:left;background:var(--surface2);border:1px solid var(--border);border-radius:8px;padding:7px 12px;font-family:"Cambria Math","STIX Two Math",Georgia,serif;font-size:17px;overflow-x:auto}
.eqrow small{display:block;color:var(--muted);font-size:14px;margin-top:2px}
.tbl{overflow-x:auto}table.vars{width:100%;border-collapse:collapse;font-size:15px}
table.vars th,table.vars td{border:1px solid var(--border);padding:6px 10px;text-align:right}table.vars th{background:var(--surface2)}table.vars td:first-child{direction:ltr;text-align:center;font-family:Georgia,serif;font-weight:700}
.two{display:grid;grid-template-columns:1fr;gap:0 24px}@media(min-width:760px){.two{grid-template-columns:1fr 1fr}}
/* الحاسبة */
#calc-form{display:grid;grid-template-columns:minmax(0,1fr);gap:12px;margin:10px 0}
@media(min-width:640px){#calc-form{grid-template-columns:minmax(0,1fr) minmax(0,1fr)}}
.fld{min-width:0}
.fld label{display:block;font-weight:600;font-size:15px;margin-bottom:4px}.u{font-weight:400;color:var(--muted);font-size:13px}
.fr{display:flex;gap:8px}.fr input,.fr select{flex:1;min-width:0;padding:10px 12px;border-radius:10px;border:1px solid var(--border);background:var(--surface);color:var(--text);font:inherit;min-height:44px}
.fr select.unit{flex:0 0 96px}.fr input{text-align:left}
.fr [aria-invalid=true]{border-color:var(--bad);box-shadow:0 0 0 2px var(--bad)}
.ferr{color:var(--bad);font-size:13px}.hint{grid-column:1/-1;margin:0;color:var(--muted);font-size:14.5px}
.fld[hidden]{display:none}
.actions{display:flex;gap:10px;flex-wrap:wrap;margin:6px 0 0;grid-column:1/-1}
#calc-errors{border:1px solid var(--bad);border-radius:10px;padding:10px 14px;margin:12px 0;color:var(--bad);background:var(--surface2)}#calc-errors ul{margin:4px 0;padding-inline-start:22px}
#calc-results{margin-top:16px;border-top:2px dashed var(--border);padding-top:14px;outline:none}
.rgrid{display:grid;grid-template-columns:repeat(auto-fit,minmax(160px,1fr));gap:10px}
.rc{background:var(--surface2);border:1px solid var(--border);border-radius:10px;padding:8px 12px}.rc span{display:block;font-size:13.5px;color:var(--muted);line-height:1.5}.rc b{font-size:20px;display:inline-block}.rc small{font-weight:400;color:var(--muted);font-size:13px}
ol.steps{padding-inline-start:20px}ol.steps li{margin:8px 0}.sl{font-weight:600;font-size:15px}
.interp{background:var(--surface2);border-radius:10px;padding:10px 14px;margin:10px 0}
.fig svg{width:100%;height:auto;max-width:460px;display:block;margin:6px auto;background:var(--surface);border:1px solid var(--border);border-radius:10px}
figure.dg{margin:0}figure.dg svg{width:100%;height:auto;background:var(--surface);border:1px solid var(--border);border-radius:10px}figcaption{font-size:14px;color:var(--muted);margin-top:4px}
table.ex{width:100%;border-collapse:collapse;font-size:15px;margin:6px 0}table.ex td,table.ex th{border:1px solid var(--border);padding:5px 10px;text-align:right}table.ex th{background:var(--surface2)}
details{border:1px solid var(--border);border-radius:10px;padding:8px 14px;margin:8px 0;background:var(--surface)}summary{font-weight:700;cursor:pointer;min-height:32px}
.links{display:flex;gap:10px;flex-wrap:wrap}.links a.chip{padding:7px 14px;border:1px solid var(--border);border-radius:99px;text-decoration:none;background:var(--surface);font-size:15px}
.share{display:flex;gap:8px;flex-wrap:wrap}.share a,.share button{padding:8px 14px;border-radius:10px;border:1px solid var(--border);background:var(--surface);color:var(--text);font:inherit;font-size:15px;text-decoration:none;cursor:pointer;min-height:42px}
/* التذييل */
footer.site{margin-top:36px;padding:8px 0 34px;border-top:1px solid var(--border);background:var(--surface)}
footer.site .cols{display:grid;grid-template-columns:1fr;gap:18px}@media(min-width:760px){footer.site .cols{grid-template-columns:1fr 1fr}}
footer.site h2{font-size:19px;margin:16px 0 6px}footer.site ul{list-style:none;padding:0;margin:0;display:flex;flex-wrap:wrap;gap:8px 12px}
footer.site .projects{flex-direction:column;gap:2px}footer.site .projects a{display:inline-block;padding:4px 0}
a.soc{display:inline-flex;align-items:center;gap:6px;padding:7px 12px;border:1px solid var(--border);border-radius:99px;text-decoration:none;background:var(--bg);color:var(--text);font-size:15px;min-height:42px}
a.soc svg{width:20px;height:20px}
.author{font-size:15px;color:var(--muted);margin:10px 0 0}
/* الرئيسية */
.hero{padding:18px 0 4px}.filters{display:flex;gap:8px;flex-wrap:wrap;margin:10px 0}
.filters button{border:1px solid var(--border);background:var(--surface);color:var(--text);padding:7px 14px;border-radius:99px;font:inherit;font-size:15px;cursor:pointer;min-height:40px}.filters button[aria-pressed=true]{background:var(--primary);color:var(--on-primary);border-color:var(--primary)}
#q{width:100%;max-width:480px;padding:11px 14px;border-radius:10px;border:1px solid var(--border);background:var(--surface);color:var(--text);font:inherit;min-height:44px}
.grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(260px,1fr));gap:14px}
.tool{background:var(--surface);border:1px solid var(--border);border-radius:14px;padding:16px;display:flex;flex-direction:column;gap:6px;box-shadow:var(--shadow)}.tool[hidden]{display:none}.tool h3{margin:0;font-size:18px}.tool h3 a{color:inherit;text-decoration:none}.tool p{margin:0;color:var(--muted);font-size:15px;flex:1}
/* إعلانات */
.ad-wrap{margin:34px 0;min-height:110px;text-align:center;clear:both;overflow:hidden}.ad-wrap::before{content:"إعلان";display:block;font-size:12px;color:var(--muted);margin-bottom:4px}
@media (prefers-reduced-motion:reduce){*{animation:none!important;transition:none!important;scroll-behavior:auto!important}}
.sr{position:absolute;width:1px;height:1px;overflow:hidden;clip:rect(0 0 0 0)}
.tool .badge{align-self:flex-start}.sl{unicode-bidi:plaintext;text-align:right}