/* Ham Radio Tools — restrained engineering UI */
 :root{
 --bg-primary:#f5f7f9;--bg-secondary:#ffffff;--bg-card:#ffffff;--bg-input:#f8fafb;--panel:#ffffff;
 --accent-cyan:#1769aa;--accent-green:#18794e;--accent-orange:#996515;--accent-pink:#a44b6b;--accent-purple:#5d63a8;
 --text-primary:#17212b;--text-secondary:#52616f;--text-muted:#687785;--muted:#687785;--border:#d5dde4;
 --success:#18794e;--warning:#996515;--danger:#b42318;--radius:9px;--shadow:0 4px 16px rgba(28,45,62,.08);
 --font-main:Inter,ui-sans-serif,system-ui,-apple-system,"Segoe UI",sans-serif;
 --font-mono:"JetBrains Mono","SFMono-Regular",Consolas,monospace;
}
[data-theme="dark"]{
 --bg-primary:#1b2229;--bg-secondary:#222a32;--bg-card:#27313a;--bg-input:#202830;--panel:#27313a;
 --accent-cyan:#74b7ee;--accent-green:#68c99b;--accent-orange:#e1a550;--accent-pink:#e294ad;--accent-purple:#a7acf0;
 --text-primary:#edf2f5;--text-secondary:#b9c4cd;--text-muted:#8e9ca8;--muted:#8e9ca8;--border:#3c4853;
 --success:#68c99b;--warning:#e1a550;--danger:#ef8585;--shadow:0 8px 24px rgba(0,0,0,.22)
}
*{box-sizing:border-box;margin:0;padding:0}html{scroll-behavior:smooth}body{font-family:var(--font-main);background:var(--bg-primary);color:var(--text-primary);line-height:1.65;min-height:100vh}a{color:var(--accent-cyan)}
.site-header{background:var(--bg-secondary);border-bottom:1px solid var(--border);position:sticky;top:0;z-index:1000}.nav-wrap,.header-inner{max-width:1240px;margin:auto;padding:.7rem 1.1rem;display:flex;align-items:center;justify-content:space-between;gap:1rem}
.brand,.logo{display:flex;align-items:center;gap:.65rem;color:var(--text-primary);font-weight:760;letter-spacing:-.02em;text-decoration:none;white-space:nowrap}.brand:before,.logo-icon{content:"RF";width:34px;height:34px;border:1px solid #3a5066;border-radius:7px;background:var(--bg-card);color:var(--accent-cyan);display:inline-flex;align-items:center;justify-content:center;font:700 .7rem var(--font-mono)}.logo-icon{content:none}
.main-nav{display:flex;align-items:center;gap:.15rem;flex-wrap:wrap}.main-nav a,.nav-dropdown>button{color:var(--text-secondary);text-decoration:none;padding:.48rem .68rem;border-radius:7px;font-size:.88rem;font-weight:560;background:transparent;border:0;cursor:pointer;font-family:inherit}.main-nav a:hover,.nav-dropdown>button:hover,.main-nav a.active{color:var(--text-primary);background:var(--bg-input)}.nav-dropdown{position:relative}.nav-dropdown-menu{display:none;position:absolute;top:100%;left:0;background:var(--bg-secondary);border:1px solid var(--border);border-radius:8px;min-width:240px;padding:.35rem;box-shadow:var(--shadow);z-index:100}.nav-dropdown:hover .nav-dropdown-menu,.nav-dropdown.open .nav-dropdown-menu{display:block}.nav-dropdown-menu a{display:block;padding:.55rem .68rem;border-radius:6px;font-size:.86rem}.nav-toggle{display:none;background:var(--bg-input);border:1px solid var(--border);color:var(--text-primary);padding:.55rem .7rem;border-radius:7px;cursor:pointer;font-size:1rem;min-width:44px;min-height:44px}.theme-toggle{background:var(--bg-input);border:1px solid var(--border);color:var(--text-primary);min-width:44px;min-height:40px;border-radius:7px;cursor:pointer;font-size:.82rem;padding:.4rem .65rem}
.container{max-width:1180px;padding:1.5rem 1.1rem 2rem;margin:auto}.page-header{text-align:left;max-width:840px;margin:1.1rem auto 1.7rem}.page-header h1{font-size:clamp(2rem,4vw,2.8rem);line-height:1.12;letter-spacing:-.035em;color:var(--text-primary);margin-bottom:.6rem}.page-header h1:after{content:"";display:block;width:38px;height:2px;background:var(--accent-cyan);margin-top:.8rem}.page-header p{color:var(--text-secondary);font-size:1rem;max-width:780px}
.calc-panel,.info-panel{background:var(--bg-card);border:1px solid var(--border);border-radius:11px;padding:1.35rem;box-shadow:var(--shadow)}.calc-panel h2,.info-panel h2{font-size:1.15rem;letter-spacing:-.01em;color:var(--text-primary);margin-bottom:.8rem}.calc-panel h2:after,.info-panel h2:after{content:"";display:block;width:26px;height:2px;background:var(--accent-cyan);margin-top:.45rem}.form-row{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:1rem}.form-group{margin-bottom:1rem}.form-group label{display:block;color:var(--text-primary);font-size:.82rem;font-weight:650;margin-bottom:.38rem}.form-group input,.form-group select,.form-group textarea{width:100%;background:var(--bg-input);border:1px solid var(--border);border-radius:7px;min-height:46px;color:var(--text-primary);font-size:.96rem;padding:.55rem .7rem}.form-group input:focus,.form-group select:focus,.form-group textarea:focus,.tool-search:focus{border-color:var(--accent-cyan);outline:2px solid rgba(79,156,245,.14);outline-offset:1px}
.btn{display:inline-flex;align-items:center;justify-content:center;min-height:44px;border-radius:7px;padding:.55rem .85rem;box-shadow:none!important;transform:none!important;font-size:.9rem;font-weight:650;cursor:pointer;text-decoration:none}.btn-primary{background:var(--accent-cyan);color:#07121c;border:1px solid var(--accent-cyan)}.btn-primary:hover{background:#69aafa}.btn-secondary{background:transparent;border:1px solid var(--border);color:var(--text-primary)}.btn-secondary:hover{border-color:var(--accent-cyan);color:var(--accent-cyan)}.btn-block{width:100%;margin-top:.35rem}.home-actions{display:flex;gap:.6rem;flex-wrap:wrap;margin-top:1rem}
.results{background:var(--bg-input);border:1px solid var(--border);border-radius:9px;padding:.55rem;margin-top:1rem}.result-item{display:flex;justify-content:space-between;align-items:baseline;gap:1rem;padding:.78rem .45rem;border-bottom:1px solid var(--border)}.result-item:last-child{border-bottom:0}.result-label{font-size:.85rem;color:var(--text-secondary)}.result-value,.result-item strong{font-family:var(--font-mono);font-size:1.08rem;color:var(--accent-green);text-align:right}.results .result-item:first-child .result-value,.results .result-item:first-child strong{font-size:1.32rem}.advice-box{background:rgba(216,154,61,.08);border-left:3px solid var(--accent-orange);border-radius:0 6px 6px 0;padding:.75rem 1rem;margin-top:.8rem}.formula{background:var(--bg-input);border:1px solid var(--border);color:var(--accent-cyan);border-radius:7px;padding:.7rem;font-family:var(--font-mono);overflow:auto}.diagram{background:var(--bg-input);border:1px solid var(--border);border-radius:9px;padding:1rem}.prop-card{background:var(--bg-input);border:1px solid var(--border);border-radius:8px;padding:.9rem}.prop-card .value{font-family:var(--font-mono);font-size:1.25rem;color:var(--text-primary)}
.card-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(245px,1fr));gap:1rem}.card{display:block;background:var(--bg-card);border:1px solid var(--border);border-radius:9px;padding:1.15rem;text-decoration:none;color:inherit;box-shadow:none;transition:border-color .16s,box-shadow .16s}.card:hover{border-color:#48637e;box-shadow:0 7px 18px rgba(0,0,0,.12)}.card-icon{width:42px;height:42px;border-radius:8px;background:var(--bg-input);color:var(--accent-cyan);font-size:.78rem;margin-bottom:.85rem;border:1px solid var(--border);display:flex;align-items:center;justify-content:center}.card-icon svg{width:22px;height:22px;stroke:currentColor;fill:none;stroke-width:1.7}.card h3{font-size:1.02rem;letter-spacing:-.01em}.card p{font-size:.87rem;line-height:1.5;color:var(--text-secondary)}
.band-table{font-size:.88rem;overflow:auto;border:1px solid var(--border);border-radius:8px}.band-table table{min-width:560px}.band-table th{background:var(--bg-input);color:var(--text-secondary);position:sticky;top:0}.band-table td,.band-table th{padding:.65rem .7rem}.band-table td:first-child{color:var(--accent-cyan)}.band-table tr:hover td{background:rgba(79,156,245,.035)}
.site-footer{background:var(--bg-secondary);border-top:1px solid var(--border);padding:1.8rem 1.1rem;color:var(--text-muted)}.site-footer a{color:var(--text-secondary)}.site-footer a:hover{color:var(--accent-cyan)}.footer-links{max-width:1180px;margin:auto;display:grid;gap:.65rem}.footer-note{max-width:1180px;margin:.75rem auto 0;font-size:.8rem}.section-title{display:flex;align-items:baseline;justify-content:space-between;gap:1rem;margin:2.2rem 0 1rem!important;color:var(--text-primary)!important;font-size:1.32rem!important}.section-title span{font-size:.78rem;font-weight:500;color:var(--text-muted)}
.related-tools{margin-top:1.4rem}.related-links{display:flex;flex-wrap:wrap;gap:.45rem}.related-links a{display:inline-flex;align-items:center;padding:.48rem .65rem;border:1px solid var(--border);border-radius:6px;color:var(--text-secondary);text-decoration:none;font-size:.83rem;background:var(--bg-input)}.related-links a:hover{color:var(--text-primary);border-color:#48637e}.link-accent{color:var(--accent-cyan)!important}.muted-note{color:var(--text-secondary);font-size:.92rem;margin-bottom:1rem}.tiny-note{font-size:.8rem;color:var(--text-muted);margin-top:.75rem}.center-note{text-align:center;margin:1.5rem 0}.rule{border:0;border-top:1px solid var(--border);margin:1.5rem 0}.warning-note{margin-top:.75rem;padding:.75rem 1rem;background:rgba(216,154,61,.12);border-left:4px solid var(--accent-orange);border-radius:0 8px 8px 0}.tool-utility{display:flex;align-items:center;gap:.5rem;flex-wrap:wrap;margin:-.55rem 0 1rem;color:var(--text-muted);font-size:.78rem}.tool-utility button{border:1px solid var(--border);background:var(--bg-card);color:var(--text-secondary);border-radius:6px;padding:.42rem .62rem;cursor:pointer;min-height:38px}.tool-utility button:hover{border-color:var(--accent-cyan);color:var(--accent-cyan)}.tool-search{width:min(360px,100%);min-height:42px;border:1px solid var(--border);background:var(--bg-input);border-radius:7px;padding:.5rem .7rem;color:var(--text-primary)}.tool-breadcrumb{font-size:.78rem;color:var(--text-muted);margin:.25rem 0 1rem}.tool-breadcrumb a{color:var(--text-secondary);text-decoration:none}.tool-breadcrumb a:hover{color:var(--accent-cyan)}.tool-modal{position:fixed;inset:0;background:rgba(4,9,14,.72);z-index:2000;display:none;align-items:flex-start;justify-content:center;padding:10vh 1rem}.tool-modal.open{display:flex}.tool-modal-box{width:min(620px,100%);background:var(--bg-secondary);border:1px solid var(--border);border-radius:11px;box-shadow:0 20px 50px rgba(0,0,0,.3);padding:1rem}.tool-modal-head{display:flex;justify-content:space-between;align-items:center;gap:1rem}.tool-modal-close{min-width:40px;min-height:40px;border:1px solid var(--border);background:transparent;color:var(--text-primary);border-radius:6px;font-size:1.1rem}.tool-results{max-height:52vh;overflow:auto;margin-top:.7rem}.tool-result-link{display:block;padding:.65rem .7rem;border-radius:7px;color:var(--text-primary);text-decoration:none}.tool-result-link:hover{background:var(--bg-input)}.tool-result-link small{display:block;color:var(--text-muted);margin-top:.1rem}.favorite-on{color:var(--accent-orange)!important;border-color:var(--accent-orange)!important}.home-search{display:flex;gap:.55rem;max-width:720px;margin:0 auto 1.35rem}.home-search input{flex:1;min-height:48px}.saved-tools{margin-bottom:1.5rem}.saved-label{font-size:.76rem;color:var(--text-muted);font-weight:700;text-transform:uppercase;letter-spacing:.06em;margin:.8rem 0 .4rem}
.kicker{font-size:.72rem;font-weight:750;text-transform:uppercase;letter-spacing:.08em;color:var(--accent-cyan);margin-bottom:.45rem}.featured-tools{border-top:1px solid var(--border);padding-top:1.2rem}.tool-category-grid{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:1rem}.category-card{background:var(--bg-card);border:1px solid var(--border);border-radius:9px;padding:1rem}.category-card h3{font-size:.98rem;margin-bottom:.5rem}.category-card p{font-size:.83rem;color:var(--text-secondary);margin-bottom:.65rem}.category-card a{font-size:.83rem;text-decoration:none}.mobile-only{display:none}
@media(max-width:900px){.nav-toggle{display:inline-flex;align-items:center;justify-content:center}.main-nav{display:none;position:absolute;left:0;right:0;top:60px;background:var(--bg-secondary);border-bottom:1px solid var(--border);padding:.6rem .8rem;max-height:calc(100vh - 60px);overflow:auto}.main-nav.open{display:block}.main-nav>a,.nav-dropdown>button{display:block;width:100%;text-align:left;padding:.65rem .7rem}.nav-dropdown-menu{position:static;box-shadow:none;border-radius:7px;margin:.15rem 0}.nav-dropdown-menu a{padding:.58rem .7rem}.tool-category-grid{grid-template-columns:repeat(2,minmax(0,1fr))}}
@media(max-width:700px){.container{padding-inline:1rem}.header-inner,.nav-wrap{padding-inline:.8rem}.form-row,.mini-grid{grid-template-columns:1fr!important}.calc-panel,.info-panel{padding:1rem}.page-header{margin-bottom:1.25rem}.page-header h1{font-size:clamp(1.8rem,9vw,2.35rem)}.btn{width:100%;min-height:46px}.home-actions{display:grid}.home-actions .btn{width:100%}.result-item{flex-direction:column;align-items:flex-start;gap:.2rem}.result-value,.result-item strong{text-align:left}.tool-utility{margin-top:-.35rem}.home-search{display:grid}.tool-category-grid{grid-template-columns:1fr}.card-grid{grid-template-columns:1fr}.nav-dropdown-menu{max-height:55vh;overflow:auto}.site-footer{padding-inline:1rem}}
@media(max-width:380px){.container{padding-inline:.8rem}.card,.calc-panel,.info-panel{border-radius:8px}.page-header{padding-top:.6rem}.page-header h1{font-size:1.8rem}}
@media(prefers-reduced-motion:reduce){*,*::before,*::after{transition:none!important;animation:none!important;scroll-behavior:auto!important}}

.accent-panel{background:var(--bg-card)}.body-size{font-size:1rem}.responsive-image{max-width:100%;border-radius:9px;border:1px solid var(--border)}.hidden-panel,.hidden{display:none}.muted-text{font-size:.9rem;color:var(--text-muted)}.tiny-center-note{font-size:.8rem;color:var(--text-muted);margin-top:.75rem;text-align:center}.section-gap{margin-top:2.5rem}.chat-text{font-size:1.05rem;text-align:right;max-width:75%;line-height:1.4}.danger-text{font-family:var(--font-mono);color:var(--danger)}.scrollable{overflow:auto}

.tool-empty{padding:.8rem;color:var(--text-muted)}
.engineering-notes{margin-top:1.2rem}.engineering-notes p{max-width:82ch;color:var(--text-secondary);margin:.65rem 0}.engineering-notes p:first-of-type{margin-top:0}.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}

/* Final usability refinements */
.skip-link{position:fixed;left:1rem;top:-4rem;z-index:3000;background:var(--bg-secondary);color:var(--text-primary);border:2px solid var(--accent-cyan);padding:.55rem .8rem;border-radius:7px;text-decoration:none}.skip-link:focus{top:1rem}
.toast-region{position:fixed;right:1rem;bottom:1rem;z-index:4000;display:grid;gap:.5rem;max-width:min(380px,calc(100vw - 2rem))}.tool-toast{background:var(--bg-secondary);color:var(--text-primary);border:1px solid var(--border);box-shadow:var(--shadow);border-radius:8px;padding:.7rem .85rem;font-size:.86rem}.tool-toast.error{border-color:var(--danger)}.tool-toast.success{border-color:var(--success)}
.form-error{display:block;color:var(--danger);font-size:.78rem;margin-top:.3rem}.form-group.invalid input,.form-group.invalid select,.form-group.invalid textarea{border-color:var(--danger);outline:2px solid color-mix(in srgb,var(--danger) 15%,transparent)}
.diagram-source{font-size:.72rem;color:var(--text-muted);margin-top:.55rem;line-height:1.45}.diagram-source a{color:var(--text-secondary)}.web-diagram{background:var(--bg-input);border:1px solid var(--border);border-radius:9px;padding:.7rem;text-align:center}.web-diagram img{display:block;width:100%;height:auto;max-height:430px;object-fit:contain;border-radius:6px;background:#fff}.web-diagram figcaption{margin-top:.55rem;text-align:left;color:var(--text-secondary);font-size:.8rem}.engineering-notes{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:1rem;margin-top:1.25rem}.engineering-notes article{background:var(--bg-input);border:1px solid var(--border);border-radius:8px;padding:1rem}.engineering-notes h3{font-size:.95rem;margin-bottom:.4rem}.engineering-notes p{font-size:.86rem;color:var(--text-secondary);line-height:1.6}@media(max-width:760px){.engineering-notes{grid-template-columns:1fr}.web-diagram img{max-height:360px}.page-header{margin-top:.6rem}.theme-toggle{min-height:44px}.main-nav{gap:.25rem}}
@media(max-width:700px){.form-row,.mini-grid{grid-template-columns:1fr!important}.btn-block,.calc-panel .btn-primary{width:100%}.result-item{align-items:flex-start;flex-direction:column;gap:.2rem}.result-value,.result-item strong{text-align:left}.results .result-item:first-child .result-value,.results .result-item:first-child strong{font-size:1.2rem}}


/* Antenna imagery and editorial content */
.antenna-hero{margin:1.25rem 0 1.5rem;border:1px solid var(--border);background:var(--panel);border-radius:14px;overflow:hidden;}
.antenna-hero img{display:block;width:100%;max-height:520px;object-fit:contain;background:#f3f5f7;}
.antenna-hero figcaption{padding:.7rem .9rem;font-size:.82rem;line-height:1.45;color:var(--muted);border-top:1px solid var(--border);}
.antenna-hero figcaption a{font-weight:600;}
.antenna-overview{margin:0 0 1.5rem;}
.antenna-overview p{max-width:78ch;line-height:1.72;}
@media (max-width:700px){.antenna-hero{margin:.9rem 0 1rem;border-radius:10px}.antenna-hero img{max-height:360px}.antenna-hero figcaption{font-size:.78rem}.antenna-overview p{line-height:1.65}}

/* Final design-system refinements */
:focus-visible{outline:2px solid var(--accent-cyan);outline-offset:3px}
.site-header{box-shadow:0 1px 0 rgba(23,33,43,.03)}
.brand:before,.logo-icon{background:var(--bg-card)}
.card:hover{border-color:var(--accent-cyan);box-shadow:0 7px 18px rgba(28,45,62,.08)}
.nav-dropdown-menu{box-shadow:0 12px 28px rgba(28,45,62,.14)}
.tool-modal{background:rgba(17,27,36,.58)}
.form-error{font-weight:550}
.technical-content{max-width:840px;margin:1.25rem auto 0;color:var(--text-secondary)}
.technical-content h2{margin:1.6rem 0 .55rem;color:var(--text-primary);font-size:1.18rem}
.technical-content p{margin:.65rem 0}
.technical-content ul{padding-left:1.2rem;margin:.55rem 0}.technical-content li{margin:.3rem 0}
.category-intro{max-width:840px;margin:-.55rem auto 1.25rem;color:var(--text-secondary)}
.antenna-hero{background:var(--bg-card)}
.antenna-hero img{display:block;width:100%;max-height:520px;object-fit:contain;background:var(--bg-input)}
.search-empty{padding:1rem;color:var(--text-muted)}
@media (max-width:700px){.container{padding:1rem .8rem 1.5rem}.page-header{margin:.7rem auto 1.2rem}.page-header h1{font-size:clamp(1.75rem,8vw,2.3rem)}.calc-panel,.info-panel{padding:1rem}.tool-modal{padding:5vh .7rem}.tool-modal-box{max-height:90vh;overflow:auto}.tool-results{max-height:55vh}.result-item{align-items:flex-start}.result-value,.result-item strong{max-width:58%;overflow-wrap:anywhere}.home-search{flex-direction:column}.home-search .btn{width:100%}.nav-dropdown-menu{max-height:60vh;overflow:auto}}

.nav-toggle svg,.nav-dropdown button svg{width:18px;height:18px;stroke:currentColor;fill:none;stroke-width:1.8}.nav-dropdown>button{display:inline-flex;align-items:center;gap:.35rem}


/* Consolidated page-specific rules */
/* Shared technical visualization rules */
.mini-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(190px,1fr));gap:1rem}
canvas{max-width:100%;border:1px solid var(--border);border-radius:8px;background:var(--panel)}
.result-note{font-size:.88rem;opacity:.82}
.nav-menu-group{padding:.2rem 0}.nav-menu-label{padding:.38rem .68rem .2rem;color:var(--text-muted);font-size:.68rem;font-weight:750;text-transform:uppercase;letter-spacing:.08em}.nav-menu-group a{display:block}.nav-dropdown-menu{min-width:270px}
@media (max-width:700px){.nav-dropdown-menu{width:min(92vw,360px);min-width:0}.nav-menu-label{padding-top:.5rem}}

/* Distinctive RF instrument design language */
.brand-mark{width:36px;height:36px;border:1px solid var(--accent-cyan);border-radius:8px;display:inline-flex;align-items:center;justify-content:center;background:var(--bg-input);color:var(--accent-cyan);flex:0 0 auto}
.brand-mark svg{width:27px;height:27px;fill:none;stroke:currentColor;stroke-width:1.35;stroke-linecap:round;stroke-linejoin:round}
.brand:before{display:none}
.page-header{position:relative;padding-left:1rem;border-left:3px solid var(--accent-cyan)}
.page-header:after{content:"RF / ANTENNA / FIELD";display:block;margin-top:.8rem;font:600 .64rem var(--font-mono);letter-spacing:.14em;color:var(--text-muted)}
.section-title{display:flex;align-items:center;gap:.7rem}
.section-title:before{content:"";width:18px;height:18px;border:1px solid var(--accent-cyan);border-radius:3px;box-shadow:inset 0 -5px 0 var(--accent-cyan)}
.category-card{background:var(--bg-card);border:1px solid var(--border);border-top:3px solid var(--accent-cyan);border-radius:9px;padding:1.2rem;box-shadow:var(--shadow);transition:transform .16s,border-color .16s}
.category-card:hover{transform:translateY(-2px);border-color:var(--accent-cyan)}
.results{border-left:3px solid var(--accent-green)}
.technical-content{max-width:840px}
.editorial-depth{border-top:1px solid var(--border);padding-top:.2rem}
@media(max-width:700px){.page-header{padding-left:.75rem}.page-header:after{font-size:.58rem}.brand-mark{width:34px;height:34px}.brand{gap:.5rem}.category-card:hover{transform:none}}

/* Hybrid engineering theme — warm light canvas with dark instrument surfaces */
:root{
 --bg-primary:#e9eef2;--bg-secondary:#17232d;--bg-card:#f7f8f8;--bg-input:#eef2f4;--panel:#202e39;
 --accent-cyan:#1c7f9e;--accent-green:#217a59;--accent-orange:#b47720;--accent-pink:#9a506a;--accent-purple:#5c629f;
 --text-primary:#17242d;--text-secondary:#4e5e69;--text-muted:#6d7b84;--muted:#6d7b84;--border:#cbd4da;
 --success:#217a59;--warning:#a56d19;--danger:#b42318;--radius:8px;--shadow:0 5px 18px rgba(26,42,54,.11);
}
[data-theme="dark"]{
 --bg-primary:#111a21;--bg-secondary:#17232d;--bg-card:#202d37;--bg-input:#192630;--panel:#263640;
 --accent-cyan:#65bfd3;--accent-green:#6bc69b;--accent-orange:#e0a65a;--accent-pink:#e29bb2;--accent-purple:#a8ace7;
 --text-primary:#edf3f5;--text-secondary:#b8c5cc;--text-muted:#91a0a9;--muted:#91a0a9;--border:#3a4a55;
 --success:#6bc69b;--warning:#e0a65a;--danger:#ef8c8c;--shadow:0 8px 25px rgba(0,0,0,.28);
}
body{background:var(--bg-primary)}
.site-header{background:var(--bg-secondary);border-bottom-color:#263844;box-shadow:0 2px 12px rgba(8,20,28,.18)}
.brand,.logo{color:#f1f5f6}.brand-mark{background:#21323d;border-color:#4b9eb4;color:#72c8da}
.main-nav a,.nav-dropdown>button{color:#c5d0d6}.main-nav a:hover,.nav-dropdown>button:hover,.main-nav a.active{color:#fff;background:#243640}
.nav-dropdown-menu{background:#1b2933;border-color:#334650;box-shadow:0 14px 30px rgba(0,0,0,.25)}
.nav-dropdown-menu a{color:#cbd6dc}.nav-dropdown-menu a:hover{background:#263943;color:#fff}
.theme-toggle,.nav-toggle{background:#24343e;border-color:#40525d;color:#e7eef1}
.container{padding-top:1.7rem}.page-header{background:var(--bg-card);border:1px solid var(--border);border-left:4px solid var(--accent-cyan);padding:1.25rem 1.35rem;box-shadow:var(--shadow);max-width:920px}
.page-header h1{margin-bottom:.55rem}.page-header p{max-width:820px}
.calc-panel{background:#1f2e38;color:#edf3f5;border-color:#344852;box-shadow:0 9px 25px rgba(15,28,37,.18)}
.calc-panel h2{color:#f2f6f7}.calc-panel h2:after{background:#69bfd1}.calc-panel .form-group label{color:#dce6ea}.calc-panel .form-group input,.calc-panel .form-group select,.calc-panel .form-group textarea{background:#172630;border-color:#40535e;color:#eef4f6}
.calc-panel .muted-note,.calc-panel .tiny-note{color:#aebdc5}
.calc-panel .btn-secondary{border-color:#4a5d68;color:#dce6ea}.calc-panel .btn-secondary:hover{border-color:#72c8da;color:#72c8da}
.results{background:#101a21;border-color:#3a4c57;border-left:3px solid var(--accent-green);box-shadow:inset 0 1px 0 rgba(255,255,255,.03)}
.result-label{color:#aebdc5}.result-value,.result-item strong{color:#72d0a2}
.info-panel{background:var(--bg-card);box-shadow:var(--shadow)}
.formula,.diagram,.prop-card{background:#edf2f4}
.technical-content,.engineering-notes{background:transparent}
.technical-content{max-width:920px}
.technical-content > p,.technical-content > ul,.technical-content > ol,.engineering-notes article p,.antenna-overview p,.category-intro{ text-align:justify; text-justify:inter-word; hyphens:auto }
.technical-content > p,.antenna-overview p{background:var(--bg-card);border:1px solid var(--border);padding:1rem 1.15rem;margin:.8rem 0;box-shadow:0 2px 9px rgba(30,45,56,.045)}
.engineering-notes article{background:var(--bg-card);box-shadow:0 3px 12px rgba(30,45,56,.06)}
.engineering-notes article p{margin:.65rem 0}
.category-intro{background:var(--bg-card);border:1px solid var(--border);padding:1rem 1.15rem;box-shadow:0 2px 9px rgba(30,45,56,.045)}
.antenna-hero{background:#17232d;border-color:#344852;box-shadow:var(--shadow)}
.antenna-hero figcaption{color:#c2cdd2;border-color:#344852}
.antenna-overview{background:transparent}
.card{background:var(--bg-card);box-shadow:0 3px 12px rgba(30,45,56,.055);border-color:var(--border)}
.card:nth-child(4n+1){border-top:3px solid var(--accent-cyan)}.card:nth-child(4n+2){border-top:3px solid var(--accent-green)}.card:nth-child(4n+3){border-top:3px solid var(--accent-orange)}.card:nth-child(4n){border-top:3px solid var(--accent-purple)}
.card-icon{background:#e6edf0}.section-title:before{background:var(--accent-cyan)}
.site-footer{background:#17232d;border-top-color:#30434f;color:#aebdc5}.site-footer a{color:#d0dade}.site-footer a:hover{color:#72c8da}
.band-table{background:var(--bg-card)}
@media(max-width:700px){
 .technical-content > p,.antenna-overview p,.category-intro{padding:.85rem .9rem;line-height:1.68;text-align:justify}
 .page-header{padding:1rem;border-left-width:3px}
 .calc-panel{box-shadow:0 6px 18px rgba(10,22,30,.16)}
}
@media(max-width:360px){.technical-content > p,.antenna-overview p{font-size:.94rem}}

/* ===== Final hybrid RF instrument theme ===== */
:root{
 --bg-primary:#e9eef2; --bg-secondary:#172431; --bg-card:#f8fafb; --bg-input:#eef3f6; --panel:#f7f9fa;
 --accent-cyan:#1d8ca8; --accent-green:#247a59; --accent-orange:#b97822; --accent-pink:#a65068; --accent-purple:#5967a9;
 --text-primary:#18232d; --text-secondary:#50616e; --text-muted:#6d7c87; --muted:#6d7c87; --border:#cbd5dc;
 --success:#247a59; --warning:#b97822; --danger:#b42318; --radius:6px; --shadow:0 8px 24px rgba(25,42,55,.09);
}
[data-theme="dark"]{
 --bg-primary:#111a22; --bg-secondary:#182631; --bg-card:#202f3a; --bg-input:#1a2832; --panel:#1d2c36;
 --accent-cyan:#59c4dc; --accent-green:#66c997; --accent-orange:#e3ad5e; --accent-pink:#e59caf; --accent-purple:#aeb5f2;
 --text-primary:#eef4f7; --text-secondary:#b8c6cf; --text-muted:#8d9ca7; --muted:#8d9ca7; --border:#394b57;
 --success:#66c997; --warning:#e3ad5e; --danger:#f08a8a; --shadow:0 10px 30px rgba(0,0,0,.28);
}
.site-header{background:#142331;color:#eef4f7;border-bottom:1px solid #2d4657;box-shadow:0 3px 14px rgba(8,20,29,.16)}
.site-header .brand,.site-header .main-nav a,.site-header .nav-dropdown>button{color:#eaf1f5}
.site-header .main-nav a:hover,.site-header .nav-dropdown>button:hover,.site-header .main-nav a.active{background:#203442;color:#fff}
.site-header .theme-toggle,.site-header .nav-toggle{background:#203442;border-color:#385263;color:#edf4f7}
.brand:before{display:none!important;content:none!important}
.brand-mark{width:38px;height:38px;border:1px solid #4d7183;border-radius:5px;background:#1c3443;color:#63c9dc;display:inline-flex;align-items:center;justify-content:center}
.brand-mark svg{width:25px;height:25px;stroke:currentColor;fill:none;stroke-width:1.6;stroke-linecap:round;stroke-linejoin:round}
.nav-dropdown-menu{background:#172a38;border-color:#36505f}
.nav-menu-group+.nav-menu-group{border-top:1px solid #314955;margin-top:.35rem;padding-top:.35rem}
.nav-menu-label{color:#79c9da!important;font:700 .68rem var(--font-mono);text-transform:uppercase;letter-spacing:.08em;padding:.35rem .68rem}
.nav-dropdown-menu a{color:#dbe6eb!important}.nav-dropdown-menu a:hover{background:#243b49!important;color:#fff!important}
.container{padding-top:1.8rem}
.page-header{margin-top:.65rem}.page-header h1{font-weight:790}.page-header h1:after{height:3px;width:48px;background:var(--accent-cyan);margin-top:.65rem}
.calc-panel{background:#182a36;color:#eef4f7;border-color:#304a58;box-shadow:0 12px 28px rgba(16,34,45,.16)}
.calc-panel h2{color:#f1f6f8}.calc-panel h2:after{background:#59c4dc}
.calc-panel .muted-note,.calc-panel .tiny-note{color:#b7c7cf}.calc-panel .form-group label{color:#e8f0f3}
.calc-panel .form-group input,.calc-panel .form-group select,.calc-panel .form-group textarea{background:#12222c;border-color:#3a5260;color:#eef4f7}
.calc-panel .btn-secondary{border-color:#486170;color:#dbe7ec}.calc-panel .results{background:#10202a;border-color:#3c5665}
.calc-panel .result-label{color:#a9bbc5}.calc-panel .result-value,.calc-panel .result-item strong{color:#6bd2a0}
.info-panel{background:var(--bg-card);border-radius:6px;box-shadow:var(--shadow)}
.technical-content,.engineering-notes,.antenna-overview,.section-gap,.home-intro{max-width:940px;margin-left:auto;margin-right:auto}
.technical-content p,.engineering-notes p,.antenna-overview p,.section-gap p,.home-intro p{max-width:82ch;text-align:justify;text-justify:inter-word;hyphens:auto;line-height:1.78;margin:.8rem auto;color:var(--text-secondary)}
.technical-content h2,.engineering-notes h2,.antenna-overview h2,.home-intro h2{color:var(--text-primary)}
.info-panel,.calc-panel{border-radius:6px}
.results{border-radius:5px}.result-item{padding:.8rem .55rem}
.advice-box,.warning-note{border-radius:2px 5px 5px 2px}
.card-grid{gap:.85rem}.card{border-radius:6px;padding:1.05rem;background:var(--bg-card);position:relative;overflow:hidden}.card:before{content:"";position:absolute;left:0;top:0;bottom:0;width:3px;background:var(--accent-cyan);opacity:.7}.card:nth-child(4n+2):before{background:var(--accent-green)}.card:nth-child(4n+3):before{background:var(--accent-orange)}.card:nth-child(4n+4):before{background:var(--accent-purple)}.card:hover{transform:translateY(-1px);border-color:#668094;box-shadow:0 10px 22px rgba(22,43,56,.12)}
.card-icon{border-radius:5px}.section-title{letter-spacing:-.02em}
.workflow-panel{background:#1a2c38!important;color:#eaf2f5;border-color:#304a58!important;max-width:1120px;margin:1.4rem auto 1.8rem!important;position:relative;overflow:hidden}
.workflow-panel:after{content:"RF / WORKFLOW";position:absolute;right:1rem;top:1rem;font:700 .64rem var(--font-mono);letter-spacing:.12em;color:#557988}
.workflow-intro{max-width:720px}.workflow-intro h2{color:#f2f6f8}.workflow-intro p{color:#b9c9d1;text-align:left}
.workflow-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:.7rem;margin-top:1rem}.workflow-card{min-height:142px;padding:1rem;background:#223946;border:1px solid #3b5665;border-radius:4px;text-decoration:none;color:#eef4f7;display:flex;flex-direction:column;justify-content:space-between;transition:.15s ease}.workflow-card:hover{background:#294653;border-color:#65b9ca;transform:translateY(-2px)}.workflow-card strong{font-size:1.02rem}.workflow-card>span:last-child{color:#b5c5cd;font-size:.82rem;line-height:1.5}.workflow-code{font:700 .65rem var(--font-mono);letter-spacing:.1em;color:#63c9dc}.workflow-antenna{border-top:3px solid #63c9dc}.workflow-rf{border-top:3px solid #6bcf9d}.workflow-dx{border-top:3px solid #e2aa58}.workflow-field{border-top:3px solid #aeb5f2}
.home-search{background:#dce5ea;border:1px solid #c2ced5;padding:.7rem;border-radius:5px;display:flex;gap:.6rem;max-width:900px;margin:0 auto 1.2rem;box-shadow:inset 0 1px 0 rgba(255,255,255,.7)}
.home-search .tool-search{background:#fff;border-color:#b9c7cf;flex:1}
.site-footer{background:#142331;color:#aebfc8;border-top:1px solid #304957}.site-footer a{color:#d0dde3}.footer-note{color:#91a5b0}
.band-table{border-radius:5px}.band-table th{background:#dce5ea;color:#40525f}
:focus-visible{outline:3px solid #f0b85d!important;outline-offset:2px}
.skip-link:focus{background:#142331!important;color:#fff!important}
@media(max-width:760px){.workflow-grid{grid-template-columns:repeat(2,1fr)}.home-search{align-items:stretch}.home-search .btn{width:auto}.technical-content p,.engineering-notes p,.antenna-overview p,.section-gap p,.home-intro p{text-align:left;hyphens:none;line-height:1.7}.nav-dropdown-menu{max-height:70vh;overflow:auto}}
@media(max-width:520px){.workflow-grid{grid-template-columns:1fr}.home-search{flex-direction:column}.home-search .btn{width:100%}.container{padding-left:.8rem;padding-right:.8rem}.calc-panel,.info-panel{padding:1rem}.result-item{flex-wrap:wrap}.result-value,.result-item strong{text-align:left;width:100%}.workflow-panel:after{display:none}}
@media(prefers-reduced-motion:reduce){*{scroll-behavior:auto!important;transition:none!important}}

.workflow-next{max-width:940px;margin:1rem auto}.workflow-next p{color:var(--text-secondary);text-align:justify;line-height:1.7}.workflow-next .related-links{margin-top:.7rem}

/* Final polish: preserve the hybrid contrast in dark mode */
[data-theme="dark"] .formula,[data-theme="dark"] .diagram,[data-theme="dark"] .prop-card{background:#172630;border-color:#3a4c57;color:#d9e7ec}
[data-theme="dark"] .home-search{background:#1c2b35;border-color:#3a4e5b;box-shadow:none}
[data-theme="dark"] .home-search .tool-search{background:#12202a;border-color:#3b515e;color:#eef4f7}
[data-theme="dark"] .band-table th{background:#22323d;color:#c8d5db}
@media(max-width:700px){.technical-content p,.engineering-notes p,.antenna-overview p,.section-gap p,.home-intro p,.workflow-next p{ text-align:left;hyphens:none }}


/* ===== RF laboratory refinement pass ===== */
:root{
  --lab-grid:rgba(29,140,168,.065);
  --lab-ink:#18232d;
  --lab-surface:#f8fafb;
  --lab-panel:#e2e9ed;
  --lab-dark:#142331;
  --lab-dark-2:#1b303d;
}
body{
  background-color:var(--bg-primary);
  background-image:linear-gradient(var(--lab-grid) 1px,transparent 1px),linear-gradient(90deg,var(--lab-grid) 1px,transparent 1px);
  background-size:32px 32px;
}
.site-header{position:sticky;top:0;z-index:1000}
.site-header:after{content:"";display:block;height:2px;background:linear-gradient(90deg,var(--accent-cyan) 0 22%,transparent 22% 30%,var(--accent-green) 30% 48%,transparent 48% 56%,var(--accent-orange) 56% 72%,transparent 72% 80%,var(--accent-purple) 80% 100%);opacity:.8}
.page-header{box-shadow:0 8px 22px rgba(25,42,55,.10);position:relative;overflow:hidden}
.page-header:before{content:"TEST / MEASURE / BUILD";position:absolute;right:1.2rem;top:1rem;font:700 .58rem var(--font-mono);letter-spacing:.13em;color:var(--text-muted);opacity:.75}
.calc-panel{position:relative;overflow:hidden}
.calc-panel:before{content:"INSTRUMENT PANEL";position:absolute;right:1rem;top:.75rem;font:700 .58rem var(--font-mono);letter-spacing:.12em;color:#78c9d8;opacity:.75}
.results{box-shadow:inset 0 0 0 1px rgba(255,255,255,.025),inset 0 8px 24px rgba(0,0,0,.10)}
.card,.category-card{position:relative;overflow:hidden}
.card:after,.category-card:after{content:"";position:absolute;right:10px;bottom:9px;width:24px;height:7px;border-top:1px solid var(--border);border-right:1px solid var(--border);opacity:.55}
.card:hover{transform:translateY(-2px);box-shadow:0 9px 22px rgba(25,42,55,.12)}
.card-grid .card:nth-child(-n+5){min-height:178px}
.featured-tools .category-card:nth-child(1){border-top-color:var(--accent-cyan)}
.featured-tools .category-card:nth-child(2){border-top-color:var(--accent-green)}
.featured-tools .category-card:nth-child(3){border-top-color:var(--accent-orange)}
.featured-tools .category-card:nth-child(4){border-top-color:var(--accent-purple)}
.workflow-card{box-shadow:inset 0 0 0 1px rgba(255,255,255,.025)}
.workflow-card strong{letter-spacing:-.01em}
.technical-content > p,.antenna-overview p,.category-intro{border-left:3px solid rgba(29,140,168,.28)}
.technical-content > p:nth-of-type(2n){border-left-color:rgba(36,122,89,.28)}
.technical-content > p:nth-of-type(3n){border-left-color:rgba(185,120,34,.3)}
/* Special tool layouts */
.smith-chart-page .calc-panel{border-top:4px solid var(--accent-purple);background:#172632}
.smith-chart-page .calc-panel .scrollable{background:#101a21;border:1px solid #3b515d;padding:clamp(.4rem,1.5vw,1rem);margin-top:1rem}
.smith-chart-page .calc-panel canvas{display:block;margin:auto;background:#f7f9fa}
.smith-chart-page .results{border-left-color:var(--accent-purple)}
.smith-chart-page .technical-content{max-width:980px}
.antenna-helper-page .page-header{border-left-color:var(--accent-orange)}
.antenna-helper-page .calc-panel{border-top:4px solid var(--accent-orange)}
.antenna-helper-page .calc-panel:before{content:"DESIGN SELECTION";color:#f0bd6b}
.antenna-helper-page .info-panel{border-left:3px solid rgba(185,120,34,.45)}
/* Strong keyboard visibility */
:where(a,button,input,select,textarea):focus-visible{outline:3px solid #f0b85d!important;outline-offset:3px;box-shadow:0 0 0 1px #142331!important}
/* Keep prose readable while allowing headings and controls to scan */
.technical-content h2,.technical-content h3,.engineering-notes h2,.engineering-notes h3{ text-align:left }
@media(max-width:760px){
  body{background-size:26px 26px}
  .page-header:before,.calc-panel:before{display:none}
  .container{padding-top:1rem}
  .page-header{margin-bottom:1rem}
  .calc-panel,.info-panel{padding:.9rem}
  .section-gap{margin-top:1.7rem}
  .card-grid .card:nth-child(-n+5){min-height:0}
  .smith-chart-page .calc-panel .scrollable{margin-inline:-.15rem}
}
@media(max-width:520px){
  body{background-image:none}
  .site-header:after{height:1px}
  .page-header{box-shadow:0 4px 13px rgba(25,42,55,.08)}
  .technical-content > p,.antenna-overview p,.category-intro{padding:.8rem .85rem;line-height:1.68}
  .home-intro{margin-bottom:.8rem}
}
[data-theme="dark"] body{background-color:#111a22;background-image:linear-gradient(rgba(89,196,220,.035) 1px,transparent 1px),linear-gradient(90deg,rgba(89,196,220,.035) 1px,transparent 1px);background-size:32px 32px}
[data-theme="dark"] .page-header{background:#202f3a;border-color:#394b57}
[data-theme="dark"] .technical-content > p,[data-theme="dark"] .antenna-overview p,[data-theme="dark"] .category-intro{background:#202f3a}
[data-theme="dark"] .card:after,[data-theme="dark"] .category-card:after{border-color:#536875}
@media(max-width:520px){[data-theme="dark"] body{background-image:none}}

/* Mobile nav & overflow polish (2026 refinement) */
@media (max-width:900px){
  .main-nav.open{display:block;max-height:calc(100vh - 64px);overflow-y:auto;-webkit-overflow-scrolling:touch}
  .nav-dropdown-menu{max-height:none}
  .nav-dropdown.open > .nav-dropdown-menu{display:block}
  .nav-menu-group{border-bottom:1px solid var(--border);padding-bottom:.35rem;margin-bottom:.25rem}
  .nav-menu-group:last-child{border-bottom:0}
}
@media (max-width:700px){
  .result-value,.result-item strong{max-width:100%;overflow-wrap:anywhere;word-break:break-word}
  .formula{font-size:.82rem;overflow-x:auto}
  .tool-utility{gap:.35rem}
  .tool-utility button{font-size:.78rem;padding:.38rem .55rem}
  .prop-grid{grid-template-columns:repeat(2,minmax(0,1fr));gap:.6rem}
  .band-table{font-size:.82rem}
}
/* Unit preference button visual */
#unitPrefBtn{min-width:3.2rem;font-variant-numeric:tabular-nums}

/* Assumptions & limitations callout */
.assumptions-box{border-left:3px solid var(--accent-orange);background:rgba(153,101,21,.06)}
.assumptions-box h2{font-size:1.05rem}
.assumptions-box ul{margin:.4rem 0 .2rem 1.1rem}
.assumptions-box li{margin:.25rem 0;color:var(--text-secondary);font-size:.9rem}
[data-theme="dark"] .assumptions-box{background:rgba(225,165,80,.08)}

/* Theme toggle icon button */
.theme-toggle{display:inline-flex;align-items:center;justify-content:center;min-width:44px;min-height:40px;padding:.4rem}
.theme-toggle svg{display:block}

/* Instrument-style results */
.results{font-variant-numeric:tabular-nums}
.results .result-item{border-left:2px solid transparent;padding-left:.55rem}
.results .result-item:first-child{border-left-color:var(--accent-green)}
.dual-result{display:grid;grid-template-columns:1fr 1fr;gap:.75rem;margin-top:.6rem}
.dual-result .col{background:var(--bg-input);border:1px solid var(--border);border-radius:8px;padding:.7rem}
.dual-result .col h4{font-size:.72rem;text-transform:uppercase;letter-spacing:.06em;color:var(--text-muted);margin-bottom:.4rem}
.dual-result .col .val{font-family:var(--font-mono);font-size:1.1rem;color:var(--accent-green)}

/* Print styles */
@media print{
  .site-header,.site-footer,.nav-toggle,.theme-toggle,.tool-utility,.skip-link,.home-search,.toast-region,.workflow-panel,.related-tools,.workflow-next{display:none!important}
  body{background:#fff;color:#000}
  .container{max-width:100%;padding:0}
  .calc-panel,.info-panel,.results{box-shadow:none;border:1px solid #ccc;break-inside:avoid}
  .results{border-left:3px solid #18794e}
  a{color:#000;text-decoration:none}
  .page-header:after,.section-title:before{display:none}
}