:root{--bg:#edf3f6;--panel:#fff;--ink:#173847;--muted:#506b7c;--line:#d3e0e7;--blue:#14799f;--orange:#b95e2c;--soft:#f4f8fb;--good:#e7f6ee;--bad:#fff0ee;--warn:#fff6e7;--head:#173847;color-scheme:light}*{box-sizing:border-box}body{margin:0;background:var(--bg);color:var(--ink);font:15px/1.6 'Segoe UI',Arial,sans-serif}body.dark{--bg:#0b1720;--panel:#122735;--ink:#e2edf4;--muted:#aec4d1;--line:#365361;--soft:#193342;--good:#173e31;--bad:#482b2e;--warn:#403720;--head:#0f2633;color-scheme:dark}header{display:flex;align-items:center;justify-content:space-between;gap:24px;background:var(--head);color:#fff;padding:20px max(24px,calc((100% - 1320px)/2))}.brand{font-weight:850;letter-spacing:2px;color:#fff;text-decoration:none;font-size:23px}.brand small{display:block;font-size:10px;letter-spacing:3px}.controls{display:flex;gap:12px;align-items:end}.controls label{font-size:12px;color:#d9e8f0}.controls select{background:#284e62;color:#fff;border-color:#5e8294;min-width:135px}.controls button{color:white;background:#284e62}.controls span{display:block}main{max-width:1380px;margin:auto;padding:0 24px}.hero{display:grid;grid-template-columns:1fr 260px;gap:30px;padding:40px 44px;background:var(--head);color:white;margin:0 -24px 28px}.hero>svg{align-self:center;width:100%}.hero h1{font-size:clamp(35px,5vw,62px);margin:6px 0 15px;letter-spacing:-2px;line-height:1.1}.hero p{max-width:740px;color:#d3e5ed}.eyebrow{font-size:11px;font-weight:800;letter-spacing:2px;color:var(--muted);text-transform:uppercase;margin:0 0 8px}.hero .eyebrow{color:#8ec4da}nav,.actions{display:flex;gap:9px;flex-wrap:wrap;align-items:center}nav{margin-top:22px}nav a{background:#284e62;border:1px solid #476f81;border-radius:5px;padding:9px 14px;color:#fff;text-decoration:none;font-size:13px}nav .accent{background:var(--orange);border-color:var(--orange)}.panel{background:var(--panel);border:1px solid var(--line);border-radius:10px;padding:28px 32px;margin-bottom:24px;scroll-margin-top:15px}h2{font-size:26px;line-height:1.3;margin:0 0 18px;letter-spacing:-.5px}h3{font-size:17px;margin:16px 0 10px}.material-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:15px}.material-grid article{border:1px solid var(--line);background:var(--soft);border-radius:7px;padding:18px}.material-grid svg{width:100%;height:155px}.material-grid p,.guide p{font-size:13px;color:var(--muted)}.guide{margin-top:22px}.selector{border-top:4px solid var(--blue)}.form-grid{display:grid;grid-template-columns:repeat(5,minmax(0,1fr));gap:16px;margin:20px 0}label{display:block;font-size:12px;font-weight:600}label span{display:block}label small{display:block;font-weight:400;color:var(--muted);height:20px}input,select,button{font:inherit;border:1px solid #a8c0cd;color:var(--ink);background:var(--panel);border-radius:5px;padding:9px 10px}input,select{width:100%;margin-top:5px;font-size:13px}button{font-size:12px;font-weight:650;cursor:pointer}button:hover{border-color:var(--blue)}button.primary{background:var(--blue);color:white;border-color:var(--blue)}button:disabled{opacity:.5;cursor:wait}button:focus-visible,input:focus-visible,select:focus-visible,a:focus-visible{outline:3px solid #60bddd;outline-offset:2px}.hint{font-size:12px;color:var(--muted)}details{border-top:1px solid var(--line);padding-top:14px;margin:18px 0}summary{font-size:14px;font-weight:600;cursor:pointer}.notice{background:var(--warn);padding:11px 15px;border-left:3px solid #bf8a38;border-radius:4px;font-size:13px;margin:12px 0}.notice.error{background:var(--bad);border-color:#c74646}.notice.good{background:var(--good);border-color:#29805b}.summary{font-size:17px;font-weight:650;margin:24px 0 14px}.summary small{display:block;font-size:13px;font-weight:400}.recommended{padding:22px;border:2px solid var(--blue);border-radius:7px;margin:22px 0;background:var(--soft)}.recommended h3{font-size:24px;margin:5px 0 12px}.badge{display:inline-block;border-radius:25px;padding:4px 10px;background:var(--good);font-size:11px;font-weight:700}.option-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:12px}.option-card{padding:15px;border:1px solid var(--line);border-radius:7px;font-size:12px}.option-card p{color:var(--muted)}.option-card button{width:100%}.table-wrap{overflow:auto;max-height:560px;border:1px solid var(--line);border-radius:5px;margin:15px 0}table{border-collapse:collapse;width:100%;font-size:12px;white-space:nowrap}th,td{padding:10px 12px;text-align:right;border-bottom:1px solid var(--line)}th{background:var(--head);color:#fff;position:sticky;top:0;z-index:1;font-weight:600}th:first-child,td:first-child{text-align:left}tr:nth-child(even)td{background:var(--soft)}td.reasons{white-space:normal;min-width:240px;font-size:11px}.table-tools{display:flex;gap:15px;flex-wrap:wrap}.table-tools label{min-width:220px;flex:1}.specs{display:grid;grid-template-columns:repeat(4,1fr);gap:1px;background:var(--line);border:1px solid var(--line);border-radius:6px;overflow:hidden}.specs div{background:var(--panel);padding:12px}.specs dt{font-size:12px;color:var(--muted)}.specs dd{margin:4px 0;font-weight:650}.equation{font-family:ui-monospace,monospace;background:var(--soft);border-left:3px solid var(--blue);padding:15px;overflow-wrap:anywhere}#sheetFigure svg{display:block;max-width:500px;width:100%;height:auto;margin:0 auto}footer{font-size:12px;color:var(--muted);padding:5px 0 30px}[hidden]{display:none!important}@media(max-width:1050px){.form-grid{grid-template-columns:repeat(3,minmax(0,1fr))}.option-grid,.specs{grid-template-columns:repeat(2,1fr)}}@media(max-width:700px){header{padding:16px;flex-wrap:wrap}.controls{width:100%;flex-wrap:wrap}.controls label{flex:1}.controls select{min-width:100px}main{padding:0 12px}.hero{margin:0 -12px 20px;padding:30px 24px;grid-template-columns:1fr}.hero>svg{display:none}.panel{padding:22px 18px}.form-grid{grid-template-columns:repeat(2,minmax(0,1fr))}.material-grid{grid-template-columns:1fr}h2{font-size:23px}}@media print{header,.controls,nav,form,.actions,button,.table-tools,#rejected{display:none!important}body{--bg:white;--panel:white;--ink:#111;--muted:#333;--soft:#f4f4f4}.panel{border:0;padding:15px 0;break-inside:avoid}.hero{background:#fff;color:#111}.hero p{color:#333}.table-wrap{max-height:none;overflow:visible}.hero>svg{display:none}th{position:static}.option-grid{grid-template-columns:repeat(2,1fr)}}

.original-figure{display:block;width:100%;height:auto;margin:1rem 0;border-radius:8px}.topic-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:1rem;margin-top:1rem}.topic-grid article{border:1px solid var(--border,#a3bac7);border-radius:8px;padding:1rem}.topic-grid h3{margin:.3rem 0}.topic-grid p{margin:0}.fluid-comparison{min-width:850px}.fluid-comparison th,.fluid-comparison td{white-space:normal;vertical-align:top;line-height:1.6}.fluid-comparison tbody th{min-width:150px}.fluid-comparison td{min-width:210px}@media(max-width:900px){.topic-grid{grid-template-columns:repeat(2,minmax(0,1fr))}}@media(max-width:600px){.topic-grid{grid-template-columns:1fr}

/* Aquí terminan los estilos originales */
}

/* NUEVO BOTÓN YOUTUBE */
.btn-youtube {
    display: inline-flex;
    align-items: center;
    background: #e62117;
    color: white !important;
    padding: 10px 18px;
    border-radius: 8px;
    font-size: 14px;
    font-weight: 600;
    text-decoration: none;
}

.btn-youtube:hover {
    background: #b71910;
}

}