Posición de bootstrap fijada
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Long Lyrebird
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<div class="position-relative">...</div>
<div class="position-absolute">...</div>
<div class="position-fixed">...</div>
<div class="position-sticky">...</div>
<div class="fixed-top">...</div>
<div class="fixed-bottom">...</div>
<div class="sticky-top">...</div>