JSFiddle - React, Tailwind, and code Playground
HTML
<form id="buscador" action="buscar.php"
onMouseOver="if(this.style.background != '#ffffff' && this.style.background != 'rgb(255, 255, 255)'){this.style.background='#808080'};"
onMouseOut="if(this.style.background != '#ffffff' && this.style.background != 'rgb(255, 255, 255)'){this.style.background='#696969';}"
style="margin:6px 0px 0px 5px;"
metod="get">
<input
onblur="form.style.background='#696969';if(this.value==''){this.value='Buscar personas...'};"
onFocus="form.style.background='#ffffff';if(this.value=='Buscar personas...'){this.value=''};"
value="Buscar personas..."
style="margin:0px;width:172px;border-style:none;background-color:transparent;padding:5px;"
name="busqueda" type="text" />
<input type="image" style="height:20px;padding:3px 5px 3px 5px;margin:0px 0px -8px 0px;" src="http://icones.pro/es/go.php?http://icdn.pro/images/es/b/u/buscar-buscar-ampliar-icono-6707-16.png" />
</form>
CSS
#buscador {
float:left;padding:0px 0px 0px 2px;
/* Ponemos los bordes para el formulario */
border: 1px solid #000000 ;border-bottom: 1.5px solid #000000 ;
/* Ponemos el color de fondo */
background-color: #696969;margin:4px 0px 0px 20px;
/* Redondeamos esquinas */
-moz-border-radius: 4px; -webkit-border-radius: 4px;border-radius: 4px}