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HTML

              
                <div>
  
  <p>Estilos del navegador por defecto: </p><select >
    <option>Selecciona una opción</option>
    <option>Lunes</option>
    <option>Martes</option>
    <option>Miércoles</option>
    <option>Jueves</option>   <option>Viernes</option>
  </select>
  <br><br> 
  <p>Estilos modificados:</p><select class="select-css">
    <option>Selecciona una opción</option>
    <option>Lunes</option>
    <option>Martes</option>
    <option>Miércoles</option>
    <option>Jueves</option>   <option>Viernes</option>
  </select>
  
  <div class="sidebar-box">
    <select class="styled-select">
    <option>Selecciona una opción</option>
    <option>Lunes</option>
    <option>Martes</option>
    <option>Miércoles</option>
    <option>Jueves</option>   <option>Viernes</option>
    </select></div>
              
            
!

CSS

              
                
*,*:after,*:before{
  box-sizing: border-box;
}

html{
  box-sizing: inherit;
  background: linear-gradient(to left, #E8FFF9 , #eef2f3);
}
body{
  margin: 2% auto;
  text-align: center;
  font-size: 14px;
  font-family: Verdana;
}
.select-css {
	display: block;
	font-size: 16px;
	font-family: 'Verdana', sans-serif;
	font-weight: 400;
	color: #444;
	line-height: 1.3;
	padding: .4em 1.4em .3em .8em;
	width: 400px;
	max-width: 100%; 
	box-sizing: border-box;
 margin: 20px auto;
	border: 1px solid #aaa;
	box-shadow: 0 1px 0 1px rgba(0,0,0,.03);
	border-radius: .3em;
	-moz-appearance: none;
	-webkit-appearance: none;
	appearance: none;
	background-color: #fff;
	background-image: url('data:image/svg+xml;charset=US-ASCII,%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20width%3D%22292.4%22%20height%3D%22292.4%22%3E%3Cpath%20fill%3D%22%23007CB2%22%20d%3D%22M287%2069.4a17.6%2017.6%200%200%200-13-5.4H18.4c-5%200-9.3%201.8-12.9%205.4A17.6%2017.6%200%200%200%200%2082.2c0%205%201.8%209.3%205.4%2012.9l128%20127.9c3.6%203.6%207.8%205.4%2012.8%205.4s9.2-1.8%2012.8-5.4L287%2095c3.5-3.5%205.4-7.8%205.4-12.8%200-5-1.9-9.2-5.5-12.8z%22%2F%3E%3C%2Fsvg%3E'),
	  linear-gradient(to bottom, #ffffff 0%,#f7f7f7 100%);
	background-repeat: no-repeat, repeat;
	background-position: right .7em top 50%, 0 0;
	background-size: .65em auto, 100%;
}
.select-css::-ms-expand {
	display: none;
}
.select-css:hover {
	border-color: #888;
}
.select-css:focus {
	border-color: #aaa;
	box-shadow: 0 0 1px 3px rgba(59, 153, 252, .7);
	box-shadow: 0 0 0 3px -moz-mac-focusring;
	color: #222; 
	outline: none;
}
.select-css option {
	font-weight:normal;
}


.classOfElementToColor:hover {background-color:red; color:black}

.select-css option[selected] {
    background-color: orange;
}


/* OTROS ESTILOS*/
.styled-select { width: 240px; height: 34px; overflow: hidden; background: url(new_arrow.png) no-repeat right #ddd; border: 1px solid #ccc; }

 

.sidebar-box select{
display:block;
padding: 5px 10px;
height:42px;
margin:10px auto;
min-width: 225px;
-webkit-appearance: none;
height: 34px;
/* background-color: #ffffff; */
background-image: url('data:image/svg+xml;charset=US-ASCII,%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20width%3D%22292.4%22%20height%3D%22292.4%22%3E%3Cpath%20fill%3D%22%23007CB2%22%20d%3D%22M287%2069.4a17.6%2017.6%200%200%200-13-5.4H18.4c-5%200-9.3%201.8-12.9%205.4A17.6%2017.6%200%200%200%200%2082.2c0%205%201.8%209.3%205.4%2012.9l128%20127.9c3.6%203.6%207.8%205.4%2012.8%205.4s9.2-1.8%2012.8-5.4L287%2095c3.5-3.5%205.4-7.8%205.4-12.8%200-5-1.9-9.2-5.5-12.8z%22%2F%3E%3C%2Fsvg%3E'),
	  linear-gradient(to bottom, #ffffff 0%,#f7f7f7 100%);
	background-repeat: no-repeat, repeat;
	background-position: right .7em top 50%, 0 0;
	background-size: .65em auto, 100%;}
              
            
!

JS

              
                
              
            
!
999px

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