JSFiddle - React, Tailwind, and code Playground

HTML

<div>
   	        <label class="zakaz-txt">Телефон:</label> <input required="required" class="zakaz-inpt" type="tel" pattern="8[0-9]{3}-[0-9]{3}-[0-9]{2}-[0-9]{2}" name="phone_zakaz" />
            <span class="form_hint">Пример: 8937-999-99-99</span>
        </div>

CSS

.zakaz-inpt {
	width:60%; height:28px; margin-left: 80px; padding-left: 5px;
}
.zakaz-txtarea {width:60%; max-width: 60%; height:100px; max-height: 200px; border:1px solid #ccc; margin-left: 80px; padding-left: 5px; padding-top: 5px;}

	/* form element visual styles */
	.zakaz-inpt, .zakaz-txtarea { 
		border:1px solid #aaa;
		box-shadow: 0px 0px 3px #ccc, 0 2px 10px #eee inset;
		border-radius:2px;
        margin-bottom: 35px;
	}
	.zakaz-inpt:focus, .zakaz-txtarea:focus {
		background: #fff; 
		border:1px solid #555; 
		box-shadow: 0 0 3px #aaa; 
		-moz-transition: box-shadow .25s; 
		-webkit-transition: box-shadow .25s; 
		-o-transition: box-shadow .25s;
		transition: box-shadow .25s;
	}

/* === HTML5 validation styles === */	
.zakaz-inpt:required {
	background: #fff url(../images/red_asterisk.png) no-repeat 98% center;
}
.zakaz-inpt:required:valid, .zakaz-txtarea:required:valid {
	background: #fff url(../images/valid.png) no-repeat 98% center;
	box-shadow: 0 0 5px #5cd053;
	border-color: #28921f;
}
.zakaz-inpt:focus:invalid, .zakaz-txtarea:focus:invalid {
	background: #fff url(../images/invalid.png) no-repeat 98% center;
	box-shadow: 0 0 5px #d45252;
	border-color: #b03535;
}

/* === Form hints === */
.form_hint {
	background: #d45252;
	border-radius: 3px 3px 3px 3px;
	color: white;
	margin-left:8px;
    margin-right: 4px;
	padding: 4px 6px;
	z-index: 999; /* hints stay above all other elements */
	position: absolute; /* allows proper formatting if hint is two lines */
	display: none;
}
.form_hint::before {
	content: "\25C0";
	color:#d45252;
	position: absolute;
	top:1px;
	left:-6px;	
}
.zakaz-inpt:focus + .form_hint {display: inline;}
.zakaz-inpt:required:valid + .form_hint {background: #28921f;}
.zakaz-inpt:required:valid + .form_hint::before {color:#28921f;}

.zakaz-txtarea:focus + .form_hint {display: inline;}
.zakaz-txtarea:valid + .form_hint {background: #28921f;}
.zakaz-txtarea:valid + .form_hint::before {color:#28921f;}

.required_notification...