<div class="alert alert-success alert-white rounded">
    <button type="button" class="close closebtn" onclick="this.parentElement.style.display='none';">×</button>
    <div class="icon"><i class="fas fa-check"></i></div>
    <strong class="alert-head">Success!</strong> This is a success message.
</div>
<div class="alert alert-info alert-white rounded">
    <button type="button" class="close closebtn" onclick="this.parentElement.style.display='none';">×</button>
    <div class="icon"><i class="fas fa-info-circle"></i></div>
    <strong class="alert-head">Info!</strong> This is an info message.
</div>
<div class="alert alert-warning alert-white rounded">
    <button type="button" class="close closebtn" onclick="this.parentElement.style.display='none';">×</button>
    <div class="icon"><i class="fas fa-exclamation-triangle"></i></div>
    <strong class="alert-head">Warning!</strong> This is a warning message.
</div>
<div class="alert alert-danger alert-white rounded">
    <button type="button" class="close closebtn" onclick="this.parentElement.style.display='none';">×</button>
    <div class="icon"><i class="fas fa-times-circle"></i></div>
    <strong class="alert-head">Danger!</strong> This is a danger message.
</div>

.close {
    font-size: 21px;
    font-weight: bold;
    line-height: 1;
    color: #000;
    text-shadow: 0 1px 0 #fff;
    opacity: .2;
}

.close:hover,
.close:focus {
    color: #000;
    text-decoration: none;
    cursor: pointer;
    opacity: .5;
}

button.close {
    padding: 0;
    cursor: pointer;
    background: transparent;
    border: 0;
    -webkit-appearance: none;
    position: absolute;
    right: 10px;
    top: 10px;
}

.alert {
    padding: 15px;
    margin-bottom: 20px;
    border: 1px solid transparent;
    border-radius: 4px;
    display: flex;
    flex-direction: column;
}

.alert h4 {
    margin-top: 0;
    color: inherit;
}

.alert .alert-link {
    font-weight: bold;
}

.alert>p,
.alert>ul {
    margin-bottom: 0;
}

.alert>p+p {
    margin-top: 5px;
}

.alert-dismissable {
    padding-right: 35px;
}

.alert-dismissable .close {
    position: relative;
    top: -2px;
    right: -21px;
    color: inherit;
}

.alert-success {
    background-color: #dff0d8;
    border-color: #d6e9c6;
    color: #3c763d;
}

.alert-success hr {
    border-top-color: #c9e2b3;
}

.alert-success .alert-link {
    color: #2b542c;
}

.alert-info {
    background-color: #d9edf7;
    border-color: #bce8f1;
    color: #31708f;
}

.alert-info hr {
    border-top-color: #a6e1ec;
}

.alert-info .alert-link {
    color: #245269;
}

.alert-warning {
    background-color: #fcf8e3;
    border-color: #faebcc;
    color: #8a6d3b;
}

.alert-warning hr {
    border-top-color: #f7e1b5;
}

.alert-warning .alert-link {
    color: #66512c;
}

.alert-danger {
    background-color: #f2dede;
    border-color: #ebccd1;
    color: #a94442;
}

.alert-danger hr {
    border-top-color: #e4b9c0;
}

.alert-danger .alert-link {
    color: #843534;
}

.alert {
    border-radius: 0;
    -webkit-border-radius: 0;
    box-shadow: 0 4px 8px 0 rgba(0, 0, 0, 0.2);
}

.alert:hover {
    border-radius: 0;
    -webkit-border-radius: 0;
    box-shadow: 0 8px 16px 0 rgba(0, 0, 0, 0.2);
}

.alert .sign {
    font-size: 20px;
    vertical-align: middle;
    margin-right: 5px;
    text-align: center;
    width: 25px;
    display: inline-block;
}

.alert-success {
    background-color: #dbf6d3;
    border-color: #aed4a5;
    color: #569745;
}

.alert-info {
    background-color: #d9edf7;
    border-color: #98cce6;
    color: #3a87ad;
}

.alert-warning {
    background-color: #fcf8e3;
    border-color: #f1daab;
    color: #c09853;
}

.alert-danger {
    background-color: #f2dede;
    border-color: #e0b1b8;
    color: #b94a48;
}

.alert-white {
    background-image: linear-gradient(to bottom, #ffffff, #ffffff);
    border-top-color: #ffffff;
    border-bottom-color: #ffffff;
    border-left-color: #ffffff;
    border-right-color: #ffffff;
    color: #404040;
    padding-left: 61px;
    position: relative;
}

.alert-white .icon {
    text-align: center;
    width: 45px;
    height: 90%;
    position: absolute;
    top: 6%;
    left: 3px;
    border: 1px solid #bdbdbd;
}

.alert-white .icon:after {
    -webkit-transform: rotate(45deg);
    -moz-transform: rotate(45deg);
    -ms-transform: rotate(45deg);
    -o-transform: rotate(45deg);
    -webkit-transform: rotate(45deg);
    display: block;
    content: '';
    width: 10px;
    height: 10px;
    border: 1px solid #bdbdbd;
    position: absolute;
    border-left: 0;
    border-bottom: 0;
    top: 50%;
    right: -6px;
    margin-top: -5px;
    background: #fff;
}

.alert-white.rounded {
    border-radius: 3px;
    -webkit-border-radius: 3px;
}

.alert-white.rounded .icon {
    border-radius: 3px 0 0 3px;
    -webkit-border-radius: 3px 0 0 3px;
}

.alert-white .icon i {
    font-size: 20px;
    color: #FFF;
    left: 12px;
    margin-top: -10px;
    position: absolute;
    top: 50%;
}

.alert-white.alert-danger .icon,
.alert-white.alert-danger .icon:after {
    border-color: #f28783;
    background: #f28783;
}

.alert-white.alert-info .icon,
.alert-white.alert-info .icon:after {
    border-color: #8eafdd;
    background: #8eafdd;
}

.alert-white.alert-warning .icon,
.alert-white.alert-warning .icon:after {
    border-color: #e8bd7d;
    background: #e8bd7d;
}

.alert-white.alert-success .icon,
.alert-white.alert-success .icon:after {
    border-color: #a2d8bc;
    background: #a2d8bc;
}

.alert-head {
    padding-right: 10px;
}

<script>
// Get all alert elements
var alerts = document.getElementsByClassName("alert");

// Show all alerts
for (var i = 0; i < alerts.length; i++) {
    alerts[i].style.display = "flex";
}
</script>

<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/5.15.3/css/all.min.css"/>