<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="UTF-8" />
        <meta http-equiv="X-UA-Compatible" content="IE=edge" />
        <meta name="viewport" content="width=device-width, initial-scale=1.0" />
        <title>Custom Radio Button</title>
        <link rel="stylesheet" href="style.css" />
    </head>
    <body>
        <div class="container">
            <p>Select Gender:-</p>
            <div class="btn">
                <input type="radio" name="gender" id="Male" />
                <label for="Male">Male</label>
            </div>
            <div class="btn">
                <input type="radio" name="gender" id="Female" />
                <label for="Female">Female</label>
            </div>
        </div>
    </body>
</html>

@import url("https://fonts.googleapis.com/css2?family=Poppins&display=swap");
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: "Poppins", sans-serif;
}
body {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
}
.btn {
    width: 100px;
    height: 40px;
    display: flex;
    align-items: center;
    margin-top: 1.2em;
    padding: 0 0.5em;
}
.btn input {
    position: relative;
    cursor: pointer;
    appearance: none;
    -webkit-appearance: none;
}
.btn input::before,
.btn input::after {
    content: "";
    position: absolute;
    width: 5px;
    height: 5px;
    border-radius: 50px;
}
.btn input:checked::before {
    background: #ca4444;
    transform: translate(-50%, -50%);
}
.btn input::after {
    width: 10px;
    height: 10px;
    background: none;
    border: 2px solid black;
    border-radius: 50px;
    transform: translate(-80%, -50%);
    transition: all 0.4s;
}
.btn input:checked::after {
    width: 100px;
    height: 40px;
    border-radius: 10px;
    transform: translate(-15%, -50%);
    z-index: 10;
}
.btn label {
    margin-left: 0.5em;
    cursor: pointer;
}

External CSS

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External JavaScript

This Pen doesn't use any external JavaScript resources.