HTML Form Center

Question

i want to make this form smaller and put it in the middle of the screen but i am having trouble figuring out how to do that. can someone help me?

<form action="action_page.php" method="post">
<div class="container">
<label for="uname"><b>Username</b></label>
<input type="text" placeholder="Enter Username" name="uname" required>

<label for="psw"><b>Password</b></label>
<input type="password" placeholder="Enter Password" name="psw" required>

<button type="submit">Login</button>

<label>
<input type="checkbox" checked="checked" name="remember"> Remember me
</label>
</div>

<div class="container" style="background-color:#f1f1f1">
<button type="button" class="cancelbtn">Cancel</button>
<span class="psw">Forgot <a href="#">password?</a></span>
</div>
</form>

<style>
/* Bordered form */
form {
border: 3px solid #f1f1f1;
}

/* Full-width inputs */
input[type=text], input[type=password] {
width: 100%;
padding: 12px 20px;
margin: 8px 0;
display: inline-block;
border: 1px solid #ccc;
box-sizing: border-box;
}

/* Set a style for all buttons */
button {
background-image: linear-gradient(to bottom, #0099ff 0%, #00ccff 100%);
padding: 14px 20px;
margin: 8px 0;
border: none;
cursor: pointer;
width: 100%;
}

/* Add a hover effect for buttons */
button:hover {
opacity: 0.8;
}

/* Extra style for the cancel button (red) */
.cancelbtn {
width: auto;
padding: 10px 18px;

background-color: #f44336;
}

/* Add padding to containers */
.container {
padding: 16px;
margin-left: auto;
margin-right: auto;

}

/* The "Forgot password" text */
span.psw {
float: right;
padding-top: 16px;
}

/* Change styles for span and cancel button on extra small screens */
@media screen and (max-width: 300px) {
span.psw {
display: block;
float: none;
}
.cancelbtn {
width: 100%;
}
}
</style>

Answer 1

Or just use flexbox

html, body {
height: 100%;
}
body {
display: flex;
justify-content: center;
align-items: center;
}

Answer 2

it didnt work

Answer 3

Display : block
Then try