100 Days CSS: An easy start into the challenge with a custom build number with gradient

Project Structure
The project consists of 2 main files
- index.html - the HTML structure.
- style.css - for styling.
HTML Structure
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<div class="frame">
<div class="center">
<div class="number-container">
<span class="one"></span>
<span class="zero"></span>
<span class="zero"></span>
</div>
<div class="text-container">
<p class="days">days</p>
<p class="challenge">css challenge</p>
</div>
</div>
</div>
CSS Styling
Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam posuere erat at mi sagittis ultricies. Aenean cursus libero vitae odio congue volutpat.
// edit the line if you wanna use other fonts
@import url(https://fonts.googleapis.com/css?family=Open+Sans:700,300);
* {
padding: 0;
margin: 0;
box-sizing: border-box;
}
.frame {
position: absolute;
top: 50%;
left: 50%;
width: 400px;
height: 400px;
margin-top: -200px;
margin-left: -200px;
border-radius: 4px;
box-shadow: 4px 8px 16px 0 rgba(0, 0, 0, 0.1);
overflow: hidden;
background: linear-gradient(45deg, #433ca0, #4dc2c9);
color: #333;
font-family: "Open Sans", Helvetica, sans-serif;
-webkit-font-smoothing: antialiased;
-moz-osx-font-smoothing: grayscale;
}
.center {
position: absolute;
top: 50%;
left: 50%;
transform: translate(-50%, -50%);
}
.number-container {
display: flex;
justify-content: center;
align-items: center;
}
.one {
position: relative;
width: 25px;
height: 100px;
background-color: #fff;
border-radius: 3px;
box-shadow: 0px 0px 5px #aaa;
left: 15px;
}
.one::before {
content: "";
position: absolute;
display: block;
width: 25px;
height: 40px;
border-radius: 3px;
background-color: #fff;
transform: translate(-15px, 2px) rotate(45deg);
z-index: -1;
}
.zero {
width: 100px;
height: 100px;
border-radius: 50%;
border: 25px solid #fff;
box-shadow: 0px 0px 5px #aaa;
z-index: -1;
}
.zero:last-child {
transform: translatex(-15px);
z-index: -2;
}
.text-container {
width: 95%;
margin: auto;
}
.days {
font-family: "Courier New", monospace;
text-transform: uppercase;
font-size: 5.4rem;
font-weight: 600;
color: #fff;
line-height: 4.5rem;
}
.challenge {
font-family: "Courier New", monospace;
text-transform: uppercase;
font-size: 1.6rem;
font-weight: bold;
color: #fff;
line-height: 1rem;
}