Day 2 in Web Development

Today i start learning about basic css and this is very cool from previews day.i learn about selectors(targeting as well),properties and values in One selector we can use multiple properties and values like background color's, colors, font-family,border and boarder radius.
css is very help full for making web page's look cool and attractive. Also i learn about semantic tags in html these tags are also like div tags these tags
tells google bots that the content within the tag is the most significant header contained in the HTML
header, nav, section, footer
etc..
with these tags i learn to make skeleton of a web page i use display-inline and inline-block with make
div tags in one row further i saw difference about margin and padding in div tags we have default margin and
padding, last thing which little but hard for me to understand about display:inline-block and dislpay:flex;
i will R & N in upcoming days

<Header>
    <nav>
      <ul>
        <li>Home</li>
        <li>Location</li>
        <li>Contact</li>
       </ul>
     </nav>
        <h1>Title</h1>
</Header>
     <section>
       <div>a</div>
       <div>b</div>
       <div>c</div>
     </section>   
        <section>triple-section</section>
        <footer>Footer</footer>

body {
    background: rgb(58 ,58,58);
    color: white;
    font-family: Arial, Helvetica, sans-serif;
    margin: 0;
    padding: 0;
}
header {
    background: black;
    padding: 20px;

}
section {
    background:  white;
    color: gray;
    padding: 20px;
    display: flex;
    flex-direction: row;
}
div {
    background: red;
    margin: auto;
    width: 100px;

}
ul {
    margin: 0;
    padding: 0;
    list-style: none;

}
li {
    display: inline-block;
    margin-right: 20px;
}
footer {
    background: black;
    padding: 10px 20px;
}

https://dev-to-uploads.s3.amazonaws.com/i/oahqgdoz7dqtg7wog8ft.PNG