What are the default CSS styling of heading tags? (H1, h2, h3, h4, h5)

Question

In HTML, headings are denoted with (1,2,3,4,5,6) tag.

My question is regarding following HTML code:

Answer 1

The answer is no, however you might hack the styles. Most browsers will try to use these styles

(Taken from: w3schools)

h1 { 
    display: block;
    font-size: 2em;
    margin-top: 0.67em;
    margin-bottom: 0.67em;
    margin-left: 0;
    margin-right: 0;
    font-weight: bold;
}
h2 {
    display: block;
    font-size: 1.5em;
    margin-top: 0.83em;
    margin-bottom: 0.83em;
    margin-left: 0;
    margin-right: 0;
    font-weight: bold;
}
h3 { 
    display: block;
    font-size: 1.17em;
    margin-top: 1em;
    margin-bottom: 1em;
    margin-left: 0;
    margin-right: 0;
    font-weight: bold;
}
h4 { 
    display: block;
    margin-top: 1.33em;
    margin-bottom: 1.33em;
    margin-left: 0;
    margin-right: 0;
    font-weight: bold;
}
h5 { 
    display: block;
    font-size: .83em;
    margin-top: 1.67em;
    margin-bottom: 1.67em;
    margin-left: 0;
    margin-right: 0;
    font-weight: bold;
}
h6 { 
    display: block;
    font-size: .67em;
    margin-top: 2.33em;
    margin-bottom: 2.33em;
    margin-left: 0;
    margin-right: 0;
    font-weight: bold;
}