What is "css"

Cascading Style Sheets, or simply abbreviated - CSS is a style language used to define the presentation of documents written in a markup language such as html, xml, xhtml and svg.

Formerly the visual styles were only defined with attributes in HTML, then later we were presented with the CSS that gave us control to separate the visual styles, the content itself.

Instead of putting the visual styles inside the document, the developer creates a link (link) to a page containing all styles, which will proceed in the same way for all pages of a portal. When it is necessary to change the appearance of the portal just modify a file.

A standard CSS document consists of several rule sets. Each rule set starts with a selector (a pattern matching the elements of an HTML or XML document) that follows a block containing one or more property statements defining the presentation of the corresponding elements.

Example:

/* Isto é um comentário em CSS */ 

a {                             /* Encontra todas as tags <a>, */
    color: orange;              /* muda a sua cor para laranja, */
    background-color: pink;     /* a cor de fundo para cor-de-rosa, */
    text-decoration: none;      /* e remove o sublinhado. */
}

a:hover {                       /* Mas quando se passa o "mouse" por cima de um elemento <a> */
    color: red;                 /* muda a cor para vermelho, */
    text-decoration: underline; /* e adiciona novamente o sublinhado */
}