1.  

       .       HTML    .      'H1'  ,  :
  H1 { color: blue }

     CSS.      :  ('H1')   ('color: blue').         :  ('color')   ('blue').   ,          ,    HTML ,     .      (    CSS    )       .

    HTML    ,        .      HTML [2].

C 'color'     50 ,    HTML .          .

 HTML         ,         .  UA      ,     ,      .          HTML  ,      HTML 2.0 [3].

   CSS1    B.
1.1   HTML

 ,       , UA     .  HTML [2]       HTML.     ,   :
<HTML>
  <HEAD>
    <TITLE>title</TITLE>
    <LINK REL=STYLESHEET TYPE="text/css" HREF="http://style.com/cool" TITLE="Cool">
    <STYLE TYPE=
    "text/css">
    @import url( http://style.com/basic<
     /A>
       );
      H1 { color: blue }
    </STYLE>
  </HEAD>
  <BODY>
    <H1>Headline is blue</H1>
    <P STYLE="color: green">While the paragraph is green.
  </BODY>
</HTML>

        HTML:   'LINK'      ,   'STYLE'   'HEAD',       CSS '@import'    'STYLE'     'BODY'.              .

 'LINK'     ,    ,              .

 UA   .    UA    'STYLE',     ,         .       'STYLE'  "",   SGML:

<STYLE TYPE="text/css"><!--
  H1 { color: green }
--></STYLE>

   ,   'STYLE' ,  "CDATA"  DTD [2],  SGML      ,   .
1.2 

           :

H1, H2, H3 { font-family: helvetica }

    :

  H1 {
    font-weight: bold;
    font-size: 12pt;
    line-height: 14pt;
    font-family: helvetica;
    font-variant: normal;
    font-style: normal;
  }

         :
H1 { font: bold 12pt/14pt helvetica }

   .
1.3 

     'H1'    . ,    'H1'   <EM> :
  <H1>The headline <EM>is</EM> important!</H1>

   'EM'     ,  Em "is"    , ..      .     ,  'font-family'  'font-size'.

       ,      ,       .  HTML   'BODY'   :

  BODY {
    color: black;
    background: url(texture.gif) white;
  }

        'BODY' (  )  ,     .       ,   -  .      ,    . (.    5.3)

         .           .   'background'  ,         .

        :

  P { font-size: 10pt }
  P { line-height: 120% }  /* relative to 'font-size', i.e. 12pt */

  ,      ,      .   'P'       'line-height' (12pt).
1.4    

     ,  HTML    [2] 'CLASS'.     'BODY'   ,        :
<HTML>
 <HEAD>
  <TITLE>Title</TITLE>
  <STYLE TYPE="text/css">
    H1.pastoral { color: #00FF00 }
  </STYLE>
 </HEAD>
 <BODY>
  <H1 CLASS=pastoral>Way too green</H1>
 </BODY>
</HTML>

      ,        .

          :
  .pastoral { color: green }  /* all  with CLASS pastoral */

       . 'P.pastoral.marine'       CSS1. ( ,  ,        ).

CSS        CLASS,          HTML   -        .       , ..    ,     ( HTML).           ,       .
1.5 ID   

HTML [2]     'ID',       .      ,    ,      '#':
  #z98y { letter-spacing: 0.3em }
  H1#z98y { letter-spacing: 0.5em }

  <P ID=z98y>Wide text</P>

       'P'  'ID' .       ('H1'),    ID, , ,    'P'.

 ID   ,    .            ,      ,          HTML.      .
1.6  

      CSS .  ,     ,     ,    .  ,   'EM'  'H1'   ,    :
  H1 { color: blue }
  EM { color: red }

     ,    'EM',  ,    'H1'  . , ,     'EM',    'H1'  .   , :
  H1 EM { color: red }

          ,      .      ,   (       ).      ,      (    'EM'),     ,     .    CSS1    ,            .

UL LI { font-size: small } UL UL LI { font-size: x-small }

       'LI'      'UL'.     , ..  'LI'      'UL'.   ,             . .     ( 3.2).

     ,  CLASS,  ID   :

  DIV P           { font: small sans-serif }
  .reddish H1     { color: red }
  #x78y CODE      { background: blue }
  DIV.sidenote H1 { font-size: large }

    'P',     'DIV'.      'H1'     'reddish'.      'CODE',      'ID=x78y'.      'H1',    'DIV'   'sidenote'.

    :
  H1 B, H2 B, H1 EM, H2 EM { color: red }

 :
  H1 B { color: red }
  H2 B { color: red }
  H1 EM { color: red }
  H2 EM { color: red }
1.7 

             [7]:
  EM { color: red }  /* red, really red!! */

      .   CSS1   .