LIS650 lecture 2 Major CSS

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LIS650 lecture 2Major CSS

• Thomas Krichel
• 2004-10-10

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to be done in HTML

• Tables are a major HTML topic not covered.
• They can be used
• tabular data
• general spacial layout
• Many web designers tell you not to use tables for
  special layout, but use CSS instead.
• That is OK in theory, but bad in practice because
  some user agent vendors (such as Microsoft) have
  very poor CSS support.

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today

• introduction to style sheets
• how to give style sheet data
• style locator information
• some important properties
• some more properties

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style sheets

• Style sheets are the officially sanctioned way to
  add style to your document
• We will cover Cascading Style Sheets CSS.
• This is the default style sheet language.
• We are discussing version 2.1. This is not yet a
  W3C recommendation, but it is in last call.
• http//www.w3.org/TR/CSS21 has all the fun.

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what is in a style sheet?

• A style sheet is a sequence of style rules.
• In the sheet, one rule follows the other. There
  is no nesting of rules.
• Therefore the way rules are written in a style
  sheet is much simpler than the way elements are
  written in XML.
• Remember that in XML we have nesting of elements.

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what is a style rule about?

• It is about two or three things
• Where to find what to style?
• How style it?
• Which property to set? --gt property name
• Which value to give to the property? --gt property
  value
• In this lecture I will use the following syntax
• Write property names as property-name
• Write property values as value

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why are they cascading

• You can have many style data in different places.
  Style data comes in the form of rules at this
  place, do that.
• Where there are many rules, there is potential
  for conflict. We do not learn the exact rules
  here but note
• Some rules are read after others other. Later
  rules override earlier rules.
• Some rules concern more specific locations than
  others. The specific rules override general
  rules.

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inline style

• You can add a style attribute to any element that
  admits the core attributes as in
• ltelement style"style"/gt
• where style is a style sheet.
• Example
• lth1 style"color blue"gtI am so bluelt/h1gt
• Such a declaration only takes effect for the
  element concerned.
• I do not recommend this.

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document level style

• You can add a style element as part of the header
• ltheadgtltstylegtlt/stylegtlt/headgt
• ltstylegt takes the core attributes.
• It takes a "type" attribute, "text/css" is the
  default
• It takes the "media" attribute for the intended
  media. See next slide.
• The "media" attribute allows you to set write
  different styles for different media.

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style sheet media types

• These are the list of style sheet media
• projection handheld
• print braille
• screen (default) tty
• embossed aural
• all
• Note that style sheet media are not the same as
  the MIME types. MIME types are a controlled
  vocabulary for file types.

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linking to an external style sheet

• This is the best way! Use the same style sheet
  file for all the pages in your site, by adding to
  every pages something like
• ltlink rel"stylesheet" type"text/css"
• href"URI"/gt
• where URI is a URI where the style sheet is to be
  downloaded from. On wotan, this can just be the
  file name.
• The ltlinkgt tag must appear in the ltheadgt, it can
  not appear in the ltbodygt, sorry!

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in our situation

• ltlink rel"stylesheet" type"text/css"
• href"main.css"/gt
• Then create a file main.css with a simple test
  rule such as
• h1 color blue
• main.css is just an example filename, any file
  name will do.
• Try it out!

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basic style syntax

• selector property1 value1 property2 value2
  
• selector is a selector (see following slides)
• property is the name of a property
• value is the value of a property
• note colon and semicolon use!
• all names and values are case-insensitive
• Examples
• h1 color grey text-align center
• .blue color blue / yes, with a dot /

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comments in the style sheet

• You can add comments is the style sheet by
  enclosing the comment between / and /.
• This comment syntax comes from the C programming
  language.
• This technique is especially useful if you want
  to remove code from your style sheet temporarily.

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basic selector

• the basic selector is a comma-separated list of
  elementary selectors.
• Often, the elementary selectors are HTML tags,
  e.g.
• h1, h2 text-align center
• will center all lth1gt and lth2gt element
  contents.
• but the selectors can be more precise, we are
  only look at one alternative here, class
  selectors.

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class selectors

• The is the standard way to style up a class
• .class property1 value1, property2 value2
  
• will give all the properties and values to
  any element in the class class.
• Recall HTML, you can say
• ltelement class"class"gt ... lt/elementgt
• to make the element element part of the class
  class to the element element. Note that you can
  place any tag into several classes. Use blanks to
  separate the different class names.

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id selectors

• The standard way to style up a single element is
  to use its id
• id property1 value1, property2 value2
• will give all the properties and values to
  the element with the identifier id.
• Recall HTML, you can identify an individual
  element element by giving it an id
• ltelement id"id"gt ... lt/elementgt
• will apply all the style rules the named
  element element class to the element element.

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visual style sheets

• In this class we ignore aural style sheets and
  work only on visual ones.
• We have two important concepts.
• The canvas is the support of the rendering. There
  may be several canvases on a document. On screen,
  each canvas is flat and of infinite dimensions.
• The viewport is the part of the canvas that is
  currently visible. There is only one viewport per
  canvas.
• We will now examine some important property
  values in visual style sheet regarding
• colors
• distances

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property values colors

• they follow the RGB color model.
• expressed as three hex numbers 00 to FF.
• The following standard color names are defined
• Black 000000 Green 008000
• Silver C0C0C0 Lime 00FF00
• Gray 808080 Olive 808000
• White FFFFFF Yellow FFFF00
• Maroon 800000 Navy 000080
• Red FF0000 Blue 0000FF
• Purple 800080 Teal 008080
• Fuchsia FF00FF Aqua 00FFFF
• other names may be supported by browsers.

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values measures

• relatively
• em the font-size of the relevant font
• ex the x-height of the relevant font
• px pixels, relative to the viewing device
• absolutely
• in inches 1 inch is equal to 2.54 centimeters.
  
• cm centimeters
• mm millimeters
• pt points 1 point is equal to 1/72th of an
  inch
• pc picas 1 pica is equal to 12 points
• percentage, depending on other values. That other
  value may be
• same property of another element, usually an
  ancestor
• the value used in a formating context.

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the default style sheet (extract)

• blockquote, body, dd, div, dl, dt, h1, h2, h3,
  h4, h5, h6, ol, p, ul, hr, pre display block
• li display list-item
• head display none
• body margin 8px line-height 1.12
• h1 font-size 2em margin .67em 0
• h2 font-size 1.5em margin .75em 0
• h3 font-size 1.17em margin .83em 0
• h4, p, blockquote, ul, ol, dl, margin 1.12em 0
  
• h5 font-size .83em margin 1.5em 0
• h6 font-size .75em margin 1.67em 0

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the default style sheet (extract)

• h1, h2, h3, h4, h5, h6, b, strong font-weight
  bolder
• blockquote margin-left 40px margin-right
  40px
• i, cite, em, var, address font-style italic
• pre, tt, code, kbd, samp font-family monospace
  
• pre white-space pre
• big font-size 1.17em
• small, sub, sup font-size .83em
• sub vertical-align sub
• sup vertical-align super
• del text-decoration line-through
• hr border 1px inset
• ol, ul, dd margin-left 40px
• ol list-style-type decimal

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important properties

• We will now look at the properties as defined by
  CSS. These are the things that you can set using
  CSS.
• We group properties into six groups
• colors, and background
• boxes and layout
• fonts
• text
• lists (later)
• tag classification (later)

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color background properties

• color sets the foreground color of an
  element.
• background-color gives the color of the
  background
• background-image url(URL) places a picture
  found at a URL URL.
• background-repeat can take the value repeat
  (default), repeat-x, repeat-y, and
  no-repeat.
• background-attachment can take the value of
  fixed or scroll (default) to say if the image
  scrolls with the viewport.

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color background properties II

• Background-position property places the
  background image. It can take values
• '0 0' to '100 100'
• 'length length' to put length of offset from top
  left
• mixing both is allowed
• top, center,bottom and left, right,
  center can be used too

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normal flow

• In general, very piece of HTML is placed into a
  conceptual entity called a box.
• In visual formatting, we can think about the box
  as a rectangle that fills the material that is
  being visualized.
• For in-line elements, the boxes are set
  horizontally next to each other.
• For block-level elements, the boxes are set
  vertically next to each other.

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the box model

• The total width that the box occupies is the sum
  of
• the left and right margin
• the left and right border width
• the left and right padding
• the width of the boxs contents
• A similar reasoning holds for the height that the
  box occupies.

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box properties I

• border-color can hold up to four colors,
  separated by blanks
• one value means all borders have the same color
• two values mean first number for top and bottom,
  second for left and right
• three values mean first sets top, second left
  and right, third bottom
• four values mean first sets top, second sets
  right etc.
• border-width can hold up to four widths, as
  well as the words 'thin', 'think' and 'medium'.

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box border properties

• border-style border-top-style
  border-right-style border-bottom-style
  border-right-style take the following values
• none No border. border-width becomes zero
• hidden Same as 'none', except in terms of border
  conflict resolution
• dotted The border is a series of dots.
• dashed The border is a series of short line
  segments.
• solid The border is a single line segment.
• double The border is two solid lines.
• groove The border looks as though it were carved
  into the canvas.
• ridge The border looks as though it were coming
  out of the canvas.
• inset The border makes the box look like
  embedded in the canvas.
• outset The border makes the box look like coming
  out of the canvas.

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box properties II

• border-top-width , border-bottom-width ,
  border-left-width and border-right-width
  also exist.
• same properties exists for margin-top ,
  margin-bottom etc and padding-top ,
  padding-bottom etc.
• float can be one of 'left', 'right' or 'none'
  which is the default. If a float is set on an
  element, the text near the element floats on the
  left or right site of the element's contents. For
  example, you can use this to create run-in
  headers.

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box properties III

• width sets the total width of the box and
  height sets the total height of the box, both
  take a dimension or the word 'auto' e.g. img
  width 100px height auto
• clear tells the user agent whether to place
  the current element next to a floating element or
  on the next line below it.
• value 'none' tells the user agent to put contents
  on either side of the floating element
• value 'left' means that the left side has to stay
  clear
• value 'right' means that the right side has to
  stay clear
• value 'all' means that both sides have to stay
  clear

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position

• 'static' The box is a normal box, laid out
  according to the normal flow.
• 'relative' The box's position is calculated
  according to the normal flow. Then it is offset
  relative to its normal position. The position of
  the following box is not affected.
• 'absolute' The box's position is specified by
  offsets with respect to the box's containing tag.
  There is no effect on sibling boxes.
• 'fixed' The box's position is calculated
  according to the 'absolute' model, but the
  reference is not the containing tag but
• For continuous media, the box is fixed with
  respect to the viewport
• For paged media, the box is fixed with respect to
  the page

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properties with position

• top, right, bottom, left set offsets
  if positioning is relative, absolute or fixed.
• They can take length values, percentages, and
  'auto'.
• the effect of 'auto' depends on which other
  properties have been set to 'auto
• Now check the examples in doc/examples on the
  course home page.

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text properties I

• letter-spacing set the spacing between
  letters, takes a length value or the word
  'normal'
• word-spacing same as for letter-spacing
• line-height sets the distance between several
  lines of an element's contents,
• in pt or pixel numbers
• age (referring to a percentage of current font
  size)
• with a number (referring to a multiplicity of
  the size of the text)
• 'normal'

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text properties II

• text-align can take the values left right
  center and justify.
• text-decoration can take the values
  underline, overline, line-through and
  blink.
• text-indent , margin-left take length
  units but are best expressed in the relative "em"
  unit.

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text properties III

• float can be set to left, right and
  none.
• width and height can also be set.
• vertical-align can take the values
  baseline, middle, sub, super, text-top,
  text-bottom, top, bottom, as well as
  percentages.
• text-transform can take the value
  uppercase, lowercase, capitalize and none.

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font properties I

• font-family accepts a comma-separated list of
  font names
• there are five generic names, one should be
  quoted last as a fall-back
• serif sans-serif cursive
• fantasy monospace
• example
• lang(ja-jp) font-family "Heisei Mincho
  W9", serif

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font properties II

• font-size accepts sizes as npt, n, npt,
  -npt where n is a number, or some sizes like
• xx-small x-small small medium
• large x-large xx-large larger
  smaller
• incremental font sizes may not be handled
  properly by the browser.
• font-style can be either italic, oblique
  or normal

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font properties III

• font-variant can be either normal or small
  caps
• font-weight can be
• a number between 100 for the thinnest and 900 for
  the boldest. 400 is normal.
• normal bold bolder lighter
• font-stretch can be any of
• ultra-condensed extra-condensed
  condensed
• semi-condensed normal semi-expanded
• expanded extra-expanded
  ultra-expanded

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other font properties

• There is a whole bunch of other properties
• unicode-range stemv stroke
• units-per-em stemh bbox
• definitions-src ascent dscent
• baseline widths mathline
• centerline topine panose1
• There also is a font property that allows you
  to put several of the previous properties
  together.
• But all that is not worth learning. Keep fonts
  simple.

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http//openlib.org/home/krichel

• Thank you for your attention!