来一发英文css教程：Introduction CSS
你可以将许多网页的风格格式同时更新，不用再一页一页地更新了。网页制造WEB文章简介：CSSactuallymeansCascadingStyleSheets.StylesareusedtodefinehowHTMLelementsaredisplayed.TheyareusuallystoredinSTYLESHEETSandwerefirstseenincludedinHTML4.0,withthepurposeofsolvingaproblemthatappeared.Thesearebas
FewpeoplereallyknowwhatCSSreallyis.Thatiswhyweneedtodiscussthisinthefollowingsetoftutorialsthatwewillhandoutasfastaspossible.Wewillcoverbasic,mediumandadvancedCSSinasetofCSSTutorialsthatyouwillsurelyenjoyutilizing.RememberthatyoudoneedbasicknowledgeaboutHTML/XHTMLinordertoworkwithCSS.ThisishighlyimportantandifyoudonotknowHTMLthenyoushouldfirstfocusonthatandthenonlearningfromCSSTutorials.
WhatisCSS?
CSSactuallymeansCascadingStyleSheets.StylesareusedtodefinehowHTMLelementsaredisplayed.TheyareusuallystoredinSTYLESHEETSandwerefirstseenincludedinHTML4.0,withthepurposeofsolvingaproblemthatappeared.Thesearebasicallyexternal,inthesensethattheyarenotactuallyincludedinyourHTMLcoding.ExternalStyleSheetsareusedinordertoSAVEYOUWORK.CSSfilesareutilizedtostorethemandyouneedtounderstandthatwehavetheadvantageofusingmultiplestyledefinitionsthatwilleventuallycascadeinjustone.
WhydidCSSappear?
Asalreadymentioned,CSSwasdevelopedinordertosolveaproblemwithHTML.RegularHTMLtagshavebeenbuilttodefinetheactualcontentofonedocument.WewerefacedwithsimpleHTMLtagslike<h1>,<table>,<p>etc.Therewasnoneedtouseformattingtagsbecausetheactualdocumentwastakencareofbyyourbrowser.AstimepassedwewerefacedwithbrowsersaddingHTMLattributesandtags.Thiscomplicatedeverythingandeventuallyledtodifficultyincreatingwebsites.Thestatementisextremelytruewhentalkingaboutsitesthatshowedaseparationbetweentheactualpresentationandthecontent.AsaresultofthisproblemSTYLESwereaddedtoHTML4.0byW3C.NowwecanclearlynoticethatallofthemainwebbrowsersouttheresupportCSS.
TimeSavedthroughCSS
StylesheetswillsaveyoutimebecausetheywilldefinehowsomeorallHTMLelementsaredisplayed.ThemostbasicexamplesofHTMLelements’appearancethatcanbecontrolledstandsinthecolortagandfonttag,whichappearedinHTML3.2.Inmostcasesthewebmaster/designer/adminwillstoreallstylesin.cssfiles.ThesearebasicallytheExternalStyleSheetsmentionedabove.Theactualtimesavingcomesfromthefactthatyouwilljustneedtoediton.cssfileinsteadofmanyofyourwebpages.Forinstance,letusthinkthatyouwillwanttochangethecolorofthelinksonallofyourhtmlfiles.Youwouldnormallydothisbydoingmodificationsoneverysinglefile.ThroughtheuseofCSSyouwilljustneedtomodifyONEFILE.Youwillbeabletodefineonestyleforeachwebelementthatyouwant.Thenthestylecanbeappliedtoasmanyhtmlfilesasneeded.Aglobalchangeisdoneinjustonefile.
WhatisthedealwithMultipleStylesCascadinginOne?
WedidnoticethatthereisalittleproblemwithunderstandingthisconceptsowedoneedtoaddittoourCSStutorialintroduction.Allstylesheetswillallowyoutodefineinfoaboutstyleandtheinfocanbegiveninvariousways.YoucanspecifystylesinExternalStyleSheets,inanHTMLelementinsidethewebpageorinoneHTMLelement.Thereisaposibilitytohavemorethanonestyledefinedfor1HTMLelement.Inthiscasewearefacedwithordercascading.Everystylepresentwillbereadbythebrowserandcascadeintoonenewstylessheet,whichwecanconsidervirtual.Thisisdonebyobeyingasimplelistoforderdefinedbypriority.Thewayyouseeanelementwillbegivenbytheelementwiththehighestpriority.Theorderis:
1.InlineStyle(definedinsidetheHTMLelement)
2.InternalStyleSheet(definedinsideatag)
3.ExternalStyleSheet
4.Browserdefaultsettings.
表现和内容相分离。将设计部分剥离出来放在一个独立样式文件中，你可以减少未来网页无效的可能。 在Dreamweaver里可以很轻松的完成图文混排、插入图片、插入Flash、插入音频、插入视频。 dreamweaver8中文版下载(dw)对专业网页图像设计的FIREWORKS，三者被MACROMEDIA公司称为DREAMTEAM(梦之队)。 Adobe Dreamweaver CS5 软件使设计人员和开发人员能充满自信地构建基于标准的网站。由于同新的 Adobe CS Live 在线服务 Adobe BrowserLab 集成。 这个过程其实就是交流的过程。所有的这些都需要花时间。在面对完全陌生的软件时，就要多花时间对其产生初步的印象。此外，多操作也是非常重要的。 Dreamweaver8中文版(dw)是由Macromedia公司开发的一款所见即所得的网页编辑器。和二维动画设计软件FLASH，专业网页图像设计软件FIREWORKS，并称为“网页三剑客”。 帧(frames)和表格的制作速度快的令您无法想像。进阶表格编辑功能使您简单的选择单格、行、栏或作未连续之选取。 Dreamweaver由MX版本开始使用Opera软件公司的排版引擎“Presto”作为网页预览。 足见市场的反响和MACROMEDIA公司对它们的自信。说到Dreamweaver8我们应该了解一下网页编辑器的发展过程，随着互联网(Internet) 的家喻户晓。
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