default.css 파일도 있고 style.css도 있네요...
어떤 파일의 어떤 부분을 수정해야 하는지
초보랍니다.... 구체적인 답변 부탁드립니다.

default.css
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BODY,TD,SELECT,input,DIV,form,TEXTAREA,center,option,pre,br,blockquote,span {font-family:돋움,굴림;font-size: 8pt; color:#999999; LINE-HEIGHT:14pt;
scrollbar-face-color: #FFFFFF;
scrollbar-highlight-color: #FFFFFF;
scrollbar-3dlight-color: #E4E4E4;
scrollbar-shadow-color: #999CCC;
scrollbar-darkshadow-color: #E4E4E4;
scrollbar-track-color: #FFFFFF;
scrollbar-arrow-color: #9999CC;
}

A:link    { COLOR: #777777; TEXT-DECORATION: none }
A:visited { COLOR: #000000; TEXT-DECORATION: none }
A:active  { COLOR: #000000; TEXT-DECORATION: none }
A:hover  { COLOR: #000000; TEXT-DECORATION: none }


TABLE, TR, TD { COLOR: #777777; FONT-FAMILY: Tahoma, 돋움, 굴림, Gulim; FONT-SIZE: 8pt; }
FORM          { PADDING : 0 0 0 0; MARGIN: 0 0 0 0 }
SELECT        { FONT-FAMILY: Tahoma, 돋움, 굴림, Gulim; FONT-SIZE: 8pt; BACKGROUND: #FFFFFF }
TEXTAREA      { FONT-FAMILY: Tahoma, 돋움, 굴림, Gulim; FONT-SIZE: 8pt; LINE-HEIGHT: 150% }
INPUT        { FONT-FAMILY: Tahoma, 돋움, 굴림, Gulim; FONT-SIZE: 8pt }


Body {margin-left: 0px; margin-top: 0px; margin-right: 0px; margin-bottom: 0px;}
 
img {border:0px}

/* 메인공지사항*/
.txt1 {COLOR: #4b4b4b; FONT-FAMILY: 돋움, 굴림, Gulim; FONT-SIZE: 9pt; MARGIN: 0 0 0 0; text-decoration: none; }
/*메인로그인창*/
.Input1 {background-color:#ffffff;BORDER-RIGHT: #d4c6c8 1px solid; BORDER-TOP: #d4c6c8 1px solid; FONT-SIZE: 12px; BORDER-LEFT: #d4c6c8 1px solid; BORDER-BOTTOM: #d4c6c8 1px solid;height:19px;width:142px; }
/*메인카피라이트*/
.Select_01 {background-color:#ffffff;BORDER-RIGHT: #dedede 1px solid; BORDER-TOP: #dedede 1px solid; FONT-SIZE: 12px; BORDER-LEFT: #dedede 1px solid; BORDER-BOTTOM: #dedede 1px solid;width:160px;PADDING: 2 2 2 2;}

/* TABLE */
.TD1 {BORDER-RIGHT: #dadada 1px solid;BORDER-BOTTOM: #dadada 1px solid; }
.TD2 {BORDER-BOTTOM: #dadada 1px solid;}
.TD33 {BORDER-RIGHT: #bee1e5 1px solid;}
.TD3 {BORDER-RIGHT: #dadada 1px solid;}
.TD4 {BORDER-RIGHT: #d2d2d2 1px solid;BORDER-BOTTOM: #d2d2d2 1px solid;  font-weight: bold; COLOR: #fe7609;FONT-SIZE:7pt;}
.TD6 {BORDER-RIGHT: #d2d2d2 1px solid; font-weight: bold; COLOR: #fe7609; FONT-SIZE:8pt;  }
.TD5 {font-weight: bold; COLOR: #779acf;  FONT-SIZE:8pt;}
.TD7 {BORDER-BOTTOM: #d2d2d2 1px solid; font-weight: bold; COLOR: #fe7609;  FONT-SIZE:8pt;}
.TD8 {BORDER-BOTTOM: #d2d2d2 1px solid;BORDER-RIGHT: #d2d2d2 1px solid; font-weight: bold; COLOR: #779acf;  FONT-SIZE:7pt;}
.TD9 {BORDER-RIGHT: #dfe8ef 1px solid; BORDER-BOTTOM: #dfe8ef 1px solid; }
.TD10 {BORDER-BOTTOM: #dfe8ef 1px solid;}
.TD11 {BORDER-RIGHT: #dfe8ef 1px solid;}
.TD12 {BORDER-RIGHT: #dfe8ef 1px solid; BORDER-BOTTOM: #dfe8ef 1px solid; COLOR: ##333333; FONT-SIZE: 8pt; font-weight: bold;}
.TD13 {BORDER-RIGHT: #dfe8ef 1px solid; COLOR: ##333333; FONT-SIZE: 8pt; font-weight: bold;}


/* 데이케어*/
.txt2 {COLOR: #8b272d; FONT-FAMILY: 돋움, 굴림, Gulim; FONT-SIZE: 9pt; MARGIN: 0 0 0 0; text-decoration: none; font-weight: bold;}
.txt3 {COLOR: #999999; FONT-FAMILY: 돋움, 굴림, Gulim; FONT-SIZE: 8pt; MARGIN: 0 0 0 0; text-decoration: none; }
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style.css
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body, td, p, input, button, textarea, select, .c1 { font-family:Tahoma,굴림; font-size:9pt; color:#222222; }

form { margin:0px; }

/* img {border:0px;} */

a:link, a:visited, a:active { text-decoration:none; color:#466C8A; }
a:hover { text-decoration:underline; }

a.menu:link, a.menu:visited, a.menu:active { text-decoration:none; color:#454545; }
a.menu:hover { text-decoration:none; }

.member {font-weight:bold;color:#888888;}
.guest  {font-weight:normal;color:#888888;}

.lh { line-height: 150%; }
.jt { text-align:justify; }

.li { font-weight:bold; font-size:18px; vertical-align:-4px; color:#66AEAD; }

.ul { list-style-type:square; color:#66AEAD; }

.ct { font-family: Verdana, 굴림; color:#222222; }

.ed { border:1px solid #CCCCCC; }
.tx { border:1px solid #CCCCCC; }

.small { font-size:8pt; font-family:돋움; }
.cloudy, a.cloudy {color:#888888;} /* 흐림 */

input.ed { height:20px; border:1px solid #9A9A9A; border-right:1px solid #D8D8D8; border-bottom:1px solid #D8D8D8; padding:3px 2px 0 2px; }
input.ed_password { height:20px; border:1px solid #9A9A9A; border-right:1px solid #D8D8D8; border-bottom:1px solid #D8D8D8; padding:3px 2px 0 2px; font:10px Tahoma; }
textarea.tx { border:1px solid #9A9A9A; border-right:1px solid #D8D8D8; border-bottom:1px solid #D8D8D8; padding:2px; }
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소스 올려드립니다.