メールフォームでブラウザによる項目の見え方（幅）の違いを調整するには？

一般論ですが、ブラウザのレンダリングエンジン（HTMLを解釈して表示する仕組み）が、IEとFireFoxで違うので、ちゃんと揃えようとおもったらCSSで幅の値を明示（pxとか%とか）してやるべきだと思います。CSSやHTMLについては、検索エンジン等でお調べ頂ければと思います。

追記：CSSの編集箇所ですが、まずはフォームのソースを見て頂いて、該当する部分のクラス（例：col-head）などを確認し、テーマフォルダ内の該当cssを編集してください。

 <tr id="RowMessageName1">
        <th class="col-head" width="150"><label for="MessageName1">お名前</label><span class="required">*</span></th>
        <td class="col-input"><span id="FieldMessageName1"><span class="mail-before-attachment"><small>[姓]</small></span><input name="data[Message][name_1]" size="8" maxlength="255" class="" type="text" id="MessageName1"/><span class="mail-after-attachment"></span><span class="mail-attention"></span></span><span id="FieldMessageName2"><span class="mail-before-attachment"><small>[名]</small></span><input name="data[Message][name_2]" size="8" maxlength="255" class="" type="text" id="MessageName2"/><span class="mail-after-attachment"></span><span class="mail-attention"></span></span></td>
    </tr>
    <tr id="RowMessageNameKana1">
        <th class="col-head" width="150"><label for="MessageNameKana1">フリガナ</label></th>
        <td class="col-input"><span id="FieldMessageNameKana1"><span class="mail-before-attachment"><small>[姓]</small></span><input name="data[Message][name_kana_1]" size="8" maxlength="255" class="" type="text" id="MessageNameKana1"/><span class="mail-after-attachment"></span><span class="mail-attention"></span></span><span id="FieldMessageNameKana2"><span class="mail-before-attachment"><small>[名]</small></span><input name="data[Message][name_kana_2]" size="8" maxlength="255" class="" type="text" id="MessageNameKana2"/><span class="mail-after-attachment"></span><span class="mail-attention"></span></span></td>
    </tr>

@charset "UTF-8";
/**
 * flagsystスタイルシート
 */
/* tags
----------------------------------------------- */
* {
    margin: 0;
    padding: 0;
}
.display-none{
display:none;
}
h1,h2,h3,h4,h5{
font-weight:normal;
}
body {
margin:0;
padding:0;
color: #666666;
background:url(../img/icons_bg.png);
font-family: "メイリオ", "ＭＳ Ｐゴシック", sans-serif; 
}
#ContentQ{
font-family: Arial, "ＭＳ Ｐゴシック", sans-serif; 
    background-color: #FFFFFF;
    border: 1px solid #CCCCCC;
width:200px;
height:25px;
font-size:150%;
    box-shadow: 0 0 2px 2px rgba(0, 0, 0, 0.05);
    transition: border 0.2s linear 0s, box-shadow 0.2s linear 0s;
border-radius: 17px 17px 17px 17px;
padding: 5px;
}
#ContentC{
margin-right: 15px;
}

a{/*リンクされた文字*/
    color:#6DAE0F;
    font-style:normal;
    text-decoration:underline;
}
a:link {/*未訪問のリンク*/
    color:#6DAE0F;
    font-style:normal;
    text-decoration:none;
}
a:visited {/*訪問後のリンク*/
    color:#6DAE0F;
    text-decoration:none;
}
a:hover {/*マウスをのせたとき*/
    color:#BAD98E;
    text-decoration:underline;
}
a:active {/*クリック中*/
    text-decoration:none;
}
a:hover img {
    opacity: 0.8;
}
th{
padding:5px;
}
td{
padding:5px;
}
input {
margin:3px;
}
img {
border:none;
}
pre {
padding:10px 20px;
background: #fff;
border-top: 1px solid #CCC;
border-bottom: 1px solid #CCC;
font-size:12px;
margin-bottom: 5px;
color:#000;
font-family:Verdana,Arial,sans-serif;
line-height: 1.6em;
}
/* Page
----------------------------------------------- */
#Page {
width:986px;
margin: 15px auto 20px;
text-align: left;
}
/* Alfa, Beta
----------------------------------------------- */
#Alfa,#Beta {
position: relative;
display: inline;
}
#Alfa {
width:214px;
left:0px;
float:left;
}
#Beta {
width:750px;
float:right;
}
/* Header
----------------------------------------------- */
#Header {
background: #32d65d;
border-top: 4px #ff0000 solid;
border-bottom: 1px #DDD solid;
    box-shadow:  0 1px 1px 1px rgba(0, 0, 0, 0.03) ;
-moz-box-shadow : 0 1px 1px 1px  rgba(0, 0, 0, 0.03) ;
-webkit-box-shadow : 0 1px 1px 1px rgba(0, 0, 0, 0.03) ;
height:87px;
}
#Header-page{
margin: 0 auto;
width:986px;
}

/* Footer
----------------------------------------------- */
#Footer {
text-align: center;
background: #32d65d;
border-top: 1px #32d65d solid;
border-bottom: 4px #ff0000 solid;
    box-shadow:  0 1px 1px 1px rgba(0, 0, 0, 0.03) ;
-moz-box-shadow : 0 1px 1px 1px  rgba(0, 0, 0, 0.03) ;
-webkit-box-shadow : 0 1px 1px 1px rgba(0, 0, 0, 0.03) ;
height:87px;
}
#Footer #copyright{
font-size18px;
}
/* GlobalMenus
----------------------------------------------- */
#GlobalMenus {
padding:40px auto 40px 0;
}
#GlobalMenus ul{
padding:0;
margin:0;
}

#GlobalMenus li {
    background: url("../img/sidebox/ico_home.png") no-repeat scroll 20px center transparent;
    border-bottom: 1px double #EDEDED;
    float: left;
    height: 60px;
    line-height: 60px;
    list-style: none outside none;
    width: 212px;
}

#GlobalMenus li.menu01{
    background: url("../img/icons/icons_ico_squ_99.png") no-repeat scroll 20px center transparent;
}
#GlobalMenus li.menu02{
    background: url("../img/icons/icons_ico_squ_99.png") no-repeat scroll 20px center transparent;
}
#GlobalMenus li.menu03{
    background: url("../img/icons/icons_ico_squ_99.png") no-repeat scroll 20px center transparent;
}
#GlobalMenus li.menu04{
    background: url("../img/icons/icons_ico_squ_99.png") no-repeat scroll 20px center transparent;
}
#GlobalMenus li.menu05{
    background: url("../img/icons/icons_ico_squ_99.png") no-repeat scroll 20px center transparent;
}
#GlobalMenus li.menu06{
    background: url("../img/icons/icons_ico_squ_99.png") no-repeat scroll 20px center transparent;
}
#GlobalMenus li.menu07{
    background: url("../img/icons/icons_ico_00.png") no-repeat scroll 20px center transparent;
}



#GlobalMenus li.last{
border-bottom:none;
}

#GlobalMenus li a{
font-size:1.2;
    margin-left: 20px;
    padding-left: 40px;
text-decoration:none;
}
/* Navigation
----------------------------------------------- */
#Navigation {
font-size:12px;
    background-color: #FFF;
    border: 1px solid #E3E3E3;
    border-radius: 4px 4px 4px 4px;
    box-shadow: 0 0 2px 2px rgba(0, 0, 0, 0.075);
-moz-box-shadow : 0 0 2px 2px rgba(0, 0, 0, 0.05) ;
-webkit-box-shadow : 0 0 2px 2px rgba(0, 0, 0, 0.05) ;
    margin-bottom: 10px;
    min-height: 20px;
padding:10px 10px 8px;
}
/* clearfix
----------------------------------------------- */
.clearfix:after {
content: ".";
display: block;
height: 0;
clear: both;
visibility: hidden;
}
.clearfix {
display: inline-block;
}
* html .clearfix {
height: 1%;
}
.clearfix {
display: block;
}
/* .pagination
---------------------------------------------------*/
.pagination .disabled {
display:none;
}
.pagination .number,
.pagination .prev,
.pagination .next,
.pagination .current{
padding:5px 8px;
border:1px solid #e2e2e2;
margin:0 2px;
}
/* list-num
---------------------------------------------------*/
.list-num {
text-align: right;
}
/* 検索
---------------------------------------------------*/
.search-box {
}

.search-box input[type="text"] {
}
.search-box .submit_button{
border-radius: 16px 16px 16px 16px;
text-indent: -9999px;
box-shadow:none;
    cursor: pointer;
    border: none;
    color: #fff;
    height: 34px;
    width:34px;
    background-image: url(../img/icons_search.png);
    background-color: transparent;
    background-repeat: no-repeat;
    margin-bottom: 0;
    vertical-align: top;
}

.search-result {
text-align: right;
}

h1{
padding-top:20px;
}
#Header-page h1 a{
display: block;
height:54px;
width:214px;
}
#Header-page h1 a:hover {
    opacity: 0.8;

}
/*Header serch
----------------------------------------------- */
#Header .search-box {
float: right;
text-align: center;
padding-top: 25px;
padding-right:0;
margin-bottom: 0;
}
/*ContentsBody
----------------------------------------------- */

#ContentsBody .subpage {
border-radius: 4px 4px 4px 4px;
    background-color: #FFF;
    border: 1px solid #E3E3E3;
    box-shadow:  0 0 2px 2px rgba(0, 0, 0, 0.05) ;
-moz-box-shadow :0 0 2px 2px rgba(0, 0, 0, 0.05) ;
-webkit-box-shadow :0 0 2px 2px rgba(0, 0, 0, 0.05) ;
    margin-bottom: 20px;
    min-height: 600px;
padding:20px;
}

#ContentsBody .subpage p{
    padding: 0 5px;
}
#ContentsBody h2{
border-radius: 4px 4px 4px 4px;
    background-color: #6DAE0F;
    margin-bottom: 20px;
padding: 42px 20px 10px;
color:#FFFFFF;
font-size:30px;
    letter-spacing: 0.2em;
}
#ContentsBody h3 {
font-size:24px;
 	margin-bottom: 10px;
 	padding: 10px 10px 0;
border-bottom:1px #CCC dotted;
}
#ContentsBody .post,.blog-description,.section{
padding:10px;
margin-bottom: 23px;
}
#ContentsBody .blog-description{
font-size:14px;
    padding: 0 10px;
}
.contents-head{
margin-bottom:10px;
}
#ContentsBody .eye-catch {
padding:10px;
}

/* sidebox
----------------------------------------------- */
#sidebox{
    background-color: #FFF;
    border: 1px solid #E3E3E3;
    border-radius: 4px 4px 4px 4px;
    box-shadow:  0 0 2px 2px rgba(0, 0, 0, 0.05) ;
-moz-box-shadow : 0 0 2px 2px  rgba(0, 0, 0, 0.05) ;
-webkit-box-shadow : 0 0 2px 2px rgba(0, 0, 0, 0.05) ;
    margin-bottom: 10px;
    min-height: 20px;
}

#sidebox-bnr{
    padding: 10px 0;
    text-align: center;
}
#sidebox-bnr2{
    padding: 0 0 10px;
    text-align: center;
}
#sidebox-bnr3{
margin-top:10px;
    text-align: center;
}
#sidebox-bnr4{
    text-align: center;
}

#sidebox-txt{
    padding: 5px 0;
    text-align: center;
    width: 214px;
}

.sidebox-telfax{
font-size:15px;
font-weight:bold;
color:#868686;
    line-height: 1.5;
    padding-top: 5px;
}
.sidebox-text{
font-size:12px;
color:#868686;
}

.fb-like-box{
background:#FFFFFF;
margin-top:10px;
}

div.fb_iframe_widget span {
height:300px!important;
}

div.fb_iframe_widget iframe {
height:300px!important;
}

/* widget
----------------------------------------------- */

.widget{
padding: 10px;
font-size: 12px;
}
.widget h2 {
font-size:small;
}
.widget img{
max-width: 100%;
}

table.blog-calendar{
border-collapse: collapse;
text-align: center;
font-size: 11px;
border-spacing: 0;
margin: 0 auto;
width: 190px;
}
table.blog-calendar tr{
border-bottom: 1px solid #EEE ;
}
table.blog-calendar th{
line-height: 1em;
border-bottom: 1px solid #EEE ;
font-weight:normal;
}
table.blog-calendar td{
line-height: 1em;
border-bottom: 1px solid #EEE ;
}
table.blog-calendar .sunday{
color: #FF0000;
}
table.blog-calendar td.today{
font-size: 110%;
font-weight: bold;
color: #6DAE0F;
}
.blog-widget h2{
margin-top: 5px;
}
.blog-widget ul{
list-style: none;
}
.blog-widget .depth-2 {
padding-left:10px;
}
.blog-widget .depth-3 {
padding-left:20px;
}

/*TopPage
----------------------------------------------- */

#top-main{
text-align:left;
margin-bottom:10px;
border-radius: 4px 4px 4px 4px;
}
#top-main img{
text-align:left;
margin-bottom:10px;
border-radius: 4px 4px 4px 4px;
}
#top-main .bx-window{
    border-radius: 4px 4px 4px 4px;
}

#top-contents{
margin:10px 0;
}
#top-contents-main{
    background-color: #FFF;
font-size:12px;
    border: 1px solid #E3E3E3;
    border-radius: 4px 4px 4px 4px;
    box-shadow:  0 0 2px 2px rgba(0, 0, 0, 0.05);
    margin-bottom: 20px;
    padding: 15px;
overflow:hidden;
}

#top-contents-main h2{
background:#FFFFFF!important;
color:#868686;
font-size: 16px;
font-weight: normal;
line-height:1em;
border-bottom:1px dotted #CCCCCC;
    padding: 0 10px 10px;
    border-radius: 0;
}

#top-contents-main .body{
padding:0 10px;
}

#top-contents-main .news{
width:345px;
float:left;
}
#new{
overflow:auto;
}
#new-title{
max-width:200px;
float:left;
}
#new-more{
max-width:200px;
float:right;
}

#new-new01{
max-width:50%;
float:left;
}
#new-new02{
max-width:50%;
float:right;
}


#top-bnr{
font-size:12px;
}
#top-bnr img{
margin-bottom:10px;
}
#top-bnr p{
line-height:1.4;
}
#top-bnr-left{
max-width:345px;
float:left;
}
#top-bnr-right{
max-width:345px;
float:right;
}


#top-main-telfax-title{
    background: none repeat scroll 0 0 #6DAE0F;
    border-radius: 4px 4px 4px 4px;
    color: #FFFFFF;
    text-align: center;
margin-bottom: 10px;
}

#top-main-telfax-left{
min-width:375px;
float:left;
border-right:1px #CCCCCC dotted;
}
#top-main-telfax-tel {
    background: url("../img/tel_icon.png") no-repeat scroll 0 2px transparent;
    height: 27px;
    margin-top: 10px;
    padding: 10px 0;
    position: relative;
}
.top-tel {
    font-size: 22px;
    left: 33px;
    position: absolute;
    top: 0;
}
.top-tel-time {
    font-size: 12px;
    left: 255px;
    position: absolute;
    top: -3px;
}
#top-main-telfax-mbtel {
    background: url("../img/mbtel_icon.png") no-repeat scroll 0 2px transparent;
    height: 27px;
    margin-top: 10px;
    padding: 10px 0;
    position: relative;
}
.top-tel {
    font-size: 22px;
    left: 33px;
    position: absolute;
    top: 0;
}
.top-tel-time {
    font-size: 12px;
    left: 255px;
    position: absolute;
    top: -3px;
}
#top-main-telfax-fax{
    background: url("../img/fax_icon.png") no-repeat scroll 0 2px transparent;
    height: 27px;
    padding: 10px 0;
    position: relative;
}
.top-fax {
    font-size: 22px;
    left: 33px;
    position: absolute;
    top: 0;
}
.top-fax-time {
    font-size: 12px;
    left: 255px;
    position: absolute;
    top: -3px;
}
.telfax-tel{
margin-left:5px;
}
.telfax-fax{
margin-left:5px;
}

#top-main-telfax-right{
width:315px;
float:right;
}
#top-main-contact {
    background-color: #FFFFFF;
    border: 1px solid #E3E3E3;
    border-radius: 4px 4px 4px 4px;
    box-shadow: 0 0 2px 2px rgba(0, 0, 0, 0.05);
    font-size: 15px;
    margin-bottom: 20px;
    overflow: hidden;
    padding: 10px 10px 5px;
}
#top-main-serch .search-box{
padding:0;
margin:0;
}
#top-main-serch #ContentSearchForm #ContentQ{
width:245px;
}
#top-main-webcontact {
    padding: 10px 0;
}

#footer-menu{
    margin: 0 auto;
padding-top: 10px;
    width: 986px;
color:#FFFFFF;
}
#footer-menu p{
margin-top:10px;
}
#footer-menu ul{
display: inline-block;
}
#footer-menu li{
display: inline;
float: left;
font-size:1.8;
margin: 0 10px;
}
#footer-menu a{
color:#FFFFFF;
}
#footer-menu a:hover{
color:ｆｆ0000;
}


/*会社概要map
----------------------------------------------- */
#map{
margin:0 auto;
}
table.row-table-01{
width: 100%;
}

/* slider
----------------------------------------------- */
#top-main span{
display: none;
}
#top-main .bx-pager{
    height: 15px;
    margin-top: 10px;
    padding: 5px 0;
    width: 100%;
}
#top-main .pager-link{
  background: url(../img/slider/slide_pointer_off.png) left top;
  height:12px; width:12px;
  display: block;
  float:left;
  margin: 0 5px 0 0
}
#top-main .pager-active{
  background: url(../img/slider/slide_pointer_on.png) left top;
}
#top-main .bx-prev , #top-main .bx-next{
display:none;
}
#top-main ul{
height:300px;
overflow: hidden;
}


/*Blog
----------------------------------------------- */

.more{
margin-top: 10px;
font-size: 11px;
}
#BlogComment{
padding:20px;
border: 1px #ccc solid;
margin: 10px;
    border-radius: 4px 4px 4px 4px;
}
#BlogCommentList{
    border-bottom: 1px solid #EDEDED;
    margin-bottom: 20px;
}
#BlogComment h4{
    font-size: 16px;
}
#BlogComment .submit{
    text-align: center;
}

#contentsNavi{
text-align:center;
}
#ContentsBody .meta , .tag{
text-align:right;
padding-top: 10px;
font-size: 12px;
}

#ContentsBody .post{
    border-radius: 4px 4px 4px 4px;
    background:url(../img/icons_bg_2.png);
margin: 10px 10px 30px;
padding:20px;
}
#ContentsBody .meta{
    margin-top: 20px;
    border-top:1px #ccc dotted;
}
#ContentsBody .post h4{
border-bottom:1px #CCC dotted;
    font-size: 22px;
    padding-bottom: 12px;
    margin-bottom: 17px;
}
#ContentsBody .date{
    float: left;
}

/*to-top
----------------------------------------------- */

.to-top{
text-align:right;
font-size:12px;
    margin: 5px 20px;
}
.to-top img{
vertical-align: middle;
margin-right:3px;
}
/*about
----------------------------------------------- */
.row-table-01 firstChild lastChild{
    width: 585px;
    margin: 0 auto;
}
.row-table-01 firstChild lastChild th,.row-table-01 firstChild lastChild td{
    font-weight:normal;
    border-bottom: 1px #EDEDED solid;
    line-height: 3;
}

/*sitemap
----------------------------------------------- */

#ContentsBody ul.sitemap , ul.section{
list-style-image:url(../img/icons_sankaku.png);
line-height:2.4;
margin: 0 20px;
}


/*contact
----------------------------------------------- */
.row-table-01 input,
.row-table-01 select,
.auth-captcha input,
.auth-captcha select {
    font-size: 16px;
}
.row-table-01 input,
.row-table-01 textarea,
.auth-captcha input {
padding:5px;
}
.row-table-01 textarea {
    font-size: 16px;
}
.auth-captcha{
    text-align: center;
}
.auth-captcha-image{
    vertical-align:middle;
}
#ContentsBody .submit{
text-align:center;
}
#ContentsBody .required{
color: #FF0000;
}
#flashMessage {
color: #FF0000;
border:5px solid #FF0000;
padding:15px;
margin-bottom: 30px;
}
.form-error{
background: #FFCCCC;
}
.error-message{
font-size: 16px;
color: #FF0000;
}
div.submit {
margin-top: 30px;
}
table.row-table-01 th {
text-align: right;
}
table.row-table-01 th, 
table.row-table-01 td{
padding:10px;
}
table.row-table-01 tr.odd th,
table.row-table-01 tr.odd td {
background-color:#EFEFEF;
}
.submit .button {
color:#333;
border:1px solid #CCC;
cursor:pointer;
text-shadow:rgba(255,255,255,0.4) 1px 1px 0;
-webkit-border-radius:2px;
-moz-border-radius:2px;
-o-border-radius:2px;
border-radius:2px;
-webkit-box-shadow:inset 0 0 0 1px rgba(255,255,255,0.4);
-moz-box-shadow:inset 0 0 0 1px rgba(255,255,255,0.4);
-o-box-shadow:inset 0 0 0 1px rgba(255,255,255,0.4);
box-shadow:inset 0 0 0 1px rgba(255,255,255,0.4);
background:#F3F3F3;
background:-moz-linear-gradient(top,#FFF,#F3F3F3);
background:-webkit-gradient(linear,left top,left bottom,from(#FFF),color-stop(100%,#F3F3F3));
background:-o-linear-gradient(top,#FFF,#F3F3F3);
margin:10px;
padding:3px 40px;
font-weight: bold;
font-size: 1.0em;
white-space: nowrap;
line-height: 24px;
}
.submit .button:hover {
border:1px solid #CCC;
text-decoration:none;
background:#f4f4f4;
background:-moz-linear-gradient(top,#f4f4f4,#dfdfdf 100%);
background:-webkit-gradient(linear,left top,left bottom,from(#f4f4f4),color-stop(100%,#dfdfdf));
background:-o-linear-gradient(top,#f4f4f4,#dfdfdf 100%);
}
.submit .button:active {
border:1px solid #CCC;text-decoration:none;
background:#cdcdcd;
background:-moz-linear-gradient(top,#cdcdcd,#eee 100%);
background:-webkit-gradient(linear,left top,left bottom,from(#cdcdcd),color-stop(100%,#eee));
background:-o-linear-gradient(top,#cdcdcd,#eee 100%);
}
.submit .button[disabled] {
opacity:.5
}
.submit a.button {
padding-top:5px;
padding-bottom:5.5px;
}
*:first-child+html .submit a.button {
position:absolute;
top:1px;
padding-top:3px;
padding-bottom:3px;
}
#Error #ContentsBody p {
margin-bottom: 20px;
}
#Error #ContentsBody .error {
color:#F00;
}
#Error #ContentsBody pre {
margin-bottom: 20px;
background-color: #EFEFEF;
}
#Error #ContentsBody .notice {
font-size: 14px;
color:#CCC;
}
#Error #ContentsBody .cake-stack-trace {
font-size: 14px;
list-style-position: inside;
margin-bottom: 20px;
padding-left:20px;
padding-right:20px;
}
#Error #ContentsBody .cake-stack-trace li {
margin-top:5px;
margin-bottom: 5px;
}

div.submit {
margin-top: 30px;
}
table.row-table-01 th {
text-align: right;
}
table.row-table-01 th, 
table.row-table-01 td{
padding:10px;
}

table.row-table-01 th {
text-align: left; 　/* 文字の左右寄せ default値 right */
width:200px;        /*横幅を指定 */
font-size: 14px;　　 /*文字サイズを指定 */
}