为什么我的行内块元素未水平对齐？

我正在尝试使用inline-block将所有这些链接完美地排列在5列网格中。但是，似乎最上面一行与下面一行之间的对齐偏差很小（也许为1px），我想知道是否有人可以启发我为什么会发生这种情况。这是带有以下代码的jsFiddle。

HTML：

<div class="app-control-btns-wrp">  
    <a href='javascript:;' class="app-control-btns">Link1</a>
    <a href='javascript:;' class="app-control-btns">Link2</a>
    <a href='javascript:;' class="app-control-btns">Link3</a>
    <a href='javascript:;' class="app-control-btns">Link4</a>
</div>

<div class='char-input-btns-wrp'>

    <div class='rows' >
        <a href='javascript:;' class="char-input-btns">A</a>
        <a href='javascript:;' class="char-input-btns">B</a>
        <a href='javascript:;' class="char-input-btns">C</a>
        <a href='javascript:;' class="char-input-btns">D</a>
        <a href='javascript:;' class="char-input-btns">E</a>
    </div>

</div>

CSS（包括重置文件）：

/*
    HTML5 Reset :: style.css
    ----------------------------------------------------------
    We have learned much from/been inspired by/taken code where offered from:

    Eric Meyer                  :: http://meyerweb.com
    HTML5 Doctor                :: http://html5doctor.com
    and the HTML5 Boilerplate   :: http://html5boilerplate.com

-------------------------------------------------------------------------------*/

/* Let's default this puppy out
-------------------------------------------------------------------------------*/

html, body, body div, span, object, iframe, h1, h2, h3, h4, h5, h6, p, blockquote, pre, abbr, address, cite, code, del, dfn, em, img, ins, kbd, q, samp, small, strong, sub, sup, var, b, i, dl, dt, dd, ol, ul, li, fieldset, form, label, legend, table, caption, tbody, tfoot, thead, tr, th, td, article, aside, figure, footer, header, menu, nav, section, time, mark, audio, video, details, summary {
    margin: 0;
    padding: 0;
    border: 0;
    font-size: 100%;
    vertical-align: baseline;
    background: transparent;
}                                   

/* consider resetting the default cursor: https://gist.github.com/murtaugh/5247154 */

article, aside, figure, footer, header, nav, section, details, summary {display: block;}

/* Responsive images and other embedded objects
   Note: keeping IMG here will cause problems if you're using foreground images as sprites.
   If this default setting for images is causing issues, you might want to replace it with a .responsive class instead. */
img,
object,
embed {max-width: 100%;}

/* force a vertical scrollbar to prevent a jumpy page */
html {overflow-y: scroll;}

/* we use a lot of ULs that aren't bulleted. 
    don't forget to restore the bullets within content. */
ul {list-style: none;}

blockquote, q {quotes: none;}

blockquote:before, 
blockquote:after, 
q:before, 
q:after {content: ''; content: none;}

a {margin: 0; padding: 0; font-size: 100%; vertical-align: baseline; background: transparent;}

del {text-decoration: line-through;}

abbr[title], dfn[title] {border-bottom: 1px dotted #000; cursor: help;}

/* tables still need cellspacing="0" in the markup */
table {border-collapse: collapse; border-spacing: 0;}
th {font-weight: bold; vertical-align: bottom;}
td {font-weight: normal; vertical-align: top;}

hr {display: block; height: 1px; border: 0; border-top: 1px solid #ccc; margin: 1em 0; padding: 0;}

input, select {vertical-align: middle;}

pre {
    white-space: pre; /* CSS2 */
    white-space: pre-wrap; /* CSS 2.1 */
    white-space: pre-line; /* CSS 3 (and 2.1 as well, actually) */
    word-wrap: break-word; /* IE */
}

input[type="radio"] {vertical-align: text-bottom;}
input[type="checkbox"] {vertical-align: bottom;}
.ie7 input[type="checkbox"] {vertical-align: baseline;}
.ie6 input {vertical-align: text-bottom;}

select, input, textarea {font: 99% sans-serif;}

table {font-size: inherit; font: 100%;}

small {font-size: 85%;}

strong {font-weight: bold;}

td, td img {vertical-align: top;} 

/* Make sure sup and sub don't screw with your line-heights
    gist.github.com/413930 */
sub, sup {font-size: 75%; line-height: 0; position: relative;}
sup {top: -0.5em;}
sub {bottom: -0.25em;}

/* standardize any monospaced elements */
pre, code, kbd, samp {font-family: monospace, sans-serif;}

/* hand cursor on clickable elements */
.clickable,
label, 
input[type=button], 
input[type=submit], 
input[type=file], 
button {cursor: pointer;}

/* Webkit browsers add a 2px margin outside the chrome of form elements */
button, input, select, textarea {margin: 0;}

/* make buttons play nice in IE */
button,
input[type=button] {width: auto; overflow: visible;}

/* scale images in IE7 more attractively */
.ie7 img {-ms-interpolation-mode: bicubic;}

/* prevent BG image flicker upon hover 
   (commented out as usage is rare, and the filter syntax messes with some pre-processors)
.ie6 html {filter: expression(document.execCommand("BackgroundImageCache", false, true));}
*/

/* let's clear some floats */
.clearfix:before, .clearfix:after { content: "\0020"; display: block; height: 0; overflow: hidden; }  
.clearfix:after { clear: both; }  
.clearfix { zoom: 1; }  


*, *:before, *:after {
  -moz-box-sizing: border-box; -webkit-box-sizing: border-box; box-sizing: border-box;
 }

.app-wrp{
    border:1px solid grey;
    width:50%;
    border:1px solid grey;
    margin:1em auto;
}

.app-header{
    width:100%;
    padding:1em;
    border-bottom:1px solid grey;
    background: #ccc;
}

.app-body{

}

#word{
    text-align:center;
    width:100%;
    padding:3em 0;
    border-bottom:1px solid grey;
}

#word > p{
    font-size:3em;
    line-height:1.3em;
}



.char-input-btns-wrp, .app-control-btns-wrp{
    width:100%;
}

.app-control-btns-wrp{
    border-bottom:1px solid grey;
}

.char-input-btns, .app-control-btns{
    text-align:center;
    display:inline-block;
    text-decoration:none;
    font-size:2em;
    margin-right:-4px;
}

.app-control-btns{
    border-right:1px solid grey;    
    width:20%;
}

.app-control-btns:last-child{
    border-right:none;      
    width:40%;
}

.char-input-btns{
    width:20%;

    border-left: 1px solid grey;
    border-top: 1px solid grey;
    color: #424242;
    background:yellow;
}

.char-input-btns:active{
    background:#3399bb;
    color:#fff;
}

.char-input-btns:last-child{
    border-right: 0;
}

.char-input-btns:first-child{
    border-left: 0;
}

.rows{
    width:100%;
    background:pink;
}