How did I goof up a 'simple' text-align: center; CSS method? My h1 and h2 won't center in the header

CSS for Typography: Zen Gardens project --

/* css Zen Garden default style v1.02 / / css released under Creative Commons License - http://creativecommons.org/licenses/by-nc-sa/1.0/ */

/* Your images should be linked as if the CSS file sits in the same folder as the images. ie. no paths. */

/* Colors

Primary White: #f6f4ec; Green: #9bc152; Navy-Gray: #282932;

Secondary Medium Green: #81a53d; Dark Green: #708647; Grays: #8b8d9b and #6d6f81; Blues: #6b6d85 and #47495d; Dark Navy: #1b1b21; */

/* Webfonts */ @import url (http://fonts.googleapis.com/css?family=Alegreya+Sans+SC:400,400italic|Alegreya+Sans:400,400italic|Alegreya:400italic,900italic);

/* Basic Elements */ html { margin: 0; padding: 0; } body { font-family: 'Alegreya Sans', Verdana, Tahoma, sans-serif; font-size: 1.25em; line-height: 1.6; margin: 0; padding: 0; color: #282932; background: #f6f4ec; }

p { margin: 0; }

p + p { text-indent: 1.5em; }

h1,h2,h3,h4,h5,h6 { font-family: 'Alegreya', Georgia, serif; font-weight: normal; font-style: italic; color: #95c152; }

h1 { font-size: 3.157em; line-height: 1.1; }

h2 { font-size: 2.369em; line-height: 1.15; margin: 0 0 .54em; }

h3 { font-size: 1.777em; line-height: 1.2; margin: .9em 0 .62em; }

ul { margin: 0; }

li { margin: 0; }

a:link { text-decoration: none;

} a:visited { text-decoration: none; }

a:hover, a:focus, a:active { text-decoration: none; }

abbr { font-family: 'Alegreya Sans SC', 'Alegreya Sans', Verdana, Tahoma, sans-serif; <!--text-transform: lowercase;-->

::selection { }

/* Specific Styles */

header { padding: 10em 4%; text-align: center; }

header h1 { }

header h2 { }

header abbr { }

.summary { }

.summary p { }

.summary p + p { }

.summary a { }

.summary a:hover { }

.preamble, .requirements { }

.preamble h3, .requirements h3 { }

.preamble p, .requirements p { }

.requirements a { }

.requirements a:hover { }

.requirements p:last-of-type { }

.requirements p:last-of-type a { }

.requirements p:last-of-type a:hover { }

.benefits { }

.benefits h3 { }

.benefits p { }

.explanation, .participation { }

.explanation { }

.participation { }

.explanation h3, .participation h3 { }

.explanation p, .participation p { }

.participation h3 { }

.participation a { }

.participation a:hover { }

.participation p:last-of-type a:nth-of-type(1), .participation p:last-of-type a:nth-of-type(2) { }

footer { }

footer:after { }

footer a { }

footer a:nth-of-type(even) { }

footer a:hover { }

aside { }

.sidebar { }

.design-selection { }

.design-archives, .zen-resources { }

.sidebar h3 { }

.sidebar ul { }

.sidebar li { }

.sidebar a { }

.sidebar a:hover { }

.design-selection a:nth-of-type(even) { }

.sidebar a:hover:nth-of-type(even) { }

.zen-resources h3 { }

.design-archives a, .zen-resources a { }

/* Media Queries */

@media (max-width: 64em) { body { }

.summary p { }

.explanation h3, .participation h3, .preamble h3, .requirements h3, .benefits h3 { }

.explanation p, .participation p, .preamble p, .requirements p, .benefits p { } }

@media (max-width: 54em) { body { }

.summary p { } }

@media (max-width: 47em) { header h1 { }

header h2 { }

.explanation, .participation { } }

@media (max-width: 34em) { header { } header h1 { }

header h2 { }

.summary p { }

.summary p + p { }

h3 { }

.design-selection { }

.design-selection li:last-of-type { }

.design-archives { }

.zen-resources { } }

@media (min-width: 47em) { .benefits { }

.benefits h3 { }

.benefits p { } }

@media (min-width: 54em) { .benefits { } }

@media (min-width: 64.125em) { .benefits { }

aside { }

aside:hover { }

aside:after { }

aside { } }

@media (min-width: 94em) { body { }

.summary p { }

.benefits { }

.explanation h3, .explanation p, .participation h3, .participation p { } }

@media (min-width: 120em) { body { }

.summary p { }

.preamble h3, .preamble p, .requirements h3, .requirements p { }

.explanation h3, .explanation p, .participation h3, .participation p { }

.benefits { } }

/* Animations / <eof> ** My <header> text, h1 and h2 won't align center ***