2.main.css

/* 1. Use border-box globally */
*,
*:after,
*:before {
    box-sizing: border-box; /* 1 */
}



/* typography */
body {
    font-family: Arial, 'Helvetica Neue', Helvetica, sans-serif;
    font-size: 1.25em;
    padding-top: 1em;
    line-height: 1.4;
}
h1, h2, h3, h4 { margin-top: 0; }
h1 {
    font-size: 2em;
    border-bottom: 1px solid #333;
    padding-bottom: 0.3em;
}
h2 { font-size: 1.7em; }
h3,
.h3 {
    font-size: 1.17em;
    font-weight: bold;
    margin-bottom: 1em;
}
p { margin: 0 0 1em 0;}
a { color: #0074d9; }
a:hover { color: #4dacff; }
a:focus { color: #4dacff; }
ul { margin: 0 0 1.5em 0; }
ul li { margin: 0 0 0.3em 0; }
ul ul { margin-bottom: 0.6em; }
ul ul li { margin-top: 0.3em; }
img { display: block; max-width: 100%; }
pre { margin: 0; }


/* structural */
section,
.section {
    margin-bottom: 2em;
}
section:after,
.section:after {
    content: '';
    display: block;
    height: 1px;
    background-color: #333;
    width: 50%;
    margin: 2em auto 0;
}



/* header */
.back-to {
    margin-bottom: 1em;
}

/* notice */
.c-notice {
    font-size: 0.9em;
    border: 1px solid #ccc;
    padding: 1em;
    margin-bottom: 1.5em;
    background-color: #efefef;
}
.c-notice p:last-child {
    margin: 0;
}
.c-notice--info {
    background: #e6d7f9;
}
.c-notice--help {
    background: #eaf48b;
}



/*
    grid

    inline-block grid as covered in the inlin-block
    section.
*/
.o-g-grid {
    list-style: none;
    padding: 0;
    margin: 0 0 0 -0.5em;
    display: flex;
    flex-flow: wrap;
}
.o-g-grid__item {
    display: inline-block;
    vertical-align: top;
    width: 100%;
    padding-left: 0.5em;
    display: flex;
}
.o-g-grid__item > * {
    flex-grow: 1;
}




/* footer */
.site-footer {
    display: flex;
    align-items: flex-end;
    overflow: hidden;
    margin: 2em 2em 0;
}
.site-footer img {
    width: 50%;
    margin-bottom: -5%;
    flex-grow: 1;
}


/* main nav */
.c-main-nav {
    margin: 0 0 2em 0;
}
.c-main-nav ul {
    list-style: none;
    margin: 0;
    padding: 0;
}
.c-main-nav ul ul {
    margin-left: 1.2em;
}
.c-main-nav > ul > li {
    font-weight: bold;
    margin-bottom: 1em;
}
.c-main-nav li li {
    display: inline-block;
    margin-right: 0.2em;
    font-weight: normal;
}
.c-main-nav li li:after {
    content: ',';
}
.c-main-nav li li:last-child:after {
    content: '';
}
.c-main-nav__tasks a {
    font-weight: bold;
    color: #37BC61;
}



/* holy grail */
.c-holy-grail {
    width: 100%;
}
.c-holy-grail header {
    background-color: #666666;
    padding: 1em;
    color: white;
    margin-bottom: 0.5em;
}
.c-holy-grail footer {
    background-color: #666666;
    padding: 1em;
    color: white;
}
.c-holy-grail nav {
    background-color: #84b8e0;
    padding: 1em;
    margin-bottom: 0.5em;
}
.c-holy-grail nav ul {
    list-style: none;
    margin: 0;
    padding: 0;
}
.c-holy-grail nav a {
    color: black;
}
.c-holy-grail article {
    background-color: #d6d6d6;
    padding: 1em;
    margin-bottom: 0.5em;
}
.c-holy-grail h1 {
    font-size: 1.5em;
}
.c-holy-grail aside {
    background-color: #f36a2b;
    margin-bottom: 0.5em;
}
.c-holy-grail aside h3 {
    font-size: 1em;
    font-weight: normal;
}
.c-holy-grail aside > * {
    background-color: #f36a2b;
    margin-bottom: 0;
}



/* product */
.c-product {
    background-color: #84b8e0;
    padding: 0.8em 1em;
    margin-bottom: 0.5em;
}
.c-product img {
    display: block;
    margin: 0 auto;
}



/* picture holder */
.c-picture-holder {
    margin-bottom: 0.5em;
    border: 0.5em solid #84b8e0;
    text-align: center;
}
.c-picture-holder img {
    display: block;
}
.c-picture-holder__cite {
    background: #efefef;
    padding: 0.2em;
    font-size: 0.9em;
}




/* multi dimensional layout */
.multi-dime header,
.multi-dime nav,
.multi-dime aside,
.multi-dime article {
    background: white;
    border: 10px solid black;
    padding: 20px;
    position: relative;
}
.multi-dime aside {
    background: purple;
}
.multi-dime article {
    background: green;
}
.multi-dime header {
    background: orange;
    font-size: 1.5em;
}
.multi-dime nav {
    padding: 10px;
    background: white;
}
.multi-dime nav ul {
    list-style: none;
    margin: 0;
    padding: 0;
}
.multi-dime nav li:last-child {
    margin-bottom: 0;
}
.multi-dime nav a {
    display: block;
    color: white;
    background: grey;
    padding: 0.5em;
    text-decoration: none;
}
.multi-dime nav a:hover,
.multi-dime nav a:focus {
    background: #ccc;
    color: black;
}
.multi-dime__label {
    font-size: 16px;
    position: absolute;
    top: 0;
    right: 0;
    background: black;
    color: white;
    padding: 5px 15px;
}