img {
    max-width: 100%;
}

html {
    font-size: 62.5%;
}

body {
    font-size: 1.6rem;
    color: #000;
    counter-reset: theorem;
    counter-reset: definition;
}

header {
    border-bottom: 0.2rem solid #000;
}

nav {
    text-align: right;
}

nav a {
    font-size: 1.6rem;
    font-weight: bold;
    color: black;
    text-decoration: none;
    text-transform: uppercase;
}

footer {
    margin-top: 3rem;
    padding: 1.2rem 0;
    border-top: 0.2rem solid #000;
    font-size: 1.2rem;
    color: #555;
}

h1 {
    font-size: 2.4rem;
}

h2 {
    font-size: 2rem;
}

article .header {
    font-size: 1.4rem;
    font-style: italic;
    color: #555;
}

.logo a {
    font-weight: bold;
    color: #000;
    text-decoration: none;
}

a.icon {
    Text-decoration: none;
    outline: none;
    border: 0px none transparent;
}

.sourceCode {
    display:block;
    padding-left: 1rem;
    margin-top: 1rem;
    margin-bottom: 1rem;
}

.definition, .proposition, .theorem {
    display: block;
    border-left: 2px solid #808080;
    padding-left: 1rem;
    margin-top: 1rem;
    margin-bottom: 1rem;
}

.proposition, .theorem {
    counter-increment: theorem;
    font-style: italic;
}

.definition p:first-child, .proposition p:first-child, .theorem p:first-child, .proof p:first-child {
    display: inline;
}

.definition p, .proposition p, .theorem p, .proof p {
    margin-top: 0.4rem;
    margin-bottom: 0.4rem;
    padding-left: 1rem;
}

.theorem:before {
    content: "Theorem " counter(theorem) ".";
    font-weight: bold;
    font-style: normal;
}

.proposition:before {
    content: "Proposition " counter(theorem) ".";
    font-weight: bold;
    font-style: normal;
}

.definition:before {
    counter-increment: definition;
    content: "Definition " counter(definition) ".";
    font-weight: bold;
    font-style: normal;
}

.proof:before {
    content: "Proof.";
    font-style: italic;
}

.proof:after {
    content: "\220E";
    float: right;
}

@media (max-width: 319px) {
    body {
	width: 90%;
	margin: 0;
	padding: 0 5%;
    }
    header {
	margin: 4.2rem 0;
    }
    nav {
	margin: 0 auto 3rem;
	text-align: center;
    }
    footer {
	text-align: center;
    }
    .logo {
	text-align: center;
	margin: 1rem auto 3rem;
    }
    .logo a {
	font-size: 2.4rem;
    }
    nav a {
	display: block;
	line-height: 1.6;
    }
}

@media (min-width: 320px) {
    body {
	width: 90%;
	margin: 0;
	padding: 0 5%;
    }
    header {
	margin: 4.2rem 0;
    }
    nav {
	margin: 0 auto 3rem;
	text-align: center;
    }
    footer {
	text-align: center;
    }
    .logo {
	text-align: center;
	margin: 1rem auto 3rem;
    }
    .logo a {
	font-size: 2.4rem;
    }
    nav a {
	display: inline;
	margin: 0 0.6rem;
    }
}

@media (min-width: 640px) {
    body {
	width: 80rem;
	margin: 0 auto;
	padding: 0;
    }
    header {
	margin: 0 0 3rem;
	padding: 1.2rem 0;
    }
    nav {
	margin: 0;
	text-align: right;
    }
    nav a {
	margin: 0 0 0 1.2rem;
	display: inline;
    }
    footer {
	text-align: right;
    }
    .logo {
	margin: 0;
	text-align: left;
    }
    .logo a {
	float: left;
	font-size: 1.8rem;
    }
}