:root {
    --color-background: #F7F7F7;
    --color-text: #000000;
    --color-text-muted: #666666;

    --font-body: Arial, sans-serif;

    --content-window: 75rem;

    --space-page-x: 2rem;
    --space-page-y: 4rem;
    --space-list-item: 2.5rem;

    --font-size-heading: 3rem;
    --font-size-paragraph: 1.2rem;
}

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

body {
    margin: 0;
    font-family: var(--font-body);
    background: var(--color-background);
    color: var(--color-text);
}

header {
    border-bottom: 2px solid var(--color-text);
}

nav {
    max-width: 900px;
    margin: 0 auto;
    padding: 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

nav h1 {
    margin: 0;
    font-size: 1.5rem;
}

nav ul {
    list-style: none;
    margin: 0;
    padding: 0;
    display: flex;
    gap: 20px;
}

a {
    color: var(--color-text);
    text-decoration: none;
}

a:hover {
    text-decoration: underline;
}

main {
    max-width: var(--content-window);
    margin: 0 auto;
    padding: var(--space-page-y) var(--space-page-x);
}

h1 {
    margin: 0 0 1rem;
    font-size: var(--font-size-heading);
}

p {
    margin: 1rem 0;
    font-size: var(--font-size-paragraph);
    line-height: 1.6;
}

/* Home page */

.home-page {
    text-align: center;
}

.home-page h1 {
    padding-top: 12rem;
}

/* Research page */

.research-page {
    text-align: left;
}

/* Publications page */

.publications-page {
    text-align: left;
}

.publications-page .publications {
    padding-left: 1.5rem;
    font-size: 1rem;
}

.publications-page .publications li {
    margin-bottom: 2rem;
    font-size: var(--font-size-paragraph);
    font-weight: bold;
}

.publications-page .publications a {
    color: var(--color-text);
    font-size: var(--font-size-paragraph);
    font-weight: bold;
    text-decoration: none;
}

.publications-page .reference {
    margin: 1rem 0;
    color: var(--color-text-muted);
    font-size: var(--font-size-paragraph);
    font-weight: normal;
    line-height: 1.5;
}

/* Error page */

.error-page {
    min-height: 60vh;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
}

.error-content {
    max-width: 40rem;
}

.error-code {
    margin: 0;
    color: var(--color-text-muted);
    font-size: 2rem;
    letter-spacing: 0.15em;
    text-transform: uppercase;
}

.button {
    display: inline-block;
    margin-top: 1.5rem;
    padding: 0.75rem 1.2rem;
    border: 2px solid var(--color-text);
    color: var(--color-text);
    text-decoration: none;
}

.button:hover {
    background: var(--color-text);
    color: var(--color-background);
    text-decoration: none;
}