:root{
    --black: #000000;
    --yellow: #FFCC01;
    --white: #FFFFFF;
    --purple: #0a052d;
}

html {
    scroll-behavior: smooth;
}

@media (prefers-reduced-motion) {
    html {
      scroll-behavior: auto;
    }
}
body {
    font-family: 'Source Sans Pro', 'Helvetica', sans-serif;
    font-size: 1.25rem;
    margin: 0;
    padding: 0;
}

/* Generic */
.btn {
    padding: 1.25rem 2rem;
    max-width: max-content;
    text-decoration: none;
    font-weight: bold;
    font-size: 1.75rem;
    line-height: 1.2;
    color: var(--black);
    border-radius: 5px;
}

.btn-primary {
    background-color: var(--yellow);
}

.btn-primary:hover {
    filter: brightness(0.85);
}

.btn-primary:focus-visible {
    outline: 5px solid var(--purple);
    outline-offset: 2px;
}

a:not(.header a) {
    color: var(--black);
}
a:not(.header a):hover {
    background-color: var(--yellow);
}
a:not(.header a):focus {
    outline: 3px solid var(--purple)
}

p.text-center {
    text-align: center;
}

/* Header navigation */

.skip-link {
    position: absolute;
    top: 8px;
    left: 8px;
    background: var(--yellow);
    padding: 1.5rem 2rem 1.2rem;
    border: 5px solid var(--yellow);
    font-weight: bold;
    line-height: 1;
    z-index: 2
}

.skip-link:not(:focus) {
    white-space: nowrap;
    width: 1px;
    height: 1px;
    overflow: hidden;
    border: 0;
    padding: 0;
    clip: rect(0 0 0 0);
    clip-path: inset(50%); 
    margin: -1px;
}

.skip-link:link,
.skip-link:visited {
    color: var(--black);
    text-decoration: none;
}

.header {
    position: absolute;
    width: calc(100% - 3rem);
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
    align-items: center;
    max-width: 1312px;
    left: 0;
    right: 0;
    margin: auto;
    padding: 1rem 1.5rem;
}

header.header-dark {
    background-color: #1d1649;
}

header.header-dark .header {
    position: relative;
}

.nav .nav-items {
    display: flex;
    flex-wrap: wrap;
    list-style: none;
    gap: 3rem;
    padding: 0;
}

.nav .nav-item {
    margin: 0 0.5rem;
}

.nav .nav-link {
    color: var(--white);
    text-decoration: none;
}

.nav .nav-link[aria-current=page] {
    text-decoration: underline;
}

.header a.logo {
    display: inline-block;
}

.header a:not(a.logo):hover {
    text-decoration: underline;
}

.header a:focus-visible {
    outline: 3px solid var(--white);
}

@media (max-width: 820px) {
    .nav .nav-items {
        gap: 0.5rem;
    }
}

/* Hero Section */

.hero-section {
    background: #0a052d;
    background-size: cover;
    padding: 10rem calc((100vw - 1312px)/2) 5rem;
    height: clamp(475px, calc(100vh - 12rem), 700px);
}

.site-title {
    font-size: 5.25rem;
    font-weight: 900;
    line-height: 1.2;
    text-transform: uppercase;
    color: var(--white);
    margin: 0;
    max-width: 760px;
}

.site-date {
    font-size: 3.5rem;
    font-weight: 900;
    line-height: 1.2;
    color: var(--yellow);
    margin-top: 0.5rem;
}

.hero-section .btn-primary {
    display: flex;
    justify-content: center;
    margin: 8rem auto 0;
}

.hero-section .btn-primary:focus-visible {
    outline: 5px solid var(--white);
}

@media (max-width: 820px) {
    .hero-section {
        padding: 10rem 1rem 5rem;
        min-height: 0;
        background-position: center;
    }

    .site-title {
        font-size: 4rem;
    }

    .site-date {
        font-size: 3.25rem;
    }
}

/* Site sections */

.site-section {
    max-width: 1312px;
    margin: 4rem auto 8rem ;
    padding: 0 1rem;
}

.site-section:nth-of-type(2n) {
    background: #fbfbf8;
    max-width: none;
    margin: -4rem auto 4rem;
    padding: 4rem calc((100vw - 1312px)/2);
}

.section-title {
    font-size: 3rem;
    font-weight: bold;
    line-height: 1.2;
    text-align: center;
    margin: 0;
}

.section-summary {
    text-align: center;
}

.section-heading-underline {
    border: 3px solid var(--yellow);
    width: 150px;
}

@media (max-width: 820px) {
    .site-section:nth-of-type(2n) {
        padding: 4rem 1rem;
    }
}

/* List items */

.item-title {
    font-size: 1.5rem;
    line-height: 1.2;
    margin: 0;
}

.topic-items {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(235px, 1fr));
    grid-gap: 3rem;
    list-style: none;
    padding: 0;
    margin: 4rem 0;
}

.objective-items {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(235px, 1fr));
    grid-gap: 3rem;
    list-style: none;
    padding: 0;
    margin: 4rem 0;
}

.objective-item {
    position: relative;
    padding-top: 1rem;
}

.objective-item:before {
    content : "";
    position: absolute;
    left: 0;
    top: 0;
    height: 1px;
    width: 30%;
    border-bottom: 2px solid var(--yellow);
}

/* Footer */
.site-footer {
    background-color: var(--yellow);
    padding: 2rem calc((100vw - 1312px)/2);
    display: flex;
    gap: 4rem;
}

.nav-footer {
    padding: 0;
    list-style: none;
}

@media (max-width: 820px) {
    .site-footer {
        display: block;
        padding: 2rem 1rem;
    }
}