:root {
    --color-gradient-purple: #ad7fa8;
    --color-gradient-blue: #729fcf;
    --gradient-primary: linear-gradient(to right, #ad7fa8, #729fcf);
    
    --color-dark-gray: #222222;
    --color-muted: rgba(20, 20, 20, 0.7);
    --color-muted-extra: rgba(20, 20, 20, 0.5);
    
    --bg-body: #EBEFF5;
    --bg-card: #fff;
    --bg-footer: #E3E8EE;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Px Grotesk', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    font-size: 16px;
    line-height: 1.4;
    color: var(--color-dark-gray);
    background-color: var(--bg-body);
}

header {
    padding: 3rem 4rem;
    text-align: center;
}

header h1 {
    font-size: 2.5rem;
    font-weight: 400;
    margin-bottom: 1rem;
    color: var(--color-dark-gray);
}

.subtitle {
    font-size: 1.25rem;
    font-weight: 400;
    line-height: 1.3;
    max-width: 600px;
    margin: 0 auto;
    color: var(--color-muted-extra);
}

.main-nav {
    display: flex;
    justify-content: center;
    gap: 0.5rem;
    margin-top: 2rem;
    flex-wrap: wrap;
}

.main-nav a {
    display: inline-block;
    padding: 0.1rem 0.4rem;
    background-color: var(--bg-card);
    font-size: 0.8125rem;
    border-radius: 4px;
    color: var(--color-muted-extra);
    text-decoration: none;
    transition: background-color 0.2s ease, color 0.2s ease;
}

.main-nav a:hover,
.main-nav a:focus {
    color: var(--color-dark-gray);
}

.main-nav a:focus {
    outline: 2px solid var(--color-gradient-blue);
    outline-offset: 2px;
}

main {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem 4rem;
}

section {
    margin-bottom: 4rem;
}

section h2 {
    font-size: 1.875rem;
    font-weight: 500;
    margin-bottom: 1rem;
    color: var(--color-dark-gray);
}

section h3 {
    font-size: 1.25rem;
    font-weight: 400;
    margin-top: 2rem;
    margin-bottom: 0.75rem;
    line-height: 1.3;
    color: var(--color-muted-extra);
}

section h3:first-of-type {
    margin-top: 0;
}

section h3.with-date {
    position: relative;
    padding-right: 120px;
}

section h3.with-date .updated-tag {
    position: absolute;
    right: 0;
    top: 0;
    bottom: auto;
    background-color: var(--bg-card);
}

.resource-grid {
    display: flex;
    flex-wrap: wrap;
    row-gap: 0.15rem;
    column-gap: 0.15rem;
}

.resource-card {
    position: relative;
    flex-basis: 250px;
    flex-grow: 0;
    flex-shrink: 1;
    max-width: 100%;
    padding: 1.5rem;
    border-radius: 8px;
    background-color: var(--bg-card);
    font-size: 0.9375rem;
    color: var(--color-muted);
    line-height: 1.4;
}

.resource-card h4 {
    font-size: 1.25rem;
    font-weight: 400;
    margin-bottom: 0.75rem;
    line-height: 1.3;
    color: var(--color-dark-gray);
}

p {
    margin-bottom: 0.75rem;
}

.resource-card p:last-child {
    margin-bottom: 0;
}

.links {
    margin-bottom: 0.75rem;
}

.links > div {
    overflow-wrap: anywhere;
}

.links span {
    white-space: nowrap;
}

.resource-link {
    color: var(--color-gradient-blue);
    text-decoration: none;
    transition: color 0.2s ease;
    word-break: break-all;
    overflow-wrap: anywhere;
}

.resource-link:hover,
.resource-link:focus {
    color: var(--color-gradient-purple);
    text-decoration: underline;
}

.resource-link:focus {
    outline: 2px solid var(--color-gradient-blue);
    outline-offset: 2px;
}

.updated-tag {
    position: absolute;
    bottom: 0.75rem;
    right: 0.75rem;
    display: inline-block;
    padding: 0.1rem 0.4rem;
    background-color: var(--bg-body);
    font-size: 0.8125rem;
    border-radius: 4px;
    color: var(--color-muted-extra);
}


footer {
    background-color: var(--bg-footer);
    padding: 2rem;
    text-align: center;
    margin-top: 2rem;
    color: var(--color-muted-extra);
    font-size: 0.9rem;
}

footer p {
    margin-bottom: 0.5rem;
}

.footer-contribute {
    margin-top: 1.5rem;
    padding-top: 1.5rem;
    border-top: 1px solid rgba(20, 20, 20, 0.1);
}

.footer-link {
    color: var(--color-gradient-blue);
    text-decoration: none;
    transition: color 0.2s ease;
}

.footer-link:hover,
.footer-link:focus {
    color: var(--color-gradient-purple);
    text-decoration: underline;
}

@media (min-width: 768px) {
    header {
        padding: 4rem 4rem;
    }

    header h1 {
        font-size: 3rem;
    }

    section h2 {
        font-size: 2.25rem;
    }

    .resource-card {
        flex-basis: calc(50% - 0.075rem);
        max-width: calc(50% - 0.075rem);
        flex-grow: 0;
    }
}

@media (min-width: 1024px) {
    header {
        padding: 5rem 4rem;
    }

    .resource-card {
        flex-basis: calc(33.333% - 0.1rem);
        max-width: calc(33.333% - 0.1rem);
        flex-grow: 0;
    }
}

@media (min-width: 1400px) {
    main {
        max-width: 1600px;
    }

    .resource-card {
        flex-basis: calc(25% - 0.1125rem);
        max-width: calc(25% - 0.1125rem);
        flex-grow: 0;
    }
}

@media (max-width: 1023px) {
    main {
        padding: 2rem 2rem;
    }

    header {
        padding: 3rem 2rem;
    }
}

@media (max-width: 767px) {
    main {
        padding: 2rem 1rem;
    }

    header {
        padding: 2rem 1rem;
    }

    header h1 {
        font-size: 2rem;
    }

    section h2 {
        font-size: 1.75rem;
    }

    .resource-card {
        flex-basis: 100%;
        max-width: 100%;
    }
}