.antialiased{
    -webkit-font-smoothing: antialiased;
}

header {
    position: sticky;
    top: 0;
    z-index: 100;
    background-color: rgba(168, 199, 227, 0.3);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    padding: 0 0;
    transition: box-shadow 0.2s, background-color 0.2s;
}
header nav {
    max-width: 1460px;
    padding: 0.6rem 1.5rem;
    margin: 0 auto;
}
header.scrolled {
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.15);
    background-color: rgba(168, 199, 227, 0.75);
}
nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 0;
}
.nav-logo {
    display: flex;
    align-items: center;
    gap: 0.6rem;
    text-decoration: none;
}
.seismos-logo {
    width: 48px;
    height: 48px; 
}
.nav-logo span {
    font-family: Lato;
    font-size: 1.55rem;
    font-weight: 700;
    color: white;
}
.nav-links {
    display: flex;
    font-size: 1rem;
    gap: 2.5rem;
}
.nav-links a {
    color: var(--text);
    text-decoration: none;
}
.nav-links a:hover {
    text-decoration: underline;
}
.nav-hamburger {
    display: none;
    flex-direction: column;
    justify-content: center;
    gap: 5px;
    width: 32px;
    height: 32px;
    padding: 4px;
    background: none;
    border: none;
    cursor: pointer;
}
.nav-hamburger span {
    display: block;
    width: 100%;
    height: 2px;
    background-color: var(--text);
    transition: transform 0.3s, opacity 0.3s;
}


#hero {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1.5rem;
    align-items: center;
    min-height: 75vh;
}

.hero-txt {
    display: flex;
    flex-direction: column;
    justify-content: center;
    gap: 2rem;
    transform: translateY(-5rem);
}
.pill {
    display: inline-block;
    width: fit-content;
    padding: 0.4rem 1.25rem;
    border-radius: 9999px;
    background: #D3E7F9;
    color: var(--text);
    font-size: 0.875rem;
    font-weight: 300;
}


#overview {
    margin: -2rem 0 0 0;
    display: grid;
    grid-template-columns: 2fr 3fr;
    gap: 1.5rem;
    align-items: center;
}
.overview-img img {
    max-width: 75%;
    margin: 0 auto;
}
.overview-txt {
    padding: 0 4rem 0 2rem;
}
.overview-txt h2{
    margin: 0 0 1.5rem 0;
}


#earthquakes {
    margin: 4rem 0 0 0;
    padding: 6rem 0 0 0;
}
#earthquakes a {
    color: var(--text);
    text-decoration: none;
}
#earthquakes a:hover {
    text-decoration: underline;
}
.earthquakes-stats-columns {
    margin: 0 0 0.5rem 0;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1.5rem;
}
.earthquakes-stats-col {
    text-align: center;
}
sup a:focus {
    outline: none;
}
.earthquakes-exp-columns {
    margin: 2rem 3rem 0 3rem;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
}


#technology {
    margin: 2rem 0 0 0;
    padding: 6rem 0 0 0;
}
#technology h2 {
    text-align: center;
    margin: 0 0 2rem 0;
}
.technology-columns {
    margin: 1.5rem 0 0 0;
    display: grid;
    grid-template-columns: 1fr 1fr 1fr;
    gap: 1.5rem;
}
.technology-columns h3 {
    margin: 0.25rem 0 0.75rem 0;
    text-align: center;
}


#features {
    margin: 2rem 0 6rem 0;
    padding: 8rem 0 6rem 0;
}
.features-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    grid-template-rows: auto 1fr;
    grid-template-areas:
        "img heading"
        "img accordion";
    gap: 1.5rem;
    align-items: start;
}
.features-img {
    grid-area: img;
    position: relative;
    height: 70vh;
}
.features-img picture {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 100%;
    opacity: 0;
    z-index: 0;
}
.features-img picture.previous {
    opacity: 1;
    z-index: 1;
}
.features-img picture.active {
    opacity: 1;
    z-index: 2;
    transition: opacity 0.3s;
}
.features-img img {
    width: 100%;
    height: 100%;
    object-fit: contain;
}
#features h2 {
    grid-area: heading;
    margin: 2rem 0 0 0;
}
.features-accordion {
    grid-area: accordion;
    margin: 0;
}
.accordion-header {
    padding: 0.85rem 0;
    display: flex;
    justify-content: space-between;
    align-items: center;
    width: 100%;
    text-align: left;
    background: none;
    border: none;
    border-bottom: 2px solid var(--text);
    font-family: inherit;
    font-size: 1.4rem;
    font-weight: 600;
    color: var(--text);
    cursor: pointer;
    position: relative;
}
.accordion-chevron {
    width: 50px;
    height: 50px;
    transition: transform 0.5s, color 0.1s;
}
.accordion-header:active .accordion-chevron,
.accordion-item.click-pulse .accordion-chevron {
    color: #ffffff;
}
.accordion-progress {
    position: absolute;
    bottom: 0;
    left: 0;
    height: 2px;
    width: 0;
    background-color: #ffffff;
    z-index: 99;
    transform: translateY(2px)
}
.autoplay .accordion-item.active .accordion-progress {
    animation: progress-fill 3s linear forwards;
}
@keyframes progress-fill {
    from { width: 0; }
    to { width: 100%; }
}
.accordion-body {
    padding: 0;
    display: grid;
    grid-template-rows: 0fr;
    transition: grid-template-rows 0.5s;
}
.accordion-body ul {
    margin: 0;
    padding: 0.75rem 0 0 1.5rem;
}
.accordion-body li {
    margin: 0 0 1rem 0;
    line-height: 1.35rem;
}
.accordion-body li:last-child {
    margin-bottom: 1.5rem;
}
.accordion-item.active .accordion-body {
    grid-template-rows: 1fr;;
}
.accordion-item.active .accordion-chevron {
    transform: rotate(180deg);
}
.accordion-body > div {
    overflow: hidden;
}


#about {
    padding: 8rem 2rem;
}
#about h2 {
    margin: 0 4rem 2rem 4rem;
}
#about p {
    margin: 0 4rem;
}
.about-columns {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
    margin: 3rem 1rem 0 1rem;
}
.about-col {
    text-align: center;
}
.about-col img {
    width: 60%;
    margin: 0 auto 1rem auto;
}
.about-col p {
    padding: 0.5rem 0 1rem 0;
}
.about-links {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 1.5rem;
}
.about-btn {
    width: 8rem;
    height: auto;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    padding: 0.5rem 1rem;
    border: 2px solid white;
    background-color: var(--background-dark);
    color: white;
    text-decoration: none;
    font-family: inherit;
    font-size: inherit;
    font-weight: 300;
}
.about-btn svg {
    width: auto;
    height: 1.1rem;
    fill: white;
}
.about-btn:hover {
    background-color: white;
    color: var(--background-dark);
}
.about-btn:hover svg {
    fill: var(--background-dark);
}


footer {
    max-width: 1000px;
    margin: 0 auto 0 auto;
    padding: 8rem 0 0 0;
    text-align: center;
}
footer p {
    font-size: 0.875rem;
    margin-bottom: 0.5rem;
    font-weight: 300;
}
footer p:last-child {
    margin-bottom: 0;
}
.references {
    text-align: left;
    max-width: 800px;
    margin: 0 auto 4rem auto;
    padding: 0 0 0 1.5rem;
    font-size: 0.875rem;
    font-weight: 300;
    line-height: 1rem;
}
.references li {
    padding: 0 0 1rem 0;
}
.references a:first-child {
    text-decoration: none;
    margin-right: 0.25rem;
}


@media (max-width: 1366px) {
    html { 
        font-size: 20px;
    }

    #hero {
        padding: 4rem 2rem 0 2rem;
        gap: 1rem;
        min-height: 60vh;
    }

    #overview {
        margin: 0 0 0 0;
        padding: 2rem 0 0 0;
        gap: 1rem;

    }
    .overview-img img {
        max-width: 65%;
        margin: 0 auto;
    }

    #earthquakes {
        margin: 2rem 0 0 0;
        padding: 4rem 0 0 0;
    }
    .earthquakes-stats-columns {
        margin: 0 4rem;
        gap: 0;
    }
    .earthquakes-exp-columns {
        gap: 3rem;
    }

    #technology {
    margin: 0 0 0 0;
    padding: 4rem 0 0 0;
    }

    #features {
        margin: 0rem 0 4rem 0;
        padding: 6rem 0 4rem 0;
    }
    .features-content {
        gap: 0;
    }
    .features-img {
        height: 80vh;
    }
    .features-accordion {
        margin: 1.5rem 1rem 0 0;
    }
    .accordion-chevron {
        width: 42px;
        height: 42px;
    }

    #about {
        padding: 6rem 2rem;
    }
    .about-columns {
        gap: 0;
        margin: 3rem 3rem 0 3rem;
    }
    
    footer {
        padding: 6rem 0 0 0;
    }
}


@media (max-width: 1024px) {
    h1 { 
        font-size: 3.0rem;
    }
    h2 { 
        font-size: 2.2rem;
    }

    #hero {
        padding: 3rem 2rem 0 2rem;
        gap: 1rem;
        min-height: 50vh;
    }

    #overview {
        padding: 4rem 0 0 0;
    }
    .overview-img img {
        max-width: 70%;
        margin: 0 auto;
    }

    .earthquakes-exp-columns {
        margin: 1.5rem 2rem 0 2rem;
        gap: 3rem;
    }

    #technology h2 {
        margin: 0 0 1.5rem 0;
    }

    #features {
        margin: 2rem 0 4rem 0;
        padding: 4rem 0 4rem 0;
    }
    .features-img {
        position: relative;
        height: 85vh;
    }
    .features-accordion {
        margin: 0.35rem 1rem 0 0;
    }
    #features h2 {
        margin-bottom: 0.25rem;
    }
    .accordion-header {
        padding: 0.4rem 0;
        font-size: 1.1rem;
        font-weight: 600;
    }
    .accordion-chevron {
        width: 36px;
        height: 36px;

    }
    .accordion-body ul {
        margin: 0;
        padding: 0.6rem 0 0 1.5rem;
    }
    .accordion-body li {
        margin: 0 0 0.35rem 0;
        line-height: 1.25rem;
    }
    .accordion-body li:last-child {
        margin-bottom: 0.5rem;
    }

    #about {
        padding: 6rem 0;
    }
    #about h2 {
        margin: 0 3rem 1.5rem 3rem;
    }
    #about p {
        margin: 0 3rem;
    }
    .about-columns {
        margin: 3rem 0 0 0;
    }
    .about-col img {
        width: 65%;
    }
}


@media (max-width: 768px) {
    html { font-size: 18px; }
    h1 { font-size: 4rem; }
    h2 { font-size: 2.35rem; }
    header nav {
        padding: 0.5rem 1.5rem;
        margin: 0 auto;
    }
    nav { 
        flex-wrap: wrap;
        gap: 1rem;
    }
    .seismos-logo {
        width: 36px;
        height: 36px; 
    }
    .nav-logo span {
        font-family: Lato;
        font-size: 1.35rem;
        font-weight: 700;
        color: white;
    }
    .nav-hamburger {
        display: flex;
    }
    .nav-links {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        flex-direction: column;
        gap: 0;
        padding: 0 1.5rem 0 1.5rem;
        background-color: var(--background-light);
        text-align: center; 
        font-size: 1.25rem;
    }
    .nav-links a {
        padding: 0.75rem 0 0.75rem 0;
        border-bottom: 1px solid rgba(7, 21, 40, 0.1);
    }
    .nav-links a:last-child {
        border-bottom: 0;
    }
    .nav-links.open {
        display: flex;
        box-shadow: 0 4px 8px rgba(0, 0, 0, 0.15);
    }
    header.scrolled .nav-links {
        box-shadow: 0 4px 8px rgba(0, 0, 0, 0.15);
    }
    .nav-hamburger.open span:nth-child(1) {
        transform: translateY(7px) rotate(45deg);
    }
    .nav-hamburger.open span:nth-child(2) {
        opacity: 0;
    }
    .nav-hamburger.open span:nth-child(3) {
        transform: translateY(-7px) rotate(-45deg);
    }
    
    #hero,
    .earthquakes-exp-columns,
    .technology-columns,
    .about-columns {
        grid-template-columns: 1fr;
    }
    
    #hero {
        padding: 0.5rem 0 0 0;
        align-items: center;
    }
    .hero-txt { 
        transform: none;
        align-items: center;
        text-align: center; 
    }
    #hero h1 {
        margin: -1rem 0 1rem 0;
    }
    .hero-img img {
        margin: 0 auto;
    }

    #overview { 
        margin-top: 2rem;
    }
    .overview-txt { 
        padding: 0;
    }
    .overview-img img {
        max-width: 90%;
    }
    
    .earthquakes-stats-columns {
        margin: 0 0;
        padding: 0 0;
        gap: 0;
    }
    .earthquakes-exp-columns {
        margin: 1.5rem 0;
        gap: 1rem;
    }

    #technology {
        margin: -1rem 0 0 0;
        padding: 4rem 0 0 0;
        }
    #technology h2 {
        margin: 0 0 1rem 0;
    }
    .technology-columns {
        margin: 1.5rem 0 0 0;
        gap: 0;
    }

    #features {
        padding: 4rem 0 0 0;
        min-height: 110vh;
    }
    .features-content {
        grid-template-columns: 2fr 3fr;
    }
    .features-img img {
        margin: 0 auto;
    }
    .features-accordion {
        margin: 0.2rem 0 0 0;
    }
    #features h2 {
        margin-bottom: 0.1rem;
    }
    .accordion-header {
        padding: 0.25rem 0;
        font-size: 1rem;
    }
    .accordion-chevron {
        width: 32px;
        height: 32px;
    }
    .accordion-body ul {
        padding: 0.4rem 0 0 1.5rem;
    }
    .accordion-body li {
        margin: 0 0 0.25rem 0;
        line-height: 1.2rem;
    }
    .accordion-body li:last-child {
        margin-bottom: 0.4rem;
    }

    #about {
        padding: 5rem 0;
    }
    #about h2 {
        margin: 0 1.5rem 1rem 1.5rem;
    }
    #about p {
        margin: 0 1.5rem;
    }
    .about-columns {
        margin: 0;
    }
    .about-col {
        margin: 1rem 0;
    }
    .about-col img {
        margin: 2rem auto 1rem auto;
        width: 45%;
    }
}

@media (max-width: 480px) {
    h1 {
        font-size: 3rem;
    }
    h3 {
        font-size: 1.5rem;
    }

    .light, 
    .dark, 
    .darker {
        padding-left: 18px;
        padding-right: 18px; 
    }

    #hero {
        padding: 1.25rem 0 0 0;
    }
    #hero h1 {
        margin: 0 0 1.25rem 0;
    }

    #overview, 
    .earthquakes-stats-columns, 
    .features-content {
        grid-template-columns: 1fr;
    }

    #overview { 
        margin-top: 0.5rem;
    }
    #overview h2 {
        margin: 0 0 0.5rem 0;
    }
    .overview-txt {
        padding: 0;
        order: -1;
    }
    .overview-img img {
        max-width: 80%;
    }

    #earthquakes {
        padding: 3rem 0;
    }
    .earthquakes-stats-columns {
        gap: 0.25rem;
    }
    
    #technology {
        margin: -3.5rem 0 0 0;
        padding: 4rem 0 0 0;
        }
    #technology h2 {
        margin: 0 0 1rem 0;
    }
    .technology-columns {
        margin: 1.5rem 0 0 0;
        gap: 0;
    }

    #features {
        padding: 5rem 0 0 0;
        margin: 0 0 0 0;
        min-height: 155vh;
    }
    .features-content {
        grid-template-areas:
            "heading"
            "img"
            "accordion";
    }
    #features h2 {
        margin: 0 auto 1.25rem auto;
        text-align: center;

    }
    .features-img {
        margin: 0;
        padding: 0;
        height: 75vh;
    }
    .features-accordion {
        margin: 1rem 0 0 0;
    }
    .accordion-header {
        padding: 0.75rem 0;
        font-size: 1.2rem;
    }
    .accordion-chevron {
        width: 28px;
        height: 28px;
    }
    .accordion-body ul {
        padding: 0.75rem 0 0 1.5rem;
    }
    .accordion-body li {
        margin: 0 0 0.5rem 0;
        line-height: 1.3rem;
    }
    .accordion-body li:last-child {
        margin-bottom: 0.5rem;
    }

    #about {
        padding: 5rem 0;
    }
    #about h2 {
        margin: 0 0 1rem 0;
    }
    #about p {
        margin: 0;
    }
    .about-columns {
        margin: 0;
    }
    .about-col {
        margin: 1rem 0;
    }
    .about-col img {
        margin: 2rem auto 1rem auto;
        width: 75%;
    }
}

@media (max-width: 410px) {
    #features {
        min-height: 175vh;
    }
}

@media (max-width: 400px) {
    #features {
        min-height: 180vh;
    }
}