:root {
    --bg: #f7f7fb;
    --card: #ffffff;
    --accent: #2563eb;
    --text: #111827;
}

* {
    box-sizing: border-box
}

body {
    font-family: system-ui, -apple-system, Segoe UI, Roboto, "Helvetica Neue", Arial;
    margin: 0;
    background: var(--bg);
    color: var(--text);
    line-height: 1.5
}

.teaser-img {
    display: block;
    margin: 0 auto;
    width: 100%;
    max-width: 60%;
    border-radius: 8px;
}

.diff-img,
.method-img {
    display: block;
    margin: 0 auto;
    width: 100%;
    max-width: 90%;
    border-radius: 8px;
}

figure {
    text-align: center;
    margin: 20px 0;
}

figcaption {
    font-size: 14px;
    color: #555;
    margin-top: 8px;
    line-height: 1.4;
}

.tldr {
    background-color: #f4f7fb;
    color: #1a3faa;
}

.question-box {
    background-color: #f7f7f7;
    border-left: 4px solid #002fa7;
    padding: 12px 16px;
    margin: 20px 0;
    font-size: 16px;
    line-height: 1.6;
}

.question-item {
    color: #1a3faa;
    font-weight: 500;
    margin: 6px 0;
}

.section-card {
    background: var(--card);
}

.nav {
    display: none;
    margin-left: auto
}

.hero {
    padding: 1rem;
    /* background: linear-gradient(180deg, #fff, #fbfdff); */
    /* background: url("https://images.unsplash.com/photo-1522199710521-72d69614c702?auto=format&fit=crop&w=1500&q=80")
                center/cover no-repeat; */
    background: linear-gradient(120deg, #2563eb, #9333ea, #f97316);
    background-size: 300% 300%;

    animation: hero-bg-move 12s ease-in-out infinite;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    text-align: center;
    border-radius: 8px;
    color: white;
    margin: 1rem 0
}

.hero-content {
    width: 100%;
    max-width: 1000px;
}

.paper-authors {
    margin: .35rem 0 .5rem;
    letter-spacing: .01em;
    font-weight: 600
}

.paper-authors sup {
    font-size: .65em;
    vertical-align: super;
    margin-left: .1em
}

.paper-affiliations {
    margin: 0;
    color: rgba(255, 255, 255, .9);
    font-size: .95rem
}

@keyframes hero-bg-move {
    0% {
        background-position: 0% 50%;
    }

    50% {
        background-position: 100% 50%;
    }

    100% {
        background-position: 0% 50%;
    }
}

.nav a {
    display: block;
    padding: .5rem 0;
    color: var(--accent);
    text-decoration: none
}

.brand {
    margin: 0;
    font-size: 1.125rem
}

.container {
    width: min(1100px, 92vw);
    margin: 0 auto;
    padding: 1rem
}

.site-header {
    background: var(--card);
    border-bottom: 1px solid #e6e9ef
}

.site-header .container {
    display: flex;
    align-items: center;
    gap: 1rem
}

.site-footer {
    padding: 1rem 0;
    text-align: center;
    color: #6b7280;
    font-size: .9rem
}

.paper-actions {
    display: flex;
    flex-wrap: wrap;
    gap: .75rem;
    justify-content: center;
    margin: 1rem 0 1.5rem
}

.btn {
    display: inline-grid;
    grid-auto-flow: column;
    align-items: center;
    justify-content: center;
    justify-items: center;
    padding: .65rem 1.1rem;
    border-radius: 10px;
    font-weight: 600;
    font-size: 1rem;
    font-family: inherit;
    text-decoration: none;
    transition: color 120ms ease, border-color 120ms ease;
    border: 1px solid #d7dce5;
    color: #111827;
    background: rgba(255, 255, 255, 0.9);
    min-width: 120px;
    gap: .6rem;
    appearance: none;
    cursor: pointer
}

.btn:hover {
    color: #2563eb;
    border-color: #c5cde0
}

.btn-icon {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 1.4em;
    height: 1.4em
}

.contact-modal {
    position: fixed;
    inset: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    background: rgba(0, 0, 0, 0.35);
    opacity: 0;
    pointer-events: none;
    transition: opacity 150ms ease;
    z-index: 10
}

.contact-modal.open {
    opacity: 1;
    pointer-events: auto
}

.contact-card {
    background: #fff;
    border-radius: 12px;
    padding: 1.25rem;
    min-width: 260px;
    box-shadow: 0 18px 40px -22px rgba(0, 0, 0, 0.4);
    border: 1px solid #e5e7eb
}

.contact-card__header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: .75rem;
    font-size: 1rem
}

.contact-close {
    border: none;
    background: transparent;
    font-size: 1.3rem;
    line-height: 1;
    cursor: pointer;
    padding: 0 .25rem
}

.contact-email {
    margin: 0;
    font-weight: 600
}

h1 {
    font-size: clamp(1.8rem, 3.6vw, 2.4rem);
    text-align: center;
}

@media (max-width: 768px) {
    .paper-actions {
        flex-direction: column;
        align-items: stretch;
    }

    .btn {
        width: 100%;
        justify-content: center;
    }

    .btn-icon {
        display: none;
    }

    .teaser-img,
    .diff-img,
    .method-img {
        width: 100%;
        max-width: 100%;
    }
}