/* ─────────────────────────────────────────
    PAGE HEADER
    ───────────────────────────────────────── */
    .page-header {
        background: var(--slate);
        padding: 11rem 4.5rem 6rem;
        position: relative;
        overflow: hidden;
    }
    .page-header::before {
        content: ''; position: absolute; inset: 0;
        background: radial-gradient(ellipse 80% 80% at 50% 100%, rgba(47,66,89,.6) 0%, transparent 70%);
        z-index: 0;
    }
    .header-content {
        max-width: 1180px;
        margin: 0 auto;
        position: relative;
        z-index: 1;
        text-align: center; /* Centered for the new layout */
    }
    .page-title {
        font-family: 'Cormorant Garamond', serif;
        font-size: clamp(3rem, 5vw, 4.5rem);
        font-weight: 300;
        color: var(--white);
        line-height: 1.1;
        margin-bottom: 1.5rem;
    }
    .page-title em { font-style: italic; color: var(--copper3); }
    .page-subtitle {
        font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Helvetica, sans-serif;
        font-size: 1.05rem;
        color: rgba(250,247,242,.8);
        max-width: 700px;
        line-height: 1.8;
        font-weight: 300;
        margin: 0 auto;
    }
    .kicker {
        display: inline-flex;
        align-items: center;
        justify-content: center;
        gap: .7rem;
        font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Helvetica, sans-serif;
        font-size: .65rem;
        font-weight: 700;
        letter-spacing: .3em;
        text-transform: uppercase;
        color: var(--copper2);
        margin-bottom: 1.1rem;
    }
    .kicker::before, .kicker::after { 
        content: ''; width: 24px; height: 1px; background: var(--copper2); 
    }

    /* ─────────────────────────────────────────
    FILTER BAR
    ───────────────────────────────────────── */
    .filter-container {
        background: var(--ivory2);
        padding: 2rem 4.5rem;
        border-bottom: 1px solid var(--ivory3);
        display: flex;
        justify-content: center;
        position: static;
        top: 85px; /* Adjust based on your nav height */
        z-index: 150;
        backdrop-filter: blur(10px);
        background: rgba(242, 236, 227, 0.9);
    }
    .filter-menu {
        display: flex;
        gap: .5rem;
        background: var(--white);
        padding: .5rem;
        border-radius: 50px;
        box-shadow: 0 4px 12px rgba(26,35,50,.05);
        border: 1px solid var(--ivory3);
        flex-wrap: wrap;
        justify-content: center;
    }
    .filter-btn {
        font-family: -apple-system, sans-serif;
        font-size: .75rem;
        font-weight: 600;
        letter-spacing: .08em;
        text-transform: uppercase;
        color: var(--slate);
        padding: .8rem 1.75rem;
        border-radius: 50px;
        transition: all .3s ease;
    }
    .filter-btn:hover {
        color: var(--copper);
    }
    .filter-btn.active {
        background: var(--slate);
        color: var(--white);
        box-shadow: 0 4px 12px rgba(26,35,50,.15);
    }

    /* ─────────────────────────────────────────
    PAPERS GRID
    ───────────────────────────────────────── */
    .content-section {
        padding: 6rem 4.5rem;
        background: var(--ivory);
        min-height: 60vh;
    }
    .papers-grid {
        max-width: 1180px;
        margin: 0 auto;
        display: grid;
        grid-template-columns: repeat(2, 1fr);
        gap: 2.5rem;
    }

    /* Paper Cards */
    .paper-card {
        background: var(--white);
        border: 1px solid var(--ivory3);
        padding: 3rem 2.5rem;
        position: relative;
        box-shadow: var(--card-shadow);
        transition: all .4s cubic-bezier(.4,0,.2,1);
        display: flex;
        flex-direction: column;
        /* Used for the JS filter animation */
        animation: fadeIn .6s ease forwards; 
    }
    .paper-card:hover {
        box-shadow: var(--hover-shadow);
        border-color: rgba(181,114,42,.2);
        transform: translateY(-4px);
    }
    .paper-card::before {
        content: ''; position: absolute; left: 0; right: 0; top: 0;
        height: 3px; background: linear-gradient(90deg, var(--copper), var(--copper2));
        transform: scaleX(0); transform-origin: left;
        transition: transform .4s cubic-bezier(.4,0,.2,1);
    }
    .paper-card:hover::before { transform: scaleX(1); }

    .paper-meta {
        font-family: -apple-system, sans-serif;
        font-size: .65rem;
        font-weight: 700;
        letter-spacing: .15em;
        text-transform: uppercase;
        color: var(--a11y-muted);
        margin-bottom: 1.25rem;
        display: flex;
        align-items: center;
        gap: .75rem;
    }
    .paper-category-tag {
        background: var(--ivory2);
        padding: .3rem .8rem;
        border-radius: 4px;
        color: var(--a11y-copper);
    }

    .paper-title {
            font-family: 'Cormorant Garamond', serif;
            font-size: 1.8rem;
            font-weight: 600;
            color: var(--slate);
            margin-bottom: 1rem;
            line-height: 1.2;
        }
    .paper-desc {
        font-family: -apple-system, sans-serif;
        font-size: .95rem;
        color: var(--charcoal);
        line-height: 1.7;
        font-weight: 400;
        margin-bottom: 2rem;
        flex-grow: 1; /* Pushes the button to the bottom */
    }

    .download-btn {
        display: inline-flex;
        align-items: center;
        gap: .5rem;
        font-family: -apple-system, sans-serif;
        font-size: .72rem;
        font-weight: 700;
        letter-spacing: .12em;
        text-transform: uppercase;
        color: var(--a11y-copper);   
        transition: color .3s;
        align-self: flex-start;
        padding-top: 1rem;
        border-top: 1px solid var(--ivory3);
        width: 100%;
    }
    .download-btn:hover { color: var(--slate); }
    .download-btn svg { transition: transform .3s; }
    .download-btn:hover svg { transform: translateY(3px); }

    /* No Results Message */
    .no-results {
        grid-column: 1 / -1;
        text-align: center;
        padding: 4rem;
        font-family: 'Cormorant Garamond', serif;
        font-size: 1.8rem;
        color: var(--muted);
        display: none;
    }

    @keyframes fadeIn {
        from { opacity: 0; transform: translateY(15px); }
        to { opacity: 1; transform: translateY(0); }
    }

    @media(max-width: 900px) {
        .papers-grid { grid-template-columns: 1fr; }
        .page-header { padding: 9rem 2.5rem 4rem; }
        .content-section { padding: 4rem 2.5rem; }
        .filter-container { padding: 1.5rem; }
    }