/* =========================
   ESSAY: SPACE-TIME THEME
========================= */

.essay-page {
    --essay-bg: #080f20;
    --essay-panel: rgba(19, 32, 54, 0.82);
    --essay-border: rgba(153, 190, 239, 0.16);
    --essay-text: #e4edf9;
    --essay-muted: #a9bbd3;
    --essay-accent: #9bc7ff;

    min-height: 100vh;
    background: var(--essay-bg);
    color: var(--essay-text);
    font-family: Georgia, "Times New Roman", serif;
}

/* Fixed background remains stationary while reading */

.space-background {
    position: fixed;
    inset: 0;
    z-index: 0;
    overflow: hidden;
    pointer-events: none;
    background:
        radial-gradient(ellipse at 15% 15%,
            rgba(40, 91, 157, .28), transparent 42%),
        radial-gradient(ellipse at 85% 70%,
            rgba(80, 72, 160, .20), transparent 42%),
        linear-gradient(145deg, #080f20, #101a30 55%, #090f20);
}

.space-glow {
    position: absolute;
    width: 440px;
    height: 440px;
    border-radius: 50%;
    filter: blur(20px);
    opacity: .5;
    background: radial-gradient(circle,
        rgba(79, 139, 215, .25), transparent 70%);
    animation: spaceDrift 24s ease-in-out infinite alternate;
}

.glow-one {
    top: -200px;
    right: -120px;
}

.glow-two {
    bottom: -230px;
    left: -140px;
    background: radial-gradient(circle,
        rgba(119, 105, 220, .22), transparent 70%);
    animation-delay: -10s;
}

@keyframes spaceDrift {
    from { transform: translate(-10px, 0) scale(1); }
    to { transform: translate(25px, 20px) scale(1.1); }
}

.space-grid {
    position: absolute;
    inset: 0;
    opacity: .12;
    background-image:
        linear-gradient(rgba(147, 185, 237, .13) 1px, transparent 1px),
        linear-gradient(90deg, rgba(147, 185, 237, .13) 1px, transparent 1px);
    background-size: 70px 70px;
    mask-image: linear-gradient(to bottom, black, transparent 90%);
}

.star-field {
    position: absolute;
    inset: 0;
    opacity: .38;
    background-image:
        radial-gradient(1px 1px at 12% 20%, #d8e8ff 99%, transparent),
        radial-gradient(2px 2px at 75% 18%, #b7d5ff 99%, transparent),
        radial-gradient(1px 1px at 43% 37%, #ffffff 99%, transparent),
        radial-gradient(1px 1px at 88% 58%, #c3d8ff 99%, transparent),
        radial-gradient(2px 2px at 23% 74%, #d8e8ff 99%, transparent),
        radial-gradient(1px 1px at 62% 85%, #ffffff 99%, transparent),
        radial-gradient(1px 1px at 92% 90%, #b7d5ff 99%, transparent);
    background-size: 370px 310px;
}

/* Navigation */

.essay-nav {
    position: relative;
    z-index: 2;
    width: min(1000px, 90%);
    margin: auto;
    padding: 28px 0;
    display: flex;
    justify-content: space-between;
    gap: 16px;
}

.nav-link {
    color: var(--essay-muted);
    font: 11px Arial, sans-serif;
    letter-spacing: .8px;
    text-decoration: none;
    transition: color .25s;
}

.nav-link:hover {
    color: var(--essay-accent);
}

/* Reading layout */

.essay-layout {
    position: relative;
    z-index: 1;
    width: min(820px, 90%);
    margin: auto;
    padding: 50px 0 70px;
}

.essay-header {
    padding-bottom: 45px;
    border-bottom: 1px solid var(--essay-border);
}

.essay-kicker {
    color: var(--essay-accent);
    font: 10px Arial, sans-serif;
    letter-spacing: 3px;
    margin-bottom: 25px;
}

.essay-header h1 {
    font-size: clamp(40px, 7vw, 70px);
    font-weight: normal;
    line-height: 1.08;
    letter-spacing: -1.5px;
}

.essay-subtitle {
    margin-top: 20px;
    color: var(--essay-muted);
    font-size: clamp(17px, 3vw, 23px);
    font-style: italic;
    line-height: 1.6;
}

.essay-meta {
    display: flex;
    flex-wrap: wrap;
    gap: 12px 25px;
    margin-top: 25px;
    color: #8fa8c8;
    font: 11px Arial, sans-serif;
    letter-spacing: .5px;
}

/* Conceptual disclaimer */

.essay-notice {
    margin-top: 35px;
    padding: 22px 25px;
    border: 1px solid var(--essay-border);
    border-left: 3px solid var(--essay-accent);
    border-radius: 5px;
    background: var(--essay-panel);
}

.essay-notice strong {
    display: block;
    color: var(--essay-accent);
    font: 11px Arial, sans-serif;
    letter-spacing: 1.5px;
    text-transform: uppercase;
}

.essay-notice p {
    margin-top: 10px;
    color: var(--essay-muted);
    font: 13px/1.8 Arial, sans-serif;
}

/* Article typography */

.essay-content {
    padding-top: 20px;
}

.essay-content section {
    margin: 0;
    padding: 45px 0;
    border-bottom: 1px solid var(--essay-border);
    scroll-margin-top: 25px;
}

.essay-content h2 {
    margin-bottom: 24px;
    color: #f0f5ff;
    font-size: clamp(27px, 4vw, 36px);
    font-weight: normal;
    line-height: 1.25;
}

.essay-content h3 {
    margin: 30px 0 12px;
    color: var(--essay-accent);
    font-size: 21px;
    font-weight: normal;
    line-height: 1.45;
}

.essay-content p {
    margin-bottom: 19px;
    color: #c4d1e3;
    font-size: 17px;
    line-height: 1.95;
    overflow-wrap: anywhere;
}

.essay-content p:last-child {
    margin-bottom: 0;
}

.essay-content blockquote {
    margin: 28px 0;
    padding: 22px 25px;
    border-left: 2px solid var(--essay-accent);
    background: rgba(100, 145, 205, .09);
    color: #e2edff;
    font-size: 19px;
    font-style: italic;
    line-height: 1.8;
}

/* Number-line diagram */

.number-model {
    margin: 32px 0;
    padding: 28px 22px;
    border: 1px solid var(--essay-border);
    border-radius: 8px;
    background: var(--essay-panel);
}

.number-labels {
    display: flex;
    justify-content: space-between;
    gap: 12px;
    color: #b6c9e3;
    font: 10px/1.5 Arial, sans-serif;
}

.number-labels span:nth-child(2) {
    color: var(--essay-accent);
    text-align: center;
}

.number-labels span:last-child {
    text-align: right;
}

.number-axis {
    position: relative;
    height: 2px;
    margin: 38px 8px;
    background: linear-gradient(
        90deg,
        #7184d7,
        #7daeea 45%,
        #e1edff 50%,
        #7daeea 55%,
        #7184d7
    );
}

.axis-point {
    position: absolute;
    top: 50%;
    width: 11px;
    height: 11px;
    border: 2px solid #dceaff;
    border-radius: 50%;
    background: #152640;
    transform: translate(-50%, -50%);
    box-shadow: 0 0 14px rgba(137, 186, 255, .55);
}

.point-negative { left: 0; }
.point-zero {
    left: 50%;
    width: 16px;
    height: 16px;
    background: #b7d8ff;
}
.point-positive { left: 100%; }

.number-model > p {
    margin: 0;
    color: #91a9c8;
    font: 11px/1.7 Arial, sans-serif;
    text-align: center;
}

/* Footer */

.essay-footer {
    padding-top: 35px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 18px;
}

.essay-footer p {
    color: #8fa8c8;
    font-size: 14px;
    font-style: italic;
}

.essay-footer a {
    color: var(--essay-accent);
    font: 11px Arial, sans-serif;
    text-decoration: none;
}

.essay-footer a:hover {
    text-decoration: underline;
}

/* Mobile reading experience */

@media (max-width: 600px) {
    .essay-nav {
        padding: 22px 0;
    }

    .essay-layout {
        padding-top: 35px;
        padding-bottom: 45px;
    }

    .essay-header {
        padding-bottom: 32px;
    }

    .essay-content section {
        padding: 34px 0;
    }

    .essay-content p {
        font-size: 16px;
        line-height: 1.9;
    }

    .essay-notice {
        padding: 18px;
    }

    .number-model {
        padding: 23px 14px;
    }

    .number-labels {
        font-size: 9px;
    }

    .essay-footer {
        align-items: flex-start;
        flex-direction: column;
    }
}

/* Accessibility */

@media (prefers-reduced-motion: reduce) {
    .space-glow {
        animation: none;
    }

    *,
    *::before,
    *::after {
        scroll-behavior: auto !important;
    }
}