/* =====================================================================
   tanso.in -- Carbon Archive
   Aesthetic: grainy-textured, muted-vintage, watercolor, HUD-overlay
   ===================================================================== */

:root {
    /* Palette -- exact values from DESIGN.md */
    --parchment: #D4C5A9;    /* primary background */
    --umber-dark: #2C2416;   /* primary text */
    --olive-faded: #8B7D62;  /* secondary text / HUD lines */
    --charcoal-brown: #5A4E3C; /* data / captions */
    --teal-muted: #3D6B5E;   /* accents / links */
    --sienna: #A0522D;       /* warm accent */
    --cream-pale: #F0E8D8;   /* secondary background */
    --near-black: #1E1A14;   /* sec 4 dark background */

    /* Variable font axes */
    --wght: 400;
    --casl: 0.3;
    --slnt: 0;

    /* Fonts */
    --font-display: "Recursive", "Inter", system-ui, sans-serif;
    --font-mono: "Fira Mono", "space", ui-monospace, monospace;
}

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

html, body {
    width: 100%;
    overflow-x: hidden;
}

html {
    scroll-behavior: smooth;
    background: var(--parchment);
}

body {
    font-family: var(--font-display);
    font-variation-settings: 'wght' var(--wght), 'CASL' var(--casl), 'slnt' var(--slnt);
    color: var(--umber-dark);
    background: var(--parchment);
    line-height: 1.78;
    -webkit-font-smoothing: antialiased;
    font-size: 1.05rem;
    min-height: 100vh;
    position: relative;
}

/* ---------------------------------------------------------------------
   Grain Overlay -- inline SVG noise via data URI
   --------------------------------------------------------------------- */
#grain {
    position: fixed;
    inset: 0;
    z-index: 90;
    pointer-events: none;
    opacity: 0.12;
    mix-blend-mode: multiply;
    background-image: url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' width='220' height='220'><filter id='n'><feTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='2' stitchTiles='stitch' seed='7'/><feColorMatrix values='0 0 0 0 0.17  0 0 0 0 0.14  0 0 0 0 0.08  0 0 0 0.9 0'/></filter><rect width='100%25' height='100%25' filter='url(%23n)'/></svg>");
    background-size: 220px 220px;
    transition: opacity 0.8s cubic-bezier(0.4, 0, 0.2, 1);
}

body.grain-heavy #grain {
    opacity: 0.18;
}

/* ---------------------------------------------------------------------
   HUD Overlay -- persistent viewport frame
   --------------------------------------------------------------------- */
#hud {
    position: fixed;
    top: 3vw;
    right: 3vw;
    bottom: 3vw;
    left: 3vw;
    border: 1px solid var(--olive-faded);
    pointer-events: none;
    z-index: 100;
    transition: opacity 0.2s ease-in-out;
}

.hud-corner {
    position: absolute;
    width: 15px;
    height: 15px;
}

.hud-corner::before,
.hud-corner::after {
    content: "";
    position: absolute;
    background: var(--olive-faded);
}

/* top-left */
.hud-tl { top: -1px; left: -1px; }
.hud-tl::before { top: 0; left: 0; width: 15px; height: 1px; }
.hud-tl::after  { top: 0; left: 0; width: 1px; height: 15px; }

/* top-right */
.hud-tr { top: -1px; right: -1px; }
.hud-tr::before { top: 0; right: 0; width: 15px; height: 1px; }
.hud-tr::after  { top: 0; right: 0; width: 1px; height: 15px; }

/* bottom-left */
.hud-bl { bottom: -1px; left: -1px; }
.hud-bl::before { bottom: 0; left: 0; width: 15px; height: 1px; }
.hud-bl::after  { bottom: 0; left: 0; width: 1px; height: 15px; }

/* bottom-right */
.hud-br { bottom: -1px; right: -1px; }
.hud-br::before { bottom: 0; right: 0; width: 15px; height: 1px; }
.hud-br::after  { bottom: 0; right: 0; width: 1px; height: 15px; }

.hud-readout {
    position: absolute;
    top: -0.8em;
    right: 18px;
    background: var(--parchment);
    padding: 0 10px;
    font-family: var(--font-mono);
    font-size: 0.72rem;
    letter-spacing: 0.14em;
    color: var(--charcoal-brown);
}

.hud-readout .hud-label {
    opacity: 0.6;
    margin-right: 2px;
}

.hud-meta {
    position: absolute;
    bottom: -0.8em;
    left: 18px;
    background: var(--parchment);
    padding: 0 10px;
    font-family: var(--font-mono);
    font-size: 0.7rem;
    letter-spacing: 0.16em;
    color: var(--charcoal-brown);
    display: flex;
    gap: 18px;
    align-items: center;
}

#hud-progress {
    color: var(--teal-muted);
}

/* HUD flicker (applied in sec-04 via JS) */
#hud.flicker {
    opacity: 0.3;
}

/* ---------------------------------------------------------------------
   Section base
   --------------------------------------------------------------------- */
.section {
    position: relative;
    min-height: 100vh;
    padding: 10vw 8vw;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
}

.section-number {
    font-family: var(--font-mono);
    font-size: 0.78rem;
    letter-spacing: 0.22em;
    color: var(--olive-faded);
    margin-bottom: 1.2em;
    text-transform: uppercase;
}

.section-title {
    font-family: var(--font-display);
    font-variation-settings: 'wght' 600, 'CASL' 0.2, 'slnt' 0;
    font-size: clamp(1.5rem, 3.5vw, 2.4rem);
    line-height: 1.18;
    color: var(--umber-dark);
    margin-bottom: 1.1em;
    letter-spacing: -0.01em;
}

/* ---------------------------------------------------------------------
   Fade-reveal pattern
   --------------------------------------------------------------------- */
.fade-in {
    opacity: 0;
    filter: blur(4px);
    transform: translateY(14px);
    transition:
        opacity 0.8s cubic-bezier(0.4, 0, 0.2, 1),
        filter 0.8s cubic-bezier(0.4, 0, 0.2, 1),
        transform 0.8s cubic-bezier(0.4, 0, 0.2, 1);
    transition-delay: var(--reveal-delay, 0ms);
}

.fade-in.is-visible {
    opacity: 1;
    filter: blur(0);
    transform: translateY(0);
}

/* ---------------------------------------------------------------------
   SECTION 1 -- Acquisition / Hero
   --------------------------------------------------------------------- */
.section-hero {
    background: var(--parchment);
}

.bleed-left {
    position: absolute;
    top: 0;
    left: 0;
    width: min(42vw, 520px);
    height: 100%;
    pointer-events: none;
    z-index: 1;
}

.hero-inner {
    position: relative;
    z-index: 2;
    max-width: 1100px;
    width: 100%;
    padding-left: max(18vw, 180px);
}

.hero-meta {
    display: flex;
    gap: 1.6em;
    font-family: var(--font-mono);
    font-size: 0.72rem;
    letter-spacing: 0.22em;
    color: var(--charcoal-brown);
    margin-bottom: 2em;
    flex-wrap: wrap;
}

.hero-title {
    font-family: var(--font-display);
    font-variation-settings: 'wght' var(--hero-wght, 700), 'CASL' 0, 'slnt' 0;
    font-size: clamp(3rem, 8vw, 6.5rem);
    line-height: 0.98;
    letter-spacing: -0.03em;
    color: var(--umber-dark);
    margin-bottom: 0.6em;
    transition: font-variation-settings 0.1s linear;
}

.hero-title .dot {
    color: var(--sienna);
    font-variation-settings: 'wght' 900, 'CASL' 0, 'slnt' 0;
}

.hero-sub {
    max-width: 48ch;
    color: var(--charcoal-brown);
    font-size: 1.1rem;
    line-height: 1.7;
    margin-bottom: 2.4em;
    font-variation-settings: 'wght' 400, 'CASL' 0.3, 'slnt' 0;
}

.hero-coords {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 12px 24px;
    max-width: 620px;
    padding: 14px 0;
    border-top: 1px solid rgba(139, 125, 98, 0.5);
    border-bottom: 1px solid rgba(139, 125, 98, 0.5);
    font-family: var(--font-mono);
    font-size: 0.72rem;
    letter-spacing: 0.18em;
    color: var(--charcoal-brown);
    margin-bottom: 3em;
}

.scroll-cue {
    display: flex;
    align-items: center;
    gap: 14px;
    font-family: var(--font-mono);
    font-size: 0.7rem;
    letter-spacing: 0.25em;
    color: var(--olive-faded);
    text-transform: uppercase;
}

.scroll-line {
    display: inline-block;
    width: 60px;
    height: 1px;
    background: var(--olive-faded);
    position: relative;
    overflow: hidden;
}

.scroll-line::after {
    content: "";
    position: absolute;
    top: 0;
    left: -100%;
    width: 50%;
    height: 100%;
    background: var(--sienna);
    animation: scrollcue 2.4s cubic-bezier(0.4, 0, 0.2, 1) infinite;
}

@keyframes scrollcue {
    0%   { left: -60%; }
    100% { left: 110%; }
}

/* ---------------------------------------------------------------------
   SECTION 2 -- Archive
   --------------------------------------------------------------------- */
.section-archive {
    background: linear-gradient(180deg, var(--parchment) 0%, var(--cream-pale) 100%);
}

.archive-grid {
    display: grid;
    grid-template-columns: minmax(260px, 1fr) 1.4fr;
    gap: 6vw;
    max-width: 1200px;
    width: 100%;
    align-items: start;
}

.archive-col-left {
    position: relative;
}

.kiln {
    width: 100%;
    max-width: 380px;
    height: auto;
    display: block;
}

.figure-caption {
    display: flex;
    flex-direction: column;
    gap: 2px;
    margin-top: 18px;
    font-family: var(--font-mono);
    font-size: 0.72rem;
    letter-spacing: 0.1em;
    color: var(--charcoal-brown);
    line-height: 1.5;
    max-width: 320px;
}

.figure-caption span:first-child {
    color: var(--sienna);
    letter-spacing: 0.22em;
    font-weight: 500;
}

.archive-col-right {
    padding-top: 40px;
}

.breathe-text {
    font-size: 1.05rem;
    line-height: 1.78;
    color: var(--umber-dark);
    margin-bottom: 1.4em;
    max-width: 54ch;
    font-variation-settings: 'wght' var(--breathe-wght, 400), 'CASL' 0.3, 'slnt' 0;
    transition: font-variation-settings 0.15s linear;
}

.breathe-text em {
    color: var(--teal-muted);
    font-style: italic;
    font-variation-settings: 'wght' 500, 'CASL' 0.5, 'slnt' -6;
}

.archive-list {
    list-style: none;
    margin-top: 2em;
    padding: 1.2em 0;
    border-top: 1px solid rgba(139, 125, 98, 0.45);
    border-bottom: 1px solid rgba(139, 125, 98, 0.45);
}

.archive-list li {
    display: grid;
    grid-template-columns: 56px 1fr;
    gap: 18px;
    padding: 8px 0;
    font-family: var(--font-mono);
    font-size: 0.82rem;
    letter-spacing: 0.08em;
    color: var(--charcoal-brown);
    border-bottom: 1px dotted rgba(139, 125, 98, 0.3);
}

.archive-list li:last-child { border-bottom: none; }

.archive-list li span:first-child {
    color: var(--sienna);
    letter-spacing: 0.18em;
}

/* ---------------------------------------------------------------------
   SECTION 3 -- Instrumentation
   --------------------------------------------------------------------- */
.section-instrument {
    background: var(--cream-pale);
    position: relative;
}

.wash-behind {
    position: absolute;
    inset: 0;
    width: 100%;
    height: 100%;
    z-index: 1;
    pointer-events: none;
}

.instrument-inner {
    position: relative;
    z-index: 2;
    max-width: 1100px;
    width: 100%;
}

.instrument-lede {
    max-width: 52ch;
    color: var(--charcoal-brown);
    margin-bottom: 2.2em;
    font-size: 1rem;
}

.instrument-lede em {
    color: var(--sienna);
    font-style: italic;
}

.readout-panel {
    border: 1px solid var(--olive-faded);
    background: rgba(240, 232, 216, 0.7);
    padding: 0;
    margin-bottom: 2em;
    font-family: var(--font-mono);
    color: var(--charcoal-brown);
    box-shadow: 0 0 0 1px rgba(139, 125, 98, 0.15) inset;
}

.readout-header,
.readout-footer {
    display: flex;
    justify-content: space-between;
    gap: 16px;
    padding: 10px 18px;
    border-bottom: 1px dashed rgba(139, 125, 98, 0.55);
    font-size: 0.72rem;
    letter-spacing: 0.22em;
    color: var(--charcoal-brown);
    flex-wrap: wrap;
}

.readout-footer {
    border-bottom: none;
    border-top: 1px dashed rgba(139, 125, 98, 0.55);
}

.readout-header .blink {
    color: var(--sienna);
    animation: blink 1.4s steps(2, start) infinite;
    letter-spacing: 0.3em;
}

@keyframes blink {
    0%, 50%   { opacity: 1; }
    51%, 100% { opacity: 0.2; }
}

.readout-rows {
    padding: 14px 18px;
    font-size: 0.85rem;
    line-height: 1.6;
    letter-spacing: 0.03em;
    font-weight: 400;
}

.readout-row {
    display: grid;
    grid-template-columns: 50px 70px 80px 1fr 90px;
    gap: 10px;
    padding: 2px 0;
    color: var(--charcoal-brown);
    position: relative;
    /* uneven baseline -- thermal printer skew */
    transform: translateY(var(--row-skew, 0));
}

.readout-row .lbl  { color: var(--sienna); }
.readout-row .val  { color: var(--umber-dark); }
.readout-row .unit { color: var(--olive-faded); }
.readout-row .bar {
    height: 10px;
    align-self: center;
    background: repeating-linear-gradient(
        90deg,
        var(--umber-dark) 0 2px,
        transparent 2px 3px
    );
}

.instrument-legend {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
    gap: 14px 28px;
    font-family: var(--font-mono);
    font-size: 0.78rem;
    letter-spacing: 0.1em;
    color: var(--charcoal-brown);
    margin-top: 1.2em;
}

.instrument-legend > div {
    display: flex;
    align-items: center;
    gap: 10px;
}

.instrument-legend .swatch {
    display: inline-block;
    width: 14px;
    height: 14px;
    border: 1px solid var(--olive-faded);
    opacity: 0.85;
}

/* ---------------------------------------------------------------------
   SECTION 4 -- Field Notes
   --------------------------------------------------------------------- */
.section-field {
    background: var(--near-black);
    color: var(--parchment);
    padding: 14vw 8vw;
    position: relative;
}

.section-field .section-number {
    color: var(--olive-faded);
}

.section-field .section-title {
    color: var(--cream-pale);
    font-variation-settings: 'wght' 500, 'CASL' 0.6, 'slnt' -4;
    margin-bottom: 1.4em;
}

.field-inner {
    max-width: 720px;
    margin: 0 auto;
    position: relative;
    z-index: 2;
}

.field-body p {
    font-family: var(--font-display);
    font-variation-settings: 'wght' 300, 'CASL' 0.8, 'slnt' -3;
    font-size: 1.1rem;
    line-height: 1.9;
    color: var(--parchment);
    margin-bottom: 1.6em;
    max-width: 60ch;
}

.field-body .signoff {
    margin-top: 2.4em;
    color: var(--olive-faded);
    font-size: 0.85rem;
    font-variation-settings: 'wght' 350, 'CASL' 1, 'slnt' -10;
    letter-spacing: 0.04em;
}

.molecule {
    position: absolute;
    right: 6vw;
    top: 12vw;
    width: min(320px, 28vw);
    height: auto;
    opacity: 0.55;
    z-index: 1;
    pointer-events: none;
}

.field-footer {
    position: relative;
    z-index: 2;
    margin-top: 6em;
    padding-top: 1.4em;
    border-top: 1px solid rgba(139, 125, 98, 0.4);
    display: flex;
    justify-content: space-between;
    gap: 16px;
    font-family: var(--font-mono);
    font-size: 0.72rem;
    letter-spacing: 0.22em;
    color: var(--olive-faded);
    max-width: 720px;
    margin-left: auto;
    margin-right: auto;
    flex-wrap: wrap;
}

/* ---------------------------------------------------------------------
   Responsive
   --------------------------------------------------------------------- */
@media (max-width: 900px) {
    .hero-inner {
        padding-left: 6vw;
    }
    .bleed-left {
        width: 60vw;
        opacity: 0.55;
    }
    .archive-grid {
        grid-template-columns: 1fr;
        gap: 10vw;
    }
    .archive-col-right { padding-top: 0; }
    .kiln { max-width: 260px; }
    .hero-coords {
        grid-template-columns: repeat(2, 1fr);
    }
    .readout-row {
        grid-template-columns: 40px 60px 70px 1fr 70px;
        font-size: 0.75rem;
    }
    .hud-meta {
        gap: 10px;
        font-size: 0.6rem;
    }
    .molecule {
        top: auto;
        bottom: 8vw;
        right: 4vw;
        opacity: 0.35;
    }
}

@media (max-width: 560px) {
    .section { padding: 18vw 6vw; }
    .hud-meta span:first-child { display: none; }
    .readout-header, .readout-footer { font-size: 0.62rem; }
    .readout-row {
        grid-template-columns: 34px 50px 60px 1fr 56px;
        font-size: 0.68rem;
        gap: 6px;
    }
}