/* ==========================================================================
   SengGack.xyz — 생각
   Isometric Monument to Cognition — Geological Earth-Tone Depth System
   ========================================================================== */

@import url('https://fonts.googleapis.com/css2?family=Bebas+Neue&family=DM+Mono:wght@400;500&family=Barlow+Condensed:wght@400;700&family=Noto+Serif+KR:wght@500;700&display=swap');

/* --------------------------------------------------------------------------
   Design Tokens
   -------------------------------------------------------------------------- */

:root {
    /* Geological palette — descends from pale mineral to dark earth */
    --c-chalk:       #F4EFE8;   /* Off-white chalk — page surface */
    --c-travertine:  #E8DDD0;   /* Pale travertine — light prism face */
    --c-sandstone:   #C9A882;   /* Sandstone — top faces of isometric blocks */
    --c-ochre:       #8C5E3C;   /* Oxidized ochre — geometric pattern fill */
    --c-sienna:      #6B3A2A;   /* Brick sienna — headings in non-hero sections */
    --c-terracotta:  #B5714A;   /* Burnt terracotta — accent / hover highlight */
    --c-clay:        #4A3728;   /* Dark clay — secondary dark / body text */
    --c-umber:       #2C1810;   /* Deep raw umber — shadow faces of prisms */

    /* Fonts */
    --f-display:   'Bebas Neue', 'Arial Narrow', sans-serif;
    --f-body:      'DM Mono', 'Courier New', monospace;
    --f-label:     'Barlow Condensed', 'Arial Narrow', sans-serif;
    --f-korean:    'Noto Serif KR', serif;

    /* Isometric geometry constants */
    --prism-skew-x:    -30deg;
    --prism-skew-y:     15deg;
    --prism-shadow-w:   32px;
    --prism-top-h:      28px;

    /* Transitions */
    --ease-assertive: cubic-bezier(0.34, 1.56, 0.64, 1);
    --ease-stone:     cubic-bezier(0.25, 0.46, 0.45, 0.94);
}

/* --------------------------------------------------------------------------
   Reset & Base
   -------------------------------------------------------------------------- */

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

html {
    scroll-behavior: smooth;
}

body {
    background-color: var(--c-chalk);
    color: var(--c-clay);
    font-family: var(--f-body);
    font-size: 15px;
    line-height: 26px;
    overflow-x: hidden;
}

/* --------------------------------------------------------------------------
   Isometric Navigation — Right-edge sidebar strip
   -------------------------------------------------------------------------- */

.iso-nav {
    position: fixed;
    right: 32px;
    top: 50%;
    transform: translateY(-50%);
    z-index: 100;
}

.iso-nav-track {
    display: flex;
    flex-direction: column;
    gap: 20px;
    align-items: center;
}

.iso-nav-tick {
    width: 8px;
    height: 8px;
    background: var(--c-sandstone);
    transform: rotate(45deg);
    cursor: pointer;
    transition: background 220ms var(--ease-assertive),
                transform 220ms var(--ease-assertive);
}

.iso-nav-tick:hover {
    background: var(--c-terracotta);
    transform: rotate(45deg) scale(1.4);
}

.iso-nav-tick.active {
    background: var(--c-sienna);
    transform: rotate(45deg) scale(1.3);
}

/* Connecting line between ticks */
.iso-nav-track::before {
    content: '';
    position: absolute;
    top: 0;
    bottom: 0;
    left: 50%;
    width: 1px;
    background: var(--c-sandstone);
    transform: translateX(-50%);
    z-index: -1;
}

/* --------------------------------------------------------------------------
   Main Layout Container
   -------------------------------------------------------------------------- */

.thought-descent {
    width: 100%;
}

.column-wrap {
    max-width: 780px;
    margin: 0 auto;
    padding: 0 40px;
    position: relative;
}

.column-wrap--offset-right {
    margin-left: auto;
    margin-right: 80px;
}

/* --------------------------------------------------------------------------
   Strata Background Bands
   -------------------------------------------------------------------------- */

.strata-band {
    position: absolute;
    left: 0;
    right: 0;
    top: 50%;
    height: 3px;
    background: linear-gradient(90deg,
        transparent 0%,
        var(--c-sandstone) 20%,
        var(--c-ochre) 50%,
        var(--c-sandstone) 80%,
        transparent 100%);
    opacity: 0.25;
    pointer-events: none;
}

/* --------------------------------------------------------------------------
   Section Label
   -------------------------------------------------------------------------- */

.section-label {
    font-family: var(--f-label);
    font-size: 11px;
    font-weight: 700;
    letter-spacing: 0.2em;
    text-transform: uppercase;
    color: var(--c-ochre);
    margin-bottom: 24px;
}

/* --------------------------------------------------------------------------
   Section Opener Words — Bebas Neue 120px
   -------------------------------------------------------------------------- */

.section-opener-word {
    font-family: var(--f-display);
    font-size: clamp(80px, 12vw, 120px);
    letter-spacing: 0.06em;
    color: var(--c-sienna);
    line-height: 0.9;
    margin-bottom: 16px;
    user-select: none;
}

/* --------------------------------------------------------------------------
   LAYER: Surface — Hero
   -------------------------------------------------------------------------- */

.layer-surface {
    position: relative;
    min-height: 100vh;
    background-color: var(--c-chalk);
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
}

/* Isometric grid SVG background */
.iso-grid-bg {
    position: absolute;
    inset: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
}

.iso-grid-bg--inverted {
    opacity: 0.35;
}

/* Hero content */
.surface-content {
    position: relative;
    z-index: 2;
    text-align: center;
    padding: 0 40px;
}

.hero-display-wrap {
    display: inline-flex;
    flex-direction: column;
    align-items: center;
}

.hero-hangul {
    font-family: var(--f-display);
    font-size: clamp(140px, 20vw, 240px);
    letter-spacing: 0.06em;
    color: var(--c-umber);
    line-height: 0.85;
    user-select: none;
}

.hero-roman {
    font-family: var(--f-label);
    font-size: clamp(24px, 4vw, 36px);
    font-weight: 700;
    letter-spacing: 0.18em;
    color: var(--c-sienna);
    margin-top: 16px;
    text-transform: uppercase;
}

.hero-subtitle {
    font-family: var(--f-body);
    font-size: 11px;
    letter-spacing: 0.2em;
    color: var(--c-ochre);
    margin-top: 12px;
    text-transform: uppercase;
}

/* Scroll cue */
.scroll-cue {
    margin-top: 60px;
    display: flex;
    justify-content: center;
}

.scroll-line {
    display: block;
    width: 1px;
    height: 60px;
    background: linear-gradient(to bottom, var(--c-sienna), transparent);
    animation: scroll-pulse 2.5s ease-in-out infinite;
}

@keyframes scroll-pulse {
    0%, 100% { opacity: 0.4; transform: scaleY(1); }
    50% { opacity: 1; transform: scaleY(1.2); }
}

/* --------------------------------------------------------------------------
   LAYER: Strata — First Introduction
   -------------------------------------------------------------------------- */

.layer-strata {
    position: relative;
    background-color: var(--c-chalk);
    padding: 120px 0;
    overflow: hidden;
}

/* --------------------------------------------------------------------------
   LAYER: Mid Depth Sections
   -------------------------------------------------------------------------- */

.layer-mid {
    position: relative;
    padding: 120px 0;
    overflow: hidden;
}

.layer-mid-1 {
    background-color: var(--c-travertine);
}

.layer-mid-2 {
    background-color: #DDD1C3; /* between travertine and sandstone */
}

.layer-mid-3 {
    background-color: #CFC1AE; /* closer to sandstone */
}

/* --------------------------------------------------------------------------
   LAYER: Bedrock — Final Section
   -------------------------------------------------------------------------- */

.layer-bedrock {
    position: relative;
    background-color: var(--c-umber);
    min-height: 80vh;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
}

.bedrock-content {
    position: relative;
    z-index: 2;
    text-align: center;
    padding: 80px 40px;
}

.bedrock-word {
    font-family: var(--f-display);
    font-size: clamp(56px, 8vw, 80px);
    letter-spacing: 0.06em;
    color: var(--c-travertine);
    margin-bottom: 48px;
    opacity: 0.7;
}

.bedrock-mark {
    font-family: var(--f-body);
    font-size: 11px;
    letter-spacing: 0.18em;
    color: var(--c-sandstone);
    opacity: 0.6;
    margin-top: 48px;
    text-align: center;
}

/* --------------------------------------------------------------------------
   ISOMETRIC PRISM BLOCKS — Core Design Element

   Structure:
   .prism-block
     .prism-top      (top face — angled, pattern/texture)
     .prism-front    (front face — primary content)
     .prism-shadow   (right shadow face — creates 3D illusion)

   Isometric construction using CSS skew transforms.
   All geometry shares 30°/60° isometric angles.
   -------------------------------------------------------------------------- */

.prism-block {
    position: relative;
    margin: 0 auto;
    cursor: default;
    /* Hover animation — pops forward with assertive spring */
    transition: transform 220ms var(--ease-assertive);
}

.prism-block:hover {
    transform: scale(1.03) translateY(-4px);
}

/* Top face — sits above the front face, angled */
.prism-top {
    position: relative;
    width: 100%;
    height: var(--prism-top-h);
    background-color: var(--c-sandstone);
    transform: skewX(var(--prism-skew-x));
    transform-origin: bottom left;
    margin-left: calc(var(--prism-shadow-w) / 2);
}

.prism-top--pattern {
    background-image: repeating-linear-gradient(
        60deg,
        transparent,
        transparent 10px,
        rgba(0,0,0,0.08) 10px,
        rgba(0,0,0,0.08) 11px
    );
}

.prism-top--dark {
    background-color: var(--c-clay);
    background-image: repeating-linear-gradient(
        60deg,
        transparent,
        transparent 10px,
        rgba(255,255,255,0.06) 10px,
        rgba(255,255,255,0.06) 11px
    );
}

/* Front face — primary content area */
.prism-front {
    position: relative;
    background-color: var(--c-travertine);
    border-left: 3px solid var(--c-sandstone);
    box-shadow:
        inset -1px 0 0 rgba(255,255,255,0.4),
        inset 0 -1px 0 rgba(0,0,0,0.05);
}

.prism-front-inner {
    padding: 40px 48px;
}

.prism-front-inner--dark {
    background-color: var(--c-clay);
}

/* Shadow face — right side dark umber panel */
.prism-shadow {
    position: absolute;
    right: calc(-1 * var(--prism-shadow-w));
    top: var(--prism-top-h);
    bottom: 0;
    width: var(--prism-shadow-w);
    background-color: var(--c-umber);
    transform: skewY(var(--prism-skew-y));
    transform-origin: top left;
}

.prism-shadow--dark {
    background-color: #1A0D08;
}

/* Light prism variant — travertine */
.prism-block--light .prism-front {
    background-color: var(--c-travertine);
}

.prism-block--light .prism-top {
    background-color: var(--c-sandstone);
}

/* Mid prism variant — warm sandstone */
.prism-block--mid .prism-front {
    background-color: #E0D0BC;
}

.prism-block--mid .prism-top {
    background-color: #C4976A;
}

/* Deep prism variant */
.prism-block--deep .prism-front {
    background-color: #D5C0A8;
}

.prism-block--deep .prism-top {
    background-color: var(--c-ochre);
}

/* Darker prism variant — approaching bedrock */
.prism-block--darker .prism-front {
    background-color: var(--c-clay);
    border-left-color: var(--c-sienna);
}

.prism-block--darker .prism-top {
    background-color: var(--c-sienna);
}

/* --------------------------------------------------------------------------
   Prism Typography
   -------------------------------------------------------------------------- */

.prism-body-text {
    font-family: var(--f-body);
    font-size: 15px;
    line-height: 26px;
    color: var(--c-clay);
    margin-bottom: 20px;
}

.prism-body-text:last-of-type {
    margin-bottom: 0;
}

.prism-body-text--light {
    color: var(--c-travertine);
}

.prism-annotation {
    font-family: var(--f-body);
    font-size: 11px;
    letter-spacing: 0.12em;
    color: var(--c-ochre);
    margin-top: 24px;
    padding-top: 16px;
    border-top: 1px solid var(--c-sandstone);
}

/* --------------------------------------------------------------------------
   Bedrock Prism Block
   -------------------------------------------------------------------------- */

.bedrock-prism {
    position: relative;
    display: inline-block;
    max-width: 640px;
    width: 90%;
    cursor: default;
    transition: transform 220ms var(--ease-assertive);
}

.bedrock-prism:hover {
    transform: scale(1.03) translateY(-4px);
}

.bedrock-prism-top {
    width: 100%;
    height: var(--prism-top-h);
    background-color: var(--c-clay);
    transform: skewX(var(--prism-skew-x));
    transform-origin: bottom left;
    margin-left: calc(var(--prism-shadow-w) / 2);
    background-image: repeating-linear-gradient(
        60deg,
        transparent,
        transparent 10px,
        rgba(255,255,255,0.05) 10px,
        rgba(255,255,255,0.05) 11px
    );
}

.bedrock-prism-front {
    background-color: var(--c-clay);
    border-left: 3px solid var(--c-sienna);
    padding: 48px 56px;
    text-align: left;
}

.bedrock-prism-shadow {
    position: absolute;
    right: calc(-1 * var(--prism-shadow-w));
    top: var(--prism-top-h);
    bottom: 0;
    width: var(--prism-shadow-w);
    background-color: #1A0D08;
    transform: skewY(var(--prism-skew-y));
    transform-origin: top left;
}

.bedrock-korean {
    font-family: var(--f-korean);
    font-size: clamp(18px, 3vw, 24px);
    font-weight: 700;
    color: var(--c-travertine);
    line-height: 1.8;
    margin-bottom: 12px;
}

.bedrock-translation {
    font-family: var(--f-body);
    font-size: 13px;
    letter-spacing: 0.1em;
    color: var(--c-sandstone);
    opacity: 0.7;
}

/* --------------------------------------------------------------------------
   Survey Markers — Isometric dot-grid 3×3 corner ornaments
   -------------------------------------------------------------------------- */

.survey-marker {
    position: absolute;
    width: 72px;
    height: 72px;
    opacity: 0.6;
}

.survey-marker--tr {
    top: 20px;
    right: 0;
}

.survey-marker--bl {
    bottom: 20px;
    left: 0;
}

/* --------------------------------------------------------------------------
   Scroll-Entry Animations — IntersectionObserver driven
   -------------------------------------------------------------------------- */

[data-animate="slide-iso"] {
    opacity: 0;
    transform: translate(-60px, -40px) scale(0.94);
    transition:
        opacity 600ms var(--ease-stone),
        transform 600ms var(--ease-stone);
}

[data-animate="slide-iso"].is-visible {
    opacity: 1;
    transform: translate(0, 0) scale(1);
}

/* Section labels and opener words — fade up */
.section-label,
.section-opener-word {
    opacity: 0;
    transform: translateY(20px);
    transition:
        opacity 500ms var(--ease-stone),
        transform 500ms var(--ease-stone);
}

.section-label.is-visible,
.section-opener-word.is-visible {
    opacity: 1;
    transform: translateY(0);
}

/* Hero animations */
.hero-hangul,
.hero-roman,
.hero-subtitle {
    opacity: 0;
    transform: translateY(30px);
    transition:
        opacity 800ms var(--ease-stone),
        transform 800ms var(--ease-stone);
}

.hero-hangul.is-visible { opacity: 1; transform: translateY(0); }
.hero-roman.is-visible  { opacity: 1; transform: translateY(0); transition-delay: 120ms; }
.hero-subtitle.is-visible { opacity: 1; transform: translateY(0); transition-delay: 240ms; }

/* Bedrock word animation */
.bedrock-word {
    opacity: 0;
    transform: translateY(24px);
    transition:
        opacity 700ms var(--ease-stone),
        transform 700ms var(--ease-stone);
}

.bedrock-word.is-visible { opacity: 0.7; transform: translateY(0); }

.bedrock-prism {
    opacity: 0;
    transform: translate(-60px, -40px) scale(0.94);
    transition:
        opacity 600ms var(--ease-stone),
        transform 600ms var(--ease-stone);
    transition-delay: 200ms;
}

.bedrock-prism.is-visible {
    opacity: 1;
    transform: translate(0, 0) scale(1);
}

.bedrock-mark {
    opacity: 0;
    transition: opacity 600ms var(--ease-stone);
    transition-delay: 400ms;
}

.bedrock-mark.is-visible { opacity: 0.6; }

/* --------------------------------------------------------------------------
   Isometric Grid SVG Tiles — JavaScript draws these
   The .iso-tile class handles the animated pulse effect
   -------------------------------------------------------------------------- */

.iso-tile {
    transition: fill 800ms ease;
}

.iso-tile--raised {
    fill: var(--c-sandstone);
}

.iso-tile--flat {
    fill: var(--c-travertine);
}

.iso-tile--pulse {
    fill: var(--c-ochre);
    opacity: 0.6;
}

/* Inverted bedrock grid */
.iso-tile--bedrock {
    fill: var(--c-clay);
}

.iso-tile--bedrock-raised {
    fill: var(--c-sienna);
}

.iso-tile--bedrock-pulse {
    fill: var(--c-terracotta);
    opacity: 0.5;
}

/* --------------------------------------------------------------------------
   Responsive
   -------------------------------------------------------------------------- */

@media (max-width: 900px) {
    .iso-nav { display: none; }
    .column-wrap--offset-right { margin-right: 0; }
    .prism-block:hover { transform: none; }
    .hero-hangul { font-size: clamp(100px, 22vw, 160px); }
    .column-wrap { padding: 0 24px; }
    .prism-front-inner { padding: 28px 32px; }
    .prism-shadow { width: 20px; right: -20px; }
    :root { --prism-shadow-w: 20px; }
}

@media (max-width: 600px) {
    .section-opener-word { font-size: 72px; }
    .prism-top { margin-left: calc(var(--prism-shadow-w) / 2); }
    .bedrock-prism-front { padding: 32px 28px; }
    .layer-strata, .layer-mid { padding: 80px 0; }
    .column-wrap--offset-right { margin-right: 0; margin-left: auto; }
}