/* ==========================================================================
   haskell.quest -- mid-century, minimal-navigation, kinetic, translucent-frost
   ========================================================================== */

:root {
    --frost-base: #F0F4F8;
    --frost-overlay: #E8EEF4;
    --slate: #5A6A80;
    --light-slate: #A0B0C0;
    --dark-slate: #2A3A4A;
    --warm-amber: #D0A070;
    --city-glow: #E8C090;

    --serif: 'Space Grotesk', 'Inter', sans-serif;
    --sans: 'IBM Plex Sans', 'Inter', sans-serif;
    --mono: 'IBM Plex Mono', 'Menlo', monospace;
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--sans);
    font-weight: 400;
    line-height: 1.85;
    color: var(--dark-slate);
    background: var(--frost-base);
    overflow-x: hidden;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* Layered translucent frost background */
body::before {
    content: '';
    position: fixed;
    inset: 0;
    background:
        radial-gradient(ellipse at 15% 10%, rgba(208, 160, 112, 0.06), transparent 60%),
        radial-gradient(ellipse at 85% 80%, rgba(90, 106, 128, 0.10), transparent 65%),
        radial-gradient(ellipse at 50% 50%, rgba(232, 238, 244, 0.4), transparent 70%);
    pointer-events: none;
    z-index: 0;
}

main {
    position: relative;
    z-index: 1;
}

/* ==========================================================================
   PROGRESS BAR
   ========================================================================== */

.progress-bar {
    position: fixed;
    bottom: 0;
    left: 0;
    width: 100%;
    height: 2px;
    background: var(--frost-overlay);
    z-index: 100;
    opacity: 0;
    animation: bar-fade-in 0.4s ease 1.6s forwards;
}

.progress-bar-fill {
    height: 100%;
    width: 0%;
    background: var(--warm-amber);
    transition: width 100ms linear;
}

@keyframes bar-fade-in {
    from { opacity: 0; }
    to   { opacity: 1; }
}

/* ==========================================================================
   SECTION 1 -- HERO
   ========================================================================== */

.hero {
    position: relative;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: flex-start;
    padding: clamp(40px, 6vw, 80px);
    overflow: hidden;
}

.frost-overlay {
    position: absolute;
    inset: 0;
    background:
        linear-gradient(180deg, var(--frost-overlay) 0%, var(--frost-base) 60%, var(--frost-base) 100%),
        radial-gradient(ellipse at 70% 30%, rgba(208, 160, 112, 0.08), transparent 50%);
    z-index: -1;
}

.hero-content {
    max-width: 1200px;
    width: 100%;
}

.quest-title {
    font-family: var(--serif);
    font-weight: 700;
    font-size: clamp(72px, 14vw, 200px);
    line-height: 0.9;
    letter-spacing: -0.04em;
    color: var(--dark-slate);
    margin-bottom: clamp(20px, 3vw, 40px);
    display: flex;
    flex-wrap: wrap;
}

.quest-letter {
    display: inline-block;
    transform: translateY(-30px);
    opacity: 0;
    will-change: transform;
}

.quest-letter.dropped {
    animation:
        letter-drop 0.9s cubic-bezier(0.34, 1.56, 0.64, 1) forwards,
        letter-osc-0 4.0s ease-in-out 1.2s infinite;
}

.quest-letter.dropped[data-i="1"] { animation-name: letter-drop, letter-osc-1; animation-duration: 0.9s, 4.6s; }
.quest-letter.dropped[data-i="2"] { animation-name: letter-drop, letter-osc-2; animation-duration: 0.9s, 3.4s; }
.quest-letter.dropped[data-i="3"] { animation-name: letter-drop, letter-osc-3; animation-duration: 0.9s, 5.0s; }
.quest-letter.dropped[data-i="4"] { animation-name: letter-drop, letter-osc-4; animation-duration: 0.9s, 3.8s; }

@keyframes letter-drop {
    from { transform: translateY(-30px); opacity: 0; }
    to   { transform: translateY(0);     opacity: 1; }
}

@keyframes letter-osc-0 {
    0%, 100% { transform: translateY(0px); }
    50%      { transform: translateY(-3px); }
}
@keyframes letter-osc-1 {
    0%, 100% { transform: translateY(0px); }
    50%      { transform: translateY(-2.5px); }
}
@keyframes letter-osc-2 {
    0%, 100% { transform: translateY(0px); }
    50%      { transform: translateY(-4px); }
}
@keyframes letter-osc-3 {
    0%, 100% { transform: translateY(0px); }
    50%      { transform: translateY(-2px); }
}
@keyframes letter-osc-4 {
    0%, 100% { transform: translateY(0px); }
    50%      { transform: translateY(-3.5px); }
}

.hero-subtitle {
    font-family: var(--serif);
    font-weight: 500;
    font-size: clamp(20px, 2.4vw, 32px);
    color: var(--slate);
    letter-spacing: 0.02em;
    opacity: 0;
    animation: fade-up 0.6s ease 1.0s forwards;
    margin-bottom: clamp(40px, 6vw, 80px);
}

@keyframes fade-up {
    from { opacity: 0; transform: translateY(8px); }
    to   { opacity: 1; transform: translateY(0); }
}

.hero-tagline {
    font-family: var(--mono);
    font-size: clamp(14px, 1.2vw, 18px);
    color: var(--slate);
    letter-spacing: 0.01em;
    display: inline-flex;
    align-items: center;
    min-height: 1.5em;
}

.typewriter {
    white-space: pre;
}

.cursor {
    display: inline-block;
    width: 2px;
    height: 1.1em;
    background: var(--warm-amber);
    margin-left: 4px;
    vertical-align: middle;
    animation: cursor-blink 0.6s steps(1, end) infinite;
    opacity: 0;
}

.cursor.active {
    opacity: 1;
}

@keyframes cursor-blink {
    0%, 49% { opacity: 1; }
    50%, 100% { opacity: 0; }
}

.hero-meta {
    position: absolute;
    bottom: clamp(40px, 6vw, 80px);
    left: clamp(40px, 6vw, 80px);
    right: clamp(40px, 6vw, 80px);
    display: flex;
    justify-content: space-between;
    font-family: var(--mono);
    font-size: 11px;
    letter-spacing: 0.18em;
    text-transform: uppercase;
    color: var(--light-slate);
    opacity: 0;
    animation: fade-up 0.6s ease 2.0s forwards;
}

/* ==========================================================================
   SECTION 2 -- ABSTRACT SHAPES
   ========================================================================== */

.shapes-section {
    padding: clamp(80px, 12vw, 160px) clamp(40px, 6vw, 80px);
    background: linear-gradient(180deg, var(--frost-base) 0%, var(--frost-overlay) 100%);
    border-top: 1px solid rgba(160, 176, 192, 0.25);
    border-bottom: 1px solid rgba(160, 176, 192, 0.25);
    position: relative;
}

.shapes-header {
    max-width: 720px;
    margin-bottom: clamp(40px, 6vw, 80px);
}

.section-eyebrow {
    font-family: var(--mono);
    font-weight: 400;
    font-size: 12px;
    letter-spacing: 0.2em;
    text-transform: uppercase;
    color: var(--warm-amber);
    margin-bottom: 24px;
}

.section-lede {
    font-family: var(--serif);
    font-weight: 500;
    font-size: clamp(20px, 2.2vw, 28px);
    line-height: 1.45;
    letter-spacing: -0.01em;
    color: var(--dark-slate);
}

.shapes-stage {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
}

.shapes-svg {
    display: block;
    width: 100%;
    height: auto;
    overflow: visible;
}

.shape-lines line {
    stroke: var(--light-slate);
    stroke-width: 1;
    stroke-dasharray: 3 4;
    opacity: 0.55;
}

.shape-circle {
    fill: none;
    stroke: var(--slate);
    stroke-width: 1.5;
}

.shape-circle.shape-amber {
    fill: var(--warm-amber);
    stroke: var(--warm-amber);
}

.shape-triangle {
    fill: none;
    stroke: var(--slate);
    stroke-width: 1.5;
}

.shape-triangle.shape-amber-stroke {
    stroke: var(--warm-amber);
}

.shape-rect {
    fill: var(--slate);
    stroke: none;
}

.shape-rect.shape-amber-fill {
    fill: var(--warm-amber);
}

.shape-label {
    font-family: var(--mono);
    font-size: 13px;
    fill: var(--slate);
    letter-spacing: 0.04em;
}

.shape-label.dark { fill: var(--frost-base); }
.shape-label.small { font-size: 11px; fill: var(--slate); }
.shape-label.small.dark { fill: var(--frost-base); }

/* Shape drift animations */
.shape-group {
    transform-origin: center;
    transform-box: fill-box;
    will-change: transform;
}

.shape-drift-1 { animation: drift-a 14s ease-in-out infinite; }
.shape-drift-2 { animation: drift-b 16s ease-in-out infinite; }
.shape-drift-3 { animation: drift-c 18s ease-in-out infinite; }
.shape-drift-4 { animation: drift-d 13s ease-in-out infinite; }
.shape-drift-5 { animation: drift-a 15s ease-in-out infinite reverse; }
.shape-drift-6 { animation: drift-b 19s ease-in-out infinite; }
.shape-drift-7 { animation: drift-c 12s ease-in-out infinite reverse; }
.shape-drift-8 { animation: drift-d 17s ease-in-out infinite; }

@keyframes drift-a {
    0%, 100% { transform: translate(0, 0); }
    50%      { transform: translate(4px, -3px); }
}
@keyframes drift-b {
    0%, 100% { transform: translate(0, 0); }
    50%      { transform: translate(-3px, 4px); }
}
@keyframes drift-c {
    0%, 100% { transform: translate(0, 0); }
    50%      { transform: translate(5px, 2px); }
}
@keyframes drift-d {
    0%, 100% { transform: translate(0, 0); }
    50%      { transform: translate(-4px, -4px); }
}

.shapes-legend {
    margin: clamp(40px, 5vw, 60px) auto 0;
    max-width: 1200px;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: 24px;
}

.legend-item {
    display: flex;
    align-items: center;
    gap: 14px;
    font-family: var(--mono);
    font-size: 12px;
    letter-spacing: 0.02em;
    color: var(--slate);
    border-top: 1px solid rgba(160, 176, 192, 0.4);
    padding-top: 16px;
}

.legend-mark {
    width: 24px;
    height: 24px;
    flex-shrink: 0;
    display: inline-block;
}

.legend-circle {
    border: 1.5px solid var(--slate);
    border-radius: 50%;
}

.legend-triangle {
    width: 0;
    height: 0;
    border-left: 12px solid transparent;
    border-right: 12px solid transparent;
    border-bottom: 20px solid transparent;
    border-bottom-color: transparent;
    position: relative;
}

.legend-triangle::before {
    content: '';
    position: absolute;
    left: -12px;
    top: -1px;
    width: 0;
    height: 0;
    border-left: 12px solid transparent;
    border-right: 12px solid transparent;
    border-bottom: 20px solid transparent;
}

.legend-triangle {
    background:
        linear-gradient(45deg, transparent 49%, var(--slate) 49%, var(--slate) 51%, transparent 51%),
        linear-gradient(-45deg, transparent 49%, var(--slate) 49%, var(--slate) 51%, transparent 51%);
    background-color: transparent;
    width: 0;
    height: 0;
    border: none;
    border-left: 12px solid transparent;
    border-right: 12px solid transparent;
    border-bottom: 20px solid;
    border-bottom-color: transparent;
}

/* simpler triangle marker */
.legend-triangle {
    width: 0;
    height: 0;
    background: none;
    border-left: 12px solid transparent;
    border-right: 12px solid transparent;
    border-bottom: 20px solid var(--slate);
}

.legend-rect {
    background: var(--slate);
}

.legend-text {
    line-height: 1.5;
}

/* ==========================================================================
   SECTION 3 -- LEARNING CONTENT
   ========================================================================== */

.content-section {
    padding: clamp(100px, 14vw, 200px) clamp(24px, 6vw, 80px);
    background: var(--frost-base);
    position: relative;
}

.content-section::before {
    /* margin decoration shapes */
    content: '';
    position: absolute;
    top: 15%;
    left: 6%;
    width: 24px;
    height: 24px;
    border: 1.5px solid var(--light-slate);
    border-radius: 50%;
    opacity: 0.6;
    animation: drift-a 16s ease-in-out infinite;
}

.content-section::after {
    content: '';
    position: absolute;
    top: 55%;
    right: 5%;
    width: 20px;
    height: 20px;
    background: var(--light-slate);
    opacity: 0.4;
    animation: drift-c 18s ease-in-out infinite;
}

.content-column {
    max-width: 55ch;
    margin: 0 auto;
    position: relative;
}

.article-head {
    margin-bottom: clamp(30px, 4vw, 60px);
}

.chapter-label {
    font-family: var(--mono);
    font-size: 11px;
    letter-spacing: 0.24em;
    text-transform: uppercase;
    color: var(--warm-amber);
    margin-bottom: 20px;
}

.article-title {
    font-family: var(--serif);
    font-weight: 700;
    font-size: clamp(36px, 5vw, 64px);
    line-height: 1.05;
    letter-spacing: -0.025em;
    color: var(--dark-slate);
}

.article-intro {
    font-family: var(--serif);
    font-weight: 400;
    font-size: clamp(18px, 1.6vw, 22px);
    line-height: 1.55;
    letter-spacing: -0.005em;
    color: var(--slate);
    margin-bottom: clamp(28px, 3vw, 40px);
}

.content-column p {
    font-family: var(--sans);
    font-size: clamp(15px, 1.1vw, 17px);
    line-height: 1.85;
    color: var(--dark-slate);
    margin-bottom: clamp(20px, 2.2vw, 28px);
}

.article-subhead {
    font-family: var(--serif);
    font-weight: 700;
    font-size: clamp(22px, 2.4vw, 32px);
    line-height: 1.25;
    letter-spacing: -0.015em;
    color: var(--dark-slate);
    margin: clamp(40px, 5vw, 64px) 0 clamp(16px, 1.8vw, 24px);
    border-top: 1px solid rgba(160, 176, 192, 0.35);
    padding-top: clamp(20px, 2.4vw, 32px);
}

.inline-code {
    font-family: var(--mono);
    font-size: 0.92em;
    background: var(--frost-overlay);
    color: var(--dark-slate);
    padding: 1px 6px;
    border-radius: 2px;
    border: 1px solid rgba(160, 176, 192, 0.4);
    white-space: nowrap;
}

/* code figure */
.code-figure {
    margin: clamp(28px, 3vw, 40px) 0;
}

.code-frame {
    background: var(--frost-overlay);
    border: 1px solid rgba(90, 106, 128, 0.25);
    position: relative;
    overflow: hidden;
}

.code-frame-bar {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 10px 16px;
    border-bottom: 1px solid rgba(160, 176, 192, 0.4);
    background: rgba(232, 238, 244, 0.6);
    font-family: var(--mono);
    font-size: 11px;
    letter-spacing: 0.06em;
    color: var(--slate);
}

.code-frame-tag {
    flex: 1;
    text-transform: lowercase;
}

.code-frame-dot {
    width: 6px;
    height: 6px;
    border-radius: 50%;
    background: var(--light-slate);
    opacity: 0.5;
}

.code-frame-dot:last-child { opacity: 0.8; background: var(--warm-amber); }

.code-block {
    font-family: var(--mono);
    font-size: 14px;
    line-height: 1.6;
    color: var(--dark-slate);
    padding: 20px 22px;
    overflow-x: auto;
    white-space: pre;
    min-height: 4em;
    position: relative;
    margin: 0;
}

.code-typewriter {
    white-space: pre;
}

.code-cursor {
    display: inline-block;
    width: 2px;
    height: 1.05em;
    background: var(--warm-amber);
    vertical-align: -2px;
    margin-left: 1px;
    opacity: 0;
}

.code-cursor.active {
    animation: cursor-blink 0.6s steps(1, end) infinite;
    opacity: 1;
}

.code-run {
    position: absolute;
    bottom: 12px;
    right: 12px;
    background: transparent;
    border: 1px solid var(--warm-amber);
    color: var(--warm-amber);
    font-family: var(--mono);
    font-size: 11px;
    letter-spacing: 0.12em;
    text-transform: uppercase;
    padding: 6px 10px;
    display: inline-flex;
    align-items: center;
    gap: 6px;
    cursor: pointer;
    opacity: 0;
    transform: translateY(4px);
    transition: opacity 0.4s ease, transform 0.3s ease, background 0.2s ease;
}

.code-run.shown {
    opacity: 1;
    transform: translateY(0);
}

.code-run:hover {
    transform: translateY(-2px);
    background: rgba(208, 160, 112, 0.10);
}

.code-run svg polygon {
    fill: var(--warm-amber);
}

/* pull quote */
.pull-quote {
    font-family: var(--serif);
    font-weight: 500;
    font-size: clamp(22px, 2.6vw, 32px);
    line-height: 1.35;
    letter-spacing: -0.015em;
    color: var(--dark-slate);
    margin: clamp(40px, 5vw, 60px) 0;
    padding: clamp(20px, 2.4vw, 32px) 0 clamp(20px, 2.4vw, 32px) clamp(20px, 2.4vw, 32px);
    border-left: 2px solid var(--warm-amber);
    position: relative;
}

.pull-quote-mark {
    position: absolute;
    left: clamp(20px, 2.4vw, 32px);
    top: -10px;
    font-family: var(--serif);
    font-size: clamp(48px, 5vw, 72px);
    line-height: 1;
    color: var(--warm-amber);
    opacity: 0.4;
    transform: translateX(-12px);
}

.pull-quote-text {
    display: inline-block;
    position: relative;
}

.pull-quote-text .pq-letter {
    display: inline-block;
    will-change: transform;
}

.pull-quote-alt {
    border-left-color: var(--slate);
}

.pull-quote-alt .pull-quote-mark {
    color: var(--slate);
}

/* path list */
.path-list {
    list-style: none;
    margin: clamp(28px, 3vw, 40px) 0;
    padding: 0;
    border-top: 1px solid rgba(160, 176, 192, 0.4);
}

.path-list li {
    display: flex;
    gap: 16px;
    padding: 14px 0;
    border-bottom: 1px solid rgba(160, 176, 192, 0.4);
    font-family: var(--mono);
    font-size: 13px;
    letter-spacing: 0.02em;
    color: var(--dark-slate);
    align-items: baseline;
}

.path-num {
    color: var(--warm-amber);
    font-weight: 500;
    flex-shrink: 0;
    min-width: 28px;
}

.path-text {
    flex: 1;
}

.article-outro {
    font-family: var(--serif);
    font-style: italic;
    font-size: clamp(16px, 1.4vw, 20px);
    color: var(--slate);
    margin-top: clamp(40px, 5vw, 60px);
    padding-top: clamp(20px, 2.4vw, 32px);
    border-top: 1px solid rgba(160, 176, 192, 0.4);
}

/* ==========================================================================
   SECTION 4 -- CITY SKYLINE
   ========================================================================== */

.city-section {
    padding: clamp(80px, 12vw, 160px) clamp(24px, 6vw, 80px) clamp(60px, 8vw, 100px);
    background: linear-gradient(180deg, var(--frost-base) 0%, var(--frost-overlay) 100%);
    border-top: 1px solid rgba(160, 176, 192, 0.25);
    position: relative;
}

.city-header {
    max-width: 720px;
    margin: 0 auto clamp(40px, 6vw, 80px);
    text-align: left;
}

.city-stage {
    width: 100%;
    max-width: 1440px;
    margin: 0 auto;
    position: relative;
}

.city-svg {
    display: block;
    width: 100%;
    height: auto;
}

.city-baseline {
    height: 1px;
    background: var(--slate);
    width: 100%;
    margin-top: -1px;
    opacity: 0.6;
}

.city-building {
    fill: var(--slate);
    transition: fill 600ms ease;
}

.city-building.lit {
    fill: var(--dark-slate);
}

.city-window {
    fill: var(--light-slate);
    transition: fill 500ms ease, filter 500ms ease;
}

.city-window.lit {
    fill: var(--warm-amber);
}

.city-window.glow {
    fill: var(--city-glow);
    filter: drop-shadow(0 0 4px rgba(232, 192, 144, 0.6));
}

.city-milestones {
    list-style: none;
    margin: clamp(40px, 5vw, 60px) auto 0;
    max-width: 1440px;
    padding: 0;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
    gap: 0;
    border-top: 1px solid rgba(160, 176, 192, 0.4);
}

.milestone {
    display: flex;
    flex-direction: column;
    gap: 6px;
    padding: 18px 12px;
    border-right: 1px solid rgba(160, 176, 192, 0.25);
    font-family: var(--mono);
    transition: background 400ms ease, color 400ms ease;
}

.milestone:last-child {
    border-right: none;
}

.milestone-num {
    font-size: 11px;
    letter-spacing: 0.2em;
    color: var(--light-slate);
}

.milestone-title {
    font-family: var(--serif);
    font-size: 16px;
    font-weight: 600;
    letter-spacing: -0.01em;
    color: var(--slate);
    transition: color 400ms ease;
}

.milestone-meta {
    font-size: 11px;
    line-height: 1.4;
    color: var(--light-slate);
    letter-spacing: 0.02em;
}

.milestone.reached .milestone-num { color: var(--warm-amber); }
.milestone.reached .milestone-title { color: var(--dark-slate); }
.milestone.reached .milestone-meta { color: var(--slate); }

/* ==========================================================================
   FOOTER
   ========================================================================== */

.end-footer {
    padding: clamp(80px, 10vw, 140px) clamp(24px, 6vw, 80px) clamp(40px, 6vw, 80px);
    background: var(--frost-base);
    text-align: center;
    position: relative;
}

.end-rule {
    width: 60%;
    max-width: 600px;
    height: 1px;
    background: rgba(160, 176, 192, 0.5);
    margin: 0 auto clamp(40px, 5vw, 60px);
}

.end-title {
    font-family: var(--serif);
    font-weight: 700;
    font-size: clamp(48px, 8vw, 100px);
    line-height: 0.9;
    letter-spacing: -0.04em;
    color: var(--dark-slate);
    margin-bottom: 24px;
    display: inline-flex;
    gap: 0.04em;
}

.end-letter {
    display: inline-block;
    will-change: transform;
}

.end-letter[data-i="0"] { animation: letter-osc-2 4.4s ease-in-out infinite; }
.end-letter[data-i="1"] { animation: letter-osc-3 3.8s ease-in-out infinite; }
.end-letter[data-i="2"] { animation: letter-osc-1 5.2s ease-in-out infinite; }

.end-link {
    display: inline-block;
    font-family: var(--mono);
    font-size: 13px;
    letter-spacing: 0.2em;
    text-transform: uppercase;
    color: var(--warm-amber);
    text-decoration: none;
    border-bottom: 1px solid var(--warm-amber);
    padding-bottom: 4px;
    margin-bottom: clamp(28px, 3vw, 40px);
    transition: opacity 0.2s ease, transform 0.2s ease;
}

.end-link:hover {
    opacity: 0.7;
    transform: translateY(-1px);
}

.end-note {
    font-family: var(--serif);
    font-style: italic;
    font-size: clamp(14px, 1.2vw, 16px);
    color: var(--light-slate);
    max-width: 480px;
    margin: 0 auto;
    line-height: 1.6;
}

/* ==========================================================================
   RESPONSIVE
   ========================================================================== */

@media (max-width: 720px) {
    .hero-meta {
        flex-direction: column;
        gap: 8px;
    }

    .shapes-svg {
        min-height: 360px;
    }

    .content-section::before,
    .content-section::after {
        display: none;
    }

    .city-milestones {
        grid-template-columns: repeat(3, 1fr);
    }
}

@media (max-width: 480px) {
    .city-milestones {
        grid-template-columns: repeat(2, 1fr);
    }

    .hero {
        padding: 32px 24px;
    }
}