/* =================================================================
   Daegeun Kim - Shared Design System
   site.css : tokens, base type, header/nav, footer, links, buttons,
   focus, motion, and light/dark theme variables.
   Loaded by every redesigned page. Page-specific styles live
   elsewhere and build on these tokens.
   ================================================================= */

/* -----------------------------------------------------------------
   1. Design tokens
   ----------------------------------------------------------------- */
:root {
  /* Surface & ink. Bright paper ground, charcoal ink (never pure). */
  --bg:            #f4f5f6;
  --bg-elev:       #fbfbfc;
  --ink:           #14181d;
  --ink-2:         #858585;   /* body copy - dimmer grey, sits below headings */
  --ink-3:         #656c73;   /* metadata - AA-contrast on the light ground */
  --line:          #d9dce0;   /* subtle: media frames, internal rules */
  --line-strong:   #bcc1c7;   /* strong: major section dividers */

  /* Accents. Blue primary, teal secondary. Used sparingly. */
  --blue:          #1d4ed8;
  --blue-strong:   #16337a;
  --blue-soft:     #e8edfb;
  --teal:          #0b7a75;
  --teal-strong:   #0a605c;

  --accent:        var(--blue);
  --accent-strong: var(--blue-strong);
  --accent-soft:   var(--blue-soft);

  /* Typography. Helvetica-oriented, Windows-safe fallback. */
  --font-sans: "Helvetica Neue", Helvetica, "Segoe UI", Arial, sans-serif;

  /* Weights */
  --w-regular: 400;
  --w-medium:  500;
  --w-semi:    600;
  --w-bold:    700;

  /* Type scale. Fixed sizes for small text to stay crisp; fluid for
     large display text only. Small copy never below ~15px. */
  --fs-display: clamp(2.55rem, 1.55rem + 4.3vw, 4.75rem);
  --fs-h1:      clamp(1.9rem, 1.3rem + 2.6vw, 3rem);
  --fs-h2:      clamp(1.5rem, 1.25rem + 1.1vw, 2rem);
  --fs-h3:      clamp(1.2rem, 1.08rem + 0.55vw, 1.45rem);
  --fs-lead:    clamp(1.14rem, 1.02rem + 0.5vw, 1.4rem);
  --fs-body:    1rem;                              /* 16px */
  --fs-small:   clamp(0.9375rem, 0.9rem + 0.18vw, 1rem);  /* 15-16px */
  --fs-meta:    0.8125rem;                         /* 13px, fixed */

  /* Spacing */
  --space-1: 0.5rem;
  --space-2: 0.75rem;
  --space-3: 1rem;
  --space-4: 1.5rem;
  --space-5: 2.5rem;
  --space-6: 4rem;
  --space-7: 6rem;
  --space-8: clamp(4rem, 2rem + 9vw, 9rem);

  /* Layout */
  --container: 1400px;
  --pad-x: clamp(1.15rem, 0.6rem + 2.6vw, 3rem);
  --header-h: 66px;
  --radius: 10px;
  --radius-sm: 6px;

  /* Motion */
  --ease: cubic-bezier(0.22, 0.61, 0.36, 1);
  --dur: 0.28s;

  color-scheme: light;
}

/* Dark theme. Used by selected project pages (Phase 3). Same system,
   spacing, and components; only the palette shifts. */
:root[data-theme="dark"] {
  --bg:            #14171a;
  --bg-elev:       #1c2024;
  --ink:           #f1f2f4;
  --ink-2:         #c2c7cd;
  --ink-3:         #8b9299;
  --line:          #2c3137;
  --line-strong:   #444a51;

  --blue:          #7aa2ff;
  --blue-strong:   #a9c2ff;
  --blue-soft:     #1e2740;
  --teal:          #4fd1c5;
  --teal-strong:   #7fe3da;

  color-scheme: dark;
}

/* -----------------------------------------------------------------
   2. Reset & base
   ----------------------------------------------------------------- */
*, *::before, *::after { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink-2);
  font-family: var(--font-sans);
  font-size: var(--fs-body);
  font-weight: var(--w-regular);
  line-height: 1.6;
  overflow-x: hidden;
}

img { max-width: 100%; height: auto; display: block; }

h1, h2, h3, h4 {
  color: var(--ink);
  font-weight: var(--w-semi);
  line-height: 1.15;
  margin: 0;
}

p { margin: 0; }

a { color: var(--accent); text-decoration: none; }

::selection { background: var(--accent-soft); color: var(--ink); }

/* Layout container */
.container {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: var(--pad-x);
}

/* Eyebrow / small caps label */
.eyebrow {
  font-size: var(--fs-meta);
  font-weight: var(--w-semi);
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--ink-3);
  margin: 0;
}

/* Focus. Visible for keyboard users everywhere. */
:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
  border-radius: 2px;
}

/* Skip link */
.skip-link {
  position: absolute;
  left: var(--pad-x);
  top: -100px;
  z-index: 1200;
  background: var(--ink);
  color: var(--bg);
  padding: 0.6rem 1rem;
  border-radius: var(--radius-sm);
  font-size: var(--fs-small);
}
.skip-link:focus { top: 12px; }

/* Screen-reader only */
.visually-hidden {
  position: absolute !important;
  width: 1px; height: 1px;
  padding: 0; margin: -1px;
  overflow: hidden; clip: rect(0 0 0 0);
  white-space: nowrap; border: 0;
}

/* -----------------------------------------------------------------
   3. Header & navigation
   ----------------------------------------------------------------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 1000;
  background: color-mix(in srgb, var(--bg) 88%, transparent);
  -webkit-backdrop-filter: saturate(1.4) blur(10px);
  backdrop-filter: saturate(1.4) blur(10px);
  border-bottom: 1.4px solid transparent;
  transition: border-color var(--dur) var(--ease);
}
.site-header.is-scrolled { border-bottom-color: var(--line-strong); }

.site-header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: var(--header-h);
  gap: var(--space-3);
}

.wordmark {
  font-size: clamp(1.05rem, 1rem + 0.35vw, 1.2rem);
  font-weight: var(--w-bold);
  letter-spacing: -0.01em;
  color: var(--ink);
  white-space: nowrap;
}
.wordmark:hover { color: var(--ink); }

/* Nav */
.site-nav__list {
  display: flex;
  align-items: center;
  gap: clamp(1rem, 0.4rem + 1.6vw, 2rem);
  list-style: none;
  margin: 0;
  padding: 0;
}

.nav-link {
  position: relative;
  display: inline-flex;
  align-items: center;
  gap: 0.35em;
  font-size: var(--fs-small);
  font-weight: var(--w-regular);
  letter-spacing: 0.005em;
  color: var(--ink-2);
  padding: 0.35rem 0;
  transition: color var(--dur) var(--ease);
}
.nav-link::after {
  content: "";
  position: absolute;
  left: 0; right: 100%;
  bottom: -1px;
  height: 1.5px;
  background: var(--accent);
  transition: right var(--dur) var(--ease);
}
.nav-link:hover { color: var(--ink); }
.nav-link:hover::after { right: 0; }
.nav-link[aria-current="page"] { color: var(--ink); font-weight: var(--w-medium); }
.nav-link[aria-current="page"]::after { right: 0; background: var(--ink); }

.nav-link__ext {
  font-size: 0.8em;
  color: var(--ink-3);
  transition: transform var(--dur) var(--ease), color var(--dur) var(--ease);
}
.nav-link:hover .nav-link__ext { transform: translate(1px, -1px); color: var(--accent); }

.nav-divider {
  width: 1px;
  height: 1rem;
  background: var(--line-strong);
}

/* Mobile menu toggle */
.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 42px;
  height: 42px;
  padding: 10px;
  background: none;
  border: 0;
  cursor: pointer;
}
.nav-toggle span {
  display: block;
  height: 1.5px;
  width: 100%;
  background: var(--ink);
  transition: transform var(--dur) var(--ease), opacity var(--dur) var(--ease);
}
.nav-toggle[aria-expanded="true"] span:nth-child(1) { transform: translateY(6.5px) rotate(45deg); }
.nav-toggle[aria-expanded="true"] span:nth-child(2) { opacity: 0; }
.nav-toggle[aria-expanded="true"] span:nth-child(3) { transform: translateY(-6.5px) rotate(-45deg); }

@media (max-width: 720px) {
  .nav-toggle { display: flex; }

  .site-nav {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: var(--bg);
    border-bottom: 1px solid var(--line-strong);
    max-height: 0;
    overflow: hidden;
    transition: max-height var(--dur) var(--ease);
  }
  .site-nav.is-open { max-height: 70vh; }

  .site-nav__list {
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    padding: var(--space-2) var(--pad-x) var(--space-4);
  }
  .nav-link {
    padding: 0.85rem 0;
    font-size: 1.05rem;
    border-bottom: 1px solid var(--line);
  }
  .nav-link::after { display: none; }
  .nav-divider { display: none; }
}

/* -----------------------------------------------------------------
   4. Buttons & inline links
   ----------------------------------------------------------------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5em;
  font-family: inherit;
  font-size: var(--fs-small);
  font-weight: var(--w-medium);
  color: var(--ink);
  background: transparent;
  border: 1px solid var(--line-strong);
  border-radius: 999px;
  padding: 0.6rem 1.2rem;
  cursor: pointer;
  transition: border-color var(--dur) var(--ease),
              color var(--dur) var(--ease);
}
.btn:hover { border-color: var(--accent); color: var(--accent); }

.link-inline {
  color: var(--accent);
  border-bottom: 1px solid color-mix(in srgb, var(--accent) 45%, transparent);
  transition: border-color var(--dur) var(--ease);
}
.link-inline:hover { border-bottom-color: var(--accent); }

/* -----------------------------------------------------------------
   5. Footer
   ----------------------------------------------------------------- */
.site-footer {
  border-top: 1.4px solid var(--line-strong);
  margin-top: var(--space-8);
  padding-block: var(--space-6) var(--space-5);
}
.site-footer__inner {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-4) var(--space-5);
  justify-content: space-between;
  align-items: flex-end;
}
.site-footer__brand {
  font-size: var(--fs-h3);
  color: var(--ink);
  font-weight: var(--w-bold);
  letter-spacing: -0.01em;
}
.site-footer__tag {
  font-size: var(--fs-small);
  color: var(--ink-3);
  max-width: 40ch;
  margin-top: 0.5rem;
}
.site-footer__links {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-4);
  list-style: none;
  margin: 0;
  padding: 0;
}
.site-footer__links a {
  font-size: var(--fs-small);
  color: var(--ink-2);
  display: inline-flex;
  gap: 0.35em;
  transition: color var(--dur) var(--ease);
}
.site-footer__links a:hover { color: var(--accent); }
.site-footer__legal {
  width: 100%;
  margin-top: var(--space-4);
  font-size: var(--fs-meta);
  letter-spacing: 0.04em;
  color: var(--ink-3);
}

/* -----------------------------------------------------------------
   6. Shared motion helpers (reveal on load / scroll)
   ----------------------------------------------------------------- */
.reveal {
  opacity: 0;
  transform: translateY(14px);
  transition: opacity 0.6s var(--ease), transform 0.6s var(--ease);
}
/* Clear the transform entirely once revealed so text never sits on a
   lingering composited layer (keeps small type crisp). */
.reveal.is-in { opacity: 1; transform: none; }

@media (prefers-reduced-motion: reduce) {
  .reveal { opacity: 1; transform: none; transition: none; }
  *, *::before, *::after {
    animation-duration: 0.001ms !important;
    transition-duration: 0.001ms !important;
    scroll-behavior: auto !important;
  }
}

/* =================================================================
   7. Subpage / case-study components
   Shared layer for project pages: standardized top (hero + meta) and
   common content components. Token-based, so the dark theme
   (data-theme="dark") works automatically. Scoped under .subpage so
   these never touch home / about / photography.
   ================================================================= */
.subpage {
  max-width: 1080px;
  margin-inline: auto;
  padding-inline: var(--pad-x);
  padding-top: clamp(1.5rem, 1rem + 2vw, 3rem);
}

/* --- Standardized hero / top --- */
.proj-hero { position: relative; padding-bottom: var(--space-4); }
/* Gradient accent bar (teal -> blue) ties the hero to the brand. */
.proj-hero::before {
  content: "";
  display: block;
  width: 60px;
  height: 3px;
  border-radius: 2px;
  background: linear-gradient(100deg, var(--teal) 0%, #0e93a8 45%, var(--blue) 100%);
  margin-bottom: var(--space-3);
}
.proj-hero .eyebrow { color: var(--accent-strong); }
.proj-hero__title {
  font-size: clamp(2.3rem, 1.4rem + 3.6vw, 4.2rem);
  font-weight: var(--w-bold);
  letter-spacing: -0.028em;
  line-height: 1.02;
  color: var(--ink);
  margin-top: var(--space-2);
}
.proj-hero__summary {
  font-size: var(--fs-lead);
  font-weight: var(--w-regular);
  line-height: 1.5;
  color: var(--ink-2);
  max-width: 56ch;
  margin-top: var(--space-3);
}
.proj-hero__meta {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(190px, 1fr));
  grid-auto-rows: 1fr;
  align-items: stretch;
  gap: var(--space-4) var(--space-5);
  margin-top: var(--space-5);
  margin-bottom: var(--space-6);
  padding-top: var(--space-4);
  border-top: 1.4px solid var(--line-strong);
}
.proj-hero__meta h2 {
  font-size: var(--fs-meta);
  font-weight: var(--w-bold);
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--ink-3);
  margin-bottom: 0.45rem;
}
.proj-hero__meta .val,
.proj-hero__meta p {
  font-size: var(--fs-small);
  font-weight: var(--w-regular);
  line-height: 1.55;
  color: var(--ink-2);
}
.proj-hero__meta a {
  color: var(--accent);
  display: inline-flex;
  align-items: baseline;
  gap: 0.3em;
}
.proj-hero__meta a:hover { text-decoration: underline; }

/* Hero image sits first (above the title block): tight top, gap below. */
.proj-media { margin: 0 0 var(--space-5); }
.proj-media img {
  width: 100%;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--bg-elev);
}
.proj-media figcaption,
.subpage figure.shot figcaption {
  font-size: var(--fs-small);
  color: var(--ink-3);
  line-height: 1.5;
  margin-top: 0.6rem;
}
.subpage figcaption b { color: var(--ink-2); font-weight: var(--w-semi); }

/* --- Section headings --- */
.subpage .section-title {
  font-size: var(--fs-h2);
  font-weight: var(--w-bold);
  letter-spacing: -0.015em;
  color: var(--ink);
  margin: clamp(3rem, 2rem + 3vw, 5rem) 0 var(--space-3);
}
.subpage .subsection-title {
  font-size: var(--fs-h3);
  font-weight: var(--w-bold);
  letter-spacing: -0.01em;
  color: var(--ink);
  margin: var(--space-5) 0 var(--space-2);
}

/* --- Body text --- */
.subpage .text {
  font-size: var(--fs-body);
  line-height: 1.55;
  color: var(--ink-2);
}
.subpage .text + .text { margin-top: var(--space-3); }
.subpage .text a,
.subpage .references-list a,
.subpage .adoption-note a {
  color: var(--accent);
  border-bottom: 1px solid color-mix(in srgb, var(--accent) 35%, transparent);
}
.subpage .text a:hover { border-bottom-color: var(--accent); }

.subpage code, .subpage .text code {
  font-family: ui-monospace, "Cascadia Mono", Menlo, Consolas, monospace;
  font-size: 0.86em;
  background: color-mix(in srgb, var(--ink) 7%, var(--bg-elev));
  padding: 1px 5px;
  border-radius: 3px;
  color: var(--ink);
}

.subpage .tight-list {
  margin: var(--space-2) 0 0 1.25rem;
  padding: 0;
  font-size: var(--fs-small);
  color: var(--ink-2);
  line-height: 1.65;
}
.subpage .tight-list li { margin-bottom: 0.5rem; }

/* --- Callouts --- */
.subpage .callout {
  border: 1px solid color-mix(in srgb, var(--accent) 30%, var(--line));
  background: color-mix(in srgb, var(--accent) 7%, var(--bg-elev));
  padding: var(--space-3) var(--space-4);
  margin: var(--space-4) 0;
  border-radius: var(--radius-sm);
  font-size: var(--fs-small);
  line-height: 1.6;
  color: var(--ink);
}
.subpage .callout.rule {
  border-color: color-mix(in srgb, var(--teal) 34%, var(--line));
  background: color-mix(in srgb, var(--teal) 8%, var(--bg-elev));
}
.subpage .callout .lead {
  display: block;
  font-size: var(--fs-meta);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  font-weight: var(--w-bold);
  color: var(--ink-3);
  margin-bottom: 0.4rem;
}

/* --- Info box + chip row + note strip + adoption note --- */
.subpage .arch-box, .subpage .note-strip, .subpage .adoption-note {
  background: var(--bg-elev);
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  padding: var(--space-3) var(--space-4);
  margin: var(--space-4) 0;
  font-size: var(--fs-small);
  color: var(--ink-2);
  line-height: 1.6;
}
.subpage .arch-box b { color: var(--ink); display: block; margin-bottom: 0.6rem; }
.subpage .chip-row { display: flex; flex-wrap: wrap; gap: 0.5rem; margin-top: 0.4rem; }
.subpage .chip-row code {
  background: color-mix(in srgb, var(--accent) 8%, var(--bg-elev));
  border: 1px solid color-mix(in srgb, var(--accent) 22%, var(--line));
  color: var(--accent-strong);
}

/* --- Tables --- */
.subpage .table-wrap {
  width: 100%;
  overflow-x: auto;
  margin: var(--space-4) 0;
  -webkit-overflow-scrolling: touch;
}
.subpage .data-table {
  width: 100%;
  border-collapse: collapse;
  font-size: var(--fs-small);
  min-width: 520px;
}
.subpage .data-table th, .subpage .data-table td {
  padding: 0.55rem 0.85rem;
  text-align: left;
  border-bottom: 1px solid var(--line);
  color: var(--ink-2);
  vertical-align: top;
  line-height: 1.45;
}
.subpage .data-table th {
  color: var(--ink);
  font-weight: var(--w-semi);
  border-bottom: 1.5px solid var(--line-strong);
  white-space: nowrap;
}
.subpage .data-table td.num, .subpage .data-table th.num { text-align: right; white-space: nowrap; }
.subpage .data-table tbody tr:hover { background: color-mix(in srgb, var(--ink) 3%, transparent); }
.subpage .data-table caption {
  caption-side: bottom; text-align: left;
  font-size: var(--fs-meta); color: var(--ink-3);
  padding-top: 0.6rem; line-height: 1.5;
}
.subpage .tech-table {
  width: 100%; border-collapse: collapse; margin: var(--space-3) 0; font-size: var(--fs-small);
}
.subpage .tech-table tbody tr { border-bottom: 1px solid var(--line); }
.subpage .tech-table tbody tr:first-child { border-top: 1px solid var(--line); }
.subpage .tech-table td { padding: 0.5rem 0.85rem; color: var(--ink-2); vertical-align: top; line-height: 1.45; }
.subpage .tech-table td:first-child { font-weight: var(--w-semi); color: var(--ink); width: 30%; white-space: nowrap; }

/* --- Figures --- */
.subpage figure.shot { margin: 0; display: flex; flex-direction: column; }
.subpage figure.shot img {
  width: 100%; display: block;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--bg-elev);
}
.subpage .shot-2col { display: grid; grid-template-columns: 1fr 1fr; gap: var(--space-4); margin: var(--space-4) 0; }
.subpage .shot-wide { margin: var(--space-4) 0; }
@media (max-width: 640px) { .subpage .shot-2col { grid-template-columns: 1fr; } }

/* --- References --- */
.subpage .references-list {
  margin: var(--space-3) 0 0 1.25rem; padding: 0;
  font-size: var(--fs-small); color: var(--ink-2); line-height: 1.65;
}
.subpage .references-list li + li { margin-top: var(--space-3); }
.subpage .references-list a { word-break: break-word; }
.subpage .references-list b { color: var(--ink); }

/* --- Section separator --- */
.subpage .section-separator {
  border: none;
  border-top: 1.4px solid var(--line-strong);
  margin: clamp(4rem, 3rem + 3vw, 7rem) 0 var(--space-5);
}

/* --- Subpage footer (case-study) --- */
.subpage-footer {
  border-top: 1.4px solid var(--line-strong);
  margin-top: var(--space-8);
  padding-block: var(--space-5) var(--space-6);
}
.subpage-footer .container { max-width: 1080px; }
.subpage-footer__title { font-size: var(--fs-h3); font-weight: var(--w-bold); color: var(--ink); }
.subpage-footer__sub { font-size: var(--fs-small); color: var(--ink-3); margin-top: 0.3rem; }
.subpage-footer__back {
  display: inline-flex; align-items: center; gap: 0.4em;
  margin-top: var(--space-3); font-size: var(--fs-small); color: var(--accent);
}
.subpage-footer__back:hover { text-decoration: underline; }

/* -----------------------------------------------------------------
   Bright subpages: pure-white ground.
   Many project images are white-background themselves and are meant
   to blend seamlessly into the page, so bright project pages use a
   white ground (page, header, figure backgrounds) and their images
   drop the frame and rounded corners. Dark project pages and the
   home / about / photography pages are unaffected.
   ----------------------------------------------------------------- */
:root:not([data-theme="dark"]):has(.subpage) {
  --bg: #ffffff;
  --bg-elev: #ffffff;
}
:root:not([data-theme="dark"]) .subpage .proj-media img,
:root:not([data-theme="dark"]) .subpage figure.shot img,
:root:not([data-theme="dark"]) .subpage .img-card img,
:root:not([data-theme="dark"]) .subpage .image-wide img {
  border: none;
  border-radius: 0;
  background: transparent;
}