/* ── Variables ─────────────────────────────────────────────── */
:root {
  --bg:          #0c0c0c;
  --bg-surface:  #161616;
  --bg-hover:    #1c1c1c;
  --border:      #272727;
  --text-1:      #f0ede8;
  --text-2:      #888;
  --accent:      #c8b89a;
  --header-h:    60px;
  --sidebar-w:   240px;
  --ease:        0.25s ease;
}

/* ── Light mode ────────────────────────────────────────────── */
html.light {
  --bg:          #f7f4f0;
  --bg-surface:  #edeae4;
  --bg-hover:    #e4dfd7;
  --border:      #cdc7be;
  --text-1:      #1c1a17;
  --text-2:      #7a7268;
  --accent:      #8b6840;
}
html.light body   { background: var(--bg); color: var(--text-1); }
html.light #header {
  background: rgba(247, 244, 240, 0.88);
}
html.light .hero-name {
  background: linear-gradient(145deg, var(--text-1) 40%, var(--accent));
  -webkit-background-clip: text;
  background-clip: text;
}

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

html {
  scroll-behavior: smooth;
  scrollbar-width: none;        /* Firefox */
  -ms-overflow-style: none;     /* IE, Edge */
}
html::-webkit-scrollbar { display: none; } /* Chrome, Safari, Opera */

body {
  background: var(--bg);
  color: var(--text-1);
  font-family: 'Pretendard', 'Segoe UI', system-ui, -apple-system, sans-serif;
  min-height: 100vh;
  overflow-x: hidden;
}

/* ── Header ────────────────────────────────────────────────── */
#header {
  position: fixed;
  inset: 0 0 auto 0;
  height: var(--header-h);
  background: rgba(12, 12, 12, 0.85);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--border);
  z-index: 100;
}

.header-inner {
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 2rem;
}

.logo {
  position: relative;
  font-size: 1rem;
  font-weight: 700;
  color: var(--text-1);
  text-decoration: none;
  letter-spacing: 0.04em;
  transition: opacity var(--ease);
}
.logo:hover { opacity: 0.7; }
.logo::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0; right: 0;
  height: 1px;
  background: var(--accent);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform var(--ease);
}
.logo.active::after { transform: scaleX(1); }

nav { display: flex; gap: 2rem; align-items: center; }

/* Theme toggle */
.theme-btn {
  background: none;
  border: 1px solid var(--border);
  color: var(--text-2);
  width: 30px;
  height: 30px;
  border-radius: 6px;
  cursor: pointer;
  font-size: 0.85rem;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: border-color var(--ease), color var(--ease);
  flex-shrink: 0;
}
.theme-btn:hover { border-color: var(--accent); color: var(--text-1); }

.nav-link {
  position: relative;
  color: var(--text-2);
  text-decoration: none;
  font-size: 0.875rem;
  letter-spacing: 0.02em;
  transition: color var(--ease);
}
.nav-link::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0; right: 0;
  height: 1px;
  background: var(--accent);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform var(--ease);
}
.nav-link:hover        { color: var(--text-1); }
.nav-link.active       { color: var(--text-1); }
.nav-link.active::after { transform: scaleX(1); }

/* ── Pages ─────────────────────────────────────────────────── */
#main { padding-top: var(--header-h); }

.page {
  display: none;
}
.page.active { display: block; }

/* Home & About: internal scroll container (GSAP controls snapping) */
#page-home,
#page-about {
  height: calc(100vh - var(--header-h));
  overflow-y: auto;
  scrollbar-width: none;
  -ms-overflow-style: none;
}
#page-home::-webkit-scrollbar,
#page-about::-webkit-scrollbar { display: none; }

/* Every fullscreen snap unit */
.snap-section {
  min-height: calc(100vh - var(--header-h));
}

/* ── Hero ──────────────────────────────────────────────────── */
.hero {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 2rem;
  gap: 0;
  position: relative;
}

.hero-label {
  font-size: 0.8rem;
  letter-spacing: 0.25em;
  text-transform: uppercase;
  color: var(--text-2);
  margin-bottom: 1.2rem;
}

.hero-name {
  font-size: clamp(3.5rem, 11vw, 8.5rem);
  font-weight: 800;
  letter-spacing: -0.03em;
  line-height: 1;
  margin-bottom: 1.5rem;
  background: linear-gradient(145deg, var(--text-1) 40%, var(--accent));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-desc {
  font-size: 1.1rem;
  color: var(--text-2);
}

/* Scroll hint */
.scroll-hint {
  position: absolute;
  bottom: 2rem;
  left: 50%;
  transform: translateX(-50%);
  font-size: 0.72rem;
  letter-spacing: 0.18em;
  color: var(--text-2);
  opacity: 0.5;
  animation: hint-bob 2s ease-in-out infinite;
}
@keyframes hint-bob {
  0%, 100% { transform: translateX(-50%) translateY(0); }
  50%       { transform: translateX(-50%) translateY(6px); }
}

/* ── Shared section layout ─────────────────────────────────── */
.section-inner {
  max-width: 900px;
  width: 100%;
  padding: 0 2rem;
  margin: 0 auto;
}

.section-eyebrow {
  display: block;
  font-size: 0.72rem;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 0.8rem;
}

.section-heading {
  font-size: clamp(1.8rem, 4vw, 3rem);
  font-weight: 700;
  letter-spacing: -0.025em;
  margin-bottom: 3rem;
}

/* ── Focus section ─────────────────────────────────────────── */
.focus-section {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 4rem 2rem;
}

.focus-cards {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.5rem;
}

.focus-card {
  padding: 2rem 1.5rem;
  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: 10px;
  transition: border-color var(--ease), transform var(--ease);
}
.focus-card:hover {
  border-color: var(--accent);
  transform: translateY(-4px);
}

.card-num {
  display: block;
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.15em;
  color: var(--accent);
  margin-bottom: 1rem;
}

.focus-card h3 {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 0.6rem;
}

.focus-card p {
  font-size: 0.875rem;
  color: var(--text-2);
  line-height: 1.75;
}

/* ── About bio snap-section ────────────────────────────────── */
.about-layout {
  position: relative;
}

/* ── Experience section ────────────────────────────────────── */
.exp-section {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 4rem 2rem;
}

.exp-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0;
}

.exp-item {
  display: flex;
  gap: 2.5rem;
  padding: 1.75rem 0;
  border-bottom: 1px solid var(--border);
  align-items: flex-start;
}
.exp-item:first-child { border-top: 1px solid var(--border); }

.exp-year {
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--accent);
  letter-spacing: 0.08em;
  min-width: 3rem;
  padding-top: 0.15rem;
}

.exp-body h3 {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 0.4rem;
}

.exp-body p {
  font-size: 0.875rem;
  color: var(--text-2);
  line-height: 1.75;
}

/* ── Projects layout ───────────────────────────────────────── */
.projects-layout {
  display: flex;
  height: calc(100vh - var(--header-h));
}

/* Sidebar */
.projects-sidebar {
  width: var(--sidebar-w);
  flex-shrink: 0;
  border-right: 1px solid var(--border);
  padding: 2.5rem 1.25rem;
  height: 100%;
  overflow-y: auto;
  display: flex;
  flex-direction: column;
}

.sidebar-label {
  font-size: 0.7rem;
  font-weight: 600;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--text-2);
  padding: 0 0.75rem;
  margin-bottom: 1rem;
}

.project-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.project-item {
  padding: 0.55rem 0.75rem;
  border-radius: 6px;
  cursor: pointer;
  font-size: 0.875rem;
  color: var(--text-2);
  border-left: 2px solid transparent;
  transition: color var(--ease), background var(--ease), border-color var(--ease);
}
.project-item:hover {
  color: var(--text-1);
  background: var(--bg-hover);
}
.project-item.active {
  color: var(--text-1);
  background: var(--bg-surface);
  border-left-color: var(--accent);
}

/* ── Panel track ───────────────────────────────────────────── */
.projects-track-wrapper {
  flex: 1;
  position: relative;
  overflow: hidden;
}

#projects-track {
  position: relative;
  height: 100%;
}

/* Individual panels – stacked, one visible at a time */
.project-panel {
  position: absolute;
  inset: 0;
  overflow-y: auto;
  overflow-x: hidden;
  display: flex;
  justify-content: center;
  align-items: flex-start;
  will-change: transform, opacity;
}

.article-inner {
  width: 100%;
  max-width: 864px;
  padding: 3.5rem 2rem;
}

/* ── Panel dots ────────────────────────────────────────────── */
.panel-dots {
  display: flex;
  gap: 7px;
  align-items: center;
  padding: 0 0.75rem;
  margin-top: auto;
  padding-top: 2rem;
}

.panel-dot {
  width: 5px;
  height: 5px;
  border-radius: 50%;
  background: var(--border);
  cursor: pointer;
  border: none;
  padding: 0;
  transition: background var(--ease), transform var(--ease);
}
.panel-dot.active {
  background: var(--accent);
  transform: scale(1.5);
}

/* ── Article image ─────────────────────────────────────────── */
.article-image {
  width: 100%;
  aspect-ratio: 16 / 9;
  border-radius: 10px;
  overflow: hidden;
  margin-bottom: 2rem;
  background: var(--bg-surface);
}

.article-image img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
  filter: brightness(0.9);
  transition: filter 0.4s ease;
}

.article-image img:hover { filter: brightness(1); }

/* ── Article content ───────────────────────────────────────── */
.article-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  margin-bottom: 1rem;
}

.tag {
  padding: 0.2rem 0.65rem;
  border: 1px solid var(--border);
  border-radius: 999px;
  font-size: 0.72rem;
  letter-spacing: 0.04em;
  color: var(--text-2);
}

.article-title {
  font-size: 2rem;
  font-weight: 700;
  letter-spacing: -0.025em;
  line-height: 1.2;
  margin-bottom: 0.4rem;
}

.article-date {
  font-size: 0.8rem;
  color: var(--text-2);
}

.article-divider {
  border: none;
  border-top: 1px solid var(--border);
  margin: 1.75rem 0;
}

.article-overview {
  font-size: 0.975rem;
  color: var(--text-2);
  line-height: 1.85;
  padding: 1.1rem 1.2rem;
  background: var(--bg-surface);
  border-radius: 8px;
  border-left: 2px solid var(--accent);
  margin-bottom: 2rem;
}

.article-body h3 {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text-1);
  margin: 2rem 0 0.65rem;
  letter-spacing: 0.01em;
}

.article-body p {
  font-size: 0.9rem;
  line-height: 1.9;
  color: #999;
  margin-bottom: 0.8rem;
}

.article-body ul {
  padding-left: 1.3rem;
  margin-bottom: 0.8rem;
}

.article-body li {
  font-size: 0.9rem;
  line-height: 1.85;
  color: #999;
}

.article-links {
  display: flex;
  gap: 0.6rem;
  margin-top: 2.5rem;
  flex-wrap: wrap;
}

.article-link {
  display: inline-block;
  padding: 0.5rem 1.1rem;
  border: 1px solid var(--border);
  border-radius: 6px;
  font-size: 0.82rem;
  color: var(--text-2);
  text-decoration: none;
  transition: border-color var(--ease), color var(--ease);
}
.article-link:hover {
  border-color: var(--accent);
  color: var(--text-1);
}

/* ── Body images ───────────────────────────────────────────── */
.article-body img {
  width: 100%;
  height: auto;
  border-radius: 8px;
  display: block;
  margin: 1.4rem 0;
  object-fit: cover;
}

.article-body figure {
  margin: 1.6rem 0;
}

.article-body figure img {
  margin: 0;
}

.article-body figcaption {
  margin-top: 0.5rem;
  font-size: 0.8rem;
  color: var(--text-2);
  text-align: center;
  line-height: 1.5;
}

/* ── Code blocks ───────────────────────────────────────────── */
.article-body pre {
  margin: 1.4rem 0;
  border-radius: 8px;
  overflow-x: auto;
  font-size: 0.82rem;
  line-height: 1.7;
  border: 1px solid var(--border);
}

/* override hljs background to match theme border */
.article-body pre code.hljs { border-radius: 8px; }

.article-body :not(pre) > code {
  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: 4px;
  padding: 0.15em 0.45em;
  font-size: 0.85em;
  font-family: 'Consolas', 'Menlo', 'Monaco', 'Cascadia Code', monospace;
  color: var(--accent);
}

/* ── Tables ────────────────────────────────────────────────── */
.article-body table {
  width: 100%;
  border-collapse: collapse;
  margin: 1.4rem 0;
  font-size: 0.875rem;
}

.article-body th,
.article-body td {
  padding: 0.65rem 1rem;
  text-align: left;
  border-bottom: 1px solid var(--border);
}

.article-body th {
  font-weight: 600;
  color: var(--text-1);
  background: var(--bg-surface);
  font-size: 0.78rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.article-body td { color: var(--text-2); }

.article-body tr:last-child td { border-bottom: none; }

.article-body table {
  border: 1px solid var(--border);
  border-radius: 8px;
  overflow: hidden;
}

/* ── Mermaid charts ────────────────────────────────────────── */
.article-body .mermaid {
  margin: 1.4rem 0;
  padding: 1.5rem;
  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  overflow-x: auto;
  text-align: center;
}

.article-body .mermaid svg { max-width: 100%; height: auto; }

/* ── About ─────────────────────────────────────────────────── */
.about-layout {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: calc(100vh - var(--header-h));
  padding: 4rem 2rem;
}

.about-content { max-width: 600px; width: 100%; }

.about-title {
  font-size: 2.5rem;
  font-weight: 700;
  letter-spacing: -0.025em;
  margin-bottom: 1.5rem;
}

.about-content p {
  font-size: 0.95rem;
  line-height: 1.9;
  color: var(--text-2);
  margin-bottom: 1rem;
}

.skills {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-top: 2rem;
}

.skill-tag {
  padding: 0.35rem 0.85rem;
  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: 6px;
  font-size: 0.82rem;
  color: var(--text-2);
  transition: border-color var(--ease), color var(--ease);
}
.skill-tag:hover {
  border-color: var(--accent);
  color: var(--text-1);
}

/* ── Responsive ────────────────────────────────────────────── */
@media (max-width: 768px) {
  #page-home, #page-about {
    height: auto;
    overflow-y: visible;
  }
  .snap-section { min-height: auto; padding: 4rem 1.25rem; }
  .header-inner { padding: 0 1rem; }
  .hero { min-height: 100svh; }
  .focus-cards { grid-template-columns: 1fr; }
  .exp-item { gap: 1.25rem; }
  .scroll-hint { display: none; }
  /* Column layout, full viewport height so absolute panels still work */
  .projects-layout {
    flex-direction: column;
    height: calc(100svh - var(--header-h));
  }

  .projects-sidebar {
    width: 100%;
    flex-shrink: 0;
    height: auto;
    border-right: none;
    border-bottom: 1px solid var(--border);
    padding: 1rem 1rem 0.75rem;
  }

  .project-list {
    flex-direction: row;
    flex-wrap: nowrap;       /* single row — no multi-line stacking */
    overflow-x: auto;        /* scroll horizontally on narrow screens */
    gap: 4px;
    scrollbar-width: none;
    -ms-overflow-style: none;
  }
  .project-list::-webkit-scrollbar { display: none; }

  .project-item {
    flex-shrink: 0;          /* don't shrink — keep readable size */
    white-space: nowrap;     /* prevent text wrapping within item */
    border-left: none;
    border-bottom: 2px solid transparent;
  }
  .project-item.active { border-bottom-color: var(--accent); border-left-color: transparent; }

  /* Track wrapper fills remaining height → absolute panels work just like desktop */
  .projects-track-wrapper {
    flex: 1;
    min-height: 0;
    overflow: hidden;
  }
  #projects-track { position: relative; height: 100%; }

  .panel-dots { display: none; }

  .article-inner { padding: 2rem 1.25rem; }
  .article-title { font-size: 1.5rem; }
}