/* =========================================================
   0. CSS 변수 — 라이트 / 다크 모드
   ========================================================= */
[hidden] { display: none !important; } /* 트러블슈팅 */
   :root {
  /* color — "필드 노트" 컨셉: 종이 배경 + 잉크 텍스트 + 틸 강조 + 앰버 하이라이트 */
  --color-bg: #eeece3;
  --color-surface: #f7f5ee;
  --color-ink: #1c211f;
  --color-ink-soft: #52584f;
  --color-border: #d6d2c3;
  --color-accent: #2f6f6b;
  --color-accent-strong: #204f4c;
  --color-highlight: #d9a441;
  --color-danger: #b3452f;
  --color-success: #2f6f4f;

  /* type */
  --font-body: "Noto Sans KR", system-ui, sans-serif;
  --font-mono: "JetBrains Mono", ui-monospace, "SFMono-Regular", monospace;

  /* spacing scale */
  --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;

  /* layout */
  --content-width: 1080px;
  --radius: 4px;
  --shadow-card: 0 1px 2px rgba(28, 33, 31, 0.06), 0 8px 24px rgba(28, 33, 31, 0.06);
  --shadow-card-hover: 0 2px 4px rgba(28, 33, 31, 0.08), 0 16px 32px rgba(28, 33, 31, 0.12);
  --header-h: 64px;
  --transition: 180ms ease;
}

[data-theme="dark"] {
  --color-bg: #14171a;
  --color-surface: #1b1f22;
  --color-ink: #ece9e0;
  --color-ink-soft: #a3a89c;
  --color-border: #2c322f;
  --color-accent: #59b3a8;
  --color-accent-strong: #7fd4c8;
  --color-highlight: #e8b957;
  --color-danger: #e08769;
  --color-success: #74c69d;
  --shadow-card: 0 1px 2px rgba(0, 0, 0, 0.3), 0 8px 24px rgba(0, 0, 0, 0.35);
  --shadow-card-hover: 0 2px 4px rgba(0, 0, 0, 0.35), 0 16px 32px rgba(0, 0, 0, 0.4);
}

/* =========================================================
   1. Reset & base
   ========================================================= */
*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; }

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

body {
  margin: 0;
  background: var(--color-bg);
  color: var(--color-ink);
  font-family: var(--font-body);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  transition: background var(--transition), color var(--transition);
}

img { max-width: 100%; display: block; }
a { color: inherit; text-decoration: none; }
ul { list-style: none; margin: 0; padding: 0; }
button { font-family: inherit; cursor: pointer; }

:focus-visible {
  outline: 2px solid var(--color-highlight);
  outline-offset: 2px;
}

.section-inner,
.nav-inner,
.footer-inner {
  max-width: var(--content-width);
  margin: 0 auto;
  padding-inline: var(--space-3);
}

/* =========================================================
   2. Header / Nav — Flexbox
   ========================================================= */
.site-header {
  position: fixed;
  inset-block-start: 0;
  inset-inline: 0;
  height: var(--header-h);
  z-index: 100;
  background: transparent;
  transition: background var(--transition), box-shadow var(--transition), border-color var(--transition);
  border-bottom: 1px solid transparent;
}

.site-header.is-scrolled {
  background: color-mix(in srgb, var(--color-bg) 92%, transparent);
  backdrop-filter: blur(8px);
  border-bottom-color: var(--color-border);
}

.nav-inner {
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-3);
}

.logo {
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: 1.05rem;
  letter-spacing: -0.02em;
}
.logo-dot { color: var(--color-highlight); }

.nav-tag {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--color-accent);
  margin-inline-end: 0.4em;
}

.nav-list {
  display: flex;
  align-items: center;
  gap: var(--space-4);
}

.nav-link {
  font-size: 0.92rem;
  color: var(--color-ink-soft);
  padding-block: 0.3em;
  border-bottom: 2px solid transparent;
  transition: color var(--transition), border-color var(--transition);
}
.nav-link:hover,
.nav-link:focus-visible {
  color: var(--color-ink);
  border-color: var(--color-highlight);
}

.header-actions {
  display: flex;
  align-items: center;
  gap: var(--space-2);
}

.theme-toggle {
  width: 38px;
  height: 38px;
  border-radius: 50%;
  border: 1px solid var(--color-border);
  background: var(--color-surface);
  display: grid;
  place-items: center;
  transition: transform var(--transition), border-color var(--transition);
}
.theme-toggle:hover { border-color: var(--color-accent); transform: translateY(-1px); }

.hamburger {
  display: flex;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 38px;
  height: 38px;
  border: 1px solid var(--color-border);
  background: var(--color-surface);
  border-radius: var(--radius);
}
.hamburger span {
  display: block;
  width: 18px;
  height: 2px;
  margin-inline: auto;
  background: var(--color-ink);
  transition: transform var(--transition), opacity var(--transition);
}
.hamburger.is-active span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.hamburger.is-active span:nth-child(2) { opacity: 0; }
.hamburger.is-active span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* 모바일: 네비게이션 숨김 + 슬라이드 메뉴 */
.nav {
  position: fixed;
  inset-block-start: var(--header-h);
  inset-inline-end: 0;
  width: min(78vw, 320px);
  height: calc(100vh - var(--header-h));
  background: var(--color-surface);
  border-inline-start: 1px solid var(--color-border);
  transform: translateX(100%);
  transition: transform var(--transition);
  z-index: 90;
}
.nav.is-open { transform: translateX(0); }
.nav .nav-list {
  flex-direction: column;
  align-items: flex-start;
  gap: 0;
  padding: var(--space-4) var(--space-3);
}
.nav .nav-link {
  display: block;
  width: 100%;
  padding-block: var(--space-2);
  border-bottom: 1px solid var(--color-border);
}

@media (min-width: 768px) {
  .hamburger { display: none; }
  .nav {
    position: static;
    width: auto;
    height: auto;
    background: transparent;
    border: none;
    transform: none;
  }
  .nav .nav-list {
    flex-direction: row;
    align-items: center;
    gap: var(--space-4);
    padding: 0;
  }
  .nav .nav-link {
    width: auto;
    padding-block: 0.3em;
    border-bottom: 2px solid transparent;
  }
}

/* =========================================================
   3. Hero
   ========================================================= */
.hero {
  min-height: 100svh;
  display: flex;
  flex-direction: column;
  justify-content: center;
  gap: var(--space-5);
  padding-inline: var(--space-3);
  padding-block-start: var(--header-h);
  max-width: var(--content-width);
  margin: 0 auto;
}

.eyebrow {
  font-family: var(--font-mono);
  color: var(--color-accent);
  font-size: 0.85rem;
  margin: 0 0 var(--space-1);
}

.hero-title {
  font-size: clamp(2rem, 8vw, 4.2rem);
  line-height: 1.15;
  font-weight: 900;
  margin: 0 0 var(--space-3);
  min-height: 1.2em;
}

.typing-target { white-space: pre-wrap; }
.cursor {
  color: var(--color-highlight);
  animation: blink 1s step-end infinite;
}
@keyframes blink { 50% { opacity: 0; } }

.hero-sub {
  color: var(--color-ink-soft);
  font-size: clamp(1rem, 2vw, 1.15rem);
  max-width: 42ch;
  margin: 0 0 var(--space-4);
}

.hero-actions { display: flex; flex-wrap: wrap; gap: var(--space-2); }

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.8em 1.4em;
  border-radius: var(--radius);
  font-weight: 500;
  font-size: 0.95rem;
  border: 1px solid transparent;
  transition: transform var(--transition), background var(--transition), border-color var(--transition), box-shadow var(--transition);
}
.btn-primary {
  background: var(--color-accent);
  color: #f7f5ee;
}
.btn-primary:hover { background: var(--color-accent-strong); transform: translateY(-2px); box-shadow: var(--shadow-card); }

.btn-ghost {
  background: transparent;
  border-color: var(--color-border);
  color: var(--color-ink);
}
.btn-ghost:hover { border-color: var(--color-accent); transform: translateY(-2px); }

.hero-note {
  align-self: flex-start;
  display: flex;
  gap: var(--space-2);
  align-items: center;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--color-ink-soft);
  border: 1px solid var(--color-border);
  padding: 0.5em 0.9em;
  border-radius: var(--radius);
  background: var(--color-surface);
}
.hero-note-label { color: var(--color-highlight); font-weight: 700; }

/* =========================================================
   4. Section 공통
   ========================================================= */
.section { padding-block: var(--space-6); }
.section-alt { background: var(--color-surface); }

.section-eyebrow {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--color-ink-soft);
  margin: 0 0 var(--space-1);
}

.section-title {
  font-size: clamp(1.6rem, 4vw, 2.3rem);
  margin: 0 0 var(--space-1);
}

.section-desc {
  color: var(--color-ink-soft);
  margin: 0 0 var(--space-4);
}

/* =========================================================
   5. About
   ========================================================= */
.about-grid {
  display: grid;
  gap: var(--space-4);
  margin-top: var(--space-4);
}

.about-avatar {
  width: 96px;
  height: 96px;
  border-radius: 50%;
  background: var(--color-accent);
  color: #f7f5ee;
  display: grid;
  place-items: center;
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: 1.3rem;
}

.about-body p { margin: 0 0 var(--space-3); color: var(--color-ink-soft); }

.about-facts {
  display: flex;
  flex-direction: column;
  gap: var(--space-1);
  margin-top: var(--space-3);
  font-family: var(--font-mono);
  font-size: 0.85rem;
}
.about-facts li { display: flex; gap: var(--space-2); }
.fact-label { color: var(--color-accent); min-width: 6.5em; }

@media (min-width: 768px) {
  .about-grid { grid-template-columns: 120px 1fr; align-items: start; }
}

/* =========================================================
   6. Skills — Grid
   ========================================================= */
.skills-grid {
  display: grid;
  gap: var(--space-4);
  margin-top: var(--space-4);
}
@media (min-width: 768px) {
  .skills-grid { grid-template-columns: repeat(3, 1fr); }
}

.skill-group {
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: var(--space-3);
}
.section-alt .skill-group { background: var(--color-surface); }

.skill-group h3 {
  font-family: var(--font-mono);
  font-size: 0.9rem;
  color: var(--color-accent);
  margin: 0 0 var(--space-2);
}
.skill-list { display: flex; flex-direction: column; gap: 0.4em; font-size: 0.92rem; }

/* =========================================================
   7. Projects — Grid (auto-fit / minmax) + 상태 UI
   ========================================================= */
.project-filters {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-1);
  margin-bottom: var(--space-4);
}
.filter-btn {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  padding: 0.4em 0.9em;
  border: 1px solid var(--color-border);
  border-radius: 999px;
  background: transparent;
  color: var(--color-ink-soft);
  transition: all var(--transition);
}
.filter-btn:hover { border-color: var(--color-accent); color: var(--color-ink); }
.filter-btn.is-active { background: var(--color-accent); border-color: var(--color-accent); color: #f7f5ee; }

.projects-status,
.projects-error,
.projects-empty {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  color: var(--color-ink-soft);
  padding: var(--space-4) 0;
}
.projects-error { flex-direction: column; align-items: flex-start; }
.projects-error p { color: var(--color-danger); margin: 0; }

.spinner {
  width: 18px;
  height: 18px;
  border-radius: 50%;
  border: 2px solid var(--color-border);
  border-top-color: var(--color-accent);
  animation: spin 0.7s linear infinite;
}
@keyframes spin { to { transform: rotate(360deg); } }

.projects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: var(--space-3);
}

.project-card {
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: var(--space-3);
  box-shadow: var(--shadow-card);
  transition: transform var(--transition), box-shadow var(--transition), border-color var(--transition);
  display: flex;
  flex-direction: column;
  gap: var(--space-1);
}
.section-alt .project-card { background: var(--color-surface); }

.project-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-card-hover);
  border-color: var(--color-accent);
}

.project-card h3 {
  margin: 0;
  font-size: 1.05rem;
}
.project-card h3 a:hover { color: var(--color-accent); }

.project-card p {
  margin: 0;
  color: var(--color-ink-soft);
  font-size: 0.9rem;
  flex-grow: 1;
}

.project-meta {
  display: flex;
  gap: var(--space-3);
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--color-ink-soft);
  margin-top: var(--space-1);
}
.project-meta .lang::before {
  content: "●";
  color: var(--color-highlight);
  margin-inline-end: 0.35em;
}

/* =========================================================
   8. Contact form
   ========================================================= */
.contact-form {
  max-width: 520px;
  margin-top: var(--space-4);
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
}

.form-field { display: flex; flex-direction: column; gap: 0.4em; }
.form-field label {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--color-ink-soft);
}

.form-field input,
.form-field textarea {
  font-family: var(--font-body);
  font-size: 1rem;
  padding: 0.7em 0.9em;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  background: var(--color-bg);
  color: var(--color-ink);
  transition: border-color var(--transition), box-shadow var(--transition);
}
.section-alt .form-field input,
.section-alt .form-field textarea { background: var(--color-surface); }

.form-field input:focus,
.form-field textarea:focus {
  border-color: var(--color-accent);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--color-accent) 20%, transparent);
  outline: none;
}

.form-field.has-error input,
.form-field.has-error textarea { border-color: var(--color-danger); }

.field-error {
  margin: 0;
  font-size: 0.8rem;
  color: var(--color-danger);
  min-height: 1.1em;
}

.form-success {
  color: var(--color-success);
  font-weight: 500;
  margin: 0;
}

/* =========================================================
   9. Footer
   ========================================================= */
.site-footer {
  border-top: 1px solid var(--color-border);
  padding-block: var(--space-4);
}
.footer-inner {
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
  align-items: center;
  text-align: center;
  color: var(--color-ink-soft);
  font-size: 0.85rem;
}
.footer-links { display: flex; gap: var(--space-3); }
.footer-links a:hover { color: var(--color-accent); }

@media (min-width: 768px) {
  .footer-inner { flex-direction: row; justify-content: space-between; text-align: start; }
}

/* =========================================================
   10. Top 버튼
   ========================================================= */
.top-btn {
  position: fixed;
  inset-block-end: var(--space-4);
  inset-inline-end: var(--space-4);
  width: 44px;
  height: 44px;
  border-radius: 50%;
  border: 1px solid var(--color-border);
  background: var(--color-accent);
  color: #f7f5ee;
  font-size: 1.1rem;
  box-shadow: var(--shadow-card);
  opacity: 0;
  transform: translateY(10px);
  transition: opacity var(--transition), transform var(--transition);
  z-index: 80;
}
.top-btn.is-visible { opacity: 1; transform: translateY(0); }

/* =========================================================
   11. 스크롤 등장 애니메이션 (Intersection Observer 훅)
   ========================================================= */
.reveal {
  opacity: 0;
  transform: translateY(16px);
  transition: opacity 500ms ease, transform 500ms ease;
}
.reveal.is-visible {
  opacity: 1;
  transform: translateY(0);
}