/* =========================================================
   1. 디자인 토큰 (CSS 변수)
   - :root 에 라이트 모드 값을, [data-theme="dark"] 에 다크 모드 값을 정의
   - JS는 <html data-theme="..."> 속성 하나만 바꾸고, 나머지는 CSS가 처리
   ========================================================= */
:root {
  /* 색상 */
  --color-bg: #f7f7f5;
  --color-surface: #ffffff;
  --color-surface-2: #efefec;
  --color-text: #1d1d1f;
  --color-text-muted: #5f6066;
  --color-border: #e2e2de;
  --color-primary: #4f46e5;
  --color-primary-hover: #4338ca;
  --color-on-primary: #ffffff;
  --color-error: #d92d20;
  --color-success: #12805c;
  --color-header-scrolled: rgba(255, 255, 255, 0.92);
  --shadow-sm: 0 1px 2px rgba(16, 24, 40, 0.06), 0 1px 3px rgba(16, 24, 40, 0.08);
  --shadow-md: 0 8px 24px rgba(16, 24, 40, 0.12);

  /* 폰트 */
  --font-sans: "Noto Sans KR", system-ui, -apple-system, "Segoe UI", sans-serif;
  --font-mono: "JetBrains Mono", ui-monospace, Consolas, monospace;
  --fs-sm: 0.875rem;
  --fs-base: 1rem;
  --fs-lg: 1.125rem;
  --fs-xl: 1.5rem;
  --fs-2xl: 2rem;
  --fs-hero: 2rem;

  /* 간격 */
  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-6: 1.5rem;
  --space-8: 2rem;
  --space-12: 3rem;
  --space-16: 4rem;

  /* 기타 */
  --radius: 12px;
  --radius-pill: 999px;
  --header-h: 64px;
  --container: 1120px;
  --transition: 0.25s ease;

  color-scheme: light;
}

[data-theme="dark"] {
  --color-bg: #0f1115;
  --color-surface: #181b22;
  --color-surface-2: #13161c;
  --color-text: #e8e9ed;
  --color-text-muted: #a1a4ad;
  --color-border: #2a2e37;
  --color-primary: #8b8cf8;
  --color-primary-hover: #a5a6fb;
  --color-on-primary: #0f1115;
  --color-error: #ff7a6e;
  --color-success: #4cd39b;
  --color-header-scrolled: rgba(15, 17, 21, 0.9);
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.4);
  --shadow-md: 0 10px 28px rgba(0, 0, 0, 0.5);

  color-scheme: dark;
}

/* =========================================================
   2. 기본(Reset) 스타일 — 모바일 퍼스트
   ========================================================= */
*,
*::before,
*::after { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: var(--font-sans);
  font-size: var(--fs-base);
  line-height: 1.7;
  color: var(--color-text);
  background-color: var(--color-bg);
  transition: background-color var(--transition), color var(--transition);
  word-break: keep-all;
}

img { max-width: 100%; height: auto; display: block; }
a { color: var(--color-primary); }
h1, h2, h3 { line-height: 1.3; margin: 0; }
ul { margin: 0; padding: 0; list-style: none; }
button, input, textarea { font: inherit; color: inherit; }

/* 섹션 앵커 이동 시 고정 헤더에 가려지지 않도록 */
section { scroll-margin-top: var(--header-h); }

:focus-visible {
  outline: 3px solid var(--color-primary);
  outline-offset: 2px;
}

.sr-only {
  position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px;
  overflow: hidden; clip: rect(0, 0, 0, 0); white-space: nowrap; border: 0;
}

.skip-link {
  position: absolute; left: var(--space-4); top: -100px; z-index: 200;
  padding: var(--space-2) var(--space-4);
  background: var(--color-primary); color: var(--color-on-primary);
  border-radius: var(--radius);
}
.skip-link:focus { top: var(--space-4); }

.container {
  width: 100%;
  max-width: var(--container);
  margin: 0 auto;
  padding: 0 var(--space-4);
}
.container--narrow { max-width: 680px; }

.icon {
  width: 22px; height: 22px;
  fill: none; stroke: currentColor; stroke-width: 2;
  stroke-linecap: round; stroke-linejoin: round;
}

.br-desktop { display: none; }

/* =========================================================
   3. 버튼 / 칩 공통
   ========================================================= */
.btn {
  display: inline-flex; align-items: center; justify-content: center;
  gap: var(--space-2);
  padding: var(--space-3) var(--space-6);
  border: 2px solid transparent;
  border-radius: var(--radius-pill);
  font-weight: 700;
  text-decoration: none;
  cursor: pointer;
  transition: transform var(--transition), background-color var(--transition),
              color var(--transition), border-color var(--transition), box-shadow var(--transition);
}
.btn:hover { transform: translateY(-2px); box-shadow: var(--shadow-md); }
.btn:active { transform: translateY(0); }
.btn--primary { background: var(--color-primary); color: var(--color-on-primary); }
.btn--primary:hover { background: var(--color-primary-hover); }
.btn--ghost { border-color: var(--color-primary); color: var(--color-primary); background: transparent; }
.btn--ghost:hover { background: var(--color-primary); color: var(--color-on-primary); }
.btn--block { width: 100%; }
.btn:disabled { opacity: 0.6; cursor: not-allowed; transform: none; box-shadow: none; }

.icon-btn {
  display: inline-flex; align-items: center; justify-content: center;
  width: 44px; height: 44px;
  border: 1px solid var(--color-border);
  border-radius: 50%;
  background: var(--color-surface);
  cursor: pointer;
  transition: background-color var(--transition), transform var(--transition);
}
.icon-btn:hover { background: var(--color-surface-2); transform: scale(1.06); }

.chip {
  display: inline-block;
  padding: var(--space-1) var(--space-3);
  border-radius: var(--radius-pill);
  background: var(--color-surface-2);
  border: 1px solid var(--color-border);
  font-size: var(--fs-sm);
}

/* =========================================================
   4. Header / Navigation (Flexbox)
   ========================================================= */
.site-header {
  position: fixed; inset: 0 0 auto 0; z-index: 100;
  height: var(--header-h);
  background: transparent;
  transition: background-color var(--transition), box-shadow var(--transition);
}
/* 스크롤 60px 이상: JS가 .is-scrolled 를 붙임 */
.site-header.is-scrolled {
  background: var(--color-header-scrolled);
  backdrop-filter: blur(8px);
  box-shadow: var(--shadow-sm);
}

.nav {
  display: flex;                 /* 로고 왼쪽, 메뉴/버튼 오른쪽 */
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
  height: 100%;
}

.nav__logo {
  font-family: var(--font-mono);
  font-weight: 500;
  color: var(--color-text);
  text-decoration: none;
}

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

/* 모바일: 메뉴는 숨김 상태로 헤더 아래에 드롭다운 */
.nav__menu {
  position: absolute;
  top: var(--header-h); left: 0; right: 0;
  display: flex; flex-direction: column;
  padding: var(--space-2) var(--space-4) var(--space-4);
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  box-shadow: var(--shadow-md);
  opacity: 0;
  visibility: hidden;
  transform: translateY(-8px);
  transition: opacity var(--transition), transform var(--transition), visibility var(--transition);
}
.nav__menu.active { opacity: 1; visibility: visible; transform: translateY(0); }

.nav__link {
  display: block;
  padding: var(--space-3) var(--space-2);
  color: var(--color-text);
  text-decoration: none;
  font-weight: 500;
  border-radius: 8px;
  transition: color var(--transition), background-color var(--transition);
}
.nav__link:hover,
.nav__link.is-current { color: var(--color-primary); }

/* 햄버거 버튼 */
.hamburger { flex-direction: column; gap: 4px; }
.hamburger__bar {
  display: block; width: 18px; height: 2px;
  background: currentColor; border-radius: 2px;
  transition: transform var(--transition), opacity var(--transition);
}
.hamburger.active .hamburger__bar:nth-child(1) { transform: translateY(6px) rotate(45deg); }
.hamburger.active .hamburger__bar:nth-child(2) { opacity: 0; }
.hamburger.active .hamburger__bar:nth-child(3) { transform: translateY(-6px) rotate(-45deg); }

/* 테마 토글 아이콘: 현재 테마에 따라 하나만 표시 */
.icon--sun { display: none; }
[data-theme="dark"] .icon--sun { display: block; }
[data-theme="dark"] .icon--moon { display: none; }

/* =========================================================
   5. Hero
   ========================================================= */
.hero {
  min-height: 100svh;
  display: flex; align-items: center;
  padding: calc(var(--header-h) + var(--space-8)) 0 var(--space-12);
  background:
    radial-gradient(circle at 15% 20%, color-mix(in srgb, var(--color-primary) 14%, transparent), transparent 45%),
    radial-gradient(circle at 85% 80%, color-mix(in srgb, var(--color-primary) 10%, transparent), transparent 40%);
}
.hero__inner { text-align: center; }
.hero__eyebrow {
  margin: 0 0 var(--space-3);
  font-family: var(--font-mono);
  color: var(--color-primary);
}
.hero__title { font-size: var(--fs-hero); font-weight: 700; }
.hero__typing {
  display: inline-block;
  min-height: 1.3em; /* 글자가 모두 지워진 순간에도 줄 높이 유지 → 레이아웃 흔들림 방지 */
  vertical-align: bottom;
  color: var(--color-primary);
}
.hero__cursor {
  display: inline-block; width: 3px; height: 1em;
  margin-left: 4px; vertical-align: -0.1em;
  background: var(--color-primary);
  animation: blink 1s steps(1) infinite;
}
@keyframes blink { 50% { opacity: 0; } }

.hero__desc {
  max-width: 620px;
  margin: var(--space-6) auto var(--space-8);
  color: var(--color-text-muted);
}
.hero__cta { display: flex; flex-wrap: wrap; justify-content: center; gap: var(--space-3); }

/* =========================================================
   6. 공통 섹션
   ========================================================= */
.section { padding: var(--space-16) 0; }
.section--alt { background: var(--color-surface-2); }
.section__title {
  font-size: var(--fs-2xl);
  margin-bottom: var(--space-4);
}
.section__title::after {
  content: "";
  display: block; width: 48px; height: 4px; margin-top: var(--space-2);
  background: var(--color-primary); border-radius: 2px;
}
.section__desc { margin: 0 0 var(--space-8); color: var(--color-text-muted); }

/* About: 모바일은 세로 쌓기 → 태블릿부터 가로 배치 (Flexbox) */
.about {
  display: flex; flex-direction: column; align-items: center;
  gap: var(--space-8);
  margin-top: var(--space-8);
}
.about__photo {
  width: 200px; height: 200px;
  border-radius: 50%;
  border: 4px solid var(--color-surface);
  box-shadow: var(--shadow-md);
  flex-shrink: 0;
}
.about__text p { margin-top: 0; }
.about__facts { display: grid; gap: var(--space-3); margin: var(--space-6) 0 0; }
.about__facts div {
  padding: var(--space-3) var(--space-4);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
}
.about__facts dt { font-size: var(--fs-sm); color: var(--color-text-muted); }
.about__facts dd { margin: 0; font-weight: 500; }

.subsection__title {
  margin: var(--space-12) 0 var(--space-6);
  font-size: var(--fs-xl);
}

/* Journey 타임라인: 왼쪽 세로선 + 점 */
.timeline {
  position: relative;
  margin: 0; padding: 0 0 0 var(--space-6);
  list-style: none;
  border-left: 2px solid var(--color-border);
  display: grid; gap: var(--space-6);
}
.timeline__item { position: relative; }
.timeline__item::before {
  content: "";
  position: absolute; left: calc(-1 * var(--space-6) - 7px); top: 6px;
  width: 12px; height: 12px; border-radius: 50%;
  background: var(--color-bg);
  border: 3px solid var(--color-primary);
}
.timeline__date { font-family: var(--font-mono); font-size: var(--fs-sm); color: var(--color-primary); }
.timeline__title { margin: var(--space-1) 0; font-size: var(--fs-base); line-height: 1.5; }
.timeline__tag {
  display: inline-block; margin-left: var(--space-1);
  padding: 0 var(--space-2);
  border-radius: var(--radius-pill);
  background: color-mix(in srgb, var(--color-primary) 14%, transparent);
  color: var(--color-primary);
  font-size: 0.75rem; font-weight: 500; vertical-align: 2px;
}
.timeline__desc { margin: 0; font-size: var(--fs-sm); color: var(--color-text-muted); }

/* Highlights: 대표 프로젝트 카드 (Grid) */
.highlights {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: var(--space-6);
}
.highlight-card {
  display: flex; flex-direction: column; gap: var(--space-3);
  padding: var(--space-6);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-top: 4px solid var(--color-primary);
  border-radius: var(--radius);
  box-shadow: var(--shadow-sm);
  transition: transform var(--transition), box-shadow var(--transition);
}
.highlight-card:hover { transform: translateY(-6px); box-shadow: var(--shadow-md); }
.highlight-card__meta { margin: 0; font-size: var(--fs-sm); color: var(--color-primary); font-weight: 500; }
.highlight-card__title { font-size: var(--fs-lg); }
.highlight-card__desc { flex: 1; margin: 0; font-size: var(--fs-sm); color: var(--color-text-muted); }
.highlight-card__links { display: flex; flex-wrap: wrap; gap: var(--space-4); }
.highlight-card__link { font-size: var(--fs-sm); font-weight: 700; text-decoration: none; }
.highlight-card__link:hover { text-decoration: underline; }

/* Skills: Grid */
.skills { display: grid; gap: var(--space-4); margin-top: var(--space-8); }
.skill-group {
  padding: var(--space-6);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  box-shadow: var(--shadow-sm);
  transition: transform var(--transition), box-shadow var(--transition);
}
.skill-group:hover { transform: translateY(-4px); box-shadow: var(--shadow-md); }
.skill-group__title { font-size: var(--fs-lg); margin-bottom: var(--space-4); }
.skill-list { display: flex; flex-wrap: wrap; gap: var(--space-2); }

/* =========================================================
   7. Projects — Grid(auto-fit + minmax) + 상태별 UI
   ========================================================= */
.filters { display: flex; flex-wrap: wrap; gap: var(--space-2); margin-bottom: var(--space-6); }
.filters:empty { display: none; }
.filter-btn {
  padding: var(--space-1) var(--space-4);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-pill);
  background: var(--color-surface);
  font-size: var(--fs-sm);
  cursor: pointer;
  transition: background-color var(--transition), color var(--transition), border-color var(--transition);
}
.filter-btn:hover { border-color: var(--color-primary); }
.filter-btn.is-active { background: var(--color-primary); border-color: var(--color-primary); color: var(--color-on-primary); }
.filter-btn__count { opacity: 0.7; margin-left: 2px; }

.projects__grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: var(--space-6);
}

.project-card {
  display: flex; flex-direction: column;
  padding: var(--space-6);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  box-shadow: var(--shadow-sm);
  transition: transform var(--transition), box-shadow var(--transition), border-color var(--transition);
}
.project-card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-md);
  border-color: var(--color-primary);
}
.project-card__owner { margin: 0 0 var(--space-1); font-family: var(--font-mono); font-size: 0.75rem; color: var(--color-primary); }
.project-card__title { font-size: var(--fs-lg); margin-bottom: var(--space-2); overflow-wrap: anywhere; }
.project-card__title a { color: var(--color-text); text-decoration: none; }
.project-card__title a:hover { color: var(--color-primary); }
.project-card__desc { flex: 1; margin: 0 0 var(--space-4); color: var(--color-text-muted); font-size: var(--fs-sm); }
.project-card__meta {
  display: flex; flex-wrap: wrap; align-items: center; gap: var(--space-4);
  font-size: var(--fs-sm); color: var(--color-text-muted);
}
.project-card__lang { display: inline-flex; align-items: center; gap: 6px; }
.project-card__lang::before {
  content: ""; width: 10px; height: 10px; border-radius: 50%;
  background: var(--color-primary);
}

/* 언어별 점 색상 (인라인 스타일 대신 data-lang 속성 선택자로 처리) */
.project-card__lang[data-lang="JavaScript"]::before { background: #f1e05a; }
.project-card__lang[data-lang="TypeScript"]::before { background: #3178c6; }
.project-card__lang[data-lang="HTML"]::before { background: #e34c26; }
.project-card__lang[data-lang="CSS"]::before { background: #663399; }
.project-card__lang[data-lang="Python"]::before { background: #3572a5; }
.project-card__lang[data-lang="Java"]::before { background: #b07219; }
.project-card__lang[data-lang="Ruby"]::before { background: #701516; }
.project-card__lang[data-lang="Vue"]::before { background: #41b883; }
.project-card__lang[data-lang="기타"]::before { background: var(--color-text-muted); }

.project-card__demo {
  margin-top: var(--space-4);
  font-size: var(--fs-sm);
  font-weight: 700;
  text-decoration: none;
}
.project-card__demo:hover { text-decoration: underline; }

/* 상태 박스 (로딩 / 에러 / 빈 상태) */
.state {
  display: flex; flex-direction: column; align-items: center; gap: var(--space-4);
  padding: var(--space-12) var(--space-4);
  text-align: center;
  background: var(--color-surface);
  border: 1px dashed var(--color-border);
  border-radius: var(--radius);
  color: var(--color-text-muted);
}
.state__title { margin: 0; font-weight: 700; color: var(--color-text); }
.state__detail { margin: 0; font-size: var(--fs-sm); }
.state--error .state__title { color: var(--color-error); }

.spinner {
  width: 40px; height: 40px;
  border: 4px solid var(--color-border);
  border-top-color: var(--color-primary);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}
@keyframes spin { to { transform: rotate(360deg); } }

/* =========================================================
   8. Contact Form
   ========================================================= */
.contact-form {
  display: grid; gap: var(--space-4);
  padding: var(--space-6);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  box-shadow: var(--shadow-sm);
}
.form-field { display: grid; gap: var(--space-1); }
.form-label { font-weight: 500; }
.form-input {
  width: 100%;
  padding: var(--space-3) var(--space-4);
  border: 1px solid var(--color-border);
  border-radius: 8px;
  background: var(--color-bg);
  scroll-margin-top: calc(var(--header-h) + var(--space-12)); /* 포커스 이동 시 헤더에 가려지지 않게 */
  transition: border-color var(--transition), box-shadow var(--transition);
}
.form-input:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--color-primary) 25%, transparent);
}
.form-textarea { resize: vertical; min-height: 120px; }

/* 유효성 상태: JS가 .is-invalid / .is-valid 를 붙임 */
.form-input.is-invalid { border-color: var(--color-error); }
.form-input.is-valid { border-color: var(--color-success); }

.form-error { margin: 0; min-height: 1.4em; font-size: var(--fs-sm); color: var(--color-error); }
.form-meta { display: flex; justify-content: space-between; gap: var(--space-2); }
.form-count { font-size: var(--fs-sm); color: var(--color-text-muted); white-space: nowrap; }
.form-count.is-over { color: var(--color-error); }

.form-status { margin: 0; min-height: 1.5em; text-align: center; font-weight: 500; }
.form-status.is-success { color: var(--color-success); }
.form-status.is-error { color: var(--color-error); }

/* =========================================================
   9. Footer / Scroll-top
   ========================================================= */
.site-footer {
  padding: var(--space-8) 0;
  border-top: 1px solid var(--color-border);
  font-size: var(--fs-sm);
  color: var(--color-text-muted);
}
.footer__inner {
  display: flex; flex-direction: column; align-items: center; gap: var(--space-3);
  text-align: center;
}
.footer__inner p { margin: 0; }
.social { display: flex; gap: var(--space-4); }
.social__link { color: var(--color-text-muted); text-decoration: none; transition: color var(--transition); }
.social__link:hover { color: var(--color-primary); }

.scroll-top {
  position: fixed; right: var(--space-4); bottom: var(--space-4); z-index: 90;
  display: flex; align-items: center; justify-content: center;
  width: 48px; height: 48px;
  border: none; border-radius: 50%;
  background: var(--color-primary); color: var(--color-on-primary);
  box-shadow: var(--shadow-md);
  cursor: pointer;
  opacity: 0; visibility: hidden; transform: translateY(16px);
  transition: opacity var(--transition), transform var(--transition), visibility var(--transition), background-color var(--transition);
}
.scroll-top.is-visible { opacity: 1; visibility: visible; transform: translateY(0); }
.scroll-top:hover { background: var(--color-primary-hover); }

/* =========================================================
   10. 스크롤 애니메이션 (Intersection Observer)
   - .js 클래스는 JS가 동작할 때만 붙으므로, JS가 꺼져도 내용은 보임
   ========================================================= */
.js .reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}
.js .reveal.is-visible { opacity: 1; transform: none; }

/* =========================================================
   11. 반응형 — 태블릿 (768px 이상)
   ========================================================= */
@media (min-width: 768px) {
  :root { --fs-hero: 3rem; --header-h: 72px; }

  .container { padding: 0 var(--space-8); }
  .br-desktop { display: inline; }

  /* 네비게이션: 햄버거 숨기고 메뉴를 가로로 */
  .hamburger { display: none; }
  .nav { justify-content: flex-start; }
  .nav__logo { margin-right: auto; }
  .nav__menu {
    position: static;
    flex-direction: row; gap: var(--space-1);
    padding: 0;
    background: none; border: none; box-shadow: none;
    opacity: 1; visibility: visible; transform: none;
  }
  .nav__link { padding: var(--space-2) var(--space-3); }

  .about { flex-direction: row; align-items: flex-start; }
  .about__photo { width: 240px; height: 240px; }
  .about__facts { grid-template-columns: repeat(2, 1fr); }

  .skills { grid-template-columns: repeat(2, 1fr); }

  .footer__inner { flex-direction: row; justify-content: space-between; }

  .contact-form { padding: var(--space-8); }
}

/* =========================================================
   12. 반응형 — 데스크톱 (1024px 이상)
   ========================================================= */
@media (min-width: 1024px) {
  :root { --fs-hero: 3.75rem; }
  .section { padding: 6rem 0; }
  .skills { grid-template-columns: repeat(4, 1fr); }
  .highlights { grid-template-columns: repeat(2, 1fr); }
  .scroll-top { right: var(--space-8); bottom: var(--space-8); }
}

/* 애니메이션 최소화를 원하는 사용자 배려 */
@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;
  }
  .js .reveal { opacity: 1; transform: none; }
}