/* =========================================================
   0. CSS 변수 정의 (:root)
   - 색상 / 폰트 / 간격 / 그림자 등을 한곳에서 관리
========================================================= */
:root {
  /* 색상 (라이트 모드 기본값) */
  --bg: #f6f7fb;
  --surface: #ffffff;
  --surface-2: #eef0f7;
  --text: #16172a;
  --text-muted: #5a5f7a;
  --primary: #5b3df5;
  --primary-hover: #4a2fd0;
  --primary-soft: rgba(91, 61, 245, 0.1);
  --accent: #00bfa5;
  --border: #e4e6f0;
  --danger: #e23b52;
  --success: #12a15f;

  /* 폰트 */
  --font-body: "Inter", system-ui, -apple-system, "Segoe UI", sans-serif;
  --font-display: "Space Grotesk", var(--font-body);

  /* 간격 (spacing scale) */
  --space-1: 0.5rem;
  --space-2: 1rem;
  --space-3: 1.5rem;
  --space-4: 2rem;
  --space-5: 3rem;
  --space-6: 5rem;

  /* 기타 */
  --radius: 14px;
  --radius-sm: 8px;
  --shadow: 0 10px 30px -12px rgba(22, 23, 42, 0.18);
  --shadow-lg: 0 24px 48px -20px rgba(22, 23, 42, 0.28);
  --header-h: 68px;
  --max-w: 1120px;
  --transition: 0.25s ease;
}

/* 다크 모드용 변수: data-theme="dark"일 때 덮어씀 */
[data-theme="dark"] {
  --bg: #0d0f1a;
  --surface: #161a2b;
  --surface-2: #1e2338;
  --text: #edeef5;
  --text-muted: #9aa0bd;
  --primary: #8b74ff;
  --primary-hover: #a08cff;
  --primary-soft: rgba(139, 116, 255, 0.16);
  --accent: #2dd4bf;
  --border: #262b40;
  --shadow: 0 10px 30px -12px rgba(0, 0, 0, 0.6);
  --shadow-lg: 0 24px 48px -20px rgba(0, 0, 0, 0.7);
}

/* =========================================================
   1. 리셋 & 기본 스타일
========================================================= */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
  /* 고정 헤더 높이만큼 앵커 이동 시 여백 확보 */
  scroll-padding-top: var(--header-h);
}

body {
  font-family: var(--font-body);
  background-color: var(--bg);
  color: var(--text);
  line-height: 1.6;
  word-break: keep-all;
  overflow-wrap: break-word;
  transition: background-color var(--transition), color var(--transition);
}

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

a {
  color: inherit;
  text-decoration: none;
}

ul {
  list-style: none;
}

h1,
h2,
h3,
h4 {
  font-family: var(--font-display);
  line-height: 1.15;
  font-weight: 700;
}

/* 레이아웃 컨테이너 */
.container {
  width: 100%;
  max-width: var(--max-w);
  margin-inline: auto;
  padding-inline: var(--space-3);
}

.section {
  padding-block: var(--space-6);
}

.section__title {
  font-size: clamp(1.8rem, 5vw, 2.6rem);
}

.section__subtitle {
  color: var(--text-muted);
  margin-top: var(--space-1);
  margin-bottom: var(--space-4);
}

/* =========================================================
   2. 버튼 (hover + transition)
========================================================= */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-1);
  padding: 0.75rem 1.5rem;
  border: 1px solid transparent;
  border-radius: var(--radius-sm);
  font-family: var(--font-body);
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: transform var(--transition), background-color var(--transition),
    border-color var(--transition), color var(--transition);
}

.btn--primary {
  background-color: var(--primary);
  color: #fff;
}

.btn--primary:hover {
  background-color: var(--primary-hover);
  transform: translateY(-2px);
}

.btn--ghost {
  background-color: transparent;
  border-color: var(--border);
  color: var(--text);
}

.btn--ghost:hover {
  border-color: var(--primary);
  color: var(--primary);
  transform: translateY(-2px);
}

/* 아이콘 전용 버튼 (테마 토글, 햄버거) */
.icon-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 42px;
  height: 42px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background-color: var(--surface);
  color: var(--text);
  font-size: 1.05rem;
  cursor: pointer;
  transition: background-color var(--transition), color var(--transition),
    border-color var(--transition);
}

.icon-btn:hover {
  border-color: var(--primary);
  color: var(--primary);
}

/* =========================================================
   3. 헤더 / 네비게이션 (Flexbox: 로고 왼쪽, 메뉴 오른쪽)
========================================================= */
.header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: var(--header-h);
  background-color: transparent;
  z-index: 100;
  transition: background-color var(--transition), box-shadow var(--transition),
    border-color var(--transition);
  border-bottom: 1px solid transparent;
}

/* 스크롤 60px 이상에서 JS가 붙이는 클래스 */
.header.is-scrolled {
  background-color: var(--surface);
  box-shadow: var(--shadow);
  border-bottom-color: var(--border);
}

.nav {
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between; /* 로고(좌) / 액션(우) */
}

.nav__logo {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 1.15rem;
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
}

.nav__logo-mark {
  color: var(--primary);
}

.nav__actions {
  display: flex;
  align-items: center;
  gap: var(--space-1);
  margin-left: auto;
}

/* 모바일: 메뉴는 화면 밖에서 슬라이드로 등장 */
.nav__menu {
  position: fixed;
  top: var(--header-h);
  right: 0;
  width: min(78%, 300px);
  height: calc(100vh - var(--header-h));
  background-color: var(--surface);
  border-left: 1px solid var(--border);
  box-shadow: var(--shadow-lg);
  padding: var(--space-4) var(--space-3);
  transform: translateX(100%); /* 기본: 숨김 */
  transition: transform var(--transition);
}

/* JS가 classList.toggle('active')로 열고 닫음 */
.nav__menu.active {
  transform: translateX(0);
}

.nav__list {
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
}

.nav__link {
  display: block;
  padding: 0.5rem 0;
  font-weight: 500;
  color: var(--text-muted);
  transition: color var(--transition);
}

.nav__link:hover {
  color: var(--primary);
}

/* 햄버거 버튼: 세 줄 → active 시 X 모양 */
.nav__toggle {
  flex-direction: column;
  gap: 4px;
}

.nav__toggle-bar {
  display: block;
  width: 18px;
  height: 2px;
  background-color: currentColor;
  transition: transform var(--transition), opacity var(--transition);
}

.nav__toggle.active .nav__toggle-bar:nth-child(1) {
  transform: translateY(6px) rotate(45deg);
}
.nav__toggle.active .nav__toggle-bar:nth-child(2) {
  opacity: 0;
}
.nav__toggle.active .nav__toggle-bar:nth-child(3) {
  transform: translateY(-6px) rotate(-45deg);
}

/* =========================================================
   4. HERO
========================================================= */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  padding-top: var(--header-h);
  background:
    radial-gradient(60% 50% at 80% 0%, rgba(91, 61, 245, 0.14), transparent 70%),
    radial-gradient(50% 40% at 0% 100%, rgba(0, 191, 165, 0.12), transparent 70%);
}

.hero__inner {
  max-width: 880px;
}

.hero__eyebrow {
  font-family: var(--font-display);
  color: var(--primary);
  font-weight: 500;
  margin-bottom: var(--space-2);
}

.hero__title {
  font-size: clamp(2.4rem, 8vw, 4.2rem);
  /* 타이핑 문구가 줄바꿈되어도 아래 내용이 흔들리지 않도록 3줄 높이 확보 */
  min-height: 3.45em;
}

.hero__typed {
  color: var(--primary);
}

.hero__cursor {
  color: var(--primary);
  animation: blink 1s step-end infinite;
}

@keyframes blink {
  50% {
    opacity: 0;
  }
}

.hero__lead {
  color: var(--text-muted);
  font-size: 1.1rem;
  margin-block: var(--space-3) var(--space-4);
  max-width: 60ch;
}

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

/* =========================================================
   5. ABOUT
========================================================= */
.about__inner {
  display: grid;
  gap: var(--space-4);
}

.about__photo {
  width: 100%;
  max-width: 320px;
  height: auto;
  object-fit: cover;
  border-radius: var(--radius);
  border: 1px solid var(--border);
  box-shadow: var(--shadow);
  background-color: var(--surface);
}

.about__text {
  color: var(--text-muted);
  margin-block: var(--space-2) var(--space-3);
}

.about__text strong {
  color: var(--text);
}

.about__facts {
  display: grid;
  gap: var(--space-1);
  color: var(--text-muted);
}

.about__facts i {
  color: var(--primary);
  width: 1.2rem;
}

/* 핵심 수치 */
.about__stats {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
  gap: var(--space-2);
  margin-top: var(--space-4);
}

.stat {
  display: grid;
  gap: 0.2rem;
  padding: var(--space-2);
  background-color: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
}

.stat__value {
  font-family: var(--font-display);
  font-size: 1.35rem;
  color: var(--primary);
  line-height: 1.2;
}

.stat__label {
  color: var(--text-muted);
  font-size: 0.82rem;
  line-height: 1.4;
}

/* 기술 태그 (Skills 카드 · 프로젝트 카드 공용) */
.tag-list {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
}

.tag-list--center {
  justify-content: center;
}

.tag-list li {
  padding: 0.2rem 0.65rem;
  border: 1px solid var(--border);
  border-radius: 999px;
  background-color: var(--surface-2);
  color: var(--text);
  font-size: 0.8rem;
  line-height: 1.5;
}

/* =========================================================
   6. SKILLS (반응형 Grid)
========================================================= */
.skills__grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: var(--space-3);
}

.skill-card {
  background-color: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: var(--space-3);
  text-align: center;
  box-shadow: var(--shadow);
  transition: transform var(--transition), box-shadow var(--transition);
}

.skill-card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-lg);
}

.skill-card__icon {
  font-size: 2.4rem;
  color: var(--primary);
  margin-bottom: var(--space-1);
}

.skill-card__name {
  font-size: 1.15rem;
  margin-bottom: var(--space-2);
}

.skill-card__desc {
  color: var(--text-muted);
  font-size: 0.8rem;
  margin-top: var(--space-1);
}

/* =========================================================
   6-1. EXPERIENCE (세로 타임라인)
========================================================= */
.timeline {
  list-style: none;
  display: grid;
  gap: var(--space-4);
  max-width: 820px;
  padding-left: var(--space-3);
  border-left: 2px solid var(--border);
}

.timeline__item {
  position: relative;
}

/* 타임라인 점: 왼쪽 세로선 중앙에 위치 */
.timeline__item::before {
  content: "";
  position: absolute;
  left: calc(-1 * var(--space-3) - 7px);
  top: 0.3rem;
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background-color: var(--bg);
  border: 2px solid var(--primary);
}

/* 진행 중인 항목은 채워진 점 */
.timeline__item.is-current::before {
  background-color: var(--primary);
}

.timeline__meta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.5rem;
  margin-bottom: 0.35rem;
}

.timeline__period {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 0.9rem;
  color: var(--primary);
}

.timeline__kind {
  padding: 0.05rem 0.55rem;
  border-radius: 999px;
  background-color: var(--primary-soft);
  color: var(--primary);
  font-size: 0.75rem;
  font-weight: 600;
}

.timeline__title {
  font-size: 1.2rem;
}

.timeline__org {
  color: var(--text);
  font-size: 0.92rem;
  font-weight: 500;
  margin-top: 0.2rem;
}

.timeline__desc {
  color: var(--text-muted);
  font-size: 0.95rem;
  margin-top: 0.4rem;
}

/* =========================================================
   7. PROJECTS (Grid: auto-fit + minmax)
========================================================= */
.projects__heading {
  font-size: 1.35rem;
  margin-bottom: var(--space-3);
}

.projects__heading--spaced {
  margin-top: var(--space-6);
  margin-bottom: var(--space-1);
}

.projects__caption {
  color: var(--text-muted);
  font-size: 0.92rem;
  margin-bottom: var(--space-3);
}

/* --- 주요 프로젝트 카드 (최신순) --- */
.projects__featured {
  display: grid;
  gap: var(--space-3);
}

.project-card {
  display: grid;
  gap: var(--space-2);
  background-color: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: var(--space-3);
  box-shadow: var(--shadow);
  transition: transform var(--transition), box-shadow var(--transition);
}

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

.project-card__aside {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.35rem 1rem;
}

.project-card__period {
  font-family: var(--font-display);
  font-weight: 700;
  color: var(--primary);
}

.project-card__context {
  color: var(--text-muted);
  font-size: 0.88rem;
}

.project-card__badge {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  padding: 0.15rem 0.7rem;
  border-radius: 999px;
  background-color: var(--primary-soft);
  color: var(--primary);
  font-size: 0.8rem;
  font-weight: 600;
}

.project-card__main {
  display: grid;
  gap: 0.75rem;
  min-width: 0;
}

.project-card__title {
  font-family: var(--font-display);
  font-size: 1.4rem;
  line-height: 1.2;
}

.project-card__subtitle {
  color: var(--text-muted);
  font-weight: 500;
  margin-top: -0.5rem;
}

.project-card__summary {
  color: var(--text);
}

.project-card__list {
  display: grid;
  gap: 0.4rem;
  color: var(--text-muted);
  font-size: 0.93rem;
}

.project-card__list li {
  position: relative;
  padding-left: 1.1rem;
}

.project-card__list li::before {
  content: "";
  position: absolute;
  left: 0.15rem;
  top: 0.62em;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background-color: var(--primary);
}

/* 문제해결 사례 박스 */
.project-card__case {
  padding: 0.8rem 1rem;
  border-left: 3px solid var(--primary);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  background-color: var(--surface-2);
  color: var(--text-muted);
  font-size: 0.92rem;
}

.project-card__case strong {
  display: block;
  color: var(--text);
  margin-bottom: 0.2rem;
}

.project-card__note {
  color: var(--text-muted);
  font-size: 0.85rem;
}

.project-card__note i {
  color: var(--accent);
}

.project-card__links {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
}

.project-card__link {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  color: var(--primary);
  font-size: 0.92rem;
  font-weight: 600;
}

.project-card__link:hover {
  text-decoration: underline;
}

/* --- GitHub 저장소 --- */
.projects__filters {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-1);
  margin-bottom: var(--space-4);
}

.filter-btn {
  padding: 0.4rem 1rem;
  border: 1px solid var(--border);
  border-radius: 999px;
  background-color: var(--surface);
  color: var(--text-muted);
  font-family: var(--font-body);
  font-size: 0.9rem;
  cursor: pointer;
  transition: all var(--transition);
}

.filter-btn:hover {
  border-color: var(--primary);
  color: var(--primary);
}

.filter-btn.active {
  background-color: var(--primary);
  border-color: var(--primary);
  color: #fff;
}

.projects__grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: var(--space-3);
}

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

.repo-card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-lg);
}

.repo-card__name {
  font-size: 1.15rem;
  color: var(--primary);
  word-break: break-word;
}

.repo-card__desc {
  color: var(--text-muted);
  font-size: 0.92rem;
  flex-grow: 1;
}

.repo-card__meta {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
  color: var(--text-muted);
  font-size: 0.85rem;
  margin-top: var(--space-1);
}

.repo-card__meta i {
  color: var(--accent);
}

.repo-card__lang-dot {
  display: inline-block;
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background-color: var(--primary);
  margin-right: 0.35rem;
  vertical-align: middle;
}

/* --- 상태 UI (로딩 / 에러 / 빈) --- */
.state {
  text-align: center;
  padding: var(--space-5) var(--space-2);
  color: var(--text-muted);
}

.state__icon {
  font-size: 2rem;
  margin-bottom: var(--space-1);
}

.spinner {
  width: 42px;
  height: 42px;
  margin: 0 auto var(--space-2);
  border: 4px solid var(--border);
  border-top-color: var(--primary);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

@keyframes spin {
  to {
    transform: rotate(360deg);
  }
}

/* =========================================================
   7-1. CERTIFICATIONS (자격 · 어학)
========================================================= */
.certs__grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: var(--space-2);
}

.cert-card {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-2);
  background-color: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

.cert-card__icon {
  flex-shrink: 0;
  display: grid;
  place-items: center;
  width: 2.6rem;
  height: 2.6rem;
  border-radius: var(--radius-sm);
  background-color: var(--primary-soft);
  color: var(--primary);
  font-size: 1.1rem;
}

.cert-card__name {
  font-size: 1rem;
  line-height: 1.3;
}

.cert-card__meta {
  color: var(--text-muted);
  font-size: 0.85rem;
}

/* =========================================================
   8. CONTACT (폼)
========================================================= */
.contact__inner {
  max-width: 620px;
}

.contact__email {
  color: var(--primary);
  font-weight: 600;
}

.contact__email:hover {
  text-decoration: underline;
}

.form {
  display: grid;
  gap: var(--space-3);
}

.form__field {
  display: grid;
  gap: 0.4rem;
}

.form__label {
  font-weight: 600;
  font-size: 0.95rem;
}

.form__input {
  width: 100%;
  padding: 0.75rem 1rem;
  font-family: var(--font-body);
  font-size: 1rem;
  color: var(--text);
  background-color: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  transition: border-color var(--transition), box-shadow var(--transition);
}

.form__input:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(91, 61, 245, 0.18);
}

/* JS가 오류 시 붙이는 클래스 */
.form__input.has-error {
  border-color: var(--danger);
}

.form__textarea {
  resize: vertical;
  min-height: 120px;
}

.form__error {
  color: var(--danger);
  font-size: 0.85rem;
  min-height: 1.1rem;
}

/* 에러 메시지와 글자 수 카운터를 한 줄에 좌·우로 배치 */
.form__field-foot {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--space-2);
}

.form__field-foot .form__error {
  flex: 1;
}

.form__counter {
  flex-shrink: 0;
  font-size: 0.85rem;
  color: var(--text-muted);
  font-variant-numeric: tabular-nums; /* 숫자 폭 고정 — 타이핑할 때 흔들리지 않음 */
  min-height: 1.1rem;
}

/* 한도의 90%를 넘기면 색으로 미리 알림 */
.form__counter.is-near-limit {
  color: var(--danger);
  font-weight: 600;
}

.form__submit {
  justify-self: start;
}

.form__submit:disabled {
  opacity: 0.65;
  cursor: not-allowed;
  transform: none;
}

.form__honeypot {
  display: none;
}

/* 토스트 알림: 헤더 아래 가운데에서 내려오듯 등장, JS가 is-visible 클래스로 제어 */
.toast {
  position: fixed;
  top: calc(var(--header-h) + var(--space-2));
  left: 50%;
  z-index: 110;
  display: flex;
  align-items: center;
  gap: 0.75rem;
  width: max-content;
  max-width: calc(100% - 2 * var(--space-2));
  padding: 0.85rem 0.75rem 0.85rem 1rem;
  background-color: var(--surface);
  color: var(--text);
  border: 1px solid var(--border);
  border-left: 4px solid var(--success);
  border-radius: var(--radius-sm);
  box-shadow: var(--shadow-lg);
  /* 기본: 숨김 */
  opacity: 0;
  visibility: hidden;
  transform: translate(-50%, -12px);
  transition: opacity var(--transition), transform var(--transition),
    visibility var(--transition);
}

.toast.is-visible {
  opacity: 1;
  visibility: visible;
  transform: translate(-50%, 0);
}

.toast__icon {
  flex-shrink: 0;
  color: var(--success);
  font-size: 1.2rem;
}

.toast__text {
  font-size: 0.95rem;
  font-weight: 500;
}

.toast__close {
  flex-shrink: 0;
  display: grid;
  place-items: center;
  width: 28px;
  height: 28px;
  border: none;
  border-radius: 6px;
  background: transparent;
  color: var(--text-muted);
  cursor: pointer;
  transition: background-color var(--transition), color var(--transition);
}

.toast__close:hover {
  background-color: var(--surface-2);
  color: var(--text);
}

/* 전송 결과 메시지: JS가 --success / --error 클래스를 붙임 */
.form__status {
  font-weight: 600;
}

.form__status--success {
  color: var(--success);
}

.form__status--error {
  color: var(--danger);
}

/* =========================================================
   9. FOOTER
========================================================= */
.footer {
  background-color: var(--surface);
  border-top: 1px solid var(--border);
  padding-block: var(--space-4);
}

.footer__inner {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-2);
  text-align: center;
}

.footer__copy {
  color: var(--text-muted);
  font-size: 0.9rem;
}

.footer__social {
  display: flex;
  gap: var(--space-2);
}

.footer__link {
  font-size: 1.3rem;
  color: var(--text-muted);
  transition: color var(--transition), transform var(--transition);
}

.footer__link:hover {
  color: var(--primary);
  transform: translateY(-3px);
}

/* =========================================================
   10. 스크롤 탑 버튼
========================================================= */
.scroll-top {
  position: fixed;
  right: var(--space-3);
  bottom: var(--space-3);
  width: 46px;
  height: 46px;
  display: grid;
  place-items: center;
  background-color: var(--primary);
  color: #fff;
  border: none;
  border-radius: 50%;
  font-size: 1rem;
  cursor: pointer;
  box-shadow: var(--shadow-lg);
  /* 기본: 숨김. JS가 is-visible 클래스로 노출 */
  opacity: 0;
  visibility: hidden;
  transform: translateY(12px);
  transition: opacity var(--transition), transform var(--transition),
    visibility var(--transition), background-color var(--transition);
  z-index: 90;
}

.scroll-top.is-visible {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.scroll-top:hover {
  background-color: var(--primary-hover);
}

/* =========================================================
   11. 스크롤 등장 애니메이션 (Intersection Observer 대상)
========================================================= */
.reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.reveal.is-visible {
  opacity: 1;
  transform: translateY(0);
}

/* =========================================================
   12. 반응형 (모바일 퍼스트 → 태블릿 → 데스크톱)
========================================================= */

/* 태블릿: 768px 이상 */
@media (min-width: 768px) {
  .about__inner {
    grid-template-columns: 320px 1fr;
    align-items: center;
  }

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

  /* 프로젝트 카드: 왼쪽 기간/역할, 오른쪽 내용 */
  .project-card {
    grid-template-columns: 200px 1fr;
    gap: var(--space-4);
    padding: var(--space-4);
  }

  .project-card__aside {
    flex-direction: column;
    flex-wrap: nowrap;
    align-items: flex-start;
    align-self: start;
  }
}

/* 데스크톱: 1024px 이상 → 네비 메뉴를 가로로 펼치고 햄버거 숨김 */
@media (min-width: 1024px) {
  .nav__toggle {
    display: none; /* 데스크톱에서는 햄버거 숨김 */
  }

  .nav__menu {
    position: static;
    width: auto;
    height: auto;
    background: transparent;
    border: none;
    box-shadow: none;
    padding: 0;
    transform: none;
    margin-left: auto;
  }

  .nav__list {
    flex-direction: row;
    gap: var(--space-3);
  }

  .nav__actions {
    margin-left: var(--space-3);
  }
}

/* =========================================================
   13. 접근성: 모션 최소화 설정 존중
========================================================= */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }

  .reveal {
    opacity: 1;
    transform: none;
  }
}