:root {
  /* 색상 */
  --color-bg: #f7f7fb;
  --color-surface: #ffffff;
  --color-text: #1f2330;
  --color-muted: #5b6072;
  --color-accent: #4a6cf7;

  /* 타이포그래피 */
  --font-family: -apple-system, "Segoe UI", "Malgun Gothic", sans-serif;
  --font-size-base: 17px;
  --font-size-h1: 2.6rem;
  --font-size-h2: 1.4rem;
  --font-size-tagline: 1.15rem;

  /* 레이아웃/간격 */
  --content-max-width: 720px;
  --section-gap: 48px;
  --side-padding: 24px;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  background: var(--color-bg);
  color: var(--color-text);
  font-family: var(--font-family);
  font-size: var(--font-size-base);
  line-height: 1.6;
}

/* 헤더 / 네비게이션 (모든 페이지 공통) */
.site-header {
  background: var(--color-surface);
  border-bottom: 1px solid #e5e7ef;
  position: sticky;
  top: 0;
  z-index: 10;
}

.site-header__inner {
  max-width: var(--content-max-width);
  margin: 0 auto;
  padding: 16px var(--side-padding);
  display: flex;
  align-items: center;
  justify-content: space-between;
  position: relative;
}

.brand {
  font-weight: 700;
  font-size: 1.2rem;
  color: var(--color-text);
  text-decoration: none;
}

.site-header nav {
  display: flex;
  gap: 20px;
}

.site-header nav a {
  color: var(--color-muted);
  text-decoration: none;
  font-weight: 600;
}

.site-header nav a.active,
.site-header nav a:hover {
  color: var(--color-accent);
}

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 4px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 8px;
}

.nav-toggle span {
  width: 22px;
  height: 2px;
  background: var(--color-text);
}

/* 페이지 상단 제목 (홈이 아닌 페이지에서 .hero 대신 사용) */
.page-title {
  max-width: var(--content-max-width);
  margin: 0 auto;
  padding: 48px var(--side-padding) 0;
}

.page-title h1 {
  font-size: 2rem;
  margin: 0 0 8px;
}

.page-title p {
  color: var(--color-muted);
  margin: 0;
}

/* 프로젝트 카드 (projects.html) */
.projects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 20px;
}

.project-card {
  background: var(--color-surface);
  border: 1px solid #e5e7ef;
  border-radius: 12px;
  padding: 20px;
}

.project-card h3 {
  margin: 0 0 8px;
}

.project-card p {
  margin: 0;
  color: var(--color-muted);
}

.hero {
  background: var(--color-surface);
  padding: 72px var(--side-padding) 48px;
  text-align: center;
  border-bottom: 1px solid #e5e7ef;
}

.hero h1 {
  margin: 0 0 12px;
  font-size: var(--font-size-h1);
}

.hero .tagline {
  margin: 0;
  color: var(--color-muted);
  font-size: var(--font-size-tagline);
}

main {
  max-width: var(--content-max-width);
  margin: 0 auto;
  padding: var(--section-gap) var(--side-padding);
}

section {
  margin-bottom: var(--section-gap);
}

section h2 {
  font-size: var(--font-size-h2);
  border-left: 4px solid var(--color-accent);
  padding-left: 12px;
  margin-bottom: 16px;
}

.links {
  list-style: none;
  padding: 0;
  margin: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.links a {
  display: inline-block;
  padding: 10px 18px;
  background: var(--color-surface);
  border: 1px solid #e5e7ef;
  border-radius: 999px;
  color: var(--color-accent);
  text-decoration: none;
  font-weight: 600;
}

.links a:hover {
  background: var(--color-accent);
  color: #fff;
  border-color: var(--color-accent);
}

footer {
  text-align: center;
  padding: 24px var(--side-padding) 48px;
  color: var(--color-muted);
  font-size: 0.9rem;
}

@media (max-width: 480px) {
  :root {
    --font-size-h1: 2rem;
    --side-padding: 16px;
  }

  .nav-toggle {
    display: flex;
  }

  .site-header nav {
    display: none;
    flex-direction: column;
    gap: 0;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: var(--color-surface);
    border-bottom: 1px solid #e5e7ef;
    padding: 8px var(--side-padding) 16px;
  }

  .site-header nav.is-open {
    display: flex;
  }

  .site-header nav a {
    padding: 10px 0;
  }
}