@import url('https://fonts.googleapis.com/css2?family=Host+Grotesk:ital,wght@0,300..800;1,300..800&display=swap');
@import url('https://fonts.googleapis.com/css2?family=Lexend:wght@100..900&display=swap');

/* 
 * core.css - 최적화된 기본 스타일, 변수, 레이아웃, 타이포그래피 통합
 * 성능 최적화 및 모든 테마에서 일관된 크기 유지
 */

/* ===== 1. 폰트 임포트  ===== */
@font-face {
    font-family: 'OnulSamhwagothic';
    src: url('../font/OnulSamhwagothic-Regular.otf') format('opentype');
    font-weight: normal;
    font-style: normal;
    font-display: swap;
}

/* ===== 2. 루트 변수 설정 - GitHub 스타일 ===== */
:root {
  /* 기본 텍스트 색상 유지 */
  --text-color-primary: rgb(6, 7, 39);

  /* GitHub 색상 팔레트 */
  --github-bg: #f6f8fa;
  --github-card: #ffffff;
  --github-border: #d0d7de;
  --github-accent: #0969da;
  --github-text: var(--text-color-primary);
  --github-secondary-text: #57606a;

  /* 색상 팔레트 */
  --primary-50: #f3f6fc;
  --primary-100: #daeafe;
  --primary-200: #b6e0fe;
  --primary-300: #7cc0ff;
  --primary-400: #54aeff;
  --primary-500: #0969da;
  --primary-600: #0550ae;
  --primary-700: #033d8a;

  --neutral-50: #f6f8fa;
  --neutral-100: #eaeef2;
  --neutral-200: #d0d7de;
  --neutral-300: #afb8c1;
  --neutral-400: #8c959f;
  --neutral-500: #6e7781;
  --neutral-600: #57606a;
  --neutral-700: #424a53;
  --neutral-800: #32383f;
  --neutral-900: #24292f;

  --success: #2da44e;
  --warning: #bf8700;
  --danger: #cf222e;

  /* 테마 변수 */
  --bg-primary: var(--github-bg);
  --bg-secondary: var(--github-card);
  --bg-tertiary: var(--neutral-100);
  --bg-accent: var(--github-accent);

  --text-primary: var(--text-color-primary);
  --text-secondary: var(--text-color-primary);
  --text-tertiary: var(--github-secondary-text);
  --text-accent: var(--github-accent);

  --border-color: var(--github-border);
  --border-subtle: rgba(208, 215, 222, 0.6);
  --accent-soft: rgba(9, 105, 218, 0.08);
  --accent-glow: rgba(9, 105, 218, 0.38);

  /* 타이포그래피 */
  --font-sans: 'OnulSamhwagothic', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  --font-mono: 'JetBrains Mono', 'Consolas', 'Monaco', 'Courier New', monospace;

  /* 글꼴 크기 - 모든 테마에서 동일하게 사용 */
  --font-size-xs: 0.75rem;
  --font-size-sm: 0.875rem;
  --font-size-md: 1rem;
  --font-size-lg: 1.125rem;
  --font-size-xl: 1.25rem;
  --font-size-2xl: 1.5rem;
  --font-size-3xl: 1.875rem;

  /* 간격 - 모든 테마에서 동일하게 사용 */
  --spacing-1: 0.25rem;
  --spacing-2: 0.5rem;
  --spacing-3: 0.75rem;
  --spacing-4: 1rem;
  --spacing-5: 1.25rem;
  --spacing-6: 1.5rem;
  --spacing-8: 2rem;
  --spacing-10: 2.5rem;
  --spacing-12: 3rem;
  --spacing-16: 4rem;

  /* 테두리 반경 */
  --radius-sm: 0.125rem;
  --radius-md: 0.25rem;
  --radius-lg: 0.375rem;
  --radius-xl: 0.5rem;
  --radius-full: 9999px;

  /* 그림자 */
  --shadow-sm: 0 2px 4px rgba(27, 31, 36, 0.12);
  --shadow-md: 0 4px 12px rgba(140, 149, 159, 0.2);
  --shadow-lg: 0 12px 32px rgba(140, 149, 159, 0.25);

  /* 전환 - 성능 최적화 */
  --transition-fast: 150ms ease;
  --transition-normal: 300ms ease;

  /* 레이아웃 변수 */
  --paragraph-width: 100%;
  --content-max-width: 1200px;
  --layout-gutter: var(--spacing-4);
  --container-width: calc(var(--content-max-width) + var(--layout-gutter) + var(--layout-gutter));
  --header-width: var(--content-max-width);

  /* 버튼 디자인 토큰 */
  --button-font-family: var(--font-sans);
  --button-font-weight: 600;
  --button-radius: 6px;
  --button-tag-radius: 9999px;
  --button-gap: var(--spacing-2);
  --button-transition: var(--transition-fast);
  --button-focus-ring: 0 0 0 3px var(--accent-glow);
  --button-disabled-opacity: 0.5;

  --button-height-sm: 32px;
  --button-height-regular: 40px;
  --button-height-lg: 48px;
  --button-padding-sm: var(--spacing-3);
  --button-padding-regular: var(--spacing-4);
  --button-padding-lg: var(--spacing-6);
  --button-font-size-sm: var(--font-size-sm);
  --button-font-size-regular: var(--font-size-md);
  --button-font-size-lg: var(--font-size-lg);

  --button-normal-bg: var(--bg-secondary);
  --button-normal-color: var(--text-primary);
  --button-normal-border: var(--border-color);
  --button-normal-hover-bg: var(--bg-tertiary);
  --button-normal-hover-color: var(--text-primary);
  --button-normal-hover-border: var(--neutral-300);

  --button-tag-active-bg: var(--accent-soft);
  --button-tag-active-color: var(--text-accent);
  --button-tag-active-border: var(--text-accent);

  --button-invisible-bg: transparent;
  --button-invisible-color: var(--text-primary);
  --button-invisible-border: transparent;
  --button-invisible-hover-bg: var(--accent-soft);
  --button-invisible-hover-color: var(--text-accent);
  --button-invisible-hover-border: transparent;

  --button-primary-bg: var(--github-accent);
  --button-primary-color: #ffffff;
  --button-primary-border: var(--github-accent);
  --button-primary-hover-bg: color-mix(in srgb, var(--github-accent) 88%, var(--text-primary));
  --button-primary-hover-color: #ffffff;
  --button-primary-hover-border: var(--button-primary-hover-bg);

  /* 입력 요소: normal + regular 버튼과 동일한 디자인 기준 */
  --input-height: var(--button-height-regular);
  --input-padding-x: var(--button-padding-regular);
  --input-font-family: var(--button-font-family);
  --input-font-size: var(--button-font-size-regular);
  --input-background: var(--button-normal-bg);
  --input-color: var(--button-normal-color);
  --input-border: var(--button-normal-border);
  --input-hover-border: var(--button-normal-hover-border);
  --input-focus-border: var(--text-accent);
  --input-focus-ring: var(--button-focus-ring);
  --input-radius: var(--button-radius);
  --input-placeholder-color: var(--text-tertiary);
}

/* ===== 다크 테마 설정 ===== */
html.dark-theme {
  --bg-primary: #0d1117;
  --bg-secondary: #161b22;
  --bg-tertiary: #21262d;
  --bg-accent: #1f6feb;

  --text-primary: #c9d1d9;
  --text-secondary: #c9d1d9;
  --text-tertiary: #8b949e;
  --text-accent: #58a6ff;

  --border-color: #30363d;
  --border-subtle: rgba(48, 54, 61, 0.6);
  --accent-soft: rgba(88, 166, 255, 0.16);
  --accent-glow: rgba(88, 166, 255, 0.45);

  --shadow-sm: 0 0 transparent;
  --shadow-md: 0 3px 6px rgba(0, 0, 0, 0.3);
  --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.4);

  color-scheme: dark;
}

/* ===== 기본 스타일 리셋 (최적화) ===== */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

/* ===== 푸터 고정 및 기본 레이아웃 ===== */
html, body {
  height: 100%;
  margin: 0;
  padding: 0;
  overflow: auto;
  width: 100%;
  -webkit-text-size-adjust: 100%;
  text-size-adjust: 100%;
}

body {
  background-color: var(--bg-primary);
  color: var(--text-primary);
  font-family: var(--font-sans);
  font-weight: 400;
  line-height: 1.6;
  display: flex;
  flex-direction: column;
  min-height: 100vh;
  min-height: -webkit-fill-available;
  transition: background-color 0.3s ease, color 0.3s ease;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
  position: relative;
  width: 100%;
}

main {
  flex: 1 0 auto;
  display: flex;
  flex-direction: column;
  position: relative;
  z-index: 2;
  width: 100%;
}

main .container {
  padding-top: var(--spacing-4); 
  padding-bottom: var(--spacing-8);
  max-width: var(--content-max-width);
  position: relative;
  z-index: 5;
  width: 100%;
}

footer {
  flex-shrink: 0;
  margin-top: auto;
  position: relative;
  width: 100%;
  padding: var(--spacing-6) 0;
  background-color: var(--bg-secondary);
  border-top: 2px solid var(--border-color);
}

.container {
  width: 100%;
  max-width: var(--container-width);
  margin: 0 auto;
  padding: 0 var(--layout-gutter);
}

/* 이미지 최적화 */
img {
  max-width: 100%;
  height: auto;
  will-change: auto;
}

/* Lazy Loading Images */
img.lazy-image {
  opacity: 0;
  transition: opacity 0.5s ease-in-out;
}
img.lazy-image.loaded {
  opacity: 1;
}
img.lazy-image.error {
  opacity: 0.5;
  filter: grayscale(100%);
}

a {
  color: var(--text-accent);
  text-decoration: none;
  transition: color var(--transition-fast);
}

a:hover {
  color: var(--text-accent);
  text-decoration: underline;
}

.fade-in {
  opacity: 0;
  transform: translateY(20px);
  animation: fadeInAnimation 0.5s ease forwards;
  will-change: opacity, transform;
}

@keyframes fadeInAnimation {
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* ===== 헤더 스타일 ===== */
.top-header {
  background-color: var(--bg-secondary);
  border-bottom: 1px solid var(--border-color);
  position: sticky;
  top: 0;
  z-index: 1000;
  transition: transform 0.3s ease, background-color 0.3s ease;
  padding: 0;
  display: flex;
  align-items: center;
  width: 100%;
  height: 60px;
  will-change: transform;
}

.top-header .container {
  display: flex;
  align-items: center;
  width: 100%;
  max-width: var(--header-width) !important;
  margin: 0 auto;
  padding: 0 var(--layout-gutter);
  height: 100%;
}

.logo-area {
  display: flex;
  align-items: center;
  justify-content: flex-start;
  flex: 1 1 0;
  min-width: max-content;
  height: 100%;
}

.logo {
  display: flex;
  align-items: center;
  justify-content: flex-start;
  gap: var(--spacing-3);
  text-decoration: none;
  height: 100%;
}

.logo img {
  width: 32px;
  height: 32px;
}

.site-name {
  font-size: 18px;
  font-weight: 600;
  color: var(--text-primary);
  white-space: nowrap;
  font-family: var(--font-sans);
}

.desktop-nav {
  display: flex;
  justify-content: center;
  align-items: center;
  flex: 0 0 auto;
  height: 100%;
}

.desktop-nav ul {
  display: flex;
  list-style: none;
  gap: var(--spacing-1);
  padding: 0;
  margin: 0 auto;
  height: 100%;
  justify-content: center;
  width: auto;
}

.desktop-nav li {
  height: 100%;
  margin: 0;
  padding: 0;
  display: flex;
}

.desktop-nav a {
  color: var(--text-primary);
  text-decoration: none;
  font-weight: 500;
  font-size: 1.1rem;
  transition: color var(--transition-fast), background-color var(--transition-fast);
  padding: 0 var(--spacing-4);
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-sans);
  position: relative;
  height: 60px;
  margin: 0;
  white-space: nowrap;
  -webkit-tap-highlight-color: transparent;
}

.desktop-nav a:hover {
  color: var(--text-primary);
  background-color: var(--bg-tertiary);
  text-decoration: none;
}

.desktop-nav a.active {
  font-weight: 600;
}

.desktop-nav a.active::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 100%;
  height: 2px;
  background-color: var(--github-accent);
}

.header-controls {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  gap: var(--spacing-4);
  flex: 1 1 0;
  min-width: 0;
  height: 100%;
}

.header-controls-left {
  display: flex;
  align-items: center;
  justify-content: flex-start;
  gap: var(--spacing-4);
  height: 100%;
}

.top-header .theme-toggle {
  background-color: transparent;
  border: 1px solid var(--border-subtle);
  cursor: pointer;
  color: var(--text-primary);
  padding: var(--spacing-1);
  border-radius: 6px;
  transition: background-color var(--transition-fast),
              border-color var(--transition-fast),
              box-shadow var(--transition-fast),
              transform var(--transition-fast);
  display: flex;
  align-items: center;
  justify-content: center;
  height: 44px;
  width: 44px;
  margin: 0;
  position: relative;
  overflow: hidden;
  -webkit-tap-highlight-color: transparent;
}

.top-header .theme-toggle:hover {
  background-color: transparent;
  border-color: var(--text-accent);
}

.top-header .theme-toggle:focus-visible {
  outline: 2px solid var(--text-accent);
  outline-offset: 2px;
  border-color: var(--text-accent);
}

.top-header .theme-toggle:active {
  transform: scale(0.96);
}

.theme-toggle .dark-icon,
.theme-toggle .light-icon {
  position: absolute;
  transition: opacity var(--transition-normal), transform var(--transition-normal);
}

.dark-theme .dark-icon {
  opacity: 0;
  transform: rotate(-180deg) scale(0.5);
}

.dark-theme .light-icon {
  opacity: 1;
  transform: rotate(0) scale(1);
}

:not(.dark-theme) .dark-icon {
  opacity: 1;
  transform: rotate(0) scale(1);
}

:not(.dark-theme) .light-icon {
  opacity: 0;
  transform: rotate(180deg) scale(0.5);
}

.mobile-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 8px;
  border-radius: 6px;
  transition: background-color var(--transition-fast);
  position: relative;
  width: 44px;
  height: 44px;
  align-items: center;
  justify-content: center;
  flex-direction: column;
  gap: 4px;
  -webkit-tap-highlight-color: transparent;
}

.hamburger-line {
  display: block;
  width: 20px;
  height: 2px;
  background-color: var(--text-primary);
  border-radius: 2px;
  transition: all 0.3s cubic-bezier(0.25, 0.46, 0.45, 0.94);
}

.mobile-nav {
  position: fixed;
  top: 0;
  right: 0;
  width: 320px;
  max-width: 80vw;
  height: 100vh;
  height: 100dvh;
  background: linear-gradient(135deg, var(--bg-primary) 0%, var(--bg-secondary) 100%);
  z-index: 1001;
  overflow-y: auto;
  transition: transform 0.4s cubic-bezier(0.25, 0.46, 0.45, 0.94), visibility 0.4s;
  box-shadow: -10px 0 30px rgba(0, 0, 0, 0.1);
  border-left: 1px solid var(--border-color);
  display: flex;
  flex-direction: column;
  transform: translateX(100%);
  visibility: hidden;
  -webkit-overflow-scrolling: touch;
}

.mobile-nav.active {
  transform: translateX(0);
  visibility: visible;
}

.mobile-nav-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--spacing-4) var(--spacing-5);
  border-bottom: 1px solid var(--border-color);
  background-color: var(--bg-secondary);
  min-height: 60px;
}

.mobile-nav-logo { 
  display: flex; 
  align-items: center; 
  gap: var(--spacing-3); 
}
.mobile-nav-logo img { 
  width: 28px; 
  height: 28px; 
}
.mobile-nav-logo span { 
  font-size: 1.1rem; 
  font-weight: 600; 
  color: var(--text-primary);
}

.mobile-nav-close {
  background: none; 
  border: none; 
  cursor: pointer;
  color: var(--text-primary); 
  font-size: 1.25rem;
  padding: var(--spacing-2); 
  border-radius: 6px;
  width: 36px; 
  height: 36px;
  display: flex; 
  align-items: center; 
  justify-content: center;
}

.mobile-nav-content { 
  flex: 1; 
  padding: var(--spacing-4) 0; 
}
.mobile-nav-list { 
  list-style: none; 
  padding: 0; 
  margin: 0; 
}

.mobile-nav-link {
  display: flex; 
  align-items: center; 
  gap: var(--spacing-4);
  padding: var(--spacing-4) var(--spacing-5);
  color: var(--text-primary); 
  text-decoration: none;
  font-size: 1.1rem; 
  font-weight: 500;
  transition: all 0.3s;
  position: relative; 
  border: none; 
  background: none; 
  cursor: pointer;
  width: 100%;
  -webkit-tap-highlight-color: transparent;
  min-height: 44px;
}

.mobile-nav-footer {
  padding: var(--spacing-4) var(--spacing-5);
  border-bottom: 1px solid var(--border-color);
  background-color: var(--bg-secondary);
}

.mobile-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-color: rgba(0, 0, 0, 0.6);
  z-index: 1000;
  opacity: 0;
  visibility: hidden;
  transition: all 0.3s;
  -webkit-backdrop-filter: blur(4px);
  backdrop-filter: blur(4px);
}

.mobile-overlay.active {
  opacity: 1;
  visibility: visible;
}

/* ===== 푸터 스타일 ===== */
.footer-content {
  display: flex;
  justify-content: space-between;
  align-items: center;
  max-width: var(--header-width);
  width: 100%;
  margin: 0 auto;
  padding: 0 var(--spacing-4);
}

.footer-info { 
  display: flex; 
  align-items: center; 
}
.footer-info p { 
  margin: 0; 
  color: var(--text-tertiary); 
  width: auto; 
  font-family: var(--font-sans); 
  font-size: 0.85rem; 
}
.footer-logo { 
  margin-left: var(--spacing-3); 
  display: flex; 
  align-items: center; 
}
.footer-logo img { 
  height: 24px; 
  width: auto; 
}
.footer-links { 
  display: flex; 
  gap: var(--spacing-4); 
}
.footer-links a { 
  color: var(--text-tertiary); 
  display: flex; 
  align-items: center; 
  gap: var(--spacing-2); 
  transition: color var(--transition-fast); 
  font-family: var(--font-sans); 
  font-size: 0.85rem; 
  -webkit-tap-highlight-color: transparent;
}
.footer-links a:hover { 
  color: var(--text-accent); 
}

/* 섹션 간 일관된 간격 및 너비 제한 */
.blog-section, 
.simulation-section, 
.content-section {
  margin: var(--spacing-16) auto;
  padding: 0; /* 화면 가장 바깥선까지 꽉 차도록 패딩 제거 */
  max-width: var(--content-max-width);
  width: 100%;
}

.blog-header, 
.post-header, 
.article-header {
  position: relative !important;
  z-index: 10 !important;
  background-color: var(--bg-primary, #ffffff) !important;
  margin-bottom: 2rem;
}

/* ===== 기본 타이포그래피 (1200px 컨테이너에 맞춤) ===== */
h1, h2, h3, h4, h5, h6, p {
  font-family: var(--font-sans);
  color: inherit;
  width: 100%;
  max-width: var(--content-max-width);
  margin-left: auto;
  margin-right: auto;
  text-align: left;
  word-break: keep-all;
  word-wrap: break-word;
}

h1 {
  font-size: 2.75rem;
  line-height: 1.2;
  font-weight: 700;
  margin-bottom: 1.5rem;
}

h2 {
  font-size: 1.9rem;
  line-height: 1.3;
  font-weight: 700;
  margin-top: 2.5rem;
  margin-bottom: 1rem;
}

p {
  font-size: 1.1rem;
  line-height: 1.6;
  font-weight: 400;
  margin-bottom: 1.5rem;
}

.section-title {
  font-family: var(--font-sans);
  font-size: 2.2rem;
  font-weight: 700;
  margin-bottom: var(--spacing-8);
  margin-top: var(--spacing-8);
  color: var(--text-primary);
  max-width: var(--content-max-width);
  margin-left: auto;
  margin-right: auto;
}

/* 모바일 반응형 */
@media (max-width: 768px) {
  h1 { font-size: 1.8rem; }
  h2 { font-size: 1.4rem; }
  p { font-size: 1rem; }

  .container {
    padding-left: var(--layout-gutter);
    padding-right: var(--layout-gutter);
  }

  /* 헤더 모바일 반응형 및 깨짐 해결 */
  .top-header .container {
    justify-content: space-between;
  }

  .logo-area {
    width: auto;
    flex: 1 1 auto;
    min-width: 0;
  }

  .logo {
    gap: var(--spacing-2);
  }

  .site-name {
    font-size: 16px;
  }

  .desktop-nav {
    display: none !important;
  }

  .header-controls {
    width: auto;
    gap: var(--spacing-2);
    flex: 0 0 auto;
  }

  .mobile-toggle {
    display: flex !important;
  }

  /* 모바일 네비게이션 오픈 시 본문 스크롤 차단 지원 */
  body.nav-open {
    overflow: hidden;
    position: fixed;
    width: 100%;
  }
}

html.dark-theme .mobile-nav {
  background: linear-gradient(135deg, var(--bg-primary) 0%, var(--bg-secondary) 100%);
}

html.dark-theme .mobile-nav-header, 
html.dark-theme .mobile-nav-footer {
  background-color: var(--bg-secondary);
}