/* ========================================
   BTC System - 공통 스타일
   반응형 + 다크모드 자동 + 한글 최적화
======================================== */

:root {
  /* Light Mode (Default) */
  --bg-primary: #ffffff;
  --bg-secondary: #f7f7f5;
  --bg-tertiary: #ebebea;
  --bg-code: #f1f1ef;
  --bg-table-header: #f1f1ef;
  --bg-table-row: #ffffff;
  --bg-table-row-alt: #fafaf9;
  --bg-callout: #f1f1ef;
  --bg-warning: #fef3e0;
  --bg-danger: #fbe4e4;
  --bg-success: #ddedea;
  --bg-info: #e7f3f8;
  
  --text-primary: #37352f;
  --text-secondary: #787774;
  --text-muted: #9b9a97;
  --text-link: #1d6acb;
  --text-code: #eb5757;
  
  --border-color: #e9e9e7;
  --border-strong: #d3d2cf;
  
  --shadow: 0 1px 3px rgba(15, 15, 15, 0.1);
  
  /* 색상 */
  --color-success: #0f7b6c;
  --color-warning: #cb912f;
  --color-danger: #e03e3e;
  --color-info: #0b6e99;
  --color-purple: #6940a5;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg-primary: #191919;
    --bg-secondary: #2f2f2f;
    --bg-tertiary: #373737;
    --bg-code: #2f2f2f;
    --bg-table-header: #2a2a2a;
    --bg-table-row: #1f1f1f;
    --bg-table-row-alt: #252525;
    --bg-callout: #2a2a2a;
    --bg-warning: #3a2e1c;
    --bg-danger: #3a2424;
    --bg-success: #1c3329;
    --bg-info: #1c2c3a;
    
    --text-primary: #e6e6e6;
    --text-secondary: #999999;
    --text-muted: #6e6e6e;
    --text-link: #5a9bd4;
    --text-code: #ff7369;
    
    --border-color: #373737;
    --border-strong: #4a4a4a;
    
    --shadow: 0 1px 3px rgba(0, 0, 0, 0.3);
    
    --color-success: #4dab9a;
    --color-warning: #d8a356;
    --color-danger: #e8674d;
    --color-info: #5a9bd4;
    --color-purple: #9d77c8;
  }
}

/* ========================================
   기본 리셋 + 폰트
======================================== */

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Apple SD Gothic Neo", 
               "Pretendard", "Noto Sans KR", "Malgun Gothic", 
               "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  word-break: keep-all;
  overflow-wrap: break-word;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* ========================================
   컨테이너
======================================== */

.container {
  max-width: 960px;
  margin: 0 auto;
  padding: 2rem 1.5rem 4rem;
}

/* ========================================
   네비게이션
======================================== */

.nav {
  position: sticky;
  top: 0;
  background: var(--bg-primary);
  border-bottom: 1px solid var(--border-color);
  padding: 0.75rem 1.5rem;
  z-index: 100;
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
}

.nav-inner {
  max-width: 960px;
  margin: 0 auto;
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem 1.25rem;
  align-items: center;
}

.nav-home {
  font-weight: 700;
  color: var(--text-primary);
  text-decoration: none;
}

.nav a {
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 0.9rem;
  white-space: nowrap;
}

.nav a:hover {
  color: var(--text-link);
}

/* ========================================
   타이포그래피
======================================== */

h1, h2, h3, h4, h5, h6 {
  color: var(--text-primary);
  font-weight: 700;
  line-height: 1.3;
  margin-top: 2rem;
  margin-bottom: 0.75rem;
}

h1 {
  font-size: 2rem;
  border-bottom: 1px solid var(--border-color);
  padding-bottom: 0.5rem;
  margin-top: 0.5rem;
}

h2 {
  font-size: 1.5rem;
  margin-top: 2.5rem;
}

h3 {
  font-size: 1.25rem;
}

h4 {
  font-size: 1.1rem;
}

p {
  margin: 0.75rem 0;
}

ul, ol {
  margin: 0.75rem 0;
  padding-left: 1.5rem;
}

li {
  margin: 0.25rem 0;
}

a {
  color: var(--text-link);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

strong, b {
  font-weight: 700;
  color: var(--text-primary);
}

/* ========================================
   인라인 코드 + 코드 블록
======================================== */

code {
  font-family: "SFMono-Regular", "Consolas", "Liberation Mono", 
               "Menlo", "Courier New", monospace;
  font-size: 0.875em;
  background: var(--bg-code);
  color: var(--text-code);
  padding: 0.15rem 0.4rem;
  border-radius: 3px;
}

pre {
  background: var(--bg-code);
  border: 1px solid var(--border-color);
  border-radius: 6px;
  padding: 1rem;
  margin: 1rem 0;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
}

pre code {
  background: none;
  color: var(--text-primary);
  padding: 0;
  font-size: 0.85rem;
  white-space: pre;
}

/* ========================================
   테이블 (반응형 핵심)
======================================== */

.table-wrapper {
  width: 100%;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  margin: 1rem 0;
  border: 1px solid var(--border-color);
  border-radius: 6px;
}

table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.9rem;
}

th, td {
  padding: 0.6rem 0.85rem;
  text-align: left;
  border-bottom: 1px solid var(--border-color);
  vertical-align: top;
}

th {
  background: var(--bg-table-header);
  font-weight: 700;
  white-space: nowrap;
  border-right: 1px solid var(--border-color);
}

th:last-child {
  border-right: none;
}

td {
  background: var(--bg-table-row);
}

tr:nth-child(even) td {
  background: var(--bg-table-row-alt);
}

tr:last-child td {
  border-bottom: none;
}

/* ========================================
   콜아웃 / 박스
======================================== */

.callout {
  background: var(--bg-callout);
  border-left: 4px solid var(--text-secondary);
  border-radius: 6px;
  padding: 1rem 1.25rem;
  margin: 1rem 0;
}

.callout.warning {
  background: var(--bg-warning);
  border-left-color: var(--color-warning);
}

.callout.danger {
  background: var(--bg-danger);
  border-left-color: var(--color-danger);
}

.callout.success {
  background: var(--bg-success);
  border-left-color: var(--color-success);
}

.callout.info {
  background: var(--bg-info);
  border-left-color: var(--color-info);
}

blockquote {
  border-left: 4px solid var(--border-strong);
  padding: 0.5rem 1rem;
  margin: 1rem 0;
  color: var(--text-secondary);
  background: var(--bg-secondary);
  border-radius: 0 6px 6px 0;
}

blockquote p {
  margin: 0.25rem 0;
}

/* ========================================
   토글 (details/summary)
======================================== */

details {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: 6px;
  padding: 0.75rem 1rem;
  margin: 1rem 0;
}

details summary {
  cursor: pointer;
  font-weight: 700;
  padding: 0.25rem 0;
  list-style: none;
}

details summary::-webkit-details-marker {
  display: none;
}

details summary::before {
  content: "▶";
  display: inline-block;
  margin-right: 0.5rem;
  transition: transform 0.2s;
  font-size: 0.75rem;
}

details[open] summary::before {
  transform: rotate(90deg);
}

details > *:not(summary) {
  margin-top: 0.75rem;
}

/* ========================================
   상태 배지
======================================== */

.badge {
  display: inline-block;
  padding: 0.15rem 0.55rem;
  font-size: 0.75rem;
  font-weight: 700;
  border-radius: 3px;
  white-space: nowrap;
}

.badge.success { background: var(--bg-success); color: var(--color-success); }
.badge.warning { background: var(--bg-warning); color: var(--color-warning); }
.badge.danger  { background: var(--bg-danger); color: var(--color-danger); }
.badge.info    { background: var(--bg-info); color: var(--color-info); }

/* ========================================
   유틸리티
======================================== */

.text-success { color: var(--color-success); }
.text-warning { color: var(--color-warning); }
.text-danger  { color: var(--color-danger); }
.text-info    { color: var(--color-info); }
.text-muted   { color: var(--text-muted); }

.center { text-align: center; }
.right  { text-align: right; }

hr {
  border: none;
  border-top: 1px solid var(--border-color);
  margin: 2rem 0;
}

/* ========================================
   카드 그리드 (인덱스 페이지)
======================================== */

.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1rem;
  margin: 1.5rem 0;
}

.card {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 1.25rem;
  transition: transform 0.15s, box-shadow 0.15s;
}

.card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow);
}

.card a {
  display: block;
  color: var(--text-primary);
  text-decoration: none;
}

.card h3 {
  margin-top: 0;
  margin-bottom: 0.5rem;
}

.card p {
  color: var(--text-secondary);
  font-size: 0.9rem;
  margin: 0.5rem 0 0;
}

/* ========================================
   메타 정보 (작성일 / 페이지 푸터)
======================================== */

.meta {
  font-size: 0.85rem;
  color: var(--text-muted);
  font-style: italic;
  margin-top: 2rem;
  padding-top: 1rem;
  border-top: 1px solid var(--border-color);
}

/* ========================================
   모바일 반응형
======================================== */

@media (max-width: 768px) {
  html {
    font-size: 15px;
  }
  
  .container {
    padding: 1rem 1rem 3rem;
  }
  
  .nav {
    padding: 0.5rem 1rem;
  }
  
  .nav-inner {
    gap: 0.4rem 0.85rem;
    font-size: 0.85rem;
  }
  
  h1 {
    font-size: 1.65rem;
  }
  
  h2 {
    font-size: 1.3rem;
    margin-top: 2rem;
  }
  
  h3 {
    font-size: 1.15rem;
  }
  
  table {
    font-size: 0.82rem;
  }
  
  th, td {
    padding: 0.5rem 0.6rem;
  }
  
  pre {
    padding: 0.75rem;
  }
  
  pre code {
    font-size: 0.78rem;
  }
  
  .callout {
    padding: 0.75rem 1rem;
  }
  
  .card-grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 480px) {
  html {
    font-size: 14px;
  }
  
  h1 {
    font-size: 1.5rem;
  }
  
  table {
    font-size: 0.78rem;
  }
}

/* ========================================
   인쇄
======================================== */

@media print {
  .nav {
    display: none;
  }
  
  body {
    background: white;
    color: black;
  }
  
  .container {
    max-width: 100%;
    padding: 1rem;
  }
}

/* ========================================
   접근성
======================================== */

:focus-visible {
  outline: 2px solid var(--text-link);
  outline-offset: 2px;
}

/* 스크롤바 (다크모드 친화) */
@media (prefers-color-scheme: dark) {
  ::-webkit-scrollbar {
    width: 10px;
    height: 10px;
  }
  
  ::-webkit-scrollbar-track {
    background: var(--bg-primary);
  }
  
  ::-webkit-scrollbar-thumb {
    background: var(--border-strong);
    border-radius: 5px;
  }
  
  ::-webkit-scrollbar-thumb:hover {
    background: var(--text-muted);
  }
}