:root {
  --font-family: 'Pretendard Variable', Pretendard, -apple-system, BlinkMacSystemFont, system-ui, Roboto, sans-serif;
  
  /* Light Mode (Default) */
  --bg-color: #FFFFFF;
  --bg-secondary: #F9FAFB;
  --text-primary: #191F28;
  --text-secondary: #8B95A1;
  --accent-color: #3D5AFE;
  --card-bg: #FFFFFF;
  --card-shadow: 0 4px 20px rgba(0, 0, 0, 0.05);
  --card-hover-shadow: 0 8px 30px rgba(61, 90, 254, 0.15);
  --border-color: #F2F4F6;
  --toggle-bg: #F2F4F6;
  --border-radius: 20px;
}

body.dark-mode {
  /* Dark Mode */
  --bg-color: #121212;
  --bg-secondary: #1E1E1E;
  --text-primary: #EAEAEA;
  --text-secondary: #A0A0A0;
  --accent-color: #5875FF;
  --card-bg: #2A2A2A;
  --card-shadow: 0 4px 20px rgba(0, 0, 0, 0.2);
  --card-hover-shadow: 0 8px 30px rgba(88, 117, 255, 0.25);
  --border-color: #2A2A2A;
  --toggle-bg: #2A2A2A;
}

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

body {
  font-family: var(--font-family);
  background-color: var(--bg-color);
  color: var(--text-primary);
  line-height: 1.6;
  transition: background-color 0.3s, color 0.3s;
}

/* 공통 컨테이너 (중앙 정렬 및 최대 너비 제한) */
.container {
  width: 90%;
  max-width: 1200px;
  margin: 0 auto;
}

/* --- 헤더 스타일 --- */
.site-header {
  padding: 1rem 0;
  border-bottom: 1px solid var(--border-color);
  background-color: rgba(255, 255, 255, 0.8);
  backdrop-filter: blur(10px);
  position: sticky;
  top: 0;
  z-index: 100;
  transition: background-color 0.3s, border-color 0.3s;
}

body.dark-mode .site-header {
  background-color: rgba(18, 18, 18, 0.8);
}

.header-content {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.logo {
  font-size: 2.7rem;
  font-weight: 800;
  color: var(--accent-color);
  text-align: center;
  line-height: 1;
}

.sub-logo {
  display: block;
  font-size: 1rem;
  font-weight: 500;
  color: var(--text-secondary);
  margin-top: 0.5rem;
}

/* --- 다크 모드 토글 스타일 --- */
.dark-mode-toggle {
  cursor: pointer;
  padding: 0.6rem;
  border-radius: 50%;
  background-color: var(--toggle-bg);
  display: flex;
  justify-content: center;
  align-items: center;
  transition: background-color 0.3s ease;
}

.dark-mode-toggle:hover {
  background-color: var(--accent-color);
  color: #fff;
}

.toggle-icon {
  font-size: 1.5rem;
  line-height: 0;
}

/* --- 히어로 섹션 스타일 --- */
.hero-section {
  text-align: center;
  padding: 5rem 1rem;
  background-color: var(--bg-color);
}

.hero-title {
  font-size: 3rem;
  font-weight: 800;
  margin-bottom: 1rem;
  line-height: 1.3;
}

.hero-description {
  font-size: 1.2rem;
  color: var(--text-secondary);
  max-width: 600px;
  margin: 0 auto;
}

/* --- 툴 그리드 섹션 스타일 --- */
.tools-section {
  padding: 3rem 0 5rem;
  background-color: var(--bg-secondary);
  transition: background-color 0.3s;
}

.tool-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 2rem;
}

.tool-card {
  background-color: var(--card-bg);
  border-radius: var(--border-radius);
  padding: 2.5rem;
  box-shadow: var(--card-shadow);
  transition: all 0.3s ease;
  display: flex;
  flex-direction: column;
  border: 1px solid var(--border-color);
}

.tool-card:hover {
  transform: translateY(-8px);
  box-shadow: var(--card-hover-shadow);
}

.tool-icon {
  font-size: 3rem;
  margin-bottom: 1.5rem;
}

.tool-title {
  font-size: 1.5rem;
  font-weight: 700;
  margin-bottom: 0.75rem;
  color: var(--text-primary);
}

.tool-desc {
  color: var(--text-secondary);
  font-size: 1rem;
  flex-grow: 1;
  margin-bottom: 2rem;
  word-break: keep-all;
}

.tool-link-btn {
  display: inline-block;
  text-align: center;
  text-decoration: none;
  background-color: var(--accent-color);
  color: #FFFFFF;
  padding: 1rem 1.5rem;
  border-radius: 12px;
  font-weight: 600;
  transition: all 0.2s ease;
}

.tool-link-btn:hover {
  opacity: 0.8;
}

/* --- 푸터 스타일 --- */
.site-footer {
  padding: 3rem 0;
  text-align: center;
  color: var(--text-secondary);
  border-top: 1px solid var(--border-color);
  font-size: 0.9rem;
  transition: border-color 0.3s;
}

/* --- 반응형 미디어 쿼리 (모바일) --- */
@media (max-width: 768px) {
  .header-content {
    flex-direction: row;
    justify-content: space-between;
  }
  .logo {
    font-size: 2rem;
    text-align: left;
  }
  .sub-logo {
      display: none;
  }
  .hero-title {
      font-size: 2.2rem;
  }
  .tool-grid {
      grid-template-columns: 1fr;
  }
}