/**
 * KICDA 상단 메뉴 개선 디자인 시스템
 * 작성일: 2025-10-31
 * 버전: 2.0
 * 목적: 일관된 디자인, 명확한 계층 구조, 향상된 가독성
 */

/* ============================================
   1. CSS 변수 정의 (디자인 토큰)
   ============================================ */

:root {
  /* 색상 팔레트 */
  --header-bg: #ffffff;
  --header-border: #e5e7eb;
  --header-shadow: 0 1px 3px rgba(0, 0, 0, 0.08);

  /* 텍스트 색상 */
  --text-primary: #1f2937;
  --text-secondary: #6b7280;
  --text-hover: #2563eb;
  --text-active: #1d4ed8;

  /* 버튼 색상 */
  --btn-outline-border: #d1d5db;
  --btn-outline-hover-bg: #f3f4f6;
  --btn-outline-hover-border: #9ca3af;
  --btn-primary-bg: #2563eb;
  --btn-primary-hover-bg: #1d4ed8;
  --btn-primary-shadow: 0 4px 12px rgba(37, 99, 235, 0.2);

  /* 상단 알림 배너 */
  --banner-bg: #2563eb;
  --banner-text: #ffffff;
  --banner-badge-bg: #ef4444;
  --banner-badge-text: #ffffff;
  --banner-height: 40px;

  /* 타이포그래피 */
  --logo-size: 26px;
  --logo-weight: 700;
  --menu-size: 16px;
  --menu-weight: 600;
  --dropdown-size: 15px;
  --dropdown-weight: 500;
  --button-size: 15px;
  --button-weight: 600;

  /* 간격 및 레이아웃 */
  --header-height: 72px;
  --header-padding: 0 24px;
  --logo-menu-gap: 32px;
  --menu-gap: 40px;
  --menu-padding-x: 16px;
  --menu-padding-y: 24px;
  --button-gap: 12px;
  --button-padding-x: 20px;
  --button-padding-y: 12px;

  /* 애니메이션 */
  --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-normal: 250ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: 350ms cubic-bezier(0.4, 0, 0.2, 1);

  /* 드롭다운 */
  --dropdown-bg: rgba(255, 255, 255, 0.92);
  --dropdown-border: rgba(255, 255, 255, 0.3);
  --dropdown-shadow: 0 4px 20px rgba(0, 0, 0, 0.15);
  --dropdown-radius: 8px;
  --dropdown-padding: 12px;
}

/* ============================================
   2. 상단 알림 배너 (모든 페이지 공통)
   ============================================ */

.top-banner {
  background: var(--banner-bg);
  color: var(--banner-text);
  text-align: center;
  padding: 10px 20px;
  font-size: 14px;
  font-weight: 500;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 12px;
  position: relative;
  z-index: 9001;
}

.top-banner .badge {
  background: var(--banner-badge-bg);
  color: var(--banner-badge-text);
  padding: 4px 10px;
  border-radius: 4px;
  font-size: 12px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.top-banner span {
  display: inline-flex;
  align-items: center;
  gap: 8px;
}

/* ============================================
   3. 헤더 메인 구조
   ============================================ */

header {
  background: var(--header-bg);
  border-bottom: 1px solid var(--header-border);
  box-shadow: var(--header-shadow);
  position: sticky;
  top: 0;
  z-index: 9000;
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
}

.header-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: var(--header-padding);
  height: var(--header-height);
  display: flex;
  align-items: center;
  justify-content: space-between;
  position: relative;
}

/* ============================================
   4. 로고 (1200px 왼쪽 끝 정렬)
   ============================================ */

.logo {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
  color: var(--text-hover);
  font-size: var(--logo-size);
  font-weight: var(--logo-weight);
  letter-spacing: -0.03em;
  transition: all var(--transition-fast);
}

.logo:hover {
  transform: scale(1.02);
  opacity: 0.9;
}

.logo span {
  background: linear-gradient(135deg, #2563eb, #1d4ed8);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

/* ============================================
   5. 메인 내비게이션
   ============================================ */

.navbar {
  flex: 1;
  display: flex;
  justify-content: center;
  align-items: center;
}

.nav-container {
  display: flex;
  align-items: center;
  gap: var(--logo-menu-gap);
}

.nav-menu {
  display: flex;
  list-style: none;
  margin: 0;
  padding: 0;
  gap: var(--menu-gap);
  align-items: center;
}

.nav-item {
  position: relative;
}

.nav-link {
  display: inline-block;
  color: var(--text-primary);
  font-size: var(--menu-size);
  font-weight: var(--menu-weight);
  padding: var(--menu-padding-y) var(--menu-padding-x);
  text-decoration: none;
  letter-spacing: 0;
  line-height: 1.5;
  position: relative;
  transition: color var(--transition-fast);
}

/* 호버 효과 - 밑줄 애니메이션 */
.nav-link::after {
  content: '';
  position: absolute;
  bottom: 8px;
  left: 0;
  width: 100%;
  height: 3px;
  background: var(--text-hover);
  border-radius: 2px;
  transform: scaleX(0);
  transform-origin: left;
  transition: transform var(--transition-normal);
}

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

.nav-link:hover::after {
  transform: scaleX(1);
}

/* 현재 페이지 표시 (활성 상태) */
.nav-item.active .nav-link {
  color: var(--text-active);
  font-weight: 700;
}

.nav-item.active .nav-link::after {
  transform: scaleX(1);
  background: var(--text-active);
}

/* ============================================
   6. 드롭다운 메뉴
   ============================================ */

.dropdown {
  position: absolute;
  top: 100%;
  left: 50%;
  transform: translateX(-50%) translateY(8px);
  background: var(--dropdown-bg);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border: 1px solid var(--dropdown-border);
  border-radius: var(--dropdown-radius);
  box-shadow: var(--dropdown-shadow);
  padding: var(--dropdown-padding);
  min-width: 220px;
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
  transition: all var(--transition-normal);
  z-index: 9100;
}

.nav-item:hover .dropdown {
  opacity: 1;
  visibility: visible;
  pointer-events: auto;
  transform: translateX(-50%) translateY(0);
}

.dropdown a {
  display: block;
  color: var(--text-primary);
  font-size: var(--dropdown-size);
  font-weight: var(--dropdown-weight);
  padding: 10px 16px;
  text-decoration: none;
  border-radius: 4px;
  transition: all var(--transition-fast);
}

.dropdown a:hover {
  background: var(--btn-outline-hover-bg);
  color: var(--text-hover);
  transform: translateX(4px);
}

/* 드롭다운 카테고리 */
.dropdown-category {
  position: relative;
}

.dropdown-category > a {
  font-weight: 600;
  color: var(--text-hover);
  padding-right: 32px;
  position: relative;
}

.dropdown-category > a::after {
  content: '▶';
  position: absolute;
  right: 12px;
  top: 50%;
  transform: translateY(-50%);
  font-size: 10px;
  color: var(--text-secondary);
  transition: transform var(--transition-fast);
}

.dropdown-category:hover > a::after {
  transform: translateY(-50%) translateX(2px);
}

/* 드롭다운 서브메뉴 */
.dropdown-submenu {
  position: absolute;
  left: 100%;
  top: -8px;
  margin-left: 8px;
  background: var(--dropdown-bg);
  border: 1px solid var(--dropdown-border);
  border-radius: var(--dropdown-radius);
  box-shadow: var(--dropdown-shadow);
  padding: var(--dropdown-padding);
  min-width: 200px;
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
  transition: all var(--transition-normal);
  z-index: 9101;
}

.dropdown-category:hover .dropdown-submenu {
  opacity: 1;
  visibility: visible;
  pointer-events: auto;
  transform: translateX(0);
}

.dropdown-submenu a {
  font-size: 14px;
  color: var(--text-secondary);
  padding: 8px 14px;
}

.dropdown-submenu a:hover {
  color: var(--text-hover);
  background: var(--btn-outline-hover-bg);
}

/* ============================================
   7. 버튼 (로그인, 무료체험)
   ============================================ */

.nav-buttons {
  display: flex;
  gap: var(--button-gap);
  align-items: center;
}

.nav-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: var(--button-padding-y) var(--button-padding-x);
  font-size: var(--button-size);
  font-weight: var(--button-weight);
  text-decoration: none;
  border-radius: 8px;
  border: 2px solid transparent;
  transition: all var(--transition-fast);
  white-space: nowrap;
  cursor: pointer;
}

/* 로그인 버튼 (아웃라인) */
.nav-btn-outline {
  background: transparent;
  border-color: var(--btn-outline-border);
  color: var(--text-primary);
}

.nav-btn-outline:hover {
  background: var(--btn-outline-hover-bg);
  border-color: var(--btn-outline-hover-border);
  color: var(--text-hover);
  transform: translateY(-1px);
}

/* 무료체험 버튼 (채우기) */
.nav-btn-primary {
  background: var(--btn-primary-bg);
  border-color: var(--btn-primary-bg);
  color: #ffffff;
  box-shadow: 0 2px 8px rgba(37, 99, 235, 0.15);
}

.nav-btn-primary:hover {
  background: var(--btn-primary-hover-bg);
  border-color: var(--btn-primary-hover-bg);
  box-shadow: var(--btn-primary-shadow);
  transform: translateY(-2px);
}

.nav-btn-primary:active {
  transform: translateY(0);
}

/* ============================================
   8. 모바일 햄버거 메뉴
   ============================================ */

.mobile-menu-toggle {
  display: none;
  flex-direction: column;
  justify-content: space-between;
  width: 28px;
  height: 22px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 0;
  z-index: 10000;
}

.mobile-menu-toggle span {
  display: block;
  width: 100%;
  height: 3px;
  background: var(--text-primary);
  border-radius: 2px;
  transition: all var(--transition-normal);
}

.mobile-menu-toggle.active span:first-child {
  transform: translateY(10px) rotate(45deg);
}

.mobile-menu-toggle.active span:nth-child(2) {
  opacity: 0;
}

.mobile-menu-toggle.active span:nth-child(3) {
  transform: translateY(-9px) rotate(-45deg);
}

/* ============================================
   9. 반응형 디자인
   ============================================ */

/* 태블릿 (1024px 이하) */
@media (max-width: 1024px) {
  :root {
    --header-height: 64px;
    --logo-size: 24px;
    --menu-size: 15px;
    --menu-gap: 32px;
  }

  .header-container {
    padding: 0 20px;
  }

  .nav-buttons {
    gap: 8px;
  }

  .nav-btn {
    padding: 10px 16px;
    font-size: 14px;
  }
}

/* 모바일 (768px 이하) */
@media (max-width: 768px) {
  :root {
    --header-height: 60px;
    --logo-size: 22px;
  }

  .header-container {
    grid-template-columns: auto 1fr;
    padding: 0 16px;
  }

  .mobile-menu-toggle {
    display: flex;
  }

  .navbar {
    position: fixed;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100vh;
    background: var(--header-bg);
    padding: 80px 20px 20px;
    transition: left var(--transition-slow);
    z-index: 9999;
    overflow-y: auto;
  }

  .navbar.mobile-open {
    left: 0;
  }

  .nav-container {
    flex-direction: column;
    gap: 0;
  }

  .nav-menu {
    flex-direction: column;
    gap: 0;
    width: 100%;
  }

  .nav-item {
    width: 100%;
    border-bottom: 1px solid var(--header-border);
  }

  .nav-link {
    width: 100%;
    padding: 16px 12px;
    font-size: 18px;
    display: flex;
    justify-content: space-between;
    align-items: center;
  }

  .nav-link::after {
    display: none;
  }

  .dropdown {
    position: static;
    transform: none;
    border: none;
    box-shadow: none;
    background: #f8f9fa;
    max-height: 0;
    overflow: hidden;
    transition: max-height var(--transition-normal), padding var(--transition-normal);
  }

  .nav-item.expanded .dropdown {
    max-height: 1000px;
    padding: 12px;
    opacity: 1;
    visibility: visible;
    pointer-events: auto;
  }

  .dropdown a {
    padding: 14px 20px;
    font-size: 16px;
  }

  .nav-buttons {
    flex-direction: column;
    width: 100%;
    gap: 12px;
    margin-top: 20px;
  }

  .nav-btn {
    width: 100%;
    padding: 16px;
    font-size: 16px;
    justify-content: center;
  }

  .dropdown-submenu {
    position: static;
    margin: 0;
    padding: 0;
    background: #e9ecef;
  }

  .dropdown-category.expanded .dropdown-submenu {
    max-height: 500px;
    padding: 8px 0;
  }

  .dropdown-submenu a {
    padding: 12px 32px;
    font-size: 15px;
  }
}

/* ============================================
   10. 접근성 및 포커스 스타일
   ============================================ */

.nav-link:focus-visible,
.nav-btn:focus-visible,
.dropdown a:focus-visible {
  outline: 2px solid var(--text-hover);
  outline-offset: 4px;
  border-radius: 4px;
}

/* 스크린 리더 전용 */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border-width: 0;
}

/* ============================================
   11. 다크 모드 지원 (선택적)
   ============================================ */

@media (prefers-color-scheme: dark) {
  :root {
    --header-bg: #1f2937;
    --header-border: #374151;
    --text-primary: #f3f4f6;
    --text-secondary: #9ca3af;
    --dropdown-bg: #1f2937;
    --dropdown-border: #374151;
    --btn-outline-border: #4b5563;
    --btn-outline-hover-bg: #374151;
  }

  .dropdown a:hover {
    background: #374151;
  }

  .mobile-menu-toggle span {
    background: var(--text-primary);
  }
}

/* ============================================
   12. 성능 최적화
   ============================================ */

/* GPU 가속 */
.nav-link,
.nav-btn,
.dropdown {
  will-change: transform, opacity;
}

/* 애니메이션 최소화 (사용자 설정) */
@media (prefers-reduced-motion: reduce) {
  * {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}