:root {
  --primary: #0036ce;
  --primary-dark: #0028a0;
  --secondary: #00b050;
  
  --c-humanities: #9262A4;
  --c-social: #4A89DC;
  --c-education: #3BAFDA;
  --c-engineering: #F6BB42;
  --c-natural: #8CC152;
  --c-medical: #E9573F;
  --c-arts: #D770AD;
  --c-convergence: #37BC9B;
  --c-etc: #AAB2BD;

  --text-base: #333;
  --text-muted: #666;
  --bg-white: #ffffff;
  --bg-gray: #f8f9fa;
  --border-light: #eee;
  
  --header-h: 100px;
}

* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  font-family: "Noto Sans KR", sans-serif;
  font-size: 15px;
  color: var(--text-base);
  background: var(--bg-white);
  line-height: 1.6;
}
a { color: inherit; text-decoration: none; }
ul { list-style: none; }
button { border: none; background: none; cursor: pointer; font-family: inherit; }
img, video { max-width: 100%; height: auto; display: block; }

.container { max-width: 1200px; margin: 0 auto; padding: 0 20px; }
.flex-between { display: flex; justify-content: space-between; align-items: center; }
.flex-start { display: flex; align-items: center; gap: 20px; }
.hidden { position: absolute; width: 1px; height: 1px; clip: rect(0,0,0,0); overflow: hidden; }

.skip-nav { position: absolute; top: -50px; left: 0; z-index: 9999; }
.skip-nav a:focus { top: 0; background: var(--primary); color: #fff; padding: 15px; }

.header {
  position: fixed; top: 0; left: 0; width: 100%; height: var(--header-h);
  background: #fff; border-bottom: 1px solid var(--border-light); z-index: 1000;
  display: flex; align-items: center;
}
.header .container { display: flex; align-items: center; justify-content: space-between; gap: 60px; }
.logo a { display: block; width: 160px; height: 35px; background: url(../images/header_logo.png) center/contain no-repeat; flex-shrink: 0; }
.gnb { display: flex; gap: 40px; flex: 1; justify-content: center; }
.gnb a { font-weight: 700; font-size: 17px; white-space: nowrap; }
.gnb a:hover { color: var(--primary); }
.util { display: flex; align-items: center; gap: 35px; flex-shrink: 0; }
.util a { font-weight: 500; padding: 5px 10px; }
.join-btn { background: var(--primary); color: #fff; padding: 10px 25px !important; border-radius: 4px; transition: 0.3s; }
.join-btn:hover { background: var(--primary-dark); }
.m-menu-btn { display: none; font-size: 28px; }

.main-content { padding-top: var(--header-h); }
.section { padding: 80px 0; }
.bg-light { background: var(--bg-gray); }
.bg-blue { background: #eef6ff; }
.title { font-size: 28px; font-weight: 700; text-align: center; margin-bottom: 50px; }
.title span { color: var(--primary); }

.notice-bar { background: #fff; border-bottom: 1px solid var(--border-light); padding: 15px 0; }
.label-box { display: flex; align-items: center; gap: 10px; font-weight: 700; color: #000; white-space: nowrap; }
.label-box img { width: 24px; }
.notice-slider { flex: 1; font-weight: 500; }

.search-section { padding: 50px 0; }
.search-box {
  background: url(../images/search_bg01.png) 10% center/auto 80% no-repeat var(--primary);
  border-radius: 20px; padding: 50px; color: #fff;
  display: flex; align-items: center; gap: 50px;
}
.search-box h2 { font-size: 32px; min-width: 180px; }
.form-wrapper { flex: 1; }
.input-group { display: flex; background: #fff; padding: 8px; border-radius: 10px; margin-bottom: 20px; }
.input-group input { flex: 1; border: none; padding: 12px 20px; font-size: 18px; outline: none; }
.search-submit { background: var(--primary); color: #fff; padding: 12px 30px; border-radius: 6px; font-weight: 700; }
.keywords { display: flex; gap: 20px; font-size: 14px; }

.card-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 30px; }
.card-grid-row { display: grid; grid-template-columns: repeat(3, 1fr); gap: 25px; }

.course-card {
  background: #fff; border-radius: 12px; overflow: hidden;
  box-shadow: 0 4px 15px rgba(0,0,0,0.05); border: 1px solid #eee; transition: 0.3s;
  flex-shrink: 0;
}
.course-card:hover { transform: translateY(-10px); box-shadow: 0 15px 30px rgba(0,0,0,0.1); }
.course-card .thumb { position: relative; aspect-ratio: 16/10; background: #f0f0f0; }
.badge { position: absolute; top: 12px; left: 12px; padding: 5px 10px; border-radius: 4px; font-size: 12px; color: #fff; font-weight: 700; }
.badge.active { background: var(--secondary); }
.course-card .info { padding: 25px; }
.course-card h3 { font-size: 17px; font-weight: 700; margin-bottom: 12px; height: 2.8em; overflow: hidden; line-height: 1.4; }
.course-card p { color: var(--text-muted); font-size: 14px; }

.course-item { display: flex; gap: 20px; background: #fff; padding: 20px; border-radius: 12px; border: 1px solid #eee; transition: 0.3s; }
.course-item:hover { border-color: var(--primary); box-shadow: 0 5px 15px rgba(0,0,0,0.05); }
.course-item .img { width: 120px; flex-shrink: 0; border-radius: 6px; overflow: hidden; }
.course-item h3 { font-size: 16px; margin-bottom: 8px; font-weight: 700; }
.course-item p { font-size: 13px; color: #888; }

.slider-wrapper { position: relative; width: 100%; padding: 0 60px; margin-top: 20px; }
.slider-container { width: 100%; overflow: hidden; border-radius: 12px; }
.slider-track { display: flex; gap: 30px; }

.slider-btn {
  position: absolute; top: 50%; transform: translateY(-50%);
  width: 50px; height: 50px; border-radius: 50%; background: #fff;
  box-shadow: 0 4px 15px rgba(0,0,0,0.1); font-weight: 700; z-index: 10;
  transition: 0.3s; font-size: 20px; display: flex; align-items: center; justify-content: center;
}
.slider-btn:hover { background: var(--primary); color: #fff; transform: translateY(-50%) scale(1.1); }
.slider-btn.prev { left: 0; }
.slider-btn.next { right: 0; }

.micro .course-card { flex: 0 0 calc(25% - 22.5px); }
.shorts-card { flex: 0 0 calc(25% - 22.5px); background: #fff; border-radius: 12px; overflow: hidden; box-shadow: 0 4px 15px rgba(0,0,0,0.05); border: 1px solid #eee; flex-shrink: 0; }
.shorts-card video { width: 100%; aspect-ratio: 9/16; background: #000; object-fit: cover; }
.shorts-card .info { padding: 20px; }
.shorts-card h3 { font-size: 16px; font-weight: 700; margin-bottom: 8px; height: 2.8em; overflow: hidden; }

.drag-container { overflow: hidden; cursor: grab; padding: 20px 0; }
.drag-track { display: flex; gap: 20px; width: max-content; margin: 0 auto; }
.cat-card {
  width: 140px; height: 160px; flex-shrink: 0;
  display: flex; flex-direction: column; align-items: center; justify-content: center;
  gap: 15px; background: #fff; border-radius: 12px; border: 2px solid transparent;
  box-shadow: 0 4px 10px rgba(0,0,0,0.05); transition: 0.3s;
}
.cat-card .icon { 
  width: 70px; height: 70px; border-radius: 50%; background: #f5f5f5; 
  display: flex; align-items: center; justify-content: center; 
  padding: 12px; overflow: hidden; 
}
.cat-card span { font-weight: 700; font-size: 16px; color: #444; }

.cat-card.humanities.active { background: var(--c-humanities); border-color: var(--c-humanities); }
.cat-card.social.active { background: var(--c-social); border-color: var(--c-social); }
.cat-card.education.active { background: var(--c-education); border-color: var(--c-education); }
.cat-card.engineering.active { background: var(--c-engineering); border-color: var(--c-engineering); }
.cat-card.natural.active { background: var(--c-natural); border-color: var(--c-natural); }
.cat-card.medical.active { background: var(--c-medical); border-color: var(--c-medical); }
.cat-card.arts.active { background: var(--c-arts); border-color: var(--c-arts); }
.cat-card.convergence.active { background: var(--c-convergence); border-color: var(--c-convergence); }
.cat-card.etc.active { background: var(--c-etc); border-color: var(--c-etc); }

.cat-card.active span { color: #fff; }
.cat-card.active .icon { background: rgba(255,255,255,0.2); }

.footer { background: #000; color: #fff; padding: 80px 0 50px; }
.f-top { border-bottom: 1px solid #333; padding-bottom: 30px; margin-bottom: 40px; display: flex; align-items: center; justify-content: space-between; }
.f-logo { font-size: 24px; font-weight: 800; color: var(--primary); }
.f-links { display: flex; gap: 30px; }
.f-links a { color: #aaa; font-size: 15px; }
.f-links a.privacy { color: #fff; font-weight: 700; }
.f-links a:hover { color: #fff; }

.f-sns { display: flex; gap: 15px; }
.sns-link {
  width: 40px; height: 40px; border-radius: 50%; background: #222;
  display: flex; align-items: center; justify-content: center;
  font-size: 12px; font-weight: 700; color: #fff; transition: 0.3s;
}
.sns-link:hover { background: var(--primary); }

.f-mid { display: flex; justify-content: space-between; align-items: flex-start; margin-bottom: 40px; }
.f-info p { color: #888; font-size: 14px; margin-bottom: 8px; }
.f-info strong { color: #fff; }
.f-partners { display: flex; gap: 20px; filter: grayscale(1) brightness(2); opacity: 0.5; }

.f-bottom { border-top: 1px solid #222; padding-top: 30px; }
.copy { color: #555; font-size: 13px; }

.popup-overlay { position: fixed; inset: 0; background: rgba(0,0,0,0.7); display: none; align-items: center; justify-content: center; z-index: 10000; backdrop-filter: blur(4px); }
.popup-overlay.show { display: flex; }
.popup-modal { background: #fff; padding: 40px; border-radius: 20px; width: 90%; max-width: 450px; position: relative; text-align: center; }
.popup-title { font-size: 24px; font-weight: 700; margin-bottom: 15px; color: #000; }
.popup-body p { color: #666; line-height: 1.5; font-size: 16px; }
.popup-btns { display: flex; gap: 15px; margin-top: 30px; }
.popup-btns button { flex: 1; padding: 15px; border-radius: 10px; font-weight: 700; font-size: 16px; }
.btn-main { background: var(--primary); color: #fff; }
.btn-sub { background: #f5f5f5; color: #666; }
.popup-close { position: absolute; top: 20px; right: 20px; font-size: 30px; color: #999; }

.to-top-btn {
  position: fixed; bottom: 40px; right: 40px; width: 60px; height: 60px;
  background: var(--primary); color: #fff; border-radius: 50%;
  display: none; justify-content: center; align-items: center; z-index: 1000;
  box-shadow: 0 5px 20px rgba(0,54,206,0.3); font-size: 24px;
}
.to-top-btn.show { display: flex; }

@media (max-width: 1024px) {
  .card-grid { grid-template-columns: repeat(2, 1fr); }
  .card-grid-row { grid-template-columns: repeat(2, 1fr); }
  .micro .course-card, .shorts-card { flex: 0 0 calc(50% - 15px); }
}
@media (max-width: 768px) {
  .header { height: 80px; }
  .logo a { width: 130px; }
  .gnb, .util a { display: none; }
  .m-menu-btn { display: block; }
  .card-grid, .card-grid-row { grid-template-columns: 1fr; }
  .micro .course-card, .shorts-card { flex: 0 0 100%; }
  .f-mid { flex-direction: column; gap: 30px; }
}