:root {
  --ink: #182433;
  --muted: #718092;
  --navy: #06436e;
  --navy-deep: #082c4c;
  --teal: #2ccac0;
  --sky: #edf7ff;
  --sky-deep: #d8effb;
  --line: #dbe6ee;
  --white: #fff;
  --page: min(1240px, calc(100% - 64px));
  --shadow: 0 18px 48px rgba(8, 44, 76, 0.09);
  --shadow-soft: 0 10px 28px rgba(8, 44, 76, 0.07);
  font-family: "Noto Sans SC", "PingFang SC", "Microsoft YaHei", system-ui, sans-serif;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  color: var(--ink);
  background: linear-gradient(180deg, #f2f9ff 0, #fbfdff 35%, #fff 100%);
}
button, input { font: inherit; }
button, a { -webkit-tap-highlight-color: transparent; }
button { cursor: pointer; border: 0; }
a { color: inherit; text-decoration: none; }

.site-header {
  height: 78px;
  border-bottom: 1px solid rgba(219, 230, 238, .8);
  background: rgba(255,255,255,.88);
  backdrop-filter: blur(18px);
  position: sticky;
  top: 0;
  z-index: 20;
}
.header-inner { width: var(--page); height: 100%; margin: auto; display: flex; align-items: center; justify-content: space-between; gap: 32px; }
.brand { display: inline-flex; align-items: center; gap: 11px; min-width: 260px; }
.brand-mark { width: 34px; height: 34px; border-radius: 11px; display: grid; place-items: center; background: var(--navy); color: var(--white); font-family: Georgia, serif; font-size: 22px; font-weight: 700; box-shadow: 4px 5px 0 rgba(44,202,192,.35); }
.brand strong { display: block; font-size: 17px; line-height: 20px; letter-spacing: .08em; }
.brand small { display: block; margin-top: 2px; color: var(--muted); font-size: 8px; letter-spacing: .18em; }
.site-nav { display: flex; align-items: center; gap: 38px; color: var(--muted); font-size: 14px; }
.site-nav a { height: 78px; display: inline-flex; align-items: center; position: relative; }
.site-nav a.active, .site-nav a:hover { color: var(--navy); font-weight: 700; }
.site-nav a.active::after { content: ""; position: absolute; left: 50%; bottom: 0; width: 22px; height: 3px; border-radius: 9px 9px 0 0; background: var(--teal); transform: translateX(-50%); }
.header-actions { min-width: 260px; display: flex; align-items: center; justify-content: flex-end; gap: 16px; }
.header-link, .header-profile { background: transparent; color: var(--muted); font-size: 13px; }
.header-profile { min-height: 38px; padding: 0 17px; border: 1px solid var(--line); border-radius: 999px; color: var(--navy); background: var(--white); font-weight: 700; }

main { overflow-x: hidden; }
.hero-wrap { width: var(--page); margin: 0 auto; padding: 64px 0 46px; display: grid; grid-template-columns: minmax(500px, .9fr) minmax(0, 1.6fr); gap: 44px; align-items: center; }
.hero-copy { padding: 20px 0 10px; }
.eyebrow { margin: 0 0 14px; color: var(--teal); font-size: 11px; font-weight: 800; letter-spacing: .22em; }
.hero-copy h1 { margin: 0; color: var(--navy-deep); font-size: clamp(22px, 1.8vw, 28px); line-height: 1.5; letter-spacing: -.06em; }
.hero-copy h1 em { color: var(--navy); font-style: normal; }
.hero-desc { max-width: 340px; margin: 22px 0 30px; color: var(--muted); font-size: 14px; line-height: 1.9; }
.hero-cta { display: inline-flex; align-items: center; gap: 15px; padding: 13px 19px; border-radius: 999px; color: var(--white); background: var(--navy); box-shadow: 0 8px 20px rgba(6,67,110,.2); font-size: 13px; font-weight: 700; transition: transform .2s, background .2s; }
.hero-cta:hover { background: var(--navy-deep); transform: translateY(-2px); }
.hero-slider { min-width: 0; }
.hero-track { display: grid; overflow: hidden; border-radius: 22px; box-shadow: var(--shadow); background: var(--navy); }
.hero-slide { grid-area: 1 / 1; opacity: 0; pointer-events: none; transform: scale(1.025); transition: opacity .55s ease, transform .75s ease; }
.hero-slide.active { opacity: 1; pointer-events: auto; transform: scale(1); }
.hero-slide button, .hero-slide img { display: block; width: 100%; }
.hero-slide button { padding: 0; background: none; }
.hero-slide img { aspect-ratio: 2.25 / 1; object-fit: cover; }
.slider-controls { height: 38px; display: flex; align-items: center; justify-content: center; gap: 18px; }
.slider-arrow { width: 28px; height: 28px; border-radius: 50%; color: var(--navy); background: transparent; font-size: 18px; transition: background .2s; }
.slider-arrow:hover { background: var(--sky-deep); }
.slider-dots { display: flex; align-items: center; gap: 7px; }
.slider-dots button { width: 7px; height: 7px; padding: 0; border-radius: 50%; background: #ccd7e0; transition: width .2s, border-radius .2s, background .2s; }
.slider-dots button.active { width: 22px; border-radius: 10px; background: var(--navy); }

.content-section { width: var(--page); margin: 0 auto; padding: 43px 0 35px; }
.courses-section { position: sticky; top: 0; z-index: 3; height: 100vh; min-height: 680px; overflow: hidden; padding-top: 60px; background: linear-gradient(180deg, #fbfdff 0, #fff 100%); }
.section-heading { display: flex; align-items: flex-end; justify-content: space-between; gap: 24px; margin-bottom: 24px; }
.section-heading .eyebrow { margin-bottom: 7px; }
.section-heading h2 { margin: 0; color: var(--navy-deep); font-size: 31px; line-height: 1.2; letter-spacing: -.04em; }
.section-link { padding: 0; background: transparent; color: var(--navy); font-size: 13px; font-weight: 700; }
.section-link span { margin-left: 7px; color: var(--teal); font-size: 20px; vertical-align: -2px; }
.section-note { margin: 0 0 4px; color: var(--muted); font-size: 13px; }

.mentor-grid { display: grid; grid-template-columns: repeat(5, minmax(0, 1fr)); gap: 16px; }
.mentor-card { min-width: 0; padding: 22px 18px 18px; border: 1px solid transparent; border-radius: 22px; background: var(--white); box-shadow: var(--shadow-soft); text-align: center; transition: transform .22s, border-color .22s, box-shadow .22s; }
.mentor-card:hover { border-color: var(--sky-deep); box-shadow: var(--shadow); transform: translateY(-5px); }
.mentor-avatar { width: 94px; height: 94px; margin: 0 auto 15px; display: block; border-radius: 50%; object-fit: cover; object-position: center; background: var(--sky); }
.mentor-card h3 { margin: 0; color: var(--navy-deep); font-size: 18px; line-height: 25px; }
.mentor-rating { margin: 3px 0 13px; color: var(--muted); font-size: 12px; }
.mentor-rating b { color: #eab14a; font-size: 13px; }
.mentor-course-count { display: inline-flex; min-height: 31px; padding: 0 13px; align-items: center; border-radius: 999px; color: var(--navy); background: #ddf5ff; font-size: 12px; font-weight: 800; }

.courses-layout { display: grid; grid-template-columns: 232px minmax(0, 1fr); gap: 27px; align-items: start; }
.filter-panel { position: sticky; top: 0; height: calc(100vh - 154px); overflow-y: auto; padding: 16px 12px; border: 1px solid var(--line); border-radius: 18px; background: rgba(247, 251, 254, .86); }
.filter-panel-title { padding: 0 10px 12px; color: var(--navy-deep); font-size: 14px; font-weight: 800; }
.category-list { display: grid; gap: 4px; }
.category-list button { width: 100%; min-height: 31px; padding: 0 10px; border: 0; border-radius: 8px; color: var(--muted); background: transparent; text-align: left; font-size: 11px; line-height: 1.35; transition: .2s; }
.category-list button:hover { color: var(--navy); background: #e9f6fb; }
.category-list button.active { color: var(--white); background: var(--navy); font-weight: 800; }
.course-results { min-width: 0; height: calc(100vh - 154px); overflow-y: auto; padding-right: 10px; scrollbar-width: thin; scrollbar-color: #cbdde7 transparent; }
.filter-result-label { color: var(--navy-deep); font-size: 14px; font-weight: 800; }
.course-toolbar { position: sticky; top: 0; z-index: 2; display: flex; align-items: center; justify-content: space-between; gap: 20px; margin: 0 0 25px; padding: 2px 0 14px; background: #fbfdff; }
.search-box { width: 255px; height: 38px; display: flex; align-items: center; gap: 9px; padding: 0 14px; border: 1px solid var(--line); border-radius: 999px; background: var(--white); }
.search-box span { color: var(--navy); font-size: 22px; line-height: 1; transform: rotate(-20deg); }
.search-box input { min-width: 0; width: 100%; border: 0; outline: 0; color: var(--ink); background: transparent; font-size: 12px; }
.search-box input::placeholder { color: #a4b1bd; }
.course-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 19px; }
.course-card { min-width: 0; overflow: hidden; border: 1px solid #edf1f4; border-radius: 20px; background: var(--white); box-shadow: var(--shadow-soft); transition: transform .22s, box-shadow .22s; }
.course-card:hover { box-shadow: var(--shadow); transform: translateY(-5px); }
.course-card-cover { position: relative; overflow: hidden; background: var(--sky); }
.course-card-cover img { width: 100%; aspect-ratio: 1.7 / 1; display: block; object-fit: cover; transition: transform .4s; }
.course-card:hover .course-card-cover img { transform: scale(1.04); }
.course-type { position: absolute; left: 12px; top: 12px; padding: 5px 9px; border-radius: 999px; color: var(--navy); background: rgba(255,255,255,.88); font-size: 10px; font-weight: 800; }
.course-card-body { padding: 16px 16px 17px; }
.course-card h3 { height: 24px; overflow: hidden; margin: 0 0 6px; color: var(--navy-deep); font-size: 16px; line-height: 24px; white-space: nowrap; text-overflow: ellipsis; }
.course-card p { height: 40px; overflow: hidden; margin: 0 0 15px; color: var(--muted); font-size: 12px; line-height: 20px; }
.course-bottom { display: flex; align-items: center; justify-content: space-between; gap: 8px; }
.unlimited-tag { display: inline-flex; min-height: 24px; align-items: center; padding: 0 9px; border-radius: 999px; color: var(--navy); background: #ddf5ff; font-size: 11px; font-weight: 800; white-space: nowrap; }
.rating { color: var(--muted); font-size: 11px; white-space: nowrap; }
.course-open { display: inline-flex; align-items: center; justify-content: center; width: 100%; height: 34px; margin-top: 14px; border-radius: 999px; color: var(--navy); background: #e5f7fc; font-size: 12px; font-weight: 800; transition: background .2s; }
.course-open:hover { background: #c9eef7; }
.empty-state { padding: 70px 20px; color: var(--muted); text-align: center; font-size: 14px; }

.site-footer { margin-top: 35px; padding: 34px max(32px, calc((100% - 1240px) / 2)) 38px; display: flex; align-items: flex-end; justify-content: space-between; gap: 20px; color: var(--muted); border-top: 1px solid var(--line); background: #f7fbfe; }
.site-footer strong { display: block; margin-bottom: 6px; color: var(--navy); font-size: 16px; }
.site-footer span { font-size: 12px; }
.site-footer small { font-size: 11px; }

.modal-backdrop { position: fixed; inset: 0; z-index: 50; display: grid; place-items: center; padding: 24px; background: rgba(7, 31, 52, .52); backdrop-filter: blur(7px); }
.modal-backdrop[hidden] { display: none; }
.course-modal { position: relative; width: min(900px, 100%); max-height: calc(100vh - 48px); overflow-y: auto; display: block; border-radius: 25px; background: var(--white); box-shadow: 0 28px 80px rgba(7,31,52,.25); animation: modal-in .25s ease-out; }
@keyframes modal-in { from { opacity: 0; transform: translateY(12px) scale(.98); } to { opacity: 1; transform: none; } }
.modal-close { position: absolute; z-index: 2; top: 13px; right: 15px; width: 32px; height: 32px; border-radius: 50%; color: var(--navy); background: rgba(255,255,255,.85); font-size: 22px; line-height: 1; }
.modal-video { padding: 22px 22px 0; background: #f5fbff; }
.modal-video video { width: 100%; aspect-ratio: 16 / 9; display: block; border-radius: 16px; background: #082c4c; object-fit: cover; }
.modal-video p { margin: 10px 0 0; color: var(--muted); font-size: 12px; }
.modal-content { padding: 26px 39px 36px; }
.modal-meta { display: flex; gap: 13px; margin-bottom: 17px; color: var(--teal); font-size: 11px; font-weight: 800; }
.modal-meta span + span { color: #d09c39; }
.modal-content h2 { margin: 0 0 13px; color: var(--navy-deep); font-size: 28px; line-height: 1.35; letter-spacing: -.04em; }
.modal-content p { margin: 0; color: var(--muted); font-size: 13px; line-height: 1.9; }
.modal-facts { display: flex; flex-wrap: wrap; gap: 8px; margin: 22px 0 30px; }
.modal-facts span { padding: 7px 10px; border-radius: 8px; color: var(--navy); background: var(--sky); font-size: 11px; }
.detail-block { margin-top: 26px; }
.detail-block-heading { display: flex; align-items: baseline; justify-content: space-between; gap: 12px; margin-bottom: 11px; }
.detail-block-heading h3 { margin: 0; color: var(--navy-deep); font-size: 15px; }
.detail-block-heading span { color: var(--muted); font-size: 11px; }
.chapter-list { display: grid; gap: 8px; }
.chapter-item { width: 100%; min-height: 42px; padding: 0 12px; display: flex; align-items: center; justify-content: space-between; gap: 12px; border: 1px solid #edf1f4; border-radius: 10px; color: var(--navy-deep); background: #fbfdff; text-align: left; font-size: 12px; }
.chapter-item b { display: inline-block; width: 23px; color: var(--muted); font-size: 10px; }
.chapter-item em { flex: 0 0 auto; color: var(--muted); font-size: 10px; font-style: normal; }
.chapter-item.active { border-color: #9bdce6; color: var(--navy); background: #e9f9fc; }
.chapter-item.active em { color: var(--navy); font-weight: 800; }
.comment-list { display: grid; gap: 10px; }
.comment-item { display: grid; grid-template-columns: 28px 1fr; gap: 9px; align-items: start; padding: 10px 0; border-bottom: 1px solid #edf1f4; }
.comment-item:last-child { border-bottom: 0; }
.comment-avatar { width: 28px; height: 28px; display: grid; place-items: center; border-radius: 50%; color: var(--white); background: var(--navy); font-size: 11px; font-weight: 800; }
.comment-item strong { display: block; color: var(--navy-deep); font-size: 12px; }
.comment-item p { margin: 4px 0 0; color: var(--muted); font-size: 11px; line-height: 1.7; }
.modal-actions { display: flex; gap: 10px; }
.primary-btn, .secondary-btn { min-height: 42px; padding: 0 17px; border-radius: 999px; font-size: 12px; font-weight: 800; }
.primary-btn { flex: 1; color: var(--white); background: var(--navy); }
.primary-btn span { margin-left: 5px; color: #a5f2ea; }
.secondary-btn { color: var(--navy); background: var(--sky); }
.toast { position: fixed; z-index: 70; left: 50%; bottom: 30px; padding: 10px 17px; border-radius: 999px; color: var(--white); background: var(--navy-deep); box-shadow: var(--shadow); font-size: 12px; opacity: 0; pointer-events: none; transform: translate(-50%, 12px); transition: opacity .2s, transform .2s; }
.toast.show { opacity: 1; transform: translate(-50%, 0); }

@media (max-width: 1000px) {
  :root { --page: min(100% - 40px, 760px); }
  .hero-wrap { grid-template-columns: 1fr; gap: 26px; padding-top: 42px; }
  .hero-copy { max-width: 680px; display: grid; grid-template-columns: 1fr 1.5fr; gap: 16px 30px; align-items: end; }
  .hero-copy .eyebrow, .hero-copy h1 { grid-column: 1 / -1; }
  .hero-copy .eyebrow { margin-bottom: 0; }
  .hero-desc { margin: 0; }
  .hero-cta { justify-self: start; }
  .mentor-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .courses-section { position: static; height: auto; min-height: 0; overflow: visible; }
  .courses-layout { grid-template-columns: 1fr; gap: 22px; }
  .filter-panel { position: static; height: auto; overflow: visible; }
  .category-list { display: flex; flex-wrap: nowrap; overflow-x: auto; padding-bottom: 3px; }
  .category-list button { width: auto; flex: 0 0 auto; padding: 0 12px; white-space: nowrap; }
  .course-results { height: auto; overflow: visible; padding-right: 0; }
  .course-toolbar { position: static; }
  .course-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}
@media (max-width: 640px) {
  :root { --page: calc(100% - 32px); }
  .site-header { height: 64px; }
  .header-inner { gap: 14px; }
  .brand { min-width: 0; }
  .brand-mark { width: 30px; height: 30px; font-size: 19px; }
  .brand small, .site-nav, .header-link { display: none; }
  .brand strong { font-size: 15px; }
  .header-actions { min-width: 0; }
  .header-profile { min-height: 32px; padding: 0 12px; font-size: 12px; }
  .hero-wrap { padding: 34px 0 20px; }
  .hero-copy { display: block; }
  .hero-copy h1 { font-size: 19px; line-height: 1.45; letter-spacing: -.08em; }
  .hero-desc { margin: 16px 0 20px; font-size: 13px; }
  .hero-slide img { aspect-ratio: 1.9 / 1; }
  .content-section, .courses-section { padding-top: 33px; }
  .section-heading { align-items: flex-start; margin-bottom: 18px; }
  .section-heading h2 { font-size: 26px; }
  .section-note { display: none; }
  .mentor-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 11px; }
  .mentor-card { padding: 16px 10px 14px; border-radius: 18px; }
  .mentor-avatar { width: 75px; height: 75px; margin-bottom: 10px; }
  .mentor-card h3 { font-size: 16px; }
  .mentor-course-count { padding: 0 9px; font-size: 10px; }
  .filter-panel { padding: 12px 9px 8px; border-radius: 15px; }
  .filter-panel-title { padding-bottom: 8px; }
  .category-list { padding-bottom: 6px; }
  .search-box { width: 100%; }
  .course-grid { gap: 11px; }
  .course-card { border-radius: 16px; }
  .course-card-body { padding: 12px; }
  .course-card h3 { font-size: 14px; }
  .course-card p { font-size: 11px; line-height: 18px; }
  .site-footer { display: block; padding: 28px 16px; }
  .site-footer small { display: block; margin-top: 20px; }
  .course-modal { display: block; max-height: calc(100vh - 32px); overflow-y: auto; }
  .modal-video { padding: 16px 16px 0; }
  .modal-content { padding: 22px 20px 28px; }
  .modal-content h2 { font-size: 23px; }
}