:root {
  --brand: #4d5bc4;
  --brand-deep: #3545a8;
  --brand-soft: #edf0ff;
  --accent: #1d9bff;
  --page: #f3f5f8;
  --surface: #fff;
  --text: #1c2940;
  --muted: #718096;
  --line: #e1e6ef;
  --shadow: 0 10px 28px rgba(49, 66, 122, .08);
  --radius: 5px;
}

* { box-sizing: border-box; }
html, body { min-height: 100%; margin: 0; }
body { color: var(--text); background: var(--page); font-family: "Microsoft YaHei", "PingFang SC", Arial, sans-serif; font-size: 14px; }
button, input { font: inherit; }
button { cursor: pointer; }

.app-shell { min-height: 100vh; padding-top: 76px; }
.topbar { position: fixed; inset: 0 0 auto; z-index: 10; height: 76px; display: flex; align-items: center; justify-content: space-between; padding: 0 28px 0 24px; color: #fff; background: var(--brand); overflow: hidden; }
.topbar::after { content: ""; position: absolute; inset: 0; pointer-events: none; opacity: .16; background: linear-gradient(116deg, transparent 8%, #a6baff 8% 17%, transparent 17% 36%, #8ca6ff 36% 50%, transparent 50%); }
.brand-lockup, .topbar-actions { position: relative; z-index: 1; display: flex; align-items: center; }
.brand-lockup { gap: 12px; }
.brand-mark { width: 37px; height: 37px; display: grid; place-items: center; border: 1px solid rgba(255,255,255,.7); border-radius: 50%; font-weight: 700; letter-spacing: 0; }
.brand-lockup h1 { margin: 0; font-size: 19px; line-height: 24px; }
.brand-lockup p { margin: 1px 0 0; color: rgba(255,255,255,.74); font-size: 11px; }
.topbar-actions { gap: 8px; }
.top-action, .icon-button { border: 1px solid rgba(255,255,255,.38); border-radius: 4px; color: #fff; background: rgba(30, 42, 131, .25); }
.top-action { height: 34px; padding: 0 12px; }
.top-action span { margin-right: 6px; }
.top-action.primary { background: rgba(255,255,255,.14); }
.icon-button { width: 34px; height: 34px; font-size: 20px; }
.top-action:hover, .icon-button:hover { background: rgba(255,255,255,.22); }

.sidebar { position: fixed; top: 96px; bottom: 20px; left: 20px; z-index: 9; width: 236px; display: flex; flex-direction: column; overflow: hidden; border-radius: 5px; color: #fff; background: var(--brand); box-shadow: 0 8px 18px rgba(49, 66, 122, .16); }
.profile-block { min-height: 206px; display: flex; align-items: center; flex-direction: column; justify-content: center; border-bottom: 1px solid rgba(255,255,255,.32); }
.avatar { display: grid; place-items: center; border-radius: 50%; color: #fff; background: #8d99dc; font-weight: 700; }
.avatar-large { width: 58px; height: 58px; margin-bottom: 14px; font-size: 21px; }
.profile-block strong { font-size: 16px; }
.profile-block span { margin-top: 6px; color: rgba(255,255,255,.68); font-size: 11px; }
.side-nav { padding: 10px 0; }
.nav-item { width: 100%; min-height: 49px; display: flex; align-items: center; gap: 14px; padding: 0 20px; border: 0; color: rgba(255,255,255,.87); background: transparent; text-align: left; }
.nav-item span { width: 20px; color: #fff; font-size: 20px; text-align: center; }
.nav-item:hover, .nav-item.active { color: #fff; background: rgba(255,255,255,.14); }
.nav-item.active { border-left: 3px solid #fff; padding-left: 17px; }
.sidebar-footer { display: flex; align-items: center; justify-content: space-between; margin-top: auto; padding: 14px 16px 16px 20px; border-top: 1px solid rgba(255,255,255,.22); color: rgba(255,255,255,.68); font-size: 11px; }
.collapse-button { border: 0; color: #fff; background: transparent; font-size: 25px; line-height: 1; }

.main-content { max-width: 1440px; margin-left: 276px; padding: 48px 40px 48px 14px; }
.welcome-row { display: flex; align-items: end; justify-content: space-between; gap: 32px; margin-bottom: 25px; }
.breadcrumb { margin: 0 0 8px; color: var(--muted); font-size: 12px; }
.welcome-row h2 { margin: 0; font-size: 27px; font-weight: 600; line-height: 34px; }
.section-note { margin: 6px 0 0; color: var(--muted); }
.search-box { width: min(470px, 42vw); height: 42px; display: flex; align-items: center; border: 1px solid var(--line); border-radius: 4px; background: var(--surface); box-shadow: var(--shadow); }
.search-box > span { padding-left: 13px; color: var(--brand); font-size: 22px; }
.search-box input { min-width: 0; flex: 1; height: 100%; padding: 0 10px; border: 0; outline: 0; color: var(--text); background: transparent; }
.search-box button { height: 100%; padding: 0 18px; border: 0; border-left: 1px solid var(--line); color: var(--brand-deep); background: var(--brand-soft); }
.category-strip { display: grid; grid-template-columns: repeat(6, minmax(0, 1fr)); min-height: 79px; border: 1px solid var(--line); border-radius: 4px; background: var(--surface); box-shadow: var(--shadow); }
.category-item { position: relative; padding: 13px 16px; border: 0; border-right: 1px solid var(--line); color: var(--text); background: transparent; text-align: left; }
.category-item:last-child { border-right: 0; }
.category-item strong, .category-item span { display: block; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.category-item strong { font-size: 15px; font-weight: 600; }
.category-item span { margin-top: 6px; color: var(--muted); font-size: 12px; }
.category-item:hover, .category-item.active { background: var(--brand-soft); }
.category-item.active::after { position: absolute; right: 16px; bottom: 0; left: 16px; height: 3px; content: ""; background: var(--accent); }

.content-grid { display: grid; grid-template-columns: minmax(0, 1fr) 332px; gap: 18px; margin-top: 18px; }
.content-panel, .rail-panel, .purchase-bar { border: 1px solid var(--line); border-radius: var(--radius); background: var(--surface); box-shadow: var(--shadow); }
.content-panel { min-width: 0; padding: 21px 22px 20px; }
.section-heading { display: flex; align-items: center; justify-content: space-between; gap: 16px; margin-bottom: 16px; }
.section-heading > div { display: flex; align-items: center; gap: 9px; }
.section-heading h3 { margin: 0; font-size: 18px; font-weight: 600; }
.section-dot { width: 9px; height: 9px; border-radius: 50%; background: var(--accent); }
.text-button { padding: 2px 0; border: 0; color: var(--brand-deep); background: transparent; }
.text-button:hover { color: var(--accent); }
.course-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 16px; }
.course-card { min-width: 0; overflow: hidden; border: 1px solid var(--line); border-radius: 4px; background: #fff; transition: transform .18s ease, box-shadow .18s ease, border-color .18s ease; }
.course-card:hover { transform: translateY(-2px); border-color: #a9b7ed; box-shadow: 0 10px 24px rgba(69, 83, 166, .15); }
.cover { aspect-ratio: 16 / 9; display: grid; place-items: center; padding: 20px; color: #fff; background: var(--cover, #6974c9); text-align: center; }
.cover span { max-width: 80%; font-family: Georgia, serif; font-size: clamp(17px, 1.4vw, 23px); line-height: 1.3; text-shadow: 0 2px 8px rgba(0,0,0,.24); }
.cover.blue { --cover: linear-gradient(135deg, #7ea5c9, #dde8ee); color: #173962; }
.cover.sky { --cover: linear-gradient(135deg, #7ec4e8, #d8f1f7); color: #12658d; }
.cover.orange { --cover: linear-gradient(135deg, #d7a15c, #6f5443); }
.cover.green { --cover: linear-gradient(135deg, #579c8c, #153e49); }
.cover.purple { --cover: linear-gradient(135deg, #909ee0, #4759a6); }
.cover.dark { --cover: linear-gradient(135deg, #1d3555, #4c73a3); }
.course-info { min-height: 105px; padding: 12px; }
.course-info h4 { margin: 0; overflow: hidden; font-size: 15px; font-weight: 600; text-overflow: ellipsis; white-space: nowrap; }
.course-info p { margin: 8px 0 0; overflow: hidden; color: var(--muted); font-size: 12px; text-overflow: ellipsis; white-space: nowrap; }
.course-meta { display: flex; justify-content: space-between; margin-top: 10px; color: var(--muted); font-size: 11px; }
.feature-row { display: grid; grid-template-columns: auto 1fr auto 1fr auto 1fr; align-items: center; gap: 9px 10px; margin-top: 22px; padding: 16px 6px 1px; border-top: 1px solid var(--line); }
.feature-icon { width: 28px; height: 28px; display: grid; place-items: center; border-radius: 50%; color: var(--brand); background: var(--brand-soft); font-weight: 700; }
.feature-row strong, .feature-row span { display: block; }
.feature-row strong { font-size: 13px; }
.feature-row span { margin-top: 3px; color: var(--muted); font-size: 11px; }
.right-rail { display: grid; align-content: start; gap: 18px; }
.purchase-bar { min-height: 55px; display: grid; grid-template-columns: 25px 1fr auto 18px; align-items: center; gap: 9px; padding: 0 16px; border: 0; color: #fff; background: var(--brand); text-align: left; }
.purchase-bar:hover { background: var(--brand-deep); }
.purchase-icon { font-size: 21px; }
.rail-panel { padding: 18px 16px; }
.compact { margin-bottom: 14px; }
.compact h3 { font-size: 16px; }
.recommend-item { position: relative; display: grid; grid-template-columns: 62px 1fr auto; gap: 9px; align-items: start; min-height: 77px; padding: 10px 0; border-bottom: 1px solid var(--line); }
.recommend-item:last-child { border-bottom: 0; padding-bottom: 0; }
.recommend-cover { width: 62px; height: 48px; display: grid; place-items: center; border-radius: 3px; color: #fff; background: #6d7dcb; font-size: 11px; }
.recommend-item strong { display: block; overflow: hidden; font-size: 13px; text-overflow: ellipsis; white-space: nowrap; }
.recommend-item p { margin: 5px 0 0; overflow: hidden; color: var(--muted); font-size: 11px; text-overflow: ellipsis; white-space: nowrap; }
.recommend-item em { color: #f19727; font-size: 12px; font-style: normal; }
.topic-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 8px; }
.topic-card { min-height: 68px; padding: 10px; border: 1px solid #d4daf5; border-radius: 4px; color: var(--brand-deep); background: var(--brand-soft); text-align: left; }
.topic-card:nth-child(2n) { color: #126c76; border-color: #c5e6e5; background: #effafa; }
.topic-card:hover { border-color: var(--accent); }
.topic-card strong, .topic-card span { display: block; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.topic-card strong { font-size: 13px; }
.topic-card span { margin-top: 5px; color: var(--muted); font-size: 11px; }

.toast { position: fixed; right: 26px; bottom: 24px; z-index: 30; padding: 11px 15px; border: 1px solid #cbd4f4; border-radius: 4px; color: var(--brand-deep); background: #fff; box-shadow: var(--shadow); opacity: 0; transform: translateY(8px); pointer-events: none; transition: .2s ease; }
.toast.show { opacity: 1; transform: translateY(0); }
.modal { width: min(420px, calc(100vw - 32px)); padding: 30px; border: 1px solid var(--line); border-radius: 6px; color: var(--text); box-shadow: 0 22px 60px rgba(20,30,70,.2); }
.modal::backdrop { background: rgba(23, 34, 81, .38); }
.modal-close { position: absolute; top: 10px; right: 12px; border: 0; color: var(--muted); background: transparent; font-size: 24px; }
.modal h2 { margin: 0 0 8px; font-size: 22px; }
.modal p { margin: 0; color: var(--muted); line-height: 1.7; }
.modal .modal-action { margin-top: 22px; padding: 10px 16px; border: 0; border-radius: 4px; color: #fff; background: var(--brand); }

@media (max-width: 1100px) {
  .sidebar { width: 206px; }
  .main-content { margin-left: 246px; padding-right: 24px; }
  .content-grid { grid-template-columns: minmax(0, 1fr); }
  .right-rail { grid-template-columns: repeat(3, minmax(0, 1fr)); align-items: start; }
  .purchase-bar { min-height: 100%; }
}
@media (max-width: 760px) {
  .app-shell { padding-top: 64px; }
  .topbar { height: 64px; padding: 0 14px; }
  .brand-mark { width: 31px; height: 31px; font-size: 12px; }
  .brand-lockup h1 { font-size: 16px; }
  .brand-lockup p, .top-action span, .top-action:not(.primary) { display: none; }
  .top-action { padding: 0 10px; }
  .sidebar { top: 64px; bottom: 0; left: 0; width: 68px; border-radius: 0; }
  .profile-block { min-height: 110px; }
  .avatar-large { width: 38px; height: 38px; margin-bottom: 7px; font-size: 15px; }
  .profile-block strong { font-size: 11px; }
  .profile-block span, .nav-item:not(.active)::after, .sidebar-footer span { display: none; }
  .nav-item { min-height: 54px; justify-content: center; padding: 0; font-size: 0; }
  .nav-item span { font-size: 20px; }
  .nav-item.active { padding-left: 0; border-left: 0; border-right: 3px solid #fff; }
  .collapse-button { display: none; }
  .main-content { margin-left: 68px; padding: 26px 14px 30px; }
  .welcome-row { display: block; }
  .welcome-row h2 { font-size: 22px; }
  .search-box { width: 100%; margin-top: 18px; }
  .category-strip { grid-template-columns: repeat(3, 1fr); }
  .category-item { padding: 11px 9px; }
  .category-item strong { font-size: 12px; }
  .category-item span { font-size: 10px; }
  .category-item:nth-child(-n+3) { border-bottom: 1px solid var(--line); }
  .category-item:nth-child(3) { border-right: 0; }
  .course-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 10px; }
  .content-panel { padding: 16px 12px; }
  .feature-row { grid-template-columns: auto 1fr; }
  .right-rail { grid-template-columns: 1fr; }
}
@media (max-width: 440px) {
  .course-grid { grid-template-columns: 1fr; }
  .course-card { display: grid; grid-template-columns: 42% 1fr; }
  .course-info { min-height: 0; }
  .cover { aspect-ratio: 1 / 1; }
  .cover span { font-size: 16px; }
}

/* Preserved first-pass version: blue-violet study-workbench styling. */
:root { --brand: #4d5bc4; --brand-deep: #3545a8; --brand-soft: #edf0ff; --accent: #1d9bff; --page: #f3f5f8; --surface: #fff; --text: #1c2940; --muted: #718096; --line: #e1e6ef; --shadow: 0 10px 28px rgba(49, 66, 122, .08); --radius: 5px; }
.topbar { height: 76px; padding: 0 28px 0 24px; background: var(--brand); }
.topbar::after { opacity: .16; background: linear-gradient(116deg, transparent 8%, #a6baff 8% 17%, transparent 17% 36%, #8ca6ff 36% 50%, transparent 50%); }
.brand-mark { width: 37px; height: 37px; border: 1px solid rgba(255,255,255,.7); border-radius: 50%; }
.brand-lockup h1 { font-size: 19px; }
.brand-lockup p { color: rgba(255,255,255,.74); }
.top-action, .icon-button { border-radius: 4px; background: rgba(30, 42, 131, .25); }
.top-action.primary { background: rgba(255,255,255,.14); }
.icon-button { border-radius: 4px; }
.sidebar { top: 96px; bottom: 20px; left: 20px; width: 236px; border-radius: 5px; background: var(--brand); }
.profile-block { min-height: 206px; }
.avatar-large { width: 58px; height: 58px; border-radius: 50%; background: #8d99dc; }
.profile-block span { display: block; }
.side-nav { padding: 10px 0; }
.nav-item { min-height: 49px; flex-direction: row; justify-content: flex-start; gap: 14px; padding: 0 20px; border-radius: 0; color: rgba(255,255,255,.87); font-size: 14px; text-align: left; }
.nav-item span { width: 20px; color: #fff; font-size: 20px; }
.nav-item:hover, .nav-item.active { background: rgba(255,255,255,.14); }
.nav-item.active { border-left: 3px solid #fff; padding-left: 17px; }
.sidebar-footer { justify-content: space-between; padding: 14px 16px 16px 20px; }
.sidebar-footer span { display: block; }
.main-content { max-width: 1440px; margin-left: 276px; padding: 48px 40px 48px 14px; }
.breadcrumb { color: var(--muted); text-transform: none; letter-spacing: 0; }
.welcome-row h2 { font-size: 27px; }
.search-box { width: min(470px, 42vw); height: 42px; border-radius: 4px; }
.search-box > span { color: var(--brand); }
.search-box button { border-left: 1px solid var(--line); border-radius: 0; margin-right: 0; color: var(--brand-deep); background: var(--brand-soft); }
.category-strip { display: grid; grid-template-columns: repeat(6, minmax(0, 1fr)); gap: 0; min-height: 79px; padding: 0; border: 1px solid var(--line); border-radius: 4px; background: var(--surface); box-shadow: var(--shadow); }
.category-item { min-height: 0; padding: 13px 16px; border-right: 1px solid var(--line); border-radius: 0; }
.category-item:hover, .category-item.active { background: var(--brand-soft); }
.category-item:hover span, .category-item.active span { color: var(--muted); }
.category-item.active::after { display: block; right: 16px; bottom: 0; left: 16px; height: 3px; background: var(--accent); }
.content-grid { grid-template-columns: minmax(0, 1fr) 332px; gap: 18px; margin-top: 18px; }
.content-panel, .rail-panel, .purchase-bar { border: 1px solid var(--line); border-radius: var(--radius); box-shadow: var(--shadow); }
.content-panel { padding: 21px 22px 20px; }
.section-heading h3 { font-size: 18px; }
.section-dot { width: 9px; height: 9px; border-radius: 50%; background: var(--accent); transform: none; }
.course-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 16px; }
.course-card { border: 1px solid var(--line); border-radius: 4px; background: #fff; }
.cover { aspect-ratio: 16 / 9; }
.cover span { font-family: Georgia, serif; font-size: clamp(17px, 1.4vw, 23px); font-weight: 400; }
.feature-icon { width: 28px; height: 28px; border-radius: 50%; color: var(--brand); background: var(--brand-soft); }
.purchase-bar { min-height: 55px; border-radius: var(--radius); background: var(--brand); }
.purchase-bar:hover { background: var(--brand-deep); }
.rail-panel { padding: 18px 16px; }
.recommend-cover { border-radius: 3px; background: #6d7dcb; }
.recommend-item em { color: #f19727; }
.topic-card { min-height: 68px; border-radius: 4px; color: var(--brand-deep); background: var(--brand-soft); }
.topic-card:nth-child(2n) { color: #126c76; background: #effafa; }

/* Keep the blue-violet skin, while synchronizing geometry with the corrected version. */
.topbar { height: 84px; padding: 0 38px; }
.brand-mark { width: 43px; height: 43px; border-radius: 12px 12px 12px 2px; }
.sidebar { top: 104px; bottom: 24px; left: 24px; width: 92px; border-radius: 14px; }
.profile-block { min-height: 152px; padding: 14px 6px; }
.avatar-large { width: 46px; height: 46px; margin-bottom: 9px; border-radius: 12px 12px 12px 2px; }
.profile-block span { display: none; }
.side-nav { padding: 16px 8px; }
.nav-item { min-height: 64px; flex-direction: column; justify-content: center; gap: 5px; padding: 0; border-radius: 9px; font-size: 10px; text-align: center; }
.nav-item span { width: auto; font-size: 19px; line-height: 20px; }
.nav-item.active { border-left: 0; padding-left: 0; }
.sidebar-footer { justify-content: center; padding: 11px 8px; }
.sidebar-footer span { display: none; }
.main-content { max-width: 1480px; margin-left: 140px; padding: 46px 42px 58px 14px; }
.category-strip { display: flex; gap: 8px; min-height: 0; padding: 8px; border: 0; border-radius: 12px; box-shadow: none; }
.category-item { flex: 1; min-height: 67px; padding: 13px 16px; border: 0; border-radius: 9px; }
.category-item.active::after { display: none; }
.content-grid { grid-template-columns: minmax(0, 1fr) 360px; gap: 22px; margin-top: 22px; }
.content-panel, .rail-panel, .purchase-bar { border: 0; border-radius: 12px; }
.content-panel { padding: 26px; }
.course-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 18px; }
.course-card { border: 0; border-radius: 9px; }
.cover { aspect-ratio: 1.8 / 1; }
.feature-icon { width: 32px; height: 32px; border-radius: 9px; }
.purchase-bar { min-height: 64px; border-radius: 12px; }
.rail-panel { padding: 21px 18px; }
.topic-card { min-height: 72px; border-radius: 9px; }

@media (max-width: 1100px) {
  .sidebar { width: 92px; }
  .main-content { margin-left: 140px; }
}
@media (max-width: 760px) {
  .topbar { height: 64px; padding: 0 14px; }
  .sidebar { top: 80px; bottom: 0; left: 0; width: 72px; border-radius: 0; }
  .profile-block { min-height: 108px; }
  .main-content { margin-left: 72px; padding: 28px 14px 32px; }
  .category-strip { display: grid; grid-template-columns: repeat(3, 1fr); }
  .category-item { min-height: 58px; }
  .course-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

/* Final theme override: blue-violet colors, corrected independent geometry. */
:root { --brand: #4d5bc4; --brand-deep: #3545a8; --brand-soft: #edf0ff; --accent: #1d9bff; --page: #f3f5f8; --surface: #fff; --text: #1c2940; --muted: #718096; --line: #e1e6ef; --shadow: 0 10px 28px rgba(49, 66, 122, .08); --radius: 5px; }
body { background: var(--page); }
.topbar { background: var(--brand); }
.topbar::after { opacity: .16; background: linear-gradient(116deg, transparent 8%, #a6baff 8% 17%, transparent 17% 36%, #8ca6ff 36% 50%, transparent 50%); }
.brand-mark { border-color: rgba(255,255,255,.7); border-radius: 50%; color: #fff; transform: none; }
.brand-lockup p { color: rgba(255,255,255,.74); }
.top-action, .icon-button { border-color: rgba(255,255,255,.38); border-radius: 4px; background: rgba(30, 42, 131, .25); }
.top-action.primary { border-color: rgba(255,255,255,.38); background: rgba(255,255,255,.14); }
.icon-button { border-radius: 4px; }
.sidebar { background: var(--brand); box-shadow: 0 8px 18px rgba(49, 66, 122, .16); }
.avatar-large { border-radius: 50%; color: #fff; background: #8d99dc; }
.nav-item { color: rgba(255,255,255,.87); }
.nav-item span { color: #fff; }
.nav-item:hover, .nav-item.active { background: rgba(255,255,255,.14); }
.nav-item.active { border-left: 0; }
.search-box { border-radius: 4px; background: var(--surface); box-shadow: var(--shadow); }
.search-box > span { color: var(--brand); }
.search-box button { border-left: 1px solid var(--line); border-radius: 0; margin-right: 0; color: var(--brand-deep); background: var(--brand-soft); }
.category-strip { background: var(--surface); box-shadow: var(--shadow); }
.category-item:hover, .category-item.active { color: var(--text); background: var(--brand-soft); }
.category-item:hover span, .category-item.active span { color: var(--muted); }
.content-panel, .rail-panel, .purchase-bar { border: 1px solid var(--line); border-radius: var(--radius); box-shadow: var(--shadow); }
.content-panel { padding: 21px 22px 20px; }
.section-dot { border-radius: 50%; background: var(--accent); transform: none; }
.course-card { border: 1px solid var(--line); border-radius: 4px; background: #fff; box-shadow: none; }
.course-card:hover { border-color: #a9b7ed; box-shadow: 0 10px 24px rgba(69, 83, 166, .15); }
.cover span { font-family: Georgia, serif; font-weight: 400; }
.purchase-bar { background: var(--brand); }
.purchase-bar:hover { background: var(--brand-deep); }
.recommend-cover { border-radius: 3px; background: #6d7dcb; }
.recommend-item em { color: #f19727; }
.topic-card { border-radius: 4px; color: var(--brand-deep); background: var(--brand-soft); }
.topic-card:nth-child(2n) { color: #126c76; background: #effafa; }

/* Independent visual direction: a compact sports-learning atlas, not a replica of the reference portal. */
:root {
  --brand: #173b3a;
  --brand-deep: #0d2928;
  --brand-soft: #e3f0ec;
  --accent: #e46f4d;
  --page: #edf1ee;
  --surface: #fffdf8;
  --text: #182624;
  --muted: #6c7a77;
  --line: #d8e1dc;
  --shadow: 0 12px 26px rgba(23, 59, 58, .07);
  --radius: 8px;
}

body { background: var(--page); }
.topbar { height: 84px; padding: 0 38px; background: var(--brand); }
.topbar::after { opacity: .1; background: radial-gradient(circle at 88% 30%, #e46f4d 0 10%, transparent 10.5%), linear-gradient(108deg, transparent 20%, #d6eee7 20% 21%, transparent 21% 64%, #d6eee7 64% 65%, transparent 65%); }
.brand-mark { width: 43px; height: 43px; border: 2px solid #e7b69e; border-radius: 12px 12px 12px 2px; color: #fff2e9; transform: rotate(-7deg); }
.brand-lockup h1 { font-size: 20px; letter-spacing: .04em; }
.brand-lockup p { color: #b8d4cb; }
.top-action, .icon-button { border-color: rgba(226, 241, 234, .34); border-radius: 8px; background: rgba(0,0,0,.08); }
.top-action.primary { border-color: #e6a88f; background: rgba(228,111,77,.2); }
.icon-button { border-radius: 50%; }

.sidebar { top: 104px; bottom: 24px; left: 24px; width: 92px; border-radius: 14px; background: var(--brand-deep); box-shadow: 0 12px 24px rgba(13, 41, 40, .18); }
.profile-block { min-height: 152px; padding: 14px 6px; }
.avatar-large { width: 46px; height: 46px; margin-bottom: 9px; border-radius: 12px 12px 12px 2px; color: var(--brand); background: #f0c0a8; }
.profile-block strong { font-size: 12px; }
.profile-block span { display: none; }
.side-nav { padding: 16px 8px; }
.nav-item { min-height: 64px; display: flex; flex-direction: column; justify-content: center; gap: 5px; padding: 0; border-radius: 9px; color: #b9cec7; font-size: 10px; text-align: center; }
.nav-item span { width: auto; color: #e4a18d; font-size: 19px; line-height: 20px; }
.nav-item:hover, .nav-item.active { background: #28504b; }
.nav-item.active { border: 0; padding: 0; color: #fff; }
.sidebar-footer { justify-content: center; padding: 11px 8px; }
.sidebar-footer span { display: none; }

.main-content { max-width: 1480px; margin-left: 140px; padding: 46px 42px 58px 14px; }
.welcome-row { align-items: center; margin-bottom: 28px; }
.breadcrumb { color: var(--accent); text-transform: uppercase; letter-spacing: .08em; }
.welcome-row h2 { font-size: 32px; letter-spacing: -.02em; }
.section-note { color: var(--muted); }
.search-box { width: min(480px, 42vw); height: 46px; border-radius: 24px; background: var(--surface); box-shadow: 0 8px 20px rgba(23,59,58,.06); }
.search-box > span { color: var(--accent); }
.search-box button { border-left: 0; border-radius: 18px; margin-right: 4px; color: #fff; background: var(--accent); }
.category-strip { display: flex; gap: 8px; min-height: 0; padding: 8px; border: 0; border-radius: 12px; background: #dfe9e4; box-shadow: none; }
.category-item { flex: 1; min-height: 67px; border: 0; border-radius: 9px; background: transparent; }
.category-item:last-child { border-right: 0; }
.category-item:hover, .category-item.active { color: #fff; background: var(--brand); }
.category-item:hover span, .category-item.active span { color: #b9d7cf; }
.category-item.active::after { display: none; }
.content-grid { grid-template-columns: minmax(0, 1fr) 360px; gap: 22px; margin-top: 22px; }
.content-panel, .rail-panel, .purchase-bar { border: 0; border-radius: 12px; box-shadow: var(--shadow); }
.content-panel { padding: 26px; }
.section-heading { margin-bottom: 20px; }
.section-heading h3 { font-size: 19px; }
.section-dot { width: 10px; height: 10px; border-radius: 2px; background: var(--accent); transform: rotate(45deg); }
.course-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 18px; }
.course-card { border: 0; border-radius: 9px; background: #f7faf6; box-shadow: 0 0 0 1px var(--line); }
.course-card:hover { border-color: transparent; box-shadow: 0 12px 22px rgba(23,59,58,.12); }
.cover { aspect-ratio: 1.8 / 1; background: var(--cover); }
.cover span { font-family: "Microsoft YaHei", sans-serif; font-size: 19px; font-weight: 700; }
.cover.blue { --cover: repeating-linear-gradient(135deg, #8ab6ab 0 18px, #6b9c91 18px 36px); color: #123d39; }
.cover.orange { --cover: repeating-linear-gradient(45deg, #cf8f70 0 18px, #b76f56 18px 36px); }
.cover.green { --cover: repeating-linear-gradient(135deg, #789e85 0 16px, #557b62 16px 32px); }
.cover.purple { --cover: repeating-linear-gradient(45deg, #87949a 0 18px, #647278 18px 36px); }
.cover.sky { --cover: repeating-linear-gradient(135deg, #9bbdb7 0 18px, #6d9e98 18px 36px); }
.cover.dark { --cover: repeating-linear-gradient(45deg, #496e68 0 18px, #2b504c 18px 36px); }
.course-info { min-height: 112px; padding: 14px 16px; }
.course-info h4 { font-size: 15px; }
.feature-row { gap: 12px; margin-top: 26px; padding-top: 20px; }
.feature-icon { width: 32px; height: 32px; border-radius: 9px; color: #fff; background: var(--accent); }
.right-rail { gap: 22px; }
.purchase-bar { min-height: 64px; border-radius: 12px; background: var(--accent); }
.purchase-bar:hover { background: #c85d3f; }
.rail-panel { padding: 21px 18px; }
.recommend-item { min-height: 80px; }
.recommend-cover { border-radius: 8px; background: var(--brand); }
.recommend-item em { color: var(--accent); }
.topic-card { min-height: 72px; border: 0; border-radius: 9px; color: var(--brand); background: var(--brand-soft); }
.topic-card:nth-child(2n) { color: #8b4b36; border: 0; background: #fae8df; }
.topic-card:hover { outline: 2px solid var(--accent); }
.modal { border-radius: 12px; }
.modal .modal-action { border-radius: 8px; background: var(--brand); }

@media (max-width: 1100px) {
  .sidebar { width: 92px; }
  .main-content { margin-left: 140px; }
}
@media (max-width: 760px) {
  .topbar { height: 64px; padding: 0 14px; }
  .sidebar { top: 80px; bottom: 0; left: 0; width: 72px; border-radius: 0; }
  .profile-block { min-height: 108px; }
  .main-content { margin-left: 72px; padding: 28px 14px 32px; }
  .category-strip { display: grid; grid-template-columns: repeat(3, 1fr); }
  .category-item { min-height: 58px; }
  .course-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}