:root {
    --primary: #0f766e;
    --secondary: #164e63;
    --accent: #f59e0b;
    --background: #f8fafc;
    --button: #0f766e;
    --text: #0f172a;
    --border: #e2e8f0;
    --muted: #64748b;
    --surface: #ffffff;
}

* { box-sizing: border-box; }
body {
    margin: 0;
    font-family: Inter, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    background: var(--background);
    color: var(--text);
}
a { color: var(--primary); text-decoration: none; }
.app-shell { display: grid; grid-template-columns: 260px minmax(0, 1fr); min-height: 100vh; }
.sidebar { background: #0f172a; color: #e2e8f0; padding: 20px 14px; position: sticky; top: 0; height: 100vh; overflow-y: auto; }
.brand { display: flex; align-items: center; gap: 10px; font-weight: 800; color: #fff; margin-bottom: 24px; }
.brand img { max-width: 42px; max-height: 42px; border-radius: 6px; background: #fff; }
.nav-title { color: #94a3b8; font-size: 11px; text-transform: uppercase; letter-spacing: .08em; margin: 18px 10px 8px; }
.nav-link { display: block; color: #cbd5e1; padding: 9px 10px; border-radius: 8px; font-size: 14px; }
.nav-link:hover, .nav-link.active { background: rgba(255,255,255,.08); color: #fff; }
.main { min-width: 0; }
.topbar { height: 64px; display: flex; justify-content: space-between; align-items: center; padding: 0 24px; background: var(--surface); border-bottom: 1px solid var(--border); }
.content { padding: 24px; max-width: 1400px; }
.page-title { margin: 0 0 4px; font-size: 26px; }
.muted { color: var(--muted); }
.grid { display: grid; gap: 16px; }
.grid-2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid-3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.grid-4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }
.card { background: var(--surface); border: 1px solid var(--border); border-radius: 8px; padding: 18px; }
.stat { font-size: 28px; font-weight: 800; color: var(--secondary); margin: 6px 0; }
.btn, button { display: inline-flex; align-items: center; justify-content: center; gap: 8px; background: var(--button); color: #fff; border: 0; border-radius: 7px; padding: 10px 14px; font-weight: 700; cursor: pointer; }
.btn.secondary { background: var(--secondary); }
.btn.light { background: #e2e8f0; color: #0f172a; }
.btn.danger { background: #dc2626; }
.btn.small { padding: 6px 10px; font-size: 12px; }
input, select, textarea { width: 100%; border: 1px solid var(--border); border-radius: 7px; padding: 10px 11px; font: inherit; background: #fff; color: var(--text); }
textarea { min-height: 110px; resize: vertical; }
label { display: block; font-weight: 700; font-size: 13px; margin: 0 0 6px; }
.form-row { display: grid; gap: 14px; grid-template-columns: repeat(2, minmax(0, 1fr)); margin-bottom: 14px; }
.form-row.three { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.table-wrap { overflow-x: auto; }
table { width: 100%; border-collapse: collapse; font-size: 14px; }
th, td { text-align: left; padding: 10px; border-bottom: 1px solid var(--border); vertical-align: top; }
th { color: #334155; font-size: 12px; text-transform: uppercase; letter-spacing: .04em; }
.badge { display: inline-flex; border-radius: 999px; padding: 4px 8px; font-size: 12px; font-weight: 700; background: #e0f2fe; color: #075985; }
.badge.ok { background: #dcfce7; color: #166534; }
.badge.warn { background: #fef3c7; color: #92400e; }
.progress { width: 100%; height: 9px; background: #e2e8f0; border-radius: 999px; overflow: hidden; }
.progress span { display: block; height: 100%; background: var(--primary); }
.course-cover { width: 100%; aspect-ratio: 16 / 9; object-fit: cover; background: #e2e8f0; border-radius: 8px; }
.lesson-player { width: 100%; aspect-ratio: 16 / 9; background: #020617; border: 0; border-radius: 8px; }
.alert { padding: 12px 14px; border-radius: 8px; margin-bottom: 16px; background: #dcfce7; color: #14532d; border: 1px solid #86efac; }
.login-page { min-height: 100vh; display: grid; grid-template-columns: minmax(0, 1fr) 420px; background: #0f172a; }
.login-hero { background: linear-gradient(135deg, rgba(15,118,110,.85), rgba(15,23,42,.7)); color: #fff; display: flex; align-items: end; padding: 48px; background-size: cover; background-position: center; }
.login-card { background: #fff; padding: 42px; display: flex; flex-direction: column; justify-content: center; }
.tabs { display: flex; gap: 8px; flex-wrap: wrap; margin-bottom: 16px; }
.tab { padding: 8px 12px; border-radius: 999px; background: #e2e8f0; color: #0f172a; font-size: 13px; font-weight: 700; }
@media (max-width: 900px) {
    .app-shell { grid-template-columns: 1fr; }
    .sidebar { position: relative; height: auto; }
    .grid-2, .grid-3, .grid-4, .form-row, .form-row.three, .login-page { grid-template-columns: 1fr; }
    .content { padding: 16px; }
    .topbar { padding: 0 16px; }
}

.public-header {
    height: 74px;
    display: grid;
    grid-template-columns: auto minmax(0, 1fr) auto;
    align-items: center;
    gap: 24px;
    padding: 0 32px;
    background: #fff;
    border-bottom: 1px solid var(--border);
    box-shadow: 0 6px 18px rgba(15, 23, 42, .06);
    position: sticky;
    top: 0;
    z-index: 20;
}
.public-brand {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    color: #111827;
    font-size: 24px;
    font-weight: 900;
}
.public-brand img { width: 42px; height: 42px; object-fit: contain; border-radius: 6px; }
.public-nav { display: flex; align-items: center; gap: 24px; color: #475569; }
.public-nav a { color: #475569; font-weight: 650; }
.public-nav a:hover { color: var(--primary); }
.public-actions { display: flex; align-items: center; gap: 10px; }
.public-flash {
    max-width: 1180px;
    margin: 16px auto 0;
    padding: 12px 16px;
    border-radius: 8px;
    font-weight: 700;
}
.public-flash.ok { background: #dcfce7; color: #14532d; }
.public-flash.error { background: #fee2e2; color: #991b1b; }
.public-hero {
    max-width: 1780px;
    min-height: 520px;
    margin: 0 auto;
    background-size: cover;
    background-position: center;
    display: flex;
    align-items: center;
    padding: 64px 8vw;
}
.public-hero-card {
    max-width: 560px;
    background: rgba(255, 255, 255, .94);
    border-radius: 8px;
    padding: 36px;
    box-shadow: 0 18px 50px rgba(15, 23, 42, .18);
}
.eyebrow {
    display: inline-flex;
    margin-bottom: 10px;
    font-size: 13px;
    text-transform: uppercase;
    letter-spacing: .08em;
    color: var(--secondary);
    font-weight: 900;
}
.public-hero h1, .course-detail-hero h1, .enroll-page h1 {
    margin: 0 0 14px;
    font-size: 44px;
    line-height: 1.04;
    color: #111827;
}
.public-hero p {
    color: #475569;
    font-size: 19px;
    line-height: 1.6;
}
.hero-actions { display: flex; gap: 12px; flex-wrap: wrap; margin-top: 22px; }
.public-section {
    max-width: 1400px;
    margin: 0 auto;
    padding: 54px 32px;
}
.soft-band {
    max-width: none;
    background: #fff;
}
.soft-band > * {
    max-width: 1336px;
    margin-left: auto;
    margin-right: auto;
}
.section-heading {
    display: flex;
    align-items: end;
    justify-content: space-between;
    gap: 24px;
    margin-bottom: 24px;
}
.section-heading h2 {
    margin: 0;
    font-size: 34px;
    line-height: 1.1;
}
.section-heading p { margin: 8px 0 0; color: var(--muted); font-size: 17px; }
.course-search {
    display: flex;
    gap: 8px;
    min-width: 420px;
}
.course-search input {
    border-radius: 999px;
    padding: 12px 16px;
}
.course-search button { border-radius: 999px; }
.category-tabs {
    display: flex;
    gap: 22px;
    overflow-x: auto;
    border-bottom: 1px solid var(--border);
    margin-bottom: 22px;
}
.category-tabs a {
    color: #475569;
    padding: 0 0 12px;
    white-space: nowrap;
    font-weight: 750;
    border-bottom: 3px solid transparent;
}
.category-tabs a.active {
    color: #111827;
    border-color: #111827;
}
.public-course-grid {
    display: grid;
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: 18px;
}
.public-course-card {
    background: #fff;
    border: 1px solid var(--border);
    border-radius: 8px;
    overflow: hidden;
    display: flex;
    flex-direction: column;
    min-height: 100%;
    transition: transform .16s ease, box-shadow .16s ease;
}
.public-course-card:hover {
    transform: translateY(-2px);
    box-shadow: 0 16px 36px rgba(15, 23, 42, .12);
}
.public-course-card img {
    width: 100%;
    aspect-ratio: 16 / 9;
    object-fit: cover;
    display: block;
}
.course-card-body {
    padding: 16px;
    display: flex;
    flex-direction: column;
    gap: 10px;
    flex: 1;
}
.course-card-body h3 {
    margin: 0;
    font-size: 19px;
    line-height: 1.18;
}
.course-card-body h3 a { color: #111827; }
.course-teacher { margin: 0; color: var(--muted); font-size: 14px; }
.course-meta, .course-badges, .course-footer, .course-detail-meta {
    display: flex;
    gap: 8px;
    flex-wrap: wrap;
    align-items: center;
}
.course-meta span {
    color: #64748b;
    font-size: 13px;
}
.course-badges { margin-top: auto; }
.rating {
    border: 1px solid #cbd5e1;
    color: #7c2d12;
    border-radius: 6px;
    padding: 3px 8px;
    font-size: 13px;
    font-weight: 800;
}
.course-footer {
    justify-content: space-between;
    border-top: 1px solid var(--border);
    padding-top: 12px;
}
.course-footer strong { font-size: 19px; color: #111827; }
.empty-public {
    border: 1px dashed var(--border);
    padding: 28px;
    color: var(--muted);
    border-radius: 8px;
    background: #fff;
}
.trust-band {
    text-align: center;
}
.trust-grid {
    display: grid;
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: 16px;
    margin-top: 22px;
}
.trust-grid div {
    background: #fff;
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 20px;
}
.trust-grid strong { display: block; margin-bottom: 8px; }
.trust-grid span { color: var(--muted); }
.cta-strip {
    text-align: center;
    border-top: 1px solid var(--border);
}
.course-detail-hero, .enroll-page {
    max-width: 1240px;
    margin: 0 auto;
    padding: 48px 32px;
    display: grid;
    grid-template-columns: minmax(0, 1fr) 420px;
    gap: 32px;
    align-items: start;
}
.course-detail-hero {
    background: #0f172a;
    max-width: none;
    color: #e2e8f0;
    padding-left: max(32px, calc((100vw - 1240px) / 2));
    padding-right: max(32px, calc((100vw - 1240px) / 2));
}
.course-detail-hero h1 { color: #fff; }
.course-detail-hero p { color: #cbd5e1; font-size: 18px; line-height: 1.6; }
.course-detail-meta span {
    background: rgba(255,255,255,.1);
    border: 1px solid rgba(255,255,255,.16);
    border-radius: 999px;
    padding: 6px 10px;
    color: inherit;
}
.course-detail-card {
    background: #fff;
    border-radius: 8px;
    overflow: hidden;
    color: #111827;
}
.course-detail-card img, .enroll-summary img {
    width: 100%;
    aspect-ratio: 16 / 9;
    object-fit: cover;
    display: block;
}
.course-detail-card div { padding: 16px; display: grid; gap: 6px; }
.course-detail-card strong { font-size: 24px; }
.public-status {
    background: rgba(255,255,255,.1);
    border-radius: 8px;
    padding: 12px 14px;
}
.module-preview {
    background: #fff;
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 18px;
    margin-bottom: 14px;
}
.module-preview ul { margin: 12px 0 0; padding: 0; list-style: none; }
.module-preview li {
    display: flex;
    justify-content: space-between;
    gap: 16px;
    border-top: 1px solid var(--border);
    padding: 10px 0;
}
.module-preview li span { color: var(--muted); white-space: nowrap; }
.enroll-summary, .enroll-form-card {
    background: #fff;
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 22px;
}
.enroll-summary img {
    border-radius: 8px;
    margin-bottom: 20px;
}
.enroll-summary h1 { font-size: 34px; }
.enroll-summary p { color: var(--muted); line-height: 1.6; }
.enroll-form-card h2 { margin-top: 0; }
.public-footer {
    background: #0f172a;
    color: #cbd5e1;
    margin-top: 24px;
}
.public-footer-grid {
    max-width: 1400px;
    margin: 0 auto;
    padding: 44px 32px;
    display: grid;
    grid-template-columns: minmax(280px, 1.5fr) repeat(3, minmax(160px, 1fr));
    gap: 28px;
}
.public-footer h3 {
    margin: 0 0 14px;
    color: #fff;
    font-size: 15px;
    text-transform: uppercase;
    letter-spacing: .08em;
}
.public-footer a,
.public-footer span {
    color: #cbd5e1;
}
.public-footer section > a,
.public-footer section > span {
    display: block;
    margin: 9px 0;
    font-size: 14px;
}
.public-footer a:hover {
    color: #fff;
}
.footer-brand {
    color: #fff;
    margin-bottom: 14px;
}
.footer-brand-block p {
    max-width: 460px;
    margin: 0 0 16px;
    line-height: 1.6;
    color: #94a3b8;
}
.footer-contact {
    display: inline-flex;
    border: 1px solid rgba(255,255,255,.14);
    border-radius: 999px;
    padding: 8px 12px;
    background: rgba(255,255,255,.04);
}
.public-footer-bottom {
    border-top: 1px solid rgba(255,255,255,.1);
    max-width: 1400px;
    margin: 0 auto;
    padding: 16px 32px 22px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 16px;
    color: #94a3b8;
    font-size: 13px;
}
@media (max-width: 1100px) {
    .public-course-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
    .course-detail-hero, .enroll-page { grid-template-columns: 1fr; }
    .public-footer-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}
@media (max-width: 760px) {
    .public-header {
        height: auto;
        grid-template-columns: 1fr;
        gap: 12px;
        padding: 16px;
        position: relative;
    }
    .public-nav { overflow-x: auto; gap: 16px; }
    .public-actions { justify-content: stretch; }
    .public-actions .btn { width: 100%; }
    .public-hero { min-height: auto; padding: 28px 16px; }
    .public-hero-card { padding: 24px; }
    .public-hero h1, .course-detail-hero h1 { font-size: 34px; }
    .section-heading { display: block; }
    .course-search { min-width: 0; margin-top: 16px; display: grid; }
    .public-section, .course-detail-hero, .enroll-page { padding: 32px 16px; }
    .public-course-grid, .trust-grid { grid-template-columns: 1fr; }
    .public-footer-grid { grid-template-columns: 1fr; padding: 34px 16px; }
    .public-footer-bottom { display: grid; padding: 16px; }
}