:root {
    --bg: #eef3f8;
    --ink: #17202a;
    --muted: #667085;
    --line: #d9dee7;
    --panel: #ffffff;
    --primary: #0f766e;
    --primary-dark: #115e59;
    --accent: #b45309;
    --soft: #e8f5f3;
    --gold-soft: #fff3d8;
    --blue-soft: #eaf2ff;
    --danger: #b42318;
    --success: #067647;
    --shadow: 0 18px 45px rgba(15, 23, 42, .08);
}

* { box-sizing: border-box; }
body {
    margin: 0;
    font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    background:
        linear-gradient(180deg, #f8fafc 0, var(--bg) 340px),
        var(--bg);
    color: var(--ink);
}
a { color: var(--primary-dark); text-decoration: none; }
h1, h2, h3 { margin: 0 0 10px; line-height: 1.15; letter-spacing: 0; }
p { line-height: 1.55; }
.topbar {
    min-height: 68px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 24px;
    background: rgba(255, 255, 255, .92);
    border-bottom: 1px solid var(--line);
    position: sticky;
    top: 0;
    z-index: 5;
    backdrop-filter: blur(14px);
}
.brand { font-weight: 900; color: var(--ink); letter-spacing: 0; }
nav { display: flex; gap: 16px; align-items: center; flex-wrap: wrap; }
nav a { color: var(--muted); font-size: 14px; font-weight: 700; }
.container { width: min(1180px, calc(100% - 32px)); margin: 28px auto; }
.auth-shell { min-height: 100vh; display: grid; place-items: center; padding: 24px; }
.hero {
    width: min(980px, 100%);
    min-height: 560px;
    display: grid;
    align-items: center;
    padding: 48px;
    background: linear-gradient(135deg, rgba(15,118,110,.92), rgba(23,32,42,.88)), url("https://images.unsplash.com/photo-1522202176988-66273c2fd55f?auto=format&fit=crop&w=1400&q=80");
    background-size: cover;
    background-position: center;
    color: #fff;
}
.hero h1 { font-size: clamp(36px, 6vw, 72px); max-width: 780px; }
.hero p { max-width: 640px; font-size: 19px; color: rgba(255,255,255,.88); }
.eyebrow { text-transform: uppercase; letter-spacing: .12em; font-size: 12px; font-weight: 800; }
.actions, .toolbar { display: flex; gap: 12px; align-items: center; justify-content: space-between; flex-wrap: wrap; }
.button {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-height: 40px;
    padding: 0 14px;
    border: 1px solid #cfd7e3;
    background: #fff;
    color: var(--ink);
    border-radius: 8px;
    cursor: pointer;
    font-weight: 700;
}
.button.primary { background: var(--primary); border-color: var(--primary); color: #fff; box-shadow: 0 8px 20px rgba(15, 118, 110, .18); }
.button.small { min-height: 32px; font-size: 13px; }
.panel, .card, .stat, .exercise-row {
    background: var(--panel);
    border: 1px solid var(--line);
    border-radius: 8px;
}
.panel { padding: 24px; width: min(520px, 100%); box-shadow: var(--shadow); }
.panel.wide { width: 100%; margin-bottom: 20px; }
.form { display: grid; gap: 14px; }
label { display: grid; gap: 6px; font-size: 14px; font-weight: 700; color: #344054; }
input, textarea, select {
    width: 100%;
    border: 1px solid var(--line);
    border-radius: 6px;
    padding: 11px 12px;
    font: inherit;
    background: #fff;
}
textarea { resize: vertical; }
.check { display: flex; grid-template-columns: auto 1fr; align-items: center; gap: 8px; }
.check input { width: auto; }
.notice {
    padding: 12px 14px;
    border: 1px solid var(--line);
    border-radius: 8px;
    background: #fff8e6;
    margin: 0 0 16px;
}
.notice.success { background: #ecfdf3; color: var(--success); }
.notice.danger { background: #fef3f2; color: var(--danger); }
.muted { color: var(--muted); }
.page-heading { margin-bottom: 18px; }
.grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(260px, 1fr)); gap: 16px; margin-top: 18px; }
.card { padding: 18px; display: grid; gap: 10px; align-content: start; }
.badge {
    display: inline-flex;
    width: fit-content;
    border: 1px solid var(--line);
    border-radius: 999px;
    padding: 4px 9px;
    color: var(--muted);
    font-size: 12px;
    font-weight: 800;
    text-transform: uppercase;
}
.stat-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(180px, 1fr)); gap: 14px; margin: 18px 0; }
.stat { padding: 18px; display: grid; gap: 4px; background: linear-gradient(180deg, #fff, #f9fbfd); box-shadow: var(--shadow); }
.stat strong { font-size: 28px; overflow-wrap: anywhere; }
.stat span { color: var(--muted); font-size: 14px; }
.progress { height: 10px; background: #e5e7eb; border-radius: 999px; overflow: hidden; }
.progress span { display: block; height: 100%; background: linear-gradient(90deg, var(--primary), #22c55e); }
.quick-links { display: flex; gap: 12px; flex-wrap: wrap; }
.quick-links a { background: #fff; border: 1px solid var(--line); border-radius: 8px; padding: 18px; min-width: 180px; font-weight: 800; }
.exercise-list { display: grid; gap: 10px; margin-top: 18px; }
.exercise-list.compact { margin-top: 10px; }
.exercise-row { padding: 14px; display: flex; justify-content: space-between; gap: 12px; align-items: center; box-shadow: none; }
.exercise-row h2, .exercise-row h3 { font-size: 16px; margin: 0 0 4px; }
.exercise-main { display: flex; gap: 12px; align-items: flex-start; min-width: 0; }
.number-pill {
    width: 38px;
    height: 38px;
    display: inline-grid;
    place-items: center;
    flex: 0 0 38px;
    border-radius: 10px;
    background: var(--soft);
    color: var(--primary-dark);
    font-weight: 900;
}
.exercise-detail .meta { display: flex; flex-wrap: wrap; gap: 8px; margin: 12px 0 24px; }
.exercise-detail .meta span { background: #eef7f5; color: var(--primary-dark); border-radius: 999px; padding: 6px 10px; font-size: 13px; font-weight: 800; }
.table-wrap { overflow-x: auto; background: #fff; border: 1px solid var(--line); border-radius: 8px; }
table { width: 100%; border-collapse: collapse; min-width: 720px; }
th, td { padding: 12px; border-bottom: 1px solid var(--line); text-align: left; vertical-align: top; }
th { color: var(--muted); font-size: 12px; text-transform: uppercase; }
.inline { display: flex; gap: 6px; margin: 0; }
.two-col { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 12px; }
.option-row { display: flex; gap: 16px; flex-wrap: wrap; }
.module-header {
    display: flex;
    justify-content: space-between;
    gap: 20px;
    align-items: flex-start;
    padding: 28px;
    margin-bottom: 16px;
    border: 1px solid #d7e1ea;
    border-radius: 12px;
    background:
        linear-gradient(135deg, rgba(15, 118, 110, .10), rgba(180, 83, 9, .08)),
        #fff;
    box-shadow: var(--shadow);
}
.module-header h1 { font-size: clamp(28px, 4vw, 44px); margin-top: 10px; }
.module-score {
    min-width: 150px;
    padding: 16px;
    border-radius: 10px;
    background: #fff;
    border: 1px solid var(--line);
    text-align: center;
}
.module-score strong { display: block; font-size: 34px; color: var(--primary-dark); }
.module-score span { color: var(--muted); font-size: 13px; }
.module-progress { margin: -4px 0 20px; height: 12px; }
.course-section { box-shadow: none; }
.section-title {
    display: flex;
    justify-content: space-between;
    gap: 12px;
    align-items: flex-start;
    padding-bottom: 12px;
    border-bottom: 1px solid var(--line);
}
.import-panel { background: linear-gradient(180deg, #fff, #fbfdff); }
.course-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(310px, 1fr));
    gap: 16px;
}
.course-card {
    min-height: 220px;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    gap: 24px;
    padding: 22px;
    border: 1px solid #d7e1ea;
    border-radius: 12px;
    background: #fff;
    box-shadow: var(--shadow);
}
.course-card h2 { margin-top: 10px; }
.course-card-foot {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 12px;
    border-top: 1px solid var(--line);
    padding-top: 14px;
}
.course-card-foot strong { font-size: 28px; color: var(--primary-dark); }
.workspace-layout {
    display: grid;
    grid-template-columns: minmax(280px, 380px) 1fr;
    gap: 18px;
    align-items: start;
}
.course-settings, .teacher-brief { width: 100%; }
.teacher-brief { min-height: 360px; }
.switch-row {
    display: grid;
    grid-template-columns: auto 1fr;
    gap: 12px;
    padding: 12px;
    border: 1px solid var(--line);
    border-radius: 10px;
    background: var(--soft);
}
.switch-row input { width: auto; margin-top: 4px; }
.switch-row small { display: block; color: var(--muted); font-weight: 500; margin-top: 3px; }
.editor-details {
    border: 1px solid var(--line);
    border-radius: 10px;
    padding: 12px;
    background: #fbfdff;
}
.editor-details summary { cursor: pointer; font-weight: 800; }
.markdown-preview {
    max-height: 520px;
    overflow: auto;
    padding-right: 8px;
}
.markdown-preview h1 { font-size: 24px; }
.markdown-preview h2 { font-size: 20px; margin-top: 18px; }
.markdown-preview h3 { font-size: 16px; margin-top: 14px; }
.exercise-group {
    border: 1px solid var(--line);
    border-radius: 10px;
    margin-top: 14px;
    overflow: hidden;
    background: #fff;
}
.exercise-group summary {
    display: flex;
    justify-content: space-between;
    gap: 12px;
    cursor: pointer;
    padding: 14px 16px;
    background: var(--blue-soft);
    font-weight: 900;
}
.exercise-group summary em { color: var(--muted); font-style: normal; font-weight: 700; }
.exercise-group .exercise-list { padding: 10px; }
.points {
    flex: 0 0 auto;
    color: var(--accent);
    background: var(--gold-soft);
    border-radius: 999px;
    padding: 6px 10px;
    font-weight: 900;
    font-size: 13px;
}
.chart { display: grid; gap: 12px; margin: 16px 0; }
.chart div { display: grid; grid-template-columns: 180px 1fr 42px; gap: 10px; align-items: center; }
.chart b { display: block; height: 12px; background: var(--accent); border-radius: 999px; }
.chart em { font-style: normal; color: var(--muted); }
.list-item { margin-left: 10px; }
pre { white-space: pre-wrap; background: #101828; color: #f2f4f7; padding: 14px; border-radius: 8px; overflow-x: auto; }
@media (max-width: 720px) {
    .topbar { height: auto; padding: 14px; align-items: flex-start; }
    nav { justify-content: flex-end; }
    .hero { padding: 28px; min-height: 520px; }
    .exercise-row, .toolbar, .module-header, .course-card-foot { align-items: flex-start; }
    .module-header, .exercise-row, .course-card-foot { flex-direction: column; }
    .two-col, .chart div, .workspace-layout { grid-template-columns: 1fr; }
}