.course-shell {
    min-height: 100vh;
    background: #f8fafc;
    color: var(--text-main);
}

.course-nav {
    position: sticky;
    top: 0;
    z-index: 30;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 16px;
    padding: 14px 22px;
    background: rgba(255, 255, 255, .92);
    border-bottom: 1px solid rgba(148, 163, 184, .22);
    backdrop-filter: blur(14px);
}

.course-brand {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    color: #0f172a;
    font-weight: 900;
    text-decoration: none;
}

.course-brand-mark {
    width: 34px;
    height: 34px;
    display: grid;
    place-items: center;
    border-radius: 8px;
    background: #1d4ed8;
    color: #fff;
    font-weight: 900;
}

.course-nav-links {
    display: flex;
    align-items: center;
    gap: 8px;
    flex-wrap: wrap;
    justify-content: flex-end;
}

.course-nav-links a {
    color: #334155;
    text-decoration: none;
    font-size: 14px;
    font-weight: 900;
    padding: 9px 10px;
    border-radius: 8px;
}

.course-nav-links a:hover,
.course-nav-links a.active {
    background: #eff6ff;
    color: #1d4ed8;
}

.course-page {
    width: min(1120px, calc(100% - 40px));
    margin: 0 auto;
    padding: 46px 0 58px;
}

.course-hero {
    padding: 38px;
    border-radius: 8px;
    border: 1px solid rgba(37, 99, 235, .16);
    background: linear-gradient(135deg, #eff6ff 0%, #fff7ed 58%, #f8fafc 100%);
    color: #0f172a;
    box-shadow: 0 20px 56px rgba(37, 99, 235, .10);
}

.course-hero.compact {
    padding: 34px;
}

.course-kicker {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    margin-bottom: 12px;
    padding: 7px 10px;
    border: 1px solid rgba(37, 99, 235, .18);
    border-radius: 8px;
    background: #fff;
    color: #1d4ed8;
    font-size: 13px;
    font-weight: 900;
}

.course-hero h1 {
    max-width: 860px;
    margin: 0;
    font-family: var(--font-serif);
    font-size: clamp(34px, 6vw, 58px);
    line-height: 1.08;
    letter-spacing: 0;
    overflow-wrap: anywhere;
}

.course-hero p {
    max-width: 780px;
    margin: 16px 0 0;
    color: #475569;
    font-size: 17px;
    line-height: 1.78;
}

.hero-actions {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    margin-top: 24px;
}

.course-button {
    min-height: 44px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0 16px;
    border-radius: 8px;
    border: 1px solid rgba(37, 99, 235, .22);
    background: #1d4ed8;
    color: #fff;
    font-weight: 900;
    text-decoration: none;
}

.course-button.secondary {
    background: #fff;
    color: #1d4ed8;
}

.content-band {
    margin-top: 28px;
    padding: 28px;
    border-radius: 8px;
    border: 1px solid rgba(148, 163, 184, .24);
    background: #fff;
    box-shadow: 0 16px 42px rgba(15, 23, 42, .06);
}

.content-band.tint {
    background: #fff7ed;
    border-color: rgba(249, 115, 22, .22);
}

.section-heading {
    max-width: 780px;
    margin: 0 0 18px;
}

.section-heading span {
    display: inline-block;
    color: #1d4ed8;
    font-size: 13px;
    font-weight: 900;
}

.section-heading h2 {
    margin: 7px 0 8px;
    font-family: var(--font-serif);
    font-size: clamp(26px, 4vw, 36px);
    line-height: 1.18;
    letter-spacing: 0;
}

.section-heading p {
    margin: 0;
    color: #475569;
    line-height: 1.78;
}

.summary-grid,
.grade-grid,
.change-grid,
.principle-grid {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 12px;
}

.grade-grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
}

.change-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
}

.summary-card,
.grade-card,
.change-card,
.principle-card {
    padding: 18px;
    border-radius: 8px;
    border: 1px solid rgba(148, 163, 184, .22);
    background: #fff;
}

.summary-card strong,
.grade-card strong,
.change-card strong,
.principle-card strong {
    display: block;
    color: #0f172a;
    font-size: 18px;
    line-height: 1.3;
}

.summary-card p,
.grade-card p,
.change-card p,
.principle-card p {
    margin: 9px 0 0;
    color: #475569;
    line-height: 1.68;
    font-size: 14px;
}

.grade-card {
    display: flex;
    flex-direction: column;
    min-height: 190px;
    text-decoration: none;
    transition: transform .18s ease, border-color .18s ease, box-shadow .18s ease;
}

.grade-card:hover {
    transform: translateY(-3px);
    border-color: rgba(37, 99, 235, .34);
    box-shadow: 0 20px 48px rgba(15, 23, 42, .09);
}

.grade-card small {
    color: #f97316;
    font-weight: 900;
}

.grade-card em {
    margin-top: auto;
    padding-top: 14px;
    color: #1d4ed8;
    font-style: normal;
    font-weight: 900;
}

.table-scroll {
    overflow-x: auto;
    border: 1px solid rgba(148, 163, 184, .24);
    border-radius: 8px;
    background: #fff;
}

.lesson-table {
    width: 100%;
    min-width: 900px;
    border-collapse: collapse;
    font-size: 14px;
}

.lesson-table th,
.lesson-table td {
    padding: 14px 13px;
    border-bottom: 1px solid rgba(148, 163, 184, .18);
    vertical-align: top;
    line-height: 1.58;
}

.lesson-table th {
    position: sticky;
    top: 0;
    background: #eff6ff;
    color: #0f172a;
    font-size: 13px;
    text-align: left;
    white-space: nowrap;
}

.lesson-table td:first-child {
    width: 70px;
    color: #f97316;
    font-weight: 900;
    white-space: nowrap;
}

.lesson-table tr:nth-child(even) td {
    background: #f8fafc;
}

.source-note {
    margin: 16px 0 0;
    color: #64748b;
    font-size: 13px;
    line-height: 1.7;
}

.inline-link {
    color: #1d4ed8;
    font-weight: 900;
    text-decoration: none;
}

.comparison-table {
    width: 100%;
    border-collapse: collapse;
    overflow: hidden;
    border: 1px solid rgba(148, 163, 184, .24);
    border-radius: 8px;
    background: #fff;
}

.comparison-table th,
.comparison-table td {
    padding: 15px;
    border-bottom: 1px solid rgba(148, 163, 184, .18);
    vertical-align: top;
    text-align: left;
    line-height: 1.72;
}

.comparison-table th {
    background: #eff6ff;
    color: #0f172a;
    font-size: 14px;
}

.comparison-table td {
    color: #475569;
}

.comparison-table strong {
    color: #0f172a;
}

.warning-line {
    margin-top: 18px;
    padding: 16px 18px;
    border-left: 4px solid #f97316;
    background: #fff7ed;
    color: #7c2d12;
    line-height: 1.7;
}

@media (max-width: 900px) {
    .summary-grid,
    .grade-grid,
    .change-grid,
    .principle-grid {
        grid-template-columns: 1fr 1fr;
    }
}

@media (max-width: 640px) {
    .course-nav {
        align-items: flex-start;
        padding: 10px 12px;
    }

    .course-nav-links {
        display: none;
    }

    .course-page {
        width: calc(100% - 28px);
        padding: 26px 0 42px;
    }

    .course-hero,
    .course-hero.compact,
    .content-band {
        padding: 22px;
        min-width: 0;
    }

    .course-hero h1 {
        max-width: 100%;
        font-size: 28px;
        line-height: 1.16;
        word-break: break-all;
    }

    .course-hero p,
    .course-card,
    .course-card p,
    .course-card li,
    .section-heading h2,
    .section-heading p,
    .warning-line {
        overflow-wrap: anywhere;
        word-break: break-all;
    }

    .summary-grid,
    .grade-grid,
    .change-grid,
    .principle-grid {
        grid-template-columns: 1fr;
    }

    .hero-actions .course-button {
        width: 100%;
    }

    .table-scroll {
        overflow-x: visible;
        border: 0;
        background: transparent;
    }

    .lesson-table,
    .comparison-table,
    .lesson-table thead,
    .lesson-table tbody,
    .lesson-table tr,
    .lesson-table th,
    .lesson-table td,
    .comparison-table thead,
    .comparison-table tbody,
    .comparison-table tr,
    .comparison-table th,
    .comparison-table td {
        display: block;
        width: 100%;
        min-width: 0;
    }

    .lesson-table,
    .comparison-table {
        border: 0;
        background: transparent;
    }

    .lesson-table thead,
    .comparison-table thead {
        position: absolute;
        width: 1px;
        height: 1px;
        overflow: hidden;
        clip: rect(0 0 0 0);
        white-space: nowrap;
    }

    .lesson-table tr,
    .comparison-table tr {
        margin-bottom: 12px;
        padding: 12px 14px;
        border: 1px solid rgba(148, 163, 184, .24);
        border-radius: 8px;
        background: #fff;
        box-shadow: 0 10px 26px rgba(15, 23, 42, .05);
    }

    .lesson-table tr:nth-child(even) td {
        background: transparent;
    }

    .lesson-table td,
    .comparison-table td {
        display: grid;
        grid-template-columns: 68px minmax(0, 1fr);
        gap: 10px;
        align-items: start;
        padding: 8px 0;
        border-bottom: 1px solid rgba(148, 163, 184, .14);
        line-height: 1.66;
        white-space: normal;
    }

    .lesson-table td:last-child,
    .comparison-table td:last-child {
        border-bottom: 0;
        padding-bottom: 0;
    }

    .lesson-table td:first-child {
        width: auto;
        color: #0f172a;
    }

    .lesson-table td::before,
    .comparison-table td::before {
        color: #1d4ed8;
        font-size: 12px;
        font-weight: 900;
        letter-spacing: 0;
    }

    .lesson-table td:nth-child(1)::before {
        content: "讲次";
    }

    .lesson-table td:nth-child(2)::before {
        content: "数学";
    }

    .lesson-table td:nth-child(3)::before {
        content: "英语";
    }

    .lesson-table td:nth-child(4)::before {
        content: "语文";
    }

    .lesson-table td:nth-child(5)::before {
        content: "验收点";
    }

    .comparison-table td:nth-child(1)::before {
        content: "维度";
    }

    .comparison-table td:nth-child(2)::before {
        content: "旧教材";
    }

    .comparison-table td:nth-child(3)::before {
        content: "新教材";
    }

    .comparison-table td:nth-child(4)::before {
        content: "应对";
    }
}