:root {
    --bg: #f4f8ff;
    --bg-soft: #edf4ff;
    --surface: #ffffff;
    --surface-soft: #f7fbff;
    --text: #14294b;
    --text-muted: #6b7f98;
    --primary: #2f7df6;
    --primary-strong: #1f62d6;
    --primary-soft: #dcecff;
    --line: #d7e6f7;
    --line-strong: #bfd8f5;
    --success: #2d8a57;
    --muted-fill: #eef3f8;
    --shadow: 0 14px 38px rgba(30, 80, 159, 0.08);
    --shadow-soft: 0 8px 22px rgba(22, 55, 112, 0.06);
}

@keyframes pageGlow {
    0%,
    100% {
        transform: translate3d(0, 0, 0) scale(1);
        opacity: 0.82;
    }
    50% {
        transform: translate3d(10px, -8px, 0) scale(1.04);
        opacity: 1;
    }
}

@keyframes floatCardArt {
    0%,
    100% {
        transform: translate3d(0, 0, 0);
    }
    50% {
        transform: translate3d(0, -6px, 0);
    }
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    min-height: 100vh;
    overflow-x: hidden;
    font-family: 'Inter', sans-serif;
    color: var(--text);
    line-height: 1.65;
    background:
        radial-gradient(circle at top left, rgba(187, 216, 255, 0.55), transparent 26%),
        linear-gradient(180deg, #fbfdff 0%, var(--bg) 52%, #f6faff 100%);
    position: relative;
}

body::before {
    content: '';
    position: fixed;
    top: -80px;
    right: -30px;
    width: 220px;
    height: 220px;
    border-radius: 50%;
    background: radial-gradient(circle, rgba(209, 228, 255, 0.85) 0%, rgba(209, 228, 255, 0) 72%);
    pointer-events: none;
    filter: blur(8px);
    animation: pageGlow 12s ease-in-out infinite;
}

a {
    color: inherit;
    text-decoration: none;
}

img {
    display: block;
    max-width: 100%;
}

.page-container {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

.page-content {
    flex: 1;
}

.container {
    width: min(1100px, calc(100% - 40px));
    margin: 0 auto;
}

.breadcrumb {
    padding: 18px 0 8px;
    color: var(--text-muted);
    font-size: 0.92rem;
}

.breadcrumb .container {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    align-items: center;
}

.breadcrumb a:hover {
    color: var(--primary-strong);
}

.page-header {
    padding: 18px 0 12px;
}

.page-header .container {
    position: relative;
    padding: 28px;
    border: 1px solid var(--line);
    border-radius: 26px;
    background: linear-gradient(180deg, rgba(255, 255, 255, 0.98) 0%, rgba(243, 248, 255, 0.98) 100%);
    box-shadow: var(--shadow);
    overflow: hidden;
}

.page-header .container::after {
    content: '';
    position: absolute;
    right: -30px;
    bottom: -40px;
    width: 150px;
    height: 150px;
    border-radius: 50%;
    background: radial-gradient(circle, rgba(220, 236, 255, 0.9) 0%, rgba(220, 236, 255, 0) 74%);
    animation: pageGlow 14s ease-in-out infinite reverse;
}

.page-title {
    max-width: 760px;
    font-size: clamp(2rem, 4vw, 3.4rem);
    line-height: 1.04;
    letter-spacing: -0.05em;
    overflow-wrap: anywhere;
    word-break: normal;
    color: var(--text);
}

.section-subtitle {
    max-width: 620px;
    margin-top: 10px;
    color: var(--text-muted);
    font-size: 0.98rem;
}

.section {
    padding: 20px 0 26px;
}

.section:last-of-type {
    padding-bottom: 34px;
}

.cards-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 16px;
}

.card {
    display: grid;
    gap: 10px;
    padding: 22px 20px;
    border-radius: 20px;
    border: 1px solid var(--line);
    background: rgba(255, 255, 255, 0.96);
    box-shadow: var(--shadow-soft);
    transition: transform 0.2s ease, border-color 0.2s ease, box-shadow 0.2s ease;
}

.subject-card {
    grid-template-rows: auto auto auto auto;
}

.card-media {
    position: relative;
    overflow: hidden;
    min-height: 118px;
    margin-bottom: 4px;
    border-radius: 16px;
    border: 1px solid rgba(191, 216, 245, 0.75);
    background: linear-gradient(180deg, rgba(241, 248, 255, 0.95) 0%, rgba(230, 241, 255, 0.92) 100%);
}

.card-media-image {
    width: 100%;
    height: 118px;
    object-fit: cover;
    animation: floatCardArt 7s ease-in-out infinite;
    transform-origin: center;
}

.card:hover {
    transform: translateY(-4px);
    border-color: var(--line-strong);
    box-shadow: 0 14px 28px rgba(30, 80, 159, 0.1);
}

.card:hover .card-media-image {
    animation-duration: 4.8s;
}

.card-title {
    font-size: 1.2rem;
    font-weight: 800;
    letter-spacing: -0.04em;
    color: var(--text);
}

.card-copy {
    color: var(--text-muted);
    font-size: 0.92rem;
}

.card-status {
    width: fit-content;
    padding: 6px 10px;
    border-radius: 999px;
    font-size: 0.75rem;
    font-weight: 700;
}

.card-status.active {
    color: var(--success);
    background: rgba(45, 138, 87, 0.1);
}

.card-status.coming-soon {
    color: var(--text-muted);
    background: var(--muted-fill);
}

.card.disabled,
.material-btn.disabled,
.nav-btn.disabled {
    opacity: 0.68;
    cursor: not-allowed;
}

.card.disabled:hover,
.material-btn.disabled:hover {
    transform: none;
    box-shadow: var(--shadow-soft);
    border-color: var(--line);
}

.material-list {
    display: grid;
    gap: 14px;
    max-width: 860px;
    margin: 0 auto;
}

.material-btn {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 16px;
    width: 100%;
    padding: 18px 20px;
    border-radius: 18px;
    border: 1px solid var(--line);
    background: rgba(255, 255, 255, 0.96);
    color: var(--text);
    box-shadow: var(--shadow-soft);
    transition: transform 0.2s ease, border-color 0.2s ease, box-shadow 0.2s ease;
}

.material-btn::after {
    content: '\203A';
    color: var(--primary);
    font-size: 1.35rem;
    font-weight: 700;
}

.material-btn:hover {
    transform: translateY(-3px);
    border-color: var(--line-strong);
    box-shadow: 0 14px 28px rgba(30, 80, 159, 0.09);
}

.material-btn:hover::after {
    transform: translateX(4px);
}

.material-btn::after {
    transition: transform 0.2s ease;
}

.material-btn.disabled::after {
    content: '';
}

.video-container,
.image-link-container {
    max-width: 860px;
    margin: 0 auto;
}

.video-container {
    overflow: hidden;
    aspect-ratio: 16 / 9;
    border-radius: 22px;
    border: 1px solid var(--line);
    background: #eaf2fd;
    box-shadow: var(--shadow-soft);
}

.video-container iframe {
    width: 100%;
    height: 100%;
    border: none;
}

.video-container.multi {
    display: grid;
    gap: 18px;
    aspect-ratio: auto;
    background: transparent;
    border: none;
    box-shadow: none;
}

.video-container.multi .video-frame {
    overflow: hidden;
    aspect-ratio: 16 / 9;
    border-radius: 22px;
    border: 1px solid var(--line);
    background: #eaf2fd;
    box-shadow: var(--shadow-soft);
}

.image-link-container img {
    width: 100%;
    max-width: 860px;
    margin: 0 auto;
    border-radius: 22px;
    border: 1px solid var(--line);
    box-shadow: var(--shadow-soft);
    object-fit: cover;
}

@media (prefers-reduced-motion: reduce) {
    html {
        scroll-behavior: auto;
    }

    body::before,
    .page-header .container::after,
    .card-media-image {
        animation: none;
    }

    .card,
    .material-btn,
    .material-btn::after {
        transition: none;
    }
}

.content-text {
    max-width: 860px;
    margin: 0 auto;
    padding: 28px 30px;
    border: 1px solid var(--line);
    border-radius: 24px;
    background: rgba(255, 255, 255, 0.96);
    color: var(--text);
    box-shadow: var(--shadow-soft);
    white-space: pre-line;
    font-size: 1rem;
    line-height: 1.8;
}

.content-text.is-rich {
    white-space: normal;
}

.content-text h2,
.content-text h3 {
    margin: 24px 0 10px;
    color: var(--text);
    line-height: 1.15;
    letter-spacing: -0.03em;
}

.content-text h2 {
    font-size: 1.45rem;
}

.content-text h3 {
    font-size: 1.2rem;
}

.content-text p {
    margin: 0 0 14px;
    color: var(--text);
}

.content-text ul,
.content-text ol {
    margin: 10px 0 18px 20px;
    display: grid;
    gap: 8px;
}

.content-text li {
    color: var(--text);
}

.content-text strong {
    color: #17335c;
}

.content-text code {
    padding: 2px 6px;
    border-radius: 6px;
    background: #eef5ff;
    color: #1a4fa3;
    font-family: Consolas, monospace;
}

.content-text sup {
    font-size: 0.8em;
}

.formula-block,
.tip-box,
.tips-box,
p[style*="background-color"],
div[style*="background-color: #f0f8ff"],
div[style*="background-color: #f9f9f9"],
div[style*="background-color: #fff"],
p[style*="background-color: #f9f9f9"],
p[style*="background-color: #f0f8ff"],
p[style*="background-color: white"],
div[style*="background: #f0f8ff"],
div[style*="background: #fff"] {
    margin: 18px 0;
    padding: 16px 18px;
    border-radius: 16px;
    border: 1px solid #cfe2fb !important;
    background: #f3f8ff !important;
    color: var(--text) !important;
    box-shadow: none !important;
}

.summary-cta {
    margin-top: 24px;
}

.summary-cta a {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 11px 16px;
    border-radius: 12px;
    background: var(--primary);
    color: #ffffff;
    font-size: 0.92rem;
    font-weight: 700;
}

.table-wrapper {
    width: 100%;
    overflow-x: auto;
    margin: 20px 0;
}

.content-table {
    width: 100%;
    min-width: 620px;
    border-collapse: collapse;
}

.content-table th,
.content-table td {
    padding: 12px;
    border: 1px solid var(--line);
    text-align: left;
    vertical-align: top;
}

.content-table thead tr {
    background: #eef5ff;
}

.navigation-buttons {
    display: flex;
    justify-content: space-between;
    gap: 14px;
    max-width: 860px;
    margin: 0 auto;
}

.nav-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-width: 0;
    flex: 1 1 0;
    padding: 12px 16px;
    border: 1px solid var(--line);
    border-radius: 14px;
    background: rgba(255, 255, 255, 0.96);
    color: var(--text);
    font-size: 0.92rem;
    font-weight: 700;
    box-shadow: var(--shadow-soft);
    transition: transform 0.2s ease, border-color 0.2s ease, box-shadow 0.2s ease;
}

.nav-btn:hover:not(:disabled) {
    transform: translateY(-2px);
    border-color: var(--line-strong);
    box-shadow: 0 12px 24px rgba(30, 80, 159, 0.08);
}

button.nav-btn {
    cursor: pointer;
}

button.nav-btn:disabled {
    cursor: not-allowed;
}

.nav-btn-home {
    background: #f4f8ff;
}

.footer {
    padding: 12px 0 34px;
}

.footer .container {
    padding: 18px;
    border: 1px solid var(--line);
    border-radius: 18px;
    background: rgba(255, 255, 255, 0.96);
    text-align: center;
}

.footer-text {
    color: var(--text-muted);
    font-size: 0.86rem;
}

.loading {
    padding: 22px;
    color: var(--primary-strong);
    text-align: center;
    font-weight: 700;
}

@media (max-width: 760px) {
    .container {
        width: min(100%, calc(100% - 24px));
    }

    .page-header .container,
    .content-text,
    .footer .container {
        padding: 22px 18px;
        border-radius: 18px;
    }

    .page-title {
        font-size: clamp(1.45rem, 6.8vw, 2.2rem);
        line-height: 1.08;
    }

    .section-subtitle,
    .card-copy,
    .content-text,
    .nav-btn,
    .material-btn {
        font-size: 0.92rem;
    }

    .cards-grid,
    .navigation-buttons {
        grid-template-columns: 1fr;
    }

    .navigation-buttons {
        display: grid;
    }

    .nav-btn,
    .material-btn {
        width: 100%;
    }

    .material-btn {
        align-items: flex-start;
    }

    .video-container,
    .video-container.multi .video-frame,
    .image-link-container img {
        border-radius: 18px;
    }
}