/* ========================================
   项目研究基础展示页面 — 学术风格
   配色：蓝灰 / 白色系
   ======================================== */

/* ---------- Reset & Base ---------- */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
    scroll-padding-top: 70px;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
    line-height: 1.75;
    color: #2d3748;
    background-color: #f7f8fc;
}

.container {
    max-width: 1160px;
    margin: 0 auto;
    padding: 0 24px;
}

/* ---------- 顶部导航 ---------- */
.top-nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(8px);
    border-bottom: 1px solid #e2e8f0;
    transition: box-shadow 0.3s;
}

.top-nav.scrolled {
    box-shadow: 0 2px 16px rgba(0, 0, 0, 0.08);
}

.nav-container {
    max-width: 1160px;
    margin: 0 auto;
    padding: 0 24px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 56px;
}

.nav-brand {
    font-size: 1rem;
    font-weight: 600;
    color: #1a365d;
    letter-spacing: 0.5px;
}

.nav-links {
    display: flex;
    list-style: none;
    gap: 4px;
}

.nav-links a {
    display: block;
    padding: 6px 14px;
    font-size: 0.9rem;
    color: #4a5568;
    text-decoration: none;
    border-radius: 6px;
    transition: color 0.2s, background 0.2s;
}

.nav-links a:hover,
.nav-links a.active {
    color: #2b6cb0;
    background: #ebf4ff;
}

.nav-links a:focus-visible,
.back-to-top:focus-visible {
    outline: 2px solid #3182ce;
    outline-offset: 2px;
}

.nav-toggle {
    display: none;
    flex-direction: column;
    gap: 4px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 4px;
}

.nav-toggle span {
    display: block;
    width: 20px;
    height: 2px;
    background: #4a5568;
    border-radius: 1px;
    transition: transform 0.2s;
}

/* ---------- Hero ---------- */
.hero {
    background: linear-gradient(135deg, #1a365d 0%, #2c5282 40%, #2b6cb0 100%);
    color: white;
    padding: 100px 0 60px;
    text-align: center;
    margin-top: 56px;
}

.hero-title {
    font-size: 2.4rem;
    font-weight: 700;
    margin-bottom: 14px;
    letter-spacing: 2px;
}

.hero-subtitle {
    font-size: 1.1rem;
    opacity: 0.92;
    font-weight: 400;
    margin-bottom: 12px;
    max-width: 860px;
    line-height: 1.75;
    margin-left: auto;
    margin-right: auto;
}

.hero-positioning {
    font-size: 0.95rem;
    opacity: 0.78;
    margin-bottom: 20px;
    font-style: italic;
}

.hero-description {
    font-size: 1rem;
    opacity: 0.9;
    max-width: 760px;
    margin: 0 auto 30px;
    line-height: 1.85;
    text-align: left;
}

.hero-figure-placeholder {
    max-width: 680px;
    margin: 0 auto;
}

.hero-figure {
    max-width: 900px;
    margin: 0 auto;
    background: rgba(255, 255, 255, 0.95);
    border-radius: 10px;
    padding: 16px;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.15);
}

.hero-figure-img {
    width: 100%;
    height: auto;
    display: block;
    border-radius: 6px;
}

.placeholder-box {
    background: rgba(255, 255, 255, 0.1);
    border: 2px dashed rgba(255, 255, 255, 0.3);
    border-radius: 10px;
    padding: 40px 24px;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 8px;
}

.placeholder-icon {
    font-size: 2rem;
    opacity: 0.7;
}

.placeholder-text {
    font-size: 0.85rem;
    opacity: 0.6;
}

/* ---------- 通用 Section ---------- */
.main {
    padding: 48px 0 24px;
}

.section {
    margin-bottom: 56px;
}

.section-title {
    display: flex;
    flex-direction: column;
    margin-bottom: 28px;
}

.section-title-zh {
    font-size: 1.5rem;
    color: #1a365d;
    font-weight: 600;
    padding-bottom: 8px;
    border-bottom: 3px solid #3182ce;
    display: inline-block;
    align-self: flex-start;
}

.section-title-en {
    font-size: 0.86rem;
    color: #718096;
    font-weight: 400;
    margin-top: 4px;
    letter-spacing: 0.5px;
}

/* ---------- 研究内容总览（三栏 + 箭头） ---------- */
.overview-flow {
    display: flex;
    align-items: stretch;
    gap: 0;
}

.overview-card {
    flex: 1;
    background: white;
    border-radius: 10px;
    padding: 28px 22px;
    box-shadow: 0 2px 12px rgba(0, 0, 0, 0.06);
    border-top: 4px solid #3182ce;
    transition: transform 0.2s, box-shadow 0.2s;
    cursor: pointer;
    text-decoration: none;
    color: inherit;
    display: flex;
    flex-direction: column;
}

.overview-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 8px 28px rgba(0, 0, 0, 0.1);
}

.overview-card-number {
    font-size: 2rem;
    font-weight: 700;
    color: #bee3f8;
    margin-bottom: 8px;
    line-height: 1;
}

.overview-card-title {
    font-size: 1.05rem;
    font-weight: 600;
    color: #1a365d;
    margin-bottom: 6px;
}

.overview-card-en {
    font-size: 0.78rem;
    color: #718096;
    margin-bottom: 12px;
}

.overview-card-summary {
    font-size: 0.88rem;
    color: #4a5568;
    line-height: 1.7;
    flex: 1;
}

.overview-arrow {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 48px;
    min-width: 48px;
    color: #a0aec0;
    font-size: 1.5rem;
    flex-shrink: 0;
}

.overview-arrow svg {
    width: 28px;
    height: 28px;
}

/* ---------- 研究内容模块 ---------- */
.rc-section {
    padding-top: 8px;
}

.rc-module {
    background: white;
    border-radius: 12px;
    box-shadow: 0 2px 16px rgba(0, 0, 0, 0.06);
    overflow: hidden;
}

.rc-header {
    background: linear-gradient(135deg, #ebf4ff 0%, #f0f7ff 100%);
    padding: 28px 32px;
    border-bottom: 1px solid #e2e8f0;
}

.rc-number-badge {
    display: inline-block;
    background: #3182ce;
    color: white;
    font-size: 0.75rem;
    font-weight: 600;
    padding: 3px 12px;
    border-radius: 20px;
    margin-bottom: 10px;
    letter-spacing: 1px;
}

.rc-header h3 {
    font-size: 1.35rem;
    color: #1a365d;
    margin-bottom: 4px;
    font-weight: 600;
}

.rc-header .rc-en-title {
    font-size: 0.84rem;
    color: #718096;
}

.rc-body {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 0;
}

.rc-left {
    padding: 28px 32px;
    border-right: 1px solid #edf2f7;
}

.rc-right {
    padding: 28px 32px;
    display: flex;
    flex-direction: column;
    gap: 24px;
}

/* 子块标签 */
.rc-block {
    margin-bottom: 24px;
}

.rc-block:last-child {
    margin-bottom: 0;
}

.rc-block-label {
    display: flex;
    align-items: center;
    gap: 8px;
    margin-bottom: 10px;
}

.rc-label-tag {
    display: inline-block;
    font-size: 0.8rem;
    font-weight: 600;
    padding: 3px 10px;
    border-radius: 4px;
    letter-spacing: 0.5px;
}

.rc-label-tag.tag-foundation {
    background: #ebf8ff;
    color: #2b6cb0;
}

.rc-label-tag.tag-gap {
    background: #fefcbf;
    color: #975a16;
}

.rc-label-tag.tag-breakthrough {
    background: #f0fff4;
    color: #276749;
}

.rc-label-tag.tag-evidence {
    background: #faf5ff;
    color: #6b46c1;
}

.rc-label-en {
    font-size: 0.72rem;
    color: #cbd5e0;
    font-style: italic;
}

.rc-block ul {
    list-style: none;
    padding: 0;
}

.rc-block li {
    position: relative;
    padding: 5px 0 5px 18px;
    font-size: 0.9rem;
    color: #4a5568;
    line-height: 1.75;
}

.rc-block li::before {
    content: "";
    position: absolute;
    left: 0;
    top: 13px;
    width: 6px;
    height: 6px;
    border-radius: 50%;
}

.rc-block.block-foundation li::before {
    background: #3182ce;
}

.rc-block.block-gap li::before {
    background: #d69e2e;
}

.rc-block.block-breakthrough li::before {
    background: #38a169;
}

/* 图示（实际图片） */
.rc-figure {
    background: #fff;
    border: 1px solid #e2e8f0;
    border-radius: 8px;
    padding: 12px;
    text-align: center;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.06);
}

.rc-figure-img {
    width: 100%;
    height: auto;
    display: block;
    border-radius: 4px;
}

/* 图示占位 */
.rc-figure-placeholder {
    background: #f7fafc;
    border: 2px dashed #e2e8f0;
    border-radius: 8px;
    padding: 32px 16px;
    text-align: center;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 6px;
}

.rc-figure-placeholder .placeholder-icon {
    font-size: 1.8rem;
    color: #a0aec0;
}

.rc-figure-caption {
    font-size: 0.78rem;
    color: #718096;
    margin-top: 4px;
}

/* 链接卡片 */
.evidence-cards {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.evidence-card {
    display: flex;
    align-items: center;
    gap: 14px;
    padding: 14px 16px;
    background: #f7fafc;
    border: 1px solid #e2e8f0;
    border-radius: 8px;
    text-decoration: none;
    color: inherit;
    transition: border-color 0.2s, box-shadow 0.2s;
}

.evidence-card:hover {
    border-color: #90cdf4;
    box-shadow: 0 2px 8px rgba(49, 130, 206, 0.1);
}

/* 视频封面缩略图 */
.evidence-card.has-thumbnail {
    flex-direction: column;
    padding: 0;
    overflow: hidden;
}

.evidence-card.has-thumbnail .evidence-card-body {
    padding: 12px 16px 4px;
}

.evidence-card.has-thumbnail .evidence-card-meta {
    padding: 0 16px 12px;
    flex-direction: row;
    align-items: center;
}

.evidence-card-thumb {
    position: relative;
    width: 100%;
    height: 0;
    padding-bottom: 56.25%;
    overflow: hidden;
    background: #1a365d;
    flex-shrink: 0;
}

.evidence-card-thumb img {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform 0.3s;
}

.evidence-card:hover .evidence-card-thumb img {
    transform: scale(1.05);
}

.evidence-card-play {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 44px;
    height: 44px;
    background: rgba(0, 0, 0, 0.55);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 1.1rem;
    transition: background 0.2s;
    pointer-events: none;
}

.evidence-card:hover .evidence-card-play {
    background: rgba(49, 130, 206, 0.85);
}

/* 资源列表缩略图 */
.resource-item-thumb {
    width: 56px;
    height: 42px;
    border-radius: 4px;
    overflow: hidden;
    flex-shrink: 0;
    background: #edf2f7;
}

.resource-item-thumb img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.evidence-card-icon {
    width: 40px;
    height: 40px;
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.1rem;
    flex-shrink: 0;
}

.evidence-card-icon.icon-bilibili {
    background: #fb7299;
    color: white;
}

.evidence-card-icon.icon-huggingface {
    background: #ffbd59;
    color: white;
}

.evidence-card-icon.icon-paper {
    background: #3182ce;
    color: white;
}

.evidence-card-icon.icon-github {
    background: #24292e;
    color: white;
}

.evidence-card-icon.icon-demo {
    background: #38a169;
    color: white;
}

.evidence-card-body {
    flex: 1;
    min-width: 0;
}

.evidence-card-title {
    font-size: 0.88rem;
    font-weight: 600;
    color: #2d3748;
    margin-bottom: 2px;
}

.evidence-card-desc {
    font-size: 0.78rem;
    color: #718096;
}

.evidence-card-meta {
    display: flex;
    flex-direction: column;
    align-items: flex-end;
    gap: 4px;
    flex-shrink: 0;
}

.evidence-platform-badge {
    font-size: 0.68rem;
    font-weight: 500;
    padding: 2px 8px;
    border-radius: 3px;
    background: #edf2f7;
    color: #4a5568;
}

.evidence-status-badge {
    font-size: 0.65rem;
    font-weight: 500;
    padding: 2px 8px;
    border-radius: 3px;
}

.status-published {
    background: #c6f6d5;
    color: #276749;
}

.status-submitted {
    background: #fefcbf;
    color: #975a16;
}

.status-internal {
    background: #e9d8fd;
    color: #553c9a;
}

.status-pending {
    background: #fed7d7;
    color: #9b2c2c;
}

/* ---------- 项目可行性总结 ---------- */
.summary-content {
    background: white;
    border-radius: 12px;
    box-shadow: 0 2px 16px rgba(0, 0, 0, 0.06);
    padding: 32px;
}

.summary-strengths {
    list-style: none;
    padding: 0;
    margin-bottom: 24px;
}

.summary-strengths li {
    position: relative;
    padding: 10px 0 10px 32px;
    font-size: 0.95rem;
    color: #2d3748;
    line-height: 1.8;
    border-bottom: 1px solid #edf2f7;
}

.summary-strengths li:last-child {
    border-bottom: none;
}

.summary-strengths li::before {
    content: "✓";
    position: absolute;
    left: 0;
    top: 10px;
    width: 22px;
    height: 22px;
    background: #38a169;
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.72rem;
    font-weight: 700;
}

.summary-note {
    background: linear-gradient(135deg, #ebf4ff 0%, #f0f7ff 100%);
    border-left: 4px solid #3182ce;
    border-radius: 0 8px 8px 0;
    padding: 20px 24px;
    font-size: 0.92rem;
    color: #2c5282;
    line-height: 1.85;
}

/* ---------- 资源链接区 ---------- */
.resources-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 24px;
}

.resource-category {
    background: white;
    border-radius: 10px;
    box-shadow: 0 2px 12px rgba(0, 0, 0, 0.06);
    padding: 24px;
}

.resource-category-title {
    font-size: 1rem;
    font-weight: 600;
    color: #1a365d;
    margin-bottom: 16px;
    padding-bottom: 8px;
    border-bottom: 2px solid #e2e8f0;
}

.resource-list {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.resource-item {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 10px 12px;
    border: 1px solid #edf2f7;
    border-radius: 6px;
    text-decoration: none;
    color: inherit;
    transition: border-color 0.2s, background 0.2s;
}

.resource-item:hover {
    border-color: #90cdf4;
    background: #f7fafc;
}

.resource-item-icon {
    width: 32px;
    height: 32px;
    border-radius: 6px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.9rem;
    flex-shrink: 0;
}

.resource-item-body {
    flex: 1;
    min-width: 0;
}

.resource-item-title {
    font-size: 0.85rem;
    font-weight: 600;
    color: #2d3748;
}

.resource-item-desc {
    font-size: 0.75rem;
    color: #718096;
}

.evidence-card-thumb img.is-fallback,
.resource-item-thumb img.is-fallback {
    object-fit: contain;
    padding: 8px;
    background: #f7fafc;
}

.resource-item-status {
    font-size: 0.65rem;
    font-weight: 500;
    padding: 2px 8px;
    border-radius: 3px;
    flex-shrink: 0;
}

/* ---------- 实验平台 ---------- */
.platforms-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
    gap: 16px;
}

.platform-card {
    background: white;
    border-radius: 10px;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.05);
    padding: 24px 16px;
    text-align: center;
    transition: transform 0.2s;
}

.platform-card:hover {
    transform: translateY(-3px);
}

.platform-card-icon {
    font-size: 2rem;
    margin-bottom: 10px;
    display: block;
}

.platform-card-label {
    font-size: 0.9rem;
    font-weight: 600;
    color: #1a365d;
    margin-bottom: 4px;
}

.platform-card-desc {
    font-size: 0.78rem;
    color: #718096;
}

/* ---------- 页脚 ---------- */
.footer {
    background: #1a365d;
    color: white;
    padding: 28px 0;
    text-align: center;
}

.footer p {
    font-size: 0.85rem;
    opacity: 0.85;
    margin: 4px 0;
}

/* ---------- 回到顶部 ---------- */
.back-to-top {
    position: fixed;
    bottom: 32px;
    right: 32px;
    width: 40px;
    height: 40px;
    border-radius: 50%;
    background: #3182ce;
    color: white;
    border: none;
    font-size: 1.1rem;
    cursor: pointer;
    box-shadow: 0 2px 12px rgba(49, 130, 206, 0.3);
    opacity: 0;
    transform: translateY(10px);
    transition: opacity 0.3s, transform 0.3s;
    z-index: 999;
}

.back-to-top.visible {
    opacity: 1;
    transform: translateY(0);
}

.back-to-top:hover {
    background: #2b6cb0;
}

/* ---------- 响应式 ---------- */
@media (max-width: 900px) {
    .rc-body {
        grid-template-columns: 1fr;
    }

    .rc-left {
        border-right: none;
        border-bottom: 1px solid #edf2f7;
    }

    .overview-flow {
        flex-direction: column;
        gap: 12px;
    }

    .overview-arrow {
        width: auto;
        min-width: auto;
        height: 32px;
        transform: rotate(90deg);
    }

    .resources-content {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 768px) {
    .hero {
        padding: 80px 0 40px;
    }

    .hero-title {
        font-size: 1.7rem;
    }

    .hero-subtitle {
        font-size: 0.95rem;
    }

    .nav-toggle {
        display: flex;
    }

    .nav-links {
        display: none;
        position: absolute;
        top: 56px;
        left: 0;
        right: 0;
        background: white;
        flex-direction: column;
        padding: 12px 24px;
        border-bottom: 1px solid #e2e8f0;
        box-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
    }

    .nav-links.open {
        display: flex;
    }

    .rc-header {
        padding: 20px;
    }

    .rc-left,
    .rc-right {
        padding: 20px;
    }

    .section-title-zh {
        font-size: 1.3rem;
    }

    .platforms-grid {
        grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
    }
}

@media (max-width: 480px) {
    .hero-title {
        font-size: 1.4rem;
    }

    .evidence-card {
        flex-direction: column;
        align-items: flex-start;
        gap: 8px;
    }

    .evidence-card-meta {
        flex-direction: row;
        align-items: center;
    }
}