/* ============================================
   Apple Design Language — Portfolio Styles
   ============================================ */

:root {
    /* 背景层级 */
    --bg: #f5f5f7;
    --bg-secondary: #ffffff;
    --bg-tertiary: #f2f2f7;

    /* 文字层级 */
    --text: #1d1d1f;
    --text-secondary: #86868b;
    --text-tertiary: #a1a1a6;

    /* 边框与分割线 */
    --line: rgba(0, 0, 0, 0.06);
    --line-solid: #d2d2d7;

    /* 强调色 */
    --accent: #1d1d1f;
    --accent-blue: #0066cc;

    /* 阴影 — 多层极淡阴影营造物理感 */
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.04);
    --shadow-md: 0 8px 24px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 16px 48px rgba(0, 0, 0, 0.08);

    /* 圆角 */
    --radius-sm: 12px;
    --radius-md: 18px;
    --radius-lg: 24px;

    /* 布局 */
    --max-width: 980px;

    /* 动画曲线 */
    --ease-spring: cubic-bezier(0.16, 1, 0.3, 1);
    --ease-out: cubic-bezier(0.25, 0.1, 0.25, 1);
}

/* ===== 暗色模式 ===== */
@media (prefers-color-scheme: dark) {
    :root {
        --bg: #000000;
        --bg-secondary: #1c1c1e;
        --bg-tertiary: #2c2c2e;
        --text: #f5f5f7;
        --text-secondary: #a1a1a6;
        --text-tertiary: #8e8e93;
        --line: rgba(255, 255, 255, 0.08);
        --line-solid: #38383a;
        --accent: #ffffff;
        --accent-blue: #0a84ff;
        --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.3);
        --shadow-md: 0 8px 24px rgba(0, 0, 0, 0.4);
        --shadow-lg: 0 16px 48px rgba(0, 0, 0, 0.5);
    }

    body {
        -webkit-font-smoothing: antialiased;
        -moz-osx-font-smoothing: grayscale;
    }
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: "Inter", "Noto Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.7;
    padding: 48px 20px 48px;
    -webkit-font-smoothing: antialiased;
}

.container {
    max-width: var(--max-width);
    margin: 0 auto;
}

/* ===== Header ===== */
header {
    display: flex;
    align-items: flex-start;
    justify-content: space-between;
    gap: 40px;
    flex-wrap: wrap;
    margin-bottom: 32px;
}

.header-text {
    flex: 1;
    min-width: 0;
}

.profile-photo {
    flex-shrink: 0;
    width: 140px;
    aspect-ratio: 4 / 5;
    border-radius: 12px;
    overflow: hidden;
    border: 1px solid var(--line);
    box-shadow: var(--shadow-sm);
    background: var(--bg-tertiary);
    transition: transform 0.4s var(--ease-out), box-shadow 0.4s ease;
    margin-top: -4px;
}

.profile-photo:hover {
    transform: scale(1.02);
    box-shadow: var(--shadow-md);
}

.profile-photo img {
    display: block;
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.name {
    font-size: 2rem;
    font-weight: 600;
    letter-spacing: 0;
    line-height: 1.1;
    margin-bottom: 28px;
    display: flex;
    align-items: baseline;
    flex-wrap: wrap;
    gap: 0.4em;
}

.name-en {
    font-size: 1.35rem;
    font-weight: 400;
    color: var(--text-secondary);
    letter-spacing: 0.02em;
    opacity: 0.85;
}

.intro {
    font-size: 1.0625rem;
    line-height: 1.6;
    color: var(--text-secondary);
    max-width: 640px;
    margin-bottom: 24px;
}

.contact {
    display: flex;
    flex-wrap: wrap;
    gap: 16px;
    font-size: 0.9375rem;
}

.contact a {
    color: var(--accent-blue);
    text-decoration: none;
    font-weight: 500;
    transition: all 0.2s ease;
    position: relative;
}

.contact a::after {
    content: " ↗";
    font-size: 0.85em;
    opacity: 0.6;
    transition: transform 0.2s ease;
    display: inline-block;
}

.contact a:hover {
    opacity: 0.8;
}

.contact a:hover::after {
    transform: translate(2px, -2px);
}

/* ===== Navigation ===== */
nav {
    position: sticky;
    top: 0;
    z-index: 100;
    backdrop-filter: blur(20px) saturate(180%);
    -webkit-backdrop-filter: blur(20px) saturate(180%);
    background: rgba(245, 245, 247, 0.72);
    border-bottom: 1px solid var(--line);
    margin-bottom: 48px;
    padding: 16px 0;
    transition: transform 0.4s var(--ease-out), opacity 0.3s ease, background 0.3s ease;
}

nav ul {
    list-style: none;
    display: flex;
    gap: 28px;
    overflow-x: auto;
    margin: 0;
    padding: 4px 0;
    align-items: center;
    scrollbar-width: none;
    -ms-overflow-style: none;
}

nav ul::-webkit-scrollbar {
    display: none;
}

nav a {
    text-decoration: none;
    color: var(--text-secondary);
    font-size: 0.9375rem;
    font-weight: 500;
    transition: color 0.2s ease;
    white-space: nowrap;
    display: inline-flex;
    align-items: center;
    padding: 4px 0;
}

nav a:hover {
    color: var(--text);
}

/* ===== Sections ===== */
section {
    margin-bottom: 56px;
    scroll-margin-top: 80px;
}

.section-title {
    font-size: 1.25rem;
    font-weight: 600;
    letter-spacing: -0.01em;
    margin-bottom: 24px;
    padding-bottom: 12px;
    border-bottom: 1px solid var(--line);
    color: var(--text);
}

/* ===== Collapsible Cards ===== */
.card.collapsible,
.research-theme.collapsible-area {
    background: var(--bg-secondary);
    border: none;
    border-radius: var(--radius-md);
    padding: 28px;
    margin-bottom: 16px;
    box-shadow: var(--shadow-sm);
    transition: transform 0.4s var(--ease-out), box-shadow 0.4s ease, border-color 0.3s ease;
    cursor: pointer;
    position: relative;
    overflow: hidden;
    outline: none;
}

.card.collapsible:hover,
.research-theme.collapsible-area:hover {
    transform: scale(1.005);
    box-shadow: var(--shadow-md);
}

.card.collapsible:active,
.research-theme.collapsible-area:active {
    transform: scale(0.998);
    transition-duration: 0.1s;
}

.card.collapsible:focus-visible,
.research-theme.collapsible-area:focus-visible {
    box-shadow: 0 0 0 3px rgba(0, 102, 204, 0.25), var(--shadow-md);
}

.card-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 16px;
}

.card-title {
    display: flex;
    justify-content: space-between;
    align-items: baseline;
    gap: 10px;
    flex-wrap: wrap;
    width: 100%;
    min-width: 0;
}

.card-title h3 {
    font-size: 1.0625rem;
    font-weight: 600;
    letter-spacing: -0.01em;
    white-space: nowrap;
}

.date {
    color: var(--text-secondary);
    font-size: 0.9rem;
    font-weight: 500;
    white-space: nowrap;
}

.subtitle {
    color: var(--text-secondary);
    font-size: 0.9375rem;
    font-weight: 500;
    margin-top: 4px;
    margin-bottom: 0;
}

.expand-icon {
    display: inline-block;
    font-size: 0.9rem;
    color: var(--text-secondary);
    transition: transform 0.4s var(--ease-spring), color 0.2s ease;
    flex-shrink: 0;
    width: 20px;
    text-align: center;
    user-select: none;
}

.card.open .expand-icon,
.research-theme.active .expand-icon {
    transform: rotate(90deg);
    color: var(--text);
}

.card-content {
    max-height: 0;
    overflow: hidden;
    opacity: 0;
    transition: max-height 0.5s var(--ease-spring), opacity 0.35s ease, margin-top 0.4s ease;
    margin-top: 0;
    will-change: max-height, opacity;
}

.card.open .card-content {
    margin-top: 16px;
    opacity: 1;
}

.card-content li strong {
    color: var(--text);
    font-weight: 600;
}

/* ===== Typography ===== */
p {
    margin-bottom: 12px;
}

ul {
    padding-left: 18px;
    margin-bottom: 12px;
}

li {
    margin-bottom: 8px;
    color: var(--text-secondary);
}

li strong {
    color: var(--text);
}

/* ===== Tags ===== */
.tag-group {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin-top: 14px;
}

.tag {
    display: inline-flex;
    align-items: center;
    padding: 5px 12px;
    border-radius: 100px;
    background: var(--bg-tertiary);
    color: var(--text-secondary);
    font-size: 0.8125rem;
    font-weight: 500;
    letter-spacing: -0.01em;
    border: 1px solid var(--line);
    transition: all 0.2s ease;
    cursor: default;
}

.tag:hover {
    background: var(--line-solid);
    color: var(--text);
    transform: scale(1.05);
}

/* ===== Projects ===== */
.project-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(360px, 1fr));
    gap: 18px;
}

.project-card {
    background: var(--bg-secondary);
    border: none;
    border-radius: var(--radius-md);
    padding: 24px;
    box-shadow: var(--shadow-sm);
    transition: transform 0.4s var(--ease-out), box-shadow 0.4s ease, opacity 0.8s var(--ease-spring), transform 0.8s var(--ease-spring);
    opacity: 0;
    transform: translateY(30px);
}

.project-card.reveal {
    opacity: 1;
    transform: translateY(0);
}

.project-card:hover {
    transform: translateY(-3px) scale(1.005);
    box-shadow: var(--shadow-md);
}

.project-card.reveal:hover {
    transform: translateY(-3px) scale(1.005);
}

.project-card h3 {
    font-size: 1.0625rem;
    font-weight: 600;
    margin-bottom: 10px;
    letter-spacing: -0.01em;
}

.project-card p {
    color: var(--text-secondary);
    font-size: 0.94rem;
    margin-bottom: 14px;
    line-height: 1.6;
}

.project-links {
    display: flex;
    gap: 16px;
    margin-bottom: 14px;
}

.project-links a {
    text-decoration: none;
    font-size: 0.92rem;
    color: var(--accent-blue);
    font-weight: 500;
    transition: all 0.2s ease;
}

.project-links a:hover {
    opacity: 0.8;
}

.project-links a::after {
    content: " ↗";
    font-size: 0.85em;
    opacity: 0.6;
    transition: transform 0.2s ease;
    display: inline-block;
}

.project-links a:hover::after {
    transform: translate(2px, -2px);
}

/* ===== Awards ===== */
.awards-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(170px, 1fr));
    gap: 12px;
}

.award-item {
    background: var(--bg-secondary);
    border: none;
    border-radius: var(--radius-sm);
    padding: 16px;
    box-shadow: var(--shadow-sm);
    transition: transform 0.3s ease, box-shadow 0.3s ease, opacity 0.7s var(--ease-spring), transform 0.7s var(--ease-spring);
    opacity: 0;
    transform: translateY(20px);
}

.award-item.reveal {
    opacity: 1;
    transform: translateY(0);
}

.award-item:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-md);
}

.award-title {
    font-size: 0.9rem;
    font-weight: 600;
    margin-bottom: 6px;
    letter-spacing: -0.01em;
    line-height: 1.4;
}

.award-year {
    font-size: 0.8rem;
    color: var(--text-secondary);
    font-weight: 500;
}

/* ===== Research Themes ===== */
.research-theme.collapsible-area {
    padding: 24px 28px;
}

.theme-main {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 24px;
    cursor: pointer;
}

.theme-info {
    flex: 1;
    min-width: 0;
}

.theme-title {
    font-size: 1.0625rem;
    font-weight: 600;
    margin-bottom: 6px;
    color: var(--text);
    letter-spacing: -0.01em;
}

.theme-desc {
    font-size: 0.9375rem;
    line-height: 1.6;
    color: var(--text-secondary);
    margin-bottom: 0;
}

.theme-meta {
    display: flex;
    align-items: center;
    gap: 18px;
    flex-shrink: 0;
}

.theme-time {
    font-size: 0.9rem;
    color: var(--text-secondary);
    white-space: nowrap;
    font-weight: 500;
}

.theme-content {
    max-height: 0;
    overflow: hidden;
    opacity: 0;
    transition: max-height 0.5s var(--ease-spring), opacity 0.35s ease, margin-top 0.4s ease;
    margin-top: 0;
    will-change: max-height, opacity;
}

.research-theme.active .theme-content {
    margin-top: 20px;
    opacity: 1;
}

/* ===== Research Cards ===== */
.research-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 18px;
}

.research-card {
    border: none;
    border-radius: var(--radius-sm);
    padding: 24px;
    background: var(--bg-tertiary);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
    cursor: default;
}

.research-card:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-sm);
}

.research-meta {
    font-size: 0.72rem;
    text-transform: uppercase;
    letter-spacing: 0.06em;
    color: var(--text-tertiary);
    margin-bottom: 12px;
    font-weight: 600;
}

.research-card-title {
    font-size: 1rem;
    line-height: 1.5;
    margin-bottom: 10px;
    color: var(--text);
    font-weight: 600;
    letter-spacing: -0.01em;
}

.research-text {
    font-size: 0.92rem;
    line-height: 1.7;
    color: var(--text-secondary);
    margin-bottom: 16px;
}

.publication-info {
    display: flex;
    align-items: baseline;
    flex-wrap: wrap;
    gap: 12px;
    font-size: 0.88rem;
    color: var(--text-secondary);
    margin-bottom: 14px;
}

.publication-info .journal {
    font-style: italic;
    font-weight: 500;
}

.doi-link {
    color: var(--accent-blue);
    background: rgba(0, 102, 204, 0.06);
    padding: 3px 10px;
    border-radius: 6px;
    font-size: 0.8125rem;
    font-weight: 600;
    text-decoration: none;
    transition: all 0.2s ease;
    border: 1px solid transparent;
}

.doi-link:hover {
    background: rgba(0, 102, 204, 0.12);
    border-color: rgba(0, 102, 204, 0.15);
}

.doi-link::after {
    content: " ↗";
    font-size: 0.8em;
    opacity: 0.6;
    transition: transform 0.2s ease;
    display: inline-block;
}

.doi-link:hover::after {
    transform: translate(2px, -2px);
}

/* ===== Photography ===== */
.photo-grid {
    display: flex;
    gap: 12px;
    align-items: flex-start;
}

.photo-column {
    display: flex;
    flex-direction: column;
    gap: 12px;
    flex: 1;
    min-width: 0;
}

.photo-item {
    background: var(--bg-tertiary);
    border-radius: 10px;
    overflow: hidden;
    box-shadow: var(--shadow-sm);
    transition: box-shadow 0.4s ease;
    cursor: default;
}

.photo-item:hover {
    box-shadow: var(--shadow-md);
}

.photo-item img {
    display: block;
    width: 100%;
    height: auto;
    -webkit-user-drag: none;
}

.photo-links {
    display: flex;
    justify-content: flex-start;
    align-items: center;
    gap: 16px;
    margin-top: 32px;
    padding-top: 24px;
    border-top: 1px solid var(--line);
    flex-wrap: wrap;
}

.photo-links-label {
    color: var(--text-secondary);
    font-size: 0.9375rem;
    font-weight: 500;
}

.photo-links a {
    color: var(--accent-blue);
    text-decoration: none;
    font-weight: 500;
    font-size: 0.9375rem;
    transition: all 0.2s ease;
}

.photo-links a::after {
    content: " ↗";
    font-size: 0.85em;
    opacity: 0.6;
    transition: transform 0.2s ease;
    display: inline-block;
}

.photo-links a:hover {
    opacity: 0.8;
}

.photo-links a:hover::after {
    transform: translate(2px, -2px);
}

/* ===== Footer ===== */
footer {
    margin-top: 80px;
    padding-top: 24px;
    border-top: 1px solid var(--line);
    color: var(--text-secondary);
    font-size: 0.9rem;
    text-align: center;
    font-weight: 500;
}

/* ===== Scroll Reveal Animation ===== */
section,
.card.collapsible,
.research-theme.collapsible-area {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.8s var(--ease-spring), transform 0.8s var(--ease-spring);
}

section.reveal,
.card.collapsible.reveal,
.research-theme.collapsible-area.reveal {
    opacity: 1;
    transform: translateY(0);
}


/* ===== Reduced Motion ===== */
@media (prefers-reduced-motion: reduce) {

    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
        scroll-behavior: auto !important;
    }

    .reveal,
    section.reveal,
    .card.collapsible.reveal,
    .research-theme.reveal,
    .project-card.reveal,
    .award-item.reveal,
    .photo-item.reveal {
        opacity: 1;
        transform: none;
    }
}

/* ===== Responsive: Tablet ===== */
@media (max-width: 1024px) {
    .container {
        max-width: 92vw;
    }

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

/* ===== Responsive: Mobile Landscape ===== */
@media (max-width: 768px) {
    body {
        padding: 32px 16px;
    }

    .name {
        font-size: 2.4rem;
    }

    .photo-grid {
        gap: 10px;
    }

    .photo-column {
        gap: 10px;
    }

    .awards-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 10px;
    }

    .award-item {
        padding: 14px;
    }

    nav ul {
        gap: 20px;
    }

    nav a {
        font-size: 0.9375rem;
        padding: 6px 0;
    }
}

/* ===== Responsive: Mobile Portrait ===== */
@media (max-width: 640px) {
    header {
        flex-direction: column;
        align-items: center;
        text-align: center;
        gap: 24px;
    }

    .profile-photo {
        width: 120px;
        aspect-ratio: 1 / 1;
        border-radius: 50%;
        margin: 0 auto;
    }

    .profile-photo img {
        object-position: center 20%;
    }

    .header-text {
        display: flex;
        flex-direction: column;
        align-items: center;
    }

    .intro {
        text-align: center;
    }

    .contact {
        justify-content: center;
    }

    .card.collapsible,
    .research-theme.collapsible-area {
        padding: 22px;
        border-radius: var(--radius-sm);
    }

    .card-header {
        align-items: flex-start;
    }

    .card-title {
        flex-direction: column;
        gap: 4px;
    }

    .card-title h3 {
        white-space: normal;
    }

    .theme-main {
        flex-direction: column;
        align-items: flex-start;
        gap: 12px;
    }

    .theme-meta {
        width: 100%;
        justify-content: space-between;
    }

    .research-grid,
    .project-grid {
        grid-template-columns: 1fr;
    }

    .photo-grid {
        gap: 10px;
    }
}

/* ===== Responsive: Small Mobile ===== */
@media (max-width: 480px) {
    .name {
        font-size: 2rem;
    }

    .name-en {
        font-size: 1.35rem;
        font-weight: 400;
        color: var(--text-secondary);
        letter-spacing: 0.02em;
        opacity: 0.85;
    }

    .contact {
        flex-direction: column;
        gap: 8px;
        align-items: center;
    }

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

    .award-item {
        padding: 12px;
    }

    .award-title {
        font-size: 0.85rem;
    }

    .photo-links {
        flex-direction: column;
        align-items: flex-start;
        gap: 10px;
    }
}