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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Helvetica Neue', Arial, sans-serif;
    background: #000000;
    color: #ffffff;
    line-height: 1.6;
    overflow-x: hidden;
}

/* ===== Navigation Bar - Apple Style Frosted Glass ===== */
.navbar {
    position: fixed;
    top: 1rem;
    left: 50%;
    transform: translateX(-50%);
    width: calc(100% - 3rem);
    max-width: 1400px;
    z-index: 1000;
    padding: 0.875rem 2rem;
    background: rgba(20, 20, 30, 0.3);
    backdrop-filter: blur(30px);
    -webkit-backdrop-filter: blur(30px);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 16px;
    transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
}

/* Navigation Bar Hidden State */
.navbar.hidden {
    transform: translateX(-50%) translateY(-150%);
}

/* Navigation Bar Compact Style */
.navbar.compact {
    top: 0.75rem;
    width: calc(100% - 4rem);
    max-width: 1600px;
    padding: 0.625rem 1.5rem;
    border-radius: 12px;
}

.navbar.compact .logo {
    font-size: 1.25rem;
}

.navbar.compact .nav-links a {
    font-size: 13px;
}

.navbar-content {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.5rem;
    font-weight: 600;
    color: #ffffff;
    text-decoration: none;
}

.nav-links {
    display: flex;
    gap: 2rem;
    list-style: none;
}

.nav-links a {
    color: #ffffff;
    text-decoration: none;
    font-size: 14px;
    font-weight: 400;
    transition: opacity 0.3s ease;
    padding: 0.5rem 0;
}

.nav-links a:hover,
.nav-links a.active {
    opacity: 0.7;
}

/* ===== Main Content Area ===== */
.main-content {
    min-height: 100vh;
}

.page-section {
    display: none;
    padding: 2rem;
    max-width: 1800px;
    margin: 0 auto;
    animation: fadeIn 0.5s ease;
}

.page-section.active {
    display: block;
}

.page-section.active:not(.hero) {
    background: #000000;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* ===== Home Page ===== */
.hero {
    display: none;
    text-align: center;
    padding: 0;
    margin: 0;
    width: 100vw;
    min-height: 100vh;
    max-width: 100vw;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    position: relative;
    overflow: visible;
}

.hero.active {
    display: flex;
    background: linear-gradient(-45deg, #0a1628, #0d3b5a, #1a2a52, #2d1a52, #1a3a6a, #2d1a52);
    background-size: 400% 400%;
    animation: gradientFlow 15s ease infinite;
}

@keyframes gradientFlow {
    0% {
        background-position: 0% 50%;
    }
    25% {
        background-position: 100% 50%;
    }
    50% {
        background-position: 100% 100%;
    }
    75% {
        background-position: 0% 100%;
    }
    100% {
        background-position: 0% 50%;
    }
}

.hero-content {
    position: relative;
    z-index: 1;
    padding: 2rem;
    overflow: visible;
}

.hero h1 {
    font-size: 4rem;
    font-weight: 700;
    margin-bottom: 1.5rem;
    color: #ffffff;
    letter-spacing: -0.02em;
    text-shadow: 0 2px 10px rgba(0, 0, 0, 0.3);
}

.hero .team-name {
    font-size: 6rem;
    font-weight: 800;
    margin-bottom: 2rem;
    background: linear-gradient(135deg, #ffffff, #00d4ff, #ff00d4);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    letter-spacing: -0.03em;
    line-height: 1.4;
    overflow: visible;
}

/* ===== Card Styles - Apple Style ===== */
.card-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 2rem;
    margin-top: 3rem;
}

.card {
    background: rgba(255, 255, 255, 0.05);
    border-radius: 18px;
    padding: 2rem;
    transition: all 0.3s ease;
    cursor: pointer;
    border: 1px solid rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(10px);
}

.card:hover {
    transform: translateY(-4px);
    background: rgba(255, 255, 255, 0.08);
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.3);
}

.card-avatar {
    width: 120px;
    height: 120px;
    border-radius: 50%;
    background: linear-gradient(135deg, #00d4ff, #ff00d4);
    margin: 0 auto 1.5rem;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2.5rem;
    font-weight: 600;
    color: #ffffff;
    overflow: hidden;
    border: 3px solid rgba(255, 255, 255, 0.1);
    cursor: pointer;
    perspective: 1000px;
    transition: transform 0.6s;
    transform-style: preserve-3d;
}

.card-avatar:hover {
    transform: rotateY(360deg);
}

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

.card h3 {
    font-size: 1.5rem;
    margin-bottom: 0.5rem;
    text-align: center;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
}

.card .chinese-name {
    font-size: 1.5rem;
    font-weight: 600;
}

.card .name-separator {
    font-size: 1.5rem;
    color: rgba(255, 255, 255, 0.5);
    font-weight: 400;
}

.card .english-name {
    font-size: 1.5rem;
    color: rgba(255, 255, 255, 0.8);
    font-weight: 500;
}

.card .role {
    color: rgba(255, 255, 255, 0.6);
    text-align: center;
    margin-bottom: 1rem;
}

/* ===== Member Detail Page ===== */
.member-detail {
    padding: 4rem 2rem;
}

.member-header {
    text-align: center;
    margin-bottom: 3rem;
}

.member-avatar-large {
    width: 200px;
    height: 200px;
    border-radius: 50%;
    background: linear-gradient(135deg, #00d4ff, #ff00d4);
    margin: 0 auto 2rem;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 4rem;
    font-weight: 600;
    overflow: hidden;
    border: 4px solid rgba(255, 255, 255, 0.1);
}

.member-avatar-large img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    display: block;
}

.member-detail h2 {
    font-size: 2.5rem;
    margin-bottom: 0.5rem;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
}

.member-detail .chinese-name {
    font-size: 2.5rem;
    font-weight: 600;
}

.member-detail .name-separator {
    font-size: 2.5rem;
    color: rgba(255, 255, 255, 0.4);
    margin: 0 0.5rem;
    font-weight: 300;
}

.member-detail .english-name {
    font-size: 2.5rem;
    color: rgba(255, 255, 255, 0.7);
    font-weight: 400;
}

.member-detail .role {
    font-size: 1.25rem;
    color: rgba(255, 255, 255, 0.6);
    margin-bottom: 2rem;
}

.member-section {
    max-width: 800px;
    margin: 0 auto 3rem;
}

.member-section h3 {
    font-size: 1.5rem;
    margin-bottom: 1rem;
    color: #00d4ff;
}

.member-section p {
    font-size: 1rem;
    line-height: 1.8;
    color: rgba(255, 255, 255, 0.8);
}

.skills {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-top: 1rem;
}

.skill-tag {
    background: rgba(0, 212, 255, 0.2);
    color: #00d4ff;
    padding: 0.5rem 1rem;
    border-radius: 30px;
    font-size: 0.875rem;
}

.contact-links {
    display: flex;
    gap: 1rem;
    justify-content: center;
    margin-top: 2rem;
}

.contact-link {
    color: #00d4ff;
    text-decoration: none;
    padding: 0.5rem 1.5rem;
    border: 1px solid rgba(0, 212, 255, 0.3);
    border-radius: 30px;
    transition: all 0.3s ease;
}

.contact-link:hover {
    background: rgba(0, 212, 255, 0.1);
}

/* ===== Scroll to Top Button ===== */
.back-to-top {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    width: 50px;
    height: 50px;
    background: linear-gradient(135deg, #00d4ff, #0099cc);
    color: white;
    border: none;
    border-radius: 50%;
    font-size: 1.5rem;
    cursor: pointer;
    opacity: 0;
    visibility: hidden;
    transform: translateY(20px);
    transition: all 0.3s ease;
    z-index: 999;
    box-shadow: 0 4px 15px rgba(0, 212, 255, 0.4);
    display: flex;
    align-items: center;
    justify-content: center;
}

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

.back-to-top:hover {
    transform: translateY(-3px);
    box-shadow: 0 6px 20px rgba(0, 212, 255, 0.6);
}

.back-to-top:active {
    transform: translateY(0);
}

/* ===== Project Page ===== */
.project-showcase {
    background: rgba(255, 255, 255, 0.05);
    border-radius: 18px;
    padding: 3rem;
    margin-top: 2rem;
    border: 1px solid rgba(255, 255, 255, 0.1);
}

.project-showcase h2 {
    font-size: 2rem;
    margin-bottom: 1.5rem;
}

.tech-stack {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
    margin: 2rem 0;
}

.tech-item {
    background: rgba(0, 212, 255, 0.2);
    padding: 0.5rem 1rem;
    border-radius: 8px;
    font-size: 0.875rem;
}

.progress-bar {
    width: 100%;
    height: 8px;
    background: rgba(255, 255, 255, 0.1);
    border-radius: 4px;
    overflow: hidden;
    margin: 1rem 0;
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, #00d4ff, #ff00d4);
    border-radius: 4px;
    transition: width 0.5s ease;
}

/* ===== Exercise List ===== */
.exercise-card {
    background: rgba(255, 255, 255, 0.05);
    border-radius: 12px;
    padding: 1.5rem;
    margin-bottom: 1rem;
    border: 1px solid rgba(255, 255, 255, 0.1);
    transition: all 0.3s ease;
}

.exercise-card:hover {
    background: rgba(255, 255, 255, 0.08);
    transform: translateX(4px);
}

.exercise-card h3 {
    font-size: 1.25rem;
    margin-bottom: 0.5rem;
}

.exercise-card a {
    color: #00d4ff;
    text-decoration: none;
}

.exercise-card a:hover {
    text-decoration: underline;
}

/* ===== Exercise Detail Page - Left-Right Layout ===== */
.exercise-detail-layout {
    display: flex;
    gap: 2rem;
    max-width: 1800px;
    margin: 0 auto;
    padding: 6rem 2rem 2rem 2rem;
}

/* Left Sidebar TOC Navigation */
.exercise-toc {
    width: 260px;
    flex-shrink: 0;
    position: sticky;
    top: 100px;
    max-height: calc(100vh - 120px);
    overflow-y: auto;
    padding: 1rem 0;
}

.exercise-toc::-webkit-scrollbar {
    width: 4px;
}

.exercise-toc::-webkit-scrollbar-track {
    background: rgba(255, 255, 255, 0.05);
    border-radius: 2px;
}

.exercise-toc::-webkit-scrollbar-thumb {
    background: rgba(0, 212, 255, 0.3);
    border-radius: 2px;
}

.exercise-toc h4 {
    color: #00d4ff;
    font-size: 1rem;
    margin-bottom: 1rem;
    padding-bottom: 0.5rem;
    border-bottom: 2px solid rgba(0, 212, 255, 0.3);
}

.toc-list {
    list-style: none;
    padding: 0;
    margin: 0;
}

.toc-list li {
    margin-bottom: 0.5rem;
}

.toc-list a {
    color: rgba(255, 255, 255, 0.7);
    text-decoration: none;
    font-size: 0.875rem;
    display: block;
    padding: 0.375rem 0;
    border-radius: 4px;
    transition: all 0.2s ease;
    line-height: 1.5;
}

.toc-list a:hover,
.toc-list a.active {
    color: #00d4ff;
    background: transparent;
    padding-left: 0.5rem;
}

.toc-list .toc-sub {
    padding-left: 1.25rem;
    font-size: 0.8125rem;
}

.toc-list .toc-sub a {
    font-size: 0.8125rem;
    padding: 0.25rem 0;
}

.toc-list .toc-sub-item {
    padding-left: 2rem;
    font-size: 0.75rem;
}

.toc-list .toc-sub-item a {
    font-size: 0.75rem;
    padding: 0.2rem 0;
    color: rgba(255, 255, 255, 0.6);
}

.toc-list .toc-sub-item a:hover {
    color: #ff00d4;
}

/* Right Content Area */
.exercise-content-main {
    flex: 1;
    min-width: 0;
}

/* Enlarge assignment content font size */
.homework-content-section h4 {
    font-size: 2rem !important;
    margin-bottom: 1.5rem !important;
    color: #00e5ff !important;
    text-shadow: 0 0 20px rgba(0, 229, 255, 0.3);
}

.homework-content-section h5 {
    font-size: 1.5rem !important;
    margin-top: 2.5rem !important;
    margin-bottom: 1.25rem !important;
    color: #ff4081 !important;
    text-shadow: 0 0 15px rgba(255, 64, 129, 0.2);
}

.homework-content-section h6 {
    font-size: 1.25rem !important;
    margin-bottom: 1rem !important;
    color: #ffd740 !important;
}

.homework-content-section p {
    font-size: 1.125rem !important;
    line-height: 1.9 !important;
    margin-bottom: 1.25rem !important;
}

.homework-content-section li {
    font-size: 1.125rem !important;
    line-height: 1.8 !important;
}

.homework-content-section strong {
    font-size: 1.125rem !important;
    color: #ffffff;
}

/* ===== Responsive Design ===== */
@media (max-width: 1024px) {
    .hero .team-name {
        font-size: 5rem;
    }

    .hero h1 {
        font-size: 3rem;
    }

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

@media (max-width: 768px) {
    .navbar {
        padding: 0.75rem 1rem;
    }

    .navbar-content {
        flex-direction: column;
        gap: 1rem;
    }

    .nav-links {
        flex-wrap: wrap;
        justify-content: center;
        gap: 0.75rem;
    }

    .nav-links a {
        font-size: 13px;
    }

    .main-content {
        margin-top: 90px;
        min-height: calc(100vh - 90px);
    }

    .hero {
        padding: 5rem 2rem 3rem;
    }

    .hero h1 {
        font-size: 2.5rem;
    }

    .hero .team-name {
        font-size: 4rem;
    }

    .page-title {
        font-size: 2.25rem;
        margin: 2rem 0 1.5rem;
    }

    .page-description {
        font-size: 1rem;
        padding: 0 1rem;
    }

    .card-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 1.5rem;
    }

    .card {
        padding: 1.5rem;
    }

    .card-avatar {
        width: 100px;
        height: 100px;
        font-size: 2rem;
    }

    .card h3 {
        font-size: 1.25rem;
    }

    .card h3 .chinese-name,
    .card h3 .name-separator,
    .card h3 .english-name {
        font-size: 1.25rem;
    }

    .member-avatar-large {
        width: 150px;
        height: 150px;
        font-size: 3rem;
    }

    .member-detail h2 {
        font-size: 2rem;
    }

    .member-section {
        padding: 0 1rem;
    }

    .project-showcase {
        padding: 2rem 1.5rem;
    }

    .project-showcase h2 {
        font-size: 1.75rem;
    }

    .tech-stack {
        gap: 0.75rem;
    }

    .tech-item {
        font-size: 0.8rem;
    }

    .contact-links {
        flex-direction: column;
        align-items: center;
    }

    .contact-link {
        width: 80%;
        text-align: center;
    }

    .intro-section {
        padding: 0 1rem;
    }

    .intro-section h3 {
        font-size: 1.5rem;
    }

    .team-photo {
        height: 200px;
        margin: 1rem auto;
    }

    .exercise-card {
        padding: 1.25rem;
    }

    .exercise-card h3 {
        font-size: 1.125rem;
    }
}

@media (max-width: 480px) {
    .navbar {
        padding: 0.5rem 0.75rem;
    }

    .navbar-content {
        gap: 0.75rem;
    }

    .logo {
        font-size: 1.25rem;
    }

    .nav-links {
        gap: 0.5rem;
    }

    .nav-links a {
        font-size: 12px;
        padding: 0.25rem 0;
    }

    .main-content {
        margin-top: 80px;
        min-height: calc(100vh - 80px);
    }

    .hero {
        padding: 0;
        width: 100vw;
        min-height: 100vh;
    }

    .hero-content {
        padding: 1rem;
    }

    .hero h1 {
        font-size: 1.75rem;
    }

    .hero .team-name {
        font-size: 2.5rem;
    }

    .page-title {
        font-size: 1.75rem;
        margin: 1.5rem 0 1rem;
    }

    .page-description {
        font-size: 0.875rem;
        margin-bottom: 2rem;
    }

    .card-grid {
        grid-template-columns: 1fr;
        gap: 1rem;
    }

    .card {
        padding: 1.25rem;
    }

    .card-avatar {
        width: 80px;
        height: 80px;
        font-size: 1.75rem;
        margin-bottom: 1rem;
    }

    .card h3 {
        font-size: 1.125rem;
    }

    .card .role {
        font-size: 0.875rem;
    }

    .member-avatar-large {
        width: 120px;
        height: 120px;
        font-size: 2.5rem;
        margin-bottom: 1.5rem;
    }

    .member-detail h2 {
        font-size: 1.75rem;
    }

    .member-detail .role {
        font-size: 1rem;
    }

    .member-section h3 {
        font-size: 1.25rem;
    }

    .member-section p {
        font-size: 0.875rem;
    }

    .skill-tag {
        font-size: 0.75rem;
        padding: 0.375rem 0.75rem;
    }

    .project-showcase {
        padding: 1.5rem 1rem;
    }

    .project-showcase h2 {
        font-size: 1.5rem;
    }

    .project-showcase p {
        font-size: 0.875rem;
    }

    .tech-stack {
        gap: 0.5rem;
    }

    .tech-item {
        font-size: 0.75rem;
        padding: 0.375rem 0.75rem;
    }

    .intro-section h3 {
        font-size: 1.25rem;
    }

    .intro-section p {
        font-size: 0.875rem;
    }

    .team-photo {
        height: 150px;
        font-size: 1rem;
    }

    .exercise-card {
        padding: 1rem;
    }

    .exercise-card h3 {
        font-size: 1rem;
    }

    .exercise-card p {
        font-size: 0.875rem;
    }

    .exercise-card a {
        font-size: 0.875rem;
    }
}

/* Extra Small Screen Optimization */
@media (max-width: 360px) {
    .hero .team-name {
        font-size: 2rem;
    }

    .card-avatar {
        width: 70px;
        height: 70px;
        font-size: 1.5rem;
    }

    .member-avatar-large {
        width: 100px;
        height: 100px;
        font-size: 2rem;
    }
}

/* ===== Page Title ===== */
.page-title {
    font-size: 3rem;
    font-weight: 700;
    text-align: center;
    margin: 3rem 0 2rem;
    background: linear-gradient(135deg, #ffffff, #a8a8a8);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.page-description {
    text-align: center;
    font-size: 1.125rem;
    color: rgba(255, 255, 255, 0.7);
    max-width: 800px;
    margin: 0 auto 3rem;
    line-height: 1.8;
}

/* ===== Editable Area Styles ===== */
.editable-area {
    position: relative;
}

.editable-area::before {
    content: '';
    position: absolute;
    top: -10px;
    left: -10px;
    right: -10px;
    bottom: -10px;
    border: 2px dashed transparent;
    border-radius: 16px;
    pointer-events: none;
    transition: all 0.3s ease;
}

/* Image Styles */
.editable-content img {
    max-width: 100%;
    border-radius: 8px;
    margin: 1rem 0;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.3);
}

.exercise-content-section img {
    max-width: 100%;
    border-radius: 8px;
    margin: 1rem 0;
}

/* ===== Team Introduction Page ===== */
.intro-section {
    max-width: 800px;
    margin: 0 auto 3rem;
    text-align: center;
}

.intro-section h3 {
    font-size: 1.75rem;
    margin-bottom: 1rem;
    color: #00d4ff;
}

.intro-section p {
    font-size: 1rem;
    line-height: 1.8;
    color: rgba(255, 255, 255, 0.8);
}

.team-photo {
    width: 100%;
    max-width: 800px;
    height: 300px;
    background: linear-gradient(135deg, rgba(0, 212, 255, 0.2), rgba(255, 0, 212, 0.2));
    border-radius: 18px;
    margin: 2rem auto;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.25rem;
    color: rgba(255, 255, 255, 0.5);
}