/* ------ General Styles ------ */
:root {
    --primary-color: #3a8f6f;
    --secondary-color: #5baa8e;
    --highlight-color: #60a3a1;
    --blue-color: #0E71EB;
    --orange-color: #FF7139;
    --teal-color: #1BE4B6;
    --text-dark: #2d3748;
    --text-medium: #4a5568;
    --text-light: #718096;
    --bg-light: #f8f9fa;
    --bg-medium: #e9ecef;
    --border-color: #e2e8f0;
    --green-bg-light: #f2f7f5;
    --green-bg-medium: #eaf4ef;
    --shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    --transition: all 0.3s ease;
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', sans-serif;
    line-height: 1.6;
    color: var(--text-dark);
    background-color: var(--bg-light);
}

.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

section {
    padding: 80px 0;
}

img {
    max-width: 100%;
    height: auto;
}

a {
    text-decoration: none;
    color: var(--primary-color);
    transition: var(--transition);
}

ul {
    list-style: none;
}

.btn {
    display: inline-block;
    padding: 12px 24px;
    border-radius: 6px;
    font-weight: 600;
    text-align: center;
    cursor: pointer;
    transition: var(--transition);
}

.btn-primary {
    background-color: var(--primary-color);
    color: white;
    font-size: 1.2rem;
    padding: 14px 30px;
    box-shadow: 0 4px 12px rgba(58, 143, 111, 0.3);
}

.btn-primary:hover {
    background-color: #2d7b5d;
    transform: translateY(-2px);
    box-shadow: 0 6px 15px rgba(58, 143, 111, 0.4);
}

.btn-secondary {
    background-color: transparent;
    color: var(--primary-color);
    border: 2px solid var(--primary-color);
}

.btn-secondary:hover {
    background-color: rgba(58, 143, 111, 0.1);
}

.section-header {
    text-align: center;
    margin-bottom: 50px;
}

.section-title {
    font-size: 36px;
    font-weight: 700;
    color: var(--text-dark);
    margin-bottom: 10px;
}

.section-subtitle {
    font-size: 18px;
    color: var(--text-light);
}

/* ------ Header & Navigation ------ */
.header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    background-color: white;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    z-index: 1000;
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 80px;
}

.logo h1 {
    font-size: 24px;
    color: var(--primary-color);
}

.nav-list {
    display: flex;
}

.nav-item {
    margin-left: 30px;
}

.nav-link {
    color: var(--text-medium);
    font-weight: 500;
    padding: 8px 0;
    position: relative;
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background-color: var(--primary-color);
    transition: var(--transition);
}

.nav-link:hover, .nav-link.active {
    color: var(--primary-color);
}

.nav-link:hover::after, .nav-link.active::after {
    width: 100%;
}

.mobile-nav-toggle {
    display: none;
    font-size: 24px;
    cursor: pointer;
}

/* ------ Hero Section ------ */
.hero {
    padding: 160px 0 80px;
    background-color: white;
    position: relative;
}

.hero::after {
    content: none;
}

.hero .container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 40px;
}

.hero-content {
    flex: 1;
}

.hero-image {
    flex: 1;
    display: flex;
    justify-content: center;
    align-items: center;
}

.hero-image img {
    max-width: 100%;
    border-radius: 10px;
    box-shadow: var(--shadow);
}

.hero-title {
    font-size: 48px;
    font-weight: 800;
    margin-bottom: 16px;
    color: var(--primary-color);
}

.hero-subtitle {
    font-size: 24px;
    color: var(--text-medium);
    margin-bottom: 24px;
}

.hero-description {
    font-size: 18px;
    color: var(--text-light);
    margin-bottom: 32px;
}

.hero-buttons {
    display: flex;
    gap: 12px;
    flex-wrap: wrap;
}

.hero-buttons .btn {
    margin-bottom: 8px;
}

.github-btn {
    background-color: #24292e;
    color: white;
    border: none;
}

.github-btn:hover {
    background-color: #2c3136;
    color: var(--teal-color);
}

/* ------ Problem Statement Section ------ */
.problem {
    background-color: white;
}

.problem-content {
    display: flex;
    flex-wrap: wrap;
    gap: 30px;
    align-items: flex-start;
}

.problem-text {
    flex: 1;
    min-width: 300px;
}

.problem-text h3 {
    font-size: 24px;
    margin-bottom: 20px;
    color: var(--primary-color);
}

.problem-text p {
    margin-bottom: 20px;
    color: var(--text-medium);
}

.problem-feature-list {
    margin-bottom: 20px;
    padding-left: 0;
}

.problem-feature-list li {
    display: flex;
    align-items: center;
    margin-bottom: 12px;
    color: var(--text-medium);
    font-size: 16px;
}

.feature-icon {
    display: inline-flex;
    justify-content: center;
    align-items: center;
    width: 30px;
    height: 30px;
    margin-right: 12px;
    background-color: var(--green-bg-medium);
    border-radius: 50%;
    color: var(--primary-color);
}

.feature-icon i {
    font-size: 14px;
}

.data-cards {
    display: flex;
    justify-content: space-around;
    gap: 20px;
    flex-wrap: wrap;
}

.data-card {
    background-color: white;
    border-radius: 10px;
    padding: 20px;
    box-shadow: var(--shadow);
    text-align: center;
    min-width: 160px;
    transition: var(--transition);
}

.data-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 20px rgba(0, 0, 0, 0.1);
}

.data-icon {
    width: 50px;
    height: 50px;
    border-radius: 50%;
    display: flex;
    justify-content: center;
    align-items: center;
    margin: 0 auto 15px;
    font-size: 20px;
    font-weight: 700;
    color: white;
}

.data-icon.blue {
    background-color: var(--blue-color);
}

.data-icon.orange {
    background-color: var(--orange-color);
}

.data-icon.teal {
    background-color: var(--teal-color);
}

.data-card h3 {
    font-size: 18px;
    margin-bottom: 10px;
    color: var(--text-dark);
}

.data-number {
    font-size: 28px;
    font-weight: 700;
    color: var(--primary-color);
    margin-bottom: 5px;
}

.data-card p {
    color: var(--text-medium);
    margin-bottom: 5px;
}

.data-date {
    font-size: 14px;
    color: var(--text-light);
}

/* ------ Design Evolution Section ------ */
.design {
    background-color: var(--green-bg-light);
    position: relative;
}

.design::before {
    content: none;
}

.design-versions {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(340px, 1fr));
    gap: 30px;
    margin-top: 30px;
}

.version-card {
    background-color: white;
    border-radius: 10px;
    overflow: hidden;
    box-shadow: var(--shadow);
    transition: var(--transition);
    display: flex;
    flex-direction: column;
}

.version-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 20px rgba(0, 0, 0, 0.1);
}

.version-card.featured {
    grid-column: 1 / -1;
    background-color: var(--green-bg-medium);
    border: 2px solid var(--primary-color);
}

.version-number {
    background-color: var(--primary-color);
    color: white;
    padding: 8px 16px;
    font-weight: 600;
    font-size: 16px;
}

.version-img {
    width: 100%;
    height: 250px;
    overflow: hidden;
}

.version-img img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.version-details {
    padding: 25px;
    flex-grow: 1;
    display: flex;
    flex-direction: column;
}

.version-details h4 {
    font-size: 20px;
    font-weight: 600;
    margin-bottom: 10px;
    color: var(--primary-color);
}

.version-details p {
    color: var(--text-medium);
    margin-bottom: 15px;
}

.version-features {
    margin-bottom: 20px;
    padding-left: 20px;
}

.version-features li {
    margin-bottom: 8px;
    color: var(--text-medium);
    position: relative;
}

.version-features li::before {
    content: '•';
    position: absolute;
    left: -15px;
    color: var(--primary-color);
}

.btn-small {
    padding: 8px 16px;
    font-size: 14px;
    margin-top: auto;
    align-self: flex-start;
}

/* ------ Implementation Section ------ */
.implementation {
    background-color: var(--green-bg-light);
}

.implementation-content {
    margin-top: 30px;
}

.tech-approach h3 {
    font-size: 24px;
    margin-bottom: 20px;
    color: var(--primary-color);
    text-align: center;
}

.approach-cards {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
    gap: 30px;
    margin-top: 20px;
}

.approach-card {
    background-color: white;
    border-radius: 10px;
    padding: 25px;
    box-shadow: var(--shadow);
    transition: var(--transition);
}

.approach-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 20px rgba(0, 0, 0, 0.1);
}

.approach-icon {
    width: 50px;
    height: 50px;
    border-radius: 50%;
    background-color: var(--green-bg-medium);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 15px;
}

.approach-icon i {
    font-size: 24px;
    color: var(--primary-color);
}

.approach-card h4 {
    font-size: 18px;
    font-weight: 600;
    margin-bottom: 15px;
    color: var(--primary-color);
}

.approach-card p {
    color: var(--text-medium);
    margin-bottom: 15px;
}

.approach-card ul {
    padding-left: 20px;
}

.approach-card ul li {
    margin-bottom: 8px;
    color: var(--text-medium);
    position: relative;
}

.approach-card ul li::before {
    content: '•';
    position: absolute;
    left: -15px;
    color: var(--primary-color);
}

/* ------ Research Section ------ */
.research {
    background-color: white;
    position: relative;
}

.research::before {
    content: none;
}

.research-papers {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(340px, 1fr));
    gap: 30px;
}

.paper-card {
    background-color: white;
    border-radius: 10px;
    padding: 24px;
    box-shadow: var(--shadow);
    display: flex;
    gap: 16px;
    transition: var(--transition);
}

.paper-card:hover {
    transform: translateY(-5px);
}

.paper-number {
    width: 36px;
    height: 36px;
    background-color: var(--primary-color);
    color: white;
    border-radius: 50%;
    display: flex;
    justify-content: center;
    align-items: center;
    font-weight: 700;
    flex-shrink: 0;
}

.paper-title {
    font-size: 18px;
    margin-bottom: 8px;
    color: var(--primary-color);
}

.paper-citation {
    font-style: italic;
    color: var(--text-light);
    margin-bottom: 12px;
    font-size: 14px;
}

.paper-influence {
    border-left: 3px solid var(--primary-color);
    padding-left: 12px;
    font-size: 14px;
}

.influence-result {
    color: var(--primary-color);
    font-weight: 600;
    margin-top: 6px;
}

/* ------ Team Section Updates ------ */
.team {
    background-color: var(--green-bg-light);
}

.team-groups {
    display: flex;
    flex-direction: column;
    gap: 40px;
}

.team-group {
    margin-bottom: 20px;
}

.team-group-title {
    font-size: 22px;
    font-weight: 600;
    margin-bottom: 20px;
    color: var(--primary-color);
    padding-bottom: 10px;
    border-bottom: 1px solid var(--border-color);
}

.team-members {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
    gap: 25px;
}

.member-card {
    background-color: white;
    border-radius: 10px;
    padding: 20px;
    text-align: center;
    box-shadow: var(--shadow);
    transition: var(--transition);
}

.member-card:hover {
    transform: translateY(-5px);
}

.member-photo {
    width: 80px;
    height: 80px;
    border-radius: 50%;
    background-color: var(--green-bg-medium);
    display: flex;
    justify-content: center;
    align-items: center;
    margin: 0 auto 16px;
    font-size: 24px;
    font-weight: 700;
    color: var(--primary-color);
}

.member-name {
    font-size: 18px;
    margin-bottom: 8px;
    color: var(--text-dark);
}

.member-focus {
    font-size: 14px;
    color: var(--text-medium);
}

/* ------ Footer Updates ------ */
.footer {
    background-color: var(--primary-color);
    color: white;
    padding: 30px 0;
    text-align: center;
}

.footer p {
    margin-bottom: 10px;
}

.demo-links {
    font-size: 14px;
    color: #f2f7f5;
}

.demo-links a {
    color: white;
    text-decoration: underline;
    margin: 0 5px;
    transition: var(--transition);
}

.demo-links a:hover {
    color: #dae8e2;
}

/* ------ Responsive Styles ------ */
@media (max-width: 992px) {
    .section-title {
        font-size: 32px;
    }
    
    .hero-title {
        font-size: 40px;
    }
    
    .hero-subtitle {
        font-size: 20px;
    }
    
    .hero .container {
        flex-direction: column;
    }
    
    .hero-content {
        text-align: center;
    }
    
    .hero-buttons {
        justify-content: center;
    }
    
    .design-versions {
        grid-template-columns: 1fr;
    }
    
    .version-card.featured {
        grid-column: auto;
    }
}

@media (max-width: 768px) {
    .nav-list {
        display: none;
        position: absolute;
        top: 80px;
        left: 0;
        width: 100%;
        background-color: white;
        flex-direction: column;
        align-items: center;
        box-shadow: 0 10px 10px rgba(0, 0, 0, 0.1);
    }
    
    .nav-list.active {
        display: flex;
    }
    
    .nav-item {
        margin: 0;
        width: 100%;
        text-align: center;
    }
    
    .nav-link {
        display: block;
        padding: 15px 0;
    }
    
    .mobile-nav-toggle {
        display: block;
    }
    
    .section-title {
        font-size: 28px;
    }
    
    .research-papers {
        grid-template-columns: 1fr;
    }
    
    .problem-content {
        flex-direction: column;
    }
    
    .approach-cards {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 576px) {
    .section {
        padding: 60px 0;
    }
    
    .hero {
        padding: 120px 0 60px;
    }
    
    .hero-title {
        font-size: 32px;
    }
    
    .hero-subtitle {
        font-size: 18px;
    }
    
    .hero-buttons {
        flex-direction: column;
        gap: 10px;
    }
    
    .data-cards {
        flex-direction: column;
        align-items: center;
    }
    
    .team-members {
        grid-template-columns: 1fr 1fr;
    }
    
    .version-img {
        height: 200px;
    }
}