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

:root {
    /* Colors */
    --primary-blue: #0066cc;
    --dark-blue: #0e3e5b;
    --light-blue-gradient-start: #3f51b5;
    --light-blue-gradient-mid: #2196f3;
    --light-blue-gradient-end: #00bcd4;
    --dark-gray: #222;
    --medium-gray: #333;
    --light-gray: #666;
    --border-color: #ddd;
    --background-light: #f9f9f9;
    --white: #fff;
    --carousel-bg-1: #dadfe4;
    --carousel-bg-2: #d1dfcd;
    --hover-gray: #dadada;
    --link-hover-blue: #008ccf;
    --light-border: #eee;
    --accent-blue-light: #e6f0ff;
    --accent-blue-dark: #cce4ff;

    /* Spacing */
    --header-height: 60px;
    --section-margin-bottom: 20px;
    --section-padding-desktop-horizontal: 0px;
    --section-padding-desktop-vertical: 5px;
    --section-padding-mobile-horizontal: 15px;
    --section-padding-mobile-vertical: 3px;
    --h2-padding-left-desktop: 40px;
    --h2-padding-top-desktop: 30px;
    --h3-padding-vertical: 10px;
    --h3-margin-vertical: 10px;
    --text-box-padding: 24px;
    --content-gap-desktop: 40px;
    --text-row-padding-vertical: 10px;
    --text-row-margin-bottom: 5px;

    /* Transitions */
    --transition-fast: 0.3s ease;
    --transition-medium: 0.4s ease;
    --transition-slow: 0.5s ease;

    /* Border Radius */
    --border-radius-default: 8px;
    --border-radius-small: 6px;
    --border-radius-round: 9999px;
    --border-radius-button: 40px;
    --border-radius-nav-mobile: 12px;

    /* Shadows */
    --shadow-sm: 0 4px 10px rgba(0, 123, 255, 0.2);
    --shadow-md: 0 6px 20px rgba(0, 123, 255, 0.3);
    --shadow-lg: 0 10px 30px rgba(0, 123, 255, 0.5);
    --shadow-section: 0 0 10px rgba(0, 0, 0, 0.03);
    --shadow-text-row-hover: 0 4px 12px rgba(0, 0, 0, 0.08);
    --shadow-nav-mobile: -3px 0 8px rgba(0, 0, 0, 0.1);

    /* Z-index */
    --z-index-header: 1000;
    --z-index-nav-mobile: 999;
    --z-index-carousel-button: 10;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen, Ubuntu, Cantarell, "Open Sans", "Helvetica Neue", sans-serif;
    line-height: 1.5;
    background: var(--background-light);
    color: var(--dark-gray);
    overflow-x: hidden;
}

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

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

/* --- Header --- */
header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: var(--header-height);
    background: var(--white);
    border-bottom: 1px solid var(--border-color);
    z-index: var(--z-index-header);
    transition: background-color var(--transition-medium), opacity var(--transition-medium);
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 0;
}

header.scrolled {
    background-color: rgba(255, 255, 255, 0.85);
    backdrop-filter: blur(4px);
    -webkit-backdrop-filter: blur(4px);
}

.header-inner {
    width: 100%;
    max-width: 1200px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 var(--section-padding-desktop-horizontal);
}

.logo img {
    height: var(--header-height);
    width: auto;
}

/* --- Navigation --- */
nav {
    display: flex;
    gap: 10px;
    align-items: center;
}

nav a {
    position: relative;
    display: inline-block;
    padding: 8px 14px;
    color: var(--dark-gray);
    font-weight: 500;
    font-size: 1.2rem;
    transition: all var(--transition-fast);
}

nav a::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    height: 2px;
    width: 100%;
    background: linear-gradient(to right, var(--light-blue-gradient-start), var(--light-blue-gradient-mid), var(--light-blue-gradient-end));
    transform: scaleX(0);
    transform-origin: left;
    transition: transform var(--transition-fast);
}

nav a:hover {
    color: var(--light-blue-gradient-mid);
    transform: translateY(-2px);
}

nav a:hover::after {
    transform: scaleX(1);
}

nav a.english-link {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    white-space: nowrap;
}

/* --- Hamburger Icon --- */
.hamburger {
    display: none;
    flex-direction: column;
    gap: 5px;
    cursor: pointer;
}

.hamburger div {
    width: 40px;
    height: 3px;
    background: #008ccf;
    border-radius: 2px;
}

/* --- Main & Sections --- */
main {
    padding-top: var(--header-height);
}

section {
    max-width: 1200px;
    margin: 0 auto var(--section-margin-bottom) auto;
    padding: var(--section-padding-desktop-vertical) var(--section-padding-desktop-horizontal);
    background-color: var(--white);
    color: var(--medium-gray);
    scroll-margin-top: var(--header-height);
}

section:last-of-type {
    margin-bottom: 0;
}

section h2 {
    font-family: 'Montserrat', sans-serif;
    font-weight: 900;
    font-size: 3rem;
    color: var(--dark-blue);
    text-align: left;
    padding-left: var(--h2-padding-left-desktop);
    padding-top: var(--h2-padding-top-desktop);
    position: relative;
    padding-bottom: 10px;
    margin-bottom: 30px;
}

section h2::after {
    content: '';
    position: absolute;
    left: var(--h2-padding-left-desktop);
    bottom: 0;
    height: 10px;
    width: 600px;
    background: linear-gradient(to right, var(--light-blue-gradient-end), var(--white));
    border-radius: 2px;
}

section h3 {
    font-size: 4rem;
    font-weight: 800;
    color: #FFF;
    text-align: center;
    position: relative;
    padding-left: 0px;
}

/* --- Hero Section --- */
#hero {
    padding: 0;
    margin-bottom: var(--section-margin-bottom);
}

.hero-bg {
    position: relative;
    width: 100%;
    overflow: hidden;
}

.hero-img.desktop {
    object-fit: cover;
}

.hero-img.mobile {
    display: none;
}

.hero-bg .content {
    position: absolute;
    bottom: 200px;
    left: 50%;
    transform: translateX(-50%);
    width: 100%;
    text-align: center;
    color: var(--dark-gray);
}

.hero-bg .content button {
    padding: 16px 36px;
    background: linear-gradient(135deg, var(--light-blue-gradient-start), var(--light-blue-gradient-mid), var(--light-blue-gradient-end));
    background-size: 200% 200%;
    color: var(--white);
    border: none;
    border-radius: var(--border-radius-button);
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    box-shadow: var(--shadow-md);
    transition: all var(--transition-medium) ease-in-out;
    margin-top: 20px;
}

.hero-bg .content button:hover {
    background-position: right center;
    transform: translateY(-4px) scale(1.05);
    box-shadow: var(--shadow-lg);
}

/* --- Shared Image Link --- */
.image-link {
    display: inline-block;
    border-radius: var(--border-radius-default);
    overflow: hidden;
    cursor: pointer;
    transition: transform var(--transition-fast), box-shadow var(--transition-fast);
}

.image-link img {
    border-radius: var(--border-radius-default);
    transition: transform var(--transition-fast), box-shadow var(--transition-fast);
}

.image-link:hover img {
    transform: scale(1.1);
    box-shadow: var(--shadow-lg);
}

/* --- Carousel --- */
.carousel-section {
    padding: var(--section-padding-desktop-vertical) var(--section-padding-desktop-horizontal);
}

#gallery-swiper-1 {
    background-color: var(--carousel-bg-1);
}

#gallery-swiper-2 {
    background-color: var(--carousel-bg-2);
}

.carousel-container {
    position: relative;
    overflow: hidden;
    width: 100%;
    max-width: none;
    background-color: #FFFFFF;
    padding-top: 20px;
    padding-bottom: 20px;
}

.carousel-track {
    display: flex;
    overflow-x: auto;
    scroll-behavior: smooth;
    scrollbar-width: none;
    -ms-overflow-style: none;
}

.carousel-track::-webkit-scrollbar {
    display: none;
}

.carousel-item {
    flex: 0 0 auto;
}

.carousel-item img {
    border-radius: var(--border-radius-small);
}

.carousel-button {
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
    z-index: var(--z-index-carousel-button);
    width: 60px;
    height: 60px;
    font-size: 30px;
    background-color: rgba(0, 0, 0, 0.3);
    color: var(--white);
    border: none;
    border-radius: var(--border-radius-round);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    backdrop-filter: blur(2px);
    transition: all var(--transition-fast);
}

.carousel-button:hover {
    background-color: rgba(0, 0, 0, 0.6);
    transform: translateY(-50%) scale(1.1);
}

.carousel-button.left {
    left: 12px;
}

.carousel-button.right {
    right: 12px;
}

.carousel-track.dragging {
    cursor: grabbing;
    user-select: none;
}

/* --- Content with Image (Research Highlight) --- */
#research_highlight.content-with-image-section .container {
    display: flex;
    align-items: flex-start;
    gap: var(--content-gap-desktop);
    flex-wrap: wrap;
}

#research_highlight .text-content {
    color: #236890;
    font-family: "Roboto", sans-serif;
    text-align: left;
    box-sizing: border-box;
    flex: 1;
    min-width: 300px;
}

#research_highlight .top-image-wrapper img {
    width: 100%;
    height: auto;
    max-height: 250px;
    object-fit: cover;
}

#research_highlight .text-row {
    padding-top: var(--text-row-padding-vertical);
    padding-bottom: var(--text-row-padding-vertical);
    transition: background-color var(--transition-fast), transform 0.2s ease, box-shadow 0.2s ease;
    cursor: pointer;
    border-radius: var(--border-radius-default);
    margin-bottom: var(--text-row-margin-bottom);
}

#research_highlight .text-row:last-child {
    margin-bottom: 0;
}

#research_highlight .text-row:hover {
    background-color: var(--hover-gray);
    transform: translateY(-2px);
    box-shadow: var(--shadow-text-row-hover);
}

#research_highlight .text-row p {
    font-size: 1.2rem;
    line-height: 1.4;
}

#research_highlight .text-row a {
    color: #006da1;
    font-weight: bold;
    text-decoration: none;
    display: block;
}

#research_highlight .text-row a:hover {
    color: var(--link-hover-blue);
}

#research_highlight .text-row p a span.authors {
    font-style: italic;
    color: var(--light-gray);
    font-size: 1em;
    font-weight: normal;
}

#research_highlight .image-content {
    flex-shrink: 0;
    height: auto;
    display: flex;
    justify-content: center;
    align-items: center;
    overflow: hidden;
    width: 50%;
}

#research_highlight .image-content .large-image {
    object-fit: contain;
}

/* --- Collaboration Steps Section --- */
#collaboration-steps {
    background-color: #fdf6ec;
}

.collaboration-container {
    position: relative;
    max-width: 1200px; /* Adjusted to better fit the image ratio */
    margin: 0 auto;
}

.link-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
}

.concept-sheet-link {
    position: absolute;
    display: block;
    top: 22%;
    left: 52%;
    width: 44%;
    height: 20%;
}

.contact-email-link {
    position: absolute;
    display: block;
    bottom: 5%;
    left: 10%;
    width: 25%;
    height: 10%;
}

/* --- Footer --- */
footer {
    padding: var(--section-padding-desktop-vertical) 0;
    background-color: var(--white);
    margin-bottom: 0;
    text-align: center;
}

footer img {
    max-width: 1200px;
    width: 100%;
    height: auto;
    display: block;
    margin-left: auto;
    margin-right: auto;
}

/* ==========================================================================
   Desktop Styles (min-width: 769px)
   ========================================================================== */
@media (min-width: 769px) {
    .content-row {
        display: flex;
        gap: 30px;
        align-items: center;
        justify-content: space-between;
    }

    .image-box {
        width: 37.5%;
    }

    .image-box2 {
        width: 62.5%;
    }

    .image-box3 {
        width: 66.5%;
    }

    .text-box {
        flex: 1;
        padding: var(--text-box-padding);
        background-color: var(--background-light);
        font-size: 1.2rem;
        line-height: 1.8;
        border-radius: var(--border-radius-default);
        box-shadow: var(--shadow-section);
    }

    .leader-grid2 {
        display: flex;
        flex-wrap: wrap;
        justify-content: center;
    }

    .leader-grid2 a {
        width: 30%;
        border-radius: var(--border-radius-default);
        transition: transform var(--transition-fast);
    }

    .image-grid {
        display: flex;
        flex-wrap: nowrap;
        justify-content: center;
        max-width: 1200px;
        margin-left: auto;
        margin-right: auto;
        padding: 0 var(--section-padding-desktop-horizontal);
    }

    .image-grid a {
        flex: 0 0 25%;
        max-width: 25%;
        width: 100%;
        border-radius: var(--border-radius-default);
        transition: transform var(--transition-fast);
    }

    .carousel-item {
        flex: 0 0 25%;
        max-width: 25%;
        width: 100%;
    }
}

/* ==========================================================================
   Mobile Styles (max-width: 768px)
   ========================================================================== */
@media (max-width: 768px) {
    .header-inner {
        padding: 0 var(--section-padding-mobile-horizontal);
    }

    nav {
        position: fixed;
        top: var(--header-height);
        right: 0;
        width: 220px;
        background-color: var(--white);
        flex-direction: column;
        padding: 0;
        box-shadow: var(--shadow-nav-mobile);
        border-top-left-radius: var(--border-radius-nav-mobile);
        border-bottom-left-radius: var(--border-radius-nav-mobile);
        transform: translateX(100%);
        transition: transform var(--transition-slow);
        z-index: var(--z-index-nav-mobile);
    }

    nav.open {
        transform: translateX(0);
    }

    nav a {
        display: block;
        width: 100%;
        box-sizing: border-box;
        padding: 14px 24px;
        font-size: 1.1rem;
        color: var(--medium-gray);
        border-bottom: 1px solid var(--light-border);
        background-color: var(--white);
        transition: background var(--transition-fast), color var(--transition-fast);
    }

    nav a:last-child {
        border-bottom: none;
    }

    nav a:hover {
        background-color: var(--accent-blue-light);
        color: var(--link-hover-blue);
    }

    nav a.selected {
        background-color: var(--dark-blue);
        color: var(--white);
    }

    .hamburger {
        display: flex;
    }

    section {
        padding: var(--section-padding-mobile-vertical) var(--section-padding-mobile-horizontal);
    }

    section h2 {
        font-size: 1.5rem;
        padding-left: 20px;
        padding-top: 0px;
    }

    section h2::after {
        left: 0;
        width: 100%;
        height: 6px;
    }

    section h3 {
        font-size: 1.5rem;
    }

    .hero-img.desktop {
        display: none;
    }

    .hero-img.mobile {
        display: block;
        object-fit: contain;
    }

    .hero-bg .content {
        bottom: 20px;
        padding: 0 var(--section-padding-mobile-horizontal);
    }

    .hero-bg .content button {
        margin-top: 0;
        padding: 14px 30px;
        font-size: 1rem;
        white-space: nowrap;
    }

    .content-row {
        flex-direction: column;
        gap: 20px;
    }

    .image-box,
    .image-box2,
    .image-box3,
    .text-box {
        flex: none;
        width: 100%;
        max-width: none;
    }

    .text-box {
        font-size: 1rem;
    }

    .leader-grid2 a {
        width: 48%;
    }

    .image-grid {
        display: flex;
        flex-wrap: wrap;
        justify-content: center;
        padding: 0;
        gap: 20px;
    }

    .image-grid a {
        flex: 0 0 auto;
        width: 300px;
        max-width: calc(50% - 10px);
        box-sizing: border-box;
    }

    .carousel-item {
        flex: 0 0 50%;
    }

    .carousel-button {
        width: 30px;
        height: 30px;
        font-size: 20px;
    }

    #research_highlight .text-content,
    #research_highlight .image-content {
        width: 100%;
        min-width: unset;
        flex: none;
        max-width: none;
    }

    #research_highlight .image-content {
        display: none;
    }

    #research_highlight .text-row p {
        padding-left: 15px;
        font-size: 1rem;
    }

    footer {
        padding: var(--section-padding-mobile-vertical) 0;
    }
}