/* =============================================
   PROFILE PAGE — TWO-PANEL LAYOUT
   ============================================= */

@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700&display=swap');

/* ---------- CSS Variables ---------- */
:root {
    --left-panel-width: 300px;
    --left-bg: #0a0a0a;
    --left-text: #e0e0e0;
    --left-text-muted: #888;
    --left-accent: #ffffff;
    --right-bg: #ffffff;
    --right-text: #1a1a1a;
    --right-text-secondary: #555;
    --heading-color: #111;
    --accent: #2563eb;
    --accent-hover: #1d4ed8;
    --card-bg: #f8f9fb;
    --card-border: #e5e7eb;
    --card-shadow: rgba(0, 0, 0, 0.06);
    --keyword-bg: #eef2ff;
    --keyword-text: #3730a3;
    --keyword-border: #c7d2fe;
    --kw-past-bg: #f3f4f6;
    --kw-past-text: #6b7280;
    --kw-present-bg: #dbeafe;
    --kw-present-text: #1e40af;
    --kw-future-bg: #ecfdf5;
    --kw-future-text: #065f46;
    --nav-active-bg: rgba(255, 255, 255, 0.08);
    --transition-speed: 0.3s;
    --radius: 10px;
    --radius-sm: 6px;
}

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

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    line-height: 1.7;
    color: var(--right-text);
    background: var(--right-bg);
    display: flex;
    min-height: 100vh;
    overflow-x: hidden;
}

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

a:hover {
    color: var(--accent-hover);
}

ul {
    list-style: none;
}

/* =============================================
   LEFT PANEL
   ============================================= */
.left-panel {
    position: fixed;
    top: 0;
    left: 0;
    width: var(--left-panel-width);
    height: 100vh;
    background: var(--left-bg);
    color: var(--left-text);
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 2rem 1.25rem;
    overflow-y: auto;
    z-index: 100;
    scrollbar-width: thin;
    scrollbar-color: #333 transparent;
}

.left-panel::-webkit-scrollbar {
    width: 4px;
}

.left-panel::-webkit-scrollbar-thumb {
    background: #333;
    border-radius: 2px;
}

/* ----- Profile Section ----- */
.profile-section {
    text-align: center;
    margin-bottom: 1.25rem;
}

.profile-pic-wrapper {
    position: relative;
    width: 160px;
    height: 160px;
    margin: 0 auto 0.75rem;
}

.profile-pic {
    width: 100%;
    height: 100%;
    border-radius: 50%;
    object-fit: cover;
    border: 3px solid rgba(255, 255, 255, 0.15);
    transition: transform var(--transition-speed), border-color var(--transition-speed);
}

.profile-pic:hover {
    transform: scale(1.04);
    border-color: rgba(255, 255, 255, 0.4);
}

.signature-overlay {
    position: absolute;
    bottom: -18px;
    left: 50%;
    transform: translateX(-50%);
    width: 200px;
    height: auto;
    opacity: 0.85;
    pointer-events: none;
}

.profile-name {
    font-size: 1.35rem;
    font-weight: 700;
    color: #fff;
    margin-bottom: 0.15rem;
    letter-spacing: -0.01em;
}

.profile-name-bengali {
    font-size: 0.95rem;
    color: rgba(255, 255, 255, 0.55);
    margin-bottom: 0.1rem;
    letter-spacing: 0.02em;
}

.profile-phonetic {
    font-size: 0.72rem;
    color: rgba(255, 255, 255, 0.35);
    margin-bottom: 0.2rem;
    font-style: italic;
}

.phonetic-hint {
    letter-spacing: 0.03em;
}

.profile-tagline {
    font-size: 0.8rem;
    color: var(--left-text-muted);
    margin-bottom: 0.15rem;
}

.profile-location {
    font-size: 0.75rem;
    color: var(--left-text-muted);
}

.profile-location i {
    margin-right: 4px;
}

/* ----- Social Links ----- */
.social-links {
    display: flex;
    gap: 0.65rem;
    margin-bottom: 1rem;
}

.social-links a {
    width: 38px;
    height: 38px;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.07);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--left-text);
    font-size: 1rem;
    transition: all var(--transition-speed);
    border: 1px solid rgba(255, 255, 255, 0.08);
}

.social-links a:hover {
    background: rgba(255, 255, 255, 0.15);
    color: #fff;
    transform: translateY(-2px);
}

/* ----- Download CV ----- */
.download-cv-btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.55rem 1.4rem;
    background: #fff;
    color: #0a0a0a;
    font-size: 0.8rem;
    font-weight: 600;
    border-radius: 100px;
    transition: all var(--transition-speed);
    margin-bottom: 1.5rem;
    text-decoration: none;
}

.download-cv-btn:hover {
    background: #e0e0e0;
    color: #000;
    transform: translateY(-1px);
}

.sidebar-chat-btn {
    width: 100%;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.45rem;
    padding: 0.58rem 0.9rem;
    margin-bottom: 1.1rem;
    border: 1px solid rgba(255, 255, 255, 0.22);
    border-radius: 100px;
    background: rgba(255, 255, 255, 0.08);
    color: #fff;
    font-size: 0.77rem;
    font-weight: 600;
    letter-spacing: 0.01em;
    text-decoration: none;
    transition: all var(--transition-speed);
    text-align: center;
}

.sidebar-chat-btn:hover {
    background: rgba(255, 255, 255, 0.16);
    border-color: rgba(255, 255, 255, 0.35);
    color: #fff;
    transform: translateY(-1px);
}

/* ----- Section Navigation ----- */
.section-nav {
    width: 100%;
    display: flex;
    flex-direction: column;
    gap: 0.25rem;
    flex: 1;
}

.nav-item {
    display: flex;
    align-items: center;
    gap: 0.65rem;
    width: 100%;
    padding: 0.6rem 1rem;
    background: transparent;
    border: none;
    border-radius: var(--radius-sm);
    color: var(--left-text-muted);
    font-size: 0.82rem;
    font-family: inherit;
    cursor: pointer;
    transition: all var(--transition-speed);
    text-align: left;
    position: relative;
}

.nav-item i {
    width: 18px;
    text-align: center;
    font-size: 0.85rem;
}

.nav-item:hover {
    background: var(--nav-active-bg);
    color: var(--left-text);
}

.nav-item.active {
    background: var(--nav-active-bg);
    color: #fff;
    font-weight: 600;
}

.nav-item.active::before {
    content: '';
    position: absolute;
    left: 0;
    top: 50%;
    transform: translateY(-50%);
    width: 3px;
    height: 60%;
    background: var(--accent);
    border-radius: 0 2px 2px 0;
}

/* ----- QR Code ----- */
.qr-code-wrapper {
    display: flex;
    justify-content: center;
    padding: 1rem 0 0.5rem;
}

.qr-code {
    width: 130px;
    height: 130px;
    border-radius: 6px;
    opacity: 0.85;
}

/* ----- Left Footer ----- */
.left-footer {
    margin-top: auto;
    padding-top: 1rem;
}

.left-footer p {
    font-size: 0.7rem;
    color: var(--left-text-muted);
}

/* =============================================
   RIGHT PANEL
   ============================================= */
.right-panel {
    margin-left: var(--left-panel-width);
    width: calc(100% - var(--left-panel-width));
    min-height: 100vh;
    padding: 3rem 4rem;
    overflow-y: auto;
    background: var(--right-bg);
}

/* ----- Content Sections ----- */
.content-section {
    display: none;
    animation: fadeInSection 0.4s ease-out;
}

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

@keyframes fadeInSection {
    from {
        opacity: 0;
        transform: translateY(16px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* ----- Typography ----- */
.content-section h2 {
    font-size: 2.2rem;
    font-weight: 700;
    color: var(--heading-color);
    margin-bottom: 1.75rem;
    padding-bottom: 0.75rem;
    border-bottom: 2px solid #f0f0f0;
    letter-spacing: -0.02em;
}

.content-section h3 {
    font-size: 1.3rem;
    font-weight: 600;
    color: var(--heading-color);
    margin: 2rem 0 1rem;
}

.content-section h4 {
    font-size: 1.05rem;
    font-weight: 600;
    color: var(--heading-color);
    margin-bottom: 0.5rem;
}

.content-section p {
    color: var(--right-text-secondary);
    margin-bottom: 0.75rem;
    line-height: 1.75;
}

.section-intro {
    font-size: 1.02rem;
    margin-bottom: 1.5rem;
}

/* ----- Keywords ----- */
.keyword {
    display: inline;
    background: transparent;
    color: inherit;
    padding: 0;
    border-radius: 0;
    font-size: inherit;
    font-weight: inherit;
    border: 0;
    transition: none;
}

.keyword:hover {
    transform: none;
}

.kw-past {
    background: transparent;
    color: inherit;
    border-color: transparent;
}

.kw-present {
    background: transparent;
    color: inherit;
    border-color: transparent;
}

.kw-future {
    background: transparent;
    color: inherit;
    border-color: transparent;
}

/* ----- Badge ----- */
.badge {
    display: inline;
    background: transparent;
    color: inherit;
    font-size: inherit;
    font-weight: inherit;
    padding: 0;
    border-radius: 0;
    vertical-align: middle;
    margin-left: 0;
}

/* =============================================
   INTRO TEXT
   ============================================= */
.intro-text {
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: var(--radius);
    padding: 1.75rem;
    margin-bottom: 1.5rem;
    text-align: justify;
}

.intro-text p {
    font-size: 1.05rem;
    line-height: 1.85;
    margin-bottom: 0;
}

/* Rotating horizontal affiliation logos */
.intro-logo-banner {
    position: relative;
    margin: 0.75rem 0 1.8rem;
    overflow: hidden;
    border-radius: var(--radius);
    border: 1px solid var(--card-border);
    background: linear-gradient(90deg, #f8fafc 0%, #ffffff 50%, #f8fafc 100%);
    padding: 0.7rem 0;
}

.intro-logo-track {
    display: flex;
    width: 100%;
    justify-content: center;
}

.intro-logo-group {
    display: flex;
    align-items: center;
    gap: 0.9rem;
    padding: 0 0.9rem;
}

.intro-logo-item {
    width: 180px;
    min-width: 180px;
    height: 64px;
    flex: 0 0 auto;
    border-radius: 8px;
    border: 1px solid var(--card-border);
    background: #fff;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 0.55rem 0.8rem;
}

.intro-logo-item img {
    width: 100%;
    max-width: 150px;
    max-height: 42px;
    object-fit: contain;
}

.intro-logo-ut {
    max-width: 118px;
}

.intro-logo-ece {
    max-width: 126px;
}

.intro-logo-ju {
    max-width: 140px;
}

.intro-logo-db {
    max-width: 132px;
}

@media (max-width: 700px) {
    .intro-logo-banner {
        overflow-x: auto;
        overflow-y: hidden;
    }

    .intro-logo-track {
        width: max-content;
        justify-content: flex-start;
    }

    .intro-logo-item {
        width: 148px;
        min-width: 148px;
        height: 54px;
        padding: 0.45rem 0.65rem;
    }

    .intro-logo-item img {
        max-width: 124px;
        max-height: 34px;
    }
}

/* =============================================
   TIMELINE (Introduction)
   ============================================= */
.timeline {
    position: relative;
    padding-left: 2rem;
}

.timeline::before {
    content: '';
    position: absolute;
    left: 7px;
    top: 8px;
    bottom: 8px;
    width: 2px;
    background: linear-gradient(180deg, var(--accent), #c7d2fe);
    border-radius: 1px;
}

.timeline-item {
    position: relative;
    padding-left: 2rem;
    padding-bottom: 2rem;
}

.timeline-item:last-child {
    padding-bottom: 0;
}

.timeline-dot {
    position: absolute;
    left: -2rem;
    top: 6px;
    width: 16px;
    height: 16px;
    border-radius: 50%;
    background: #fff;
    border: 3px solid var(--accent);
    z-index: 1;
}

.timeline-item:first-child .timeline-dot {
    background: var(--accent);
}

.timeline-date {
    font-size: 0.78rem;
    font-weight: 600;
    color: var(--accent);
    text-transform: uppercase;
    letter-spacing: 0.04em;
    margin-bottom: 0.35rem;
}

.timeline-body h4 {
    margin-bottom: 0.3rem;
}

.timeline-body p {
    margin-bottom: 0;
    font-size: 0.92rem;
}

/* =============================================
   RESEARCH OVERVIEW
   ============================================= */
.research-overview {
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: var(--radius);
    padding: 1.75rem;
    margin-bottom: 1.5rem;
    text-align: justify;
}

.research-note {
    margin-top: 1rem;
    padding: 0.75rem 1rem;
    background: #fffbeb;
    border: 1px solid #fde68a;
    border-radius: var(--radius-sm);
    font-size: 0.9rem;
    color: #92400e;
    margin-bottom: 0 !important;
}

.research-note i {
    margin-right: 6px;
    color: #d97706;
}

/* Achievements list */
.achievements-list {
    list-style: none;
    padding: 0;
    margin: 0;
}

.achievements-list li {
    padding: 0.75rem 1rem;
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: var(--radius-sm);
    margin-bottom: 0.5rem;
    font-size: 0.95rem;
}

.achievements-list li i {
    margin-right: 8px;
    color: var(--accent);
}

/* =============================================
   PUBLICATION / HACKATHON / RESEARCH CARDS
   ============================================= */
.card-list {
    display: flex;
    flex-direction: column;
    gap: 1.25rem;
}

.pub-card,
.hack-card,
.research-interest-card {
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: var(--radius);
    overflow: hidden;
    transition: transform var(--transition-speed);
    cursor: pointer;
}

.philosophy-list {
    margin: 0.5rem 0 0.5rem 1.2rem;
    padding: 0;
    font-size: 0.95rem;
    line-height: 1.7;
}

.philosophy-note {
    font-style: italic;
    color: var(--text-secondary);
    margin-top: 0.5rem;
    font-size: 0.92rem;
}

.pub-card:hover,
.hack-card:hover,
.research-interest-card:hover {
    transform: translateY(-2px);
}

.pub-card-header {
    padding: 1.5rem;
}

.pub-card-meta {
    display: flex;
    gap: 0.6rem;
    margin-bottom: 0.6rem;
}

.pub-year {
    font-size: inherit;
    font-weight: inherit;
    background: transparent;
    color: inherit;
    padding: 0;
    border-radius: 0;
}

.pub-venue {
    font-size: inherit;
    font-weight: inherit;
    background: transparent;
    color: inherit;
    padding: 0;
    border-radius: 0;
    border: 0;
}

.pub-card-header h4 {
    font-size: 1rem;
    line-height: 1.5;
    margin-bottom: 0.65rem;
}

.pub-card-header p {
    font-size: 0.9rem;
    line-height: 1.7;
}

/* Paper advisors */
.paper-advisors {
    font-size: 0.85rem;
    color: var(--text-secondary);
    margin-top: 0.5rem;
    font-style: italic;
}

/* Paper / proof links */
.paper-link,
.proof-link {
    display: inline-flex;
    align-items: center;
    gap: 0.4rem;
    margin-top: 0.75rem;
    padding: 0.45rem 1rem;
    background: #9ca3af;
    color: #111827;
    opacity: 0.65;
    font-size: 0.8rem;
    font-weight: 600;
    border: 1px solid #9ca3af;
    border-radius: 100px;
    transition: background var(--transition-speed), opacity var(--transition-speed), color var(--transition-speed);
}

.paper-link:hover,
.proof-link:hover {
    background: #6b7280;
    border-color: #6b7280;
    color: #f9fafb;
    opacity: 0.78;
}

/* ----- Horizontally Scrollable Images ----- */
.pub-card-images {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.4s ease;
    border-top: 0 solid var(--card-border);
}

.pub-card[data-expanded="true"] .pub-card-images,
.hack-card[data-expanded="true"] .pub-card-images,
.research-interest-card[data-expanded="true"] .pub-card-images {
    max-height: 300px;
    border-top-width: 1px;
}

/* Collapse / Minimize All Button */
.collapse-all-btn {
    display: inline-flex;
    align-items: center;
    gap: 0.35rem;
    padding: 0.3rem 0.85rem;
    font-size: 0.75rem;
    font-weight: 600;
    font-family: inherit;
    background: #f3f4f6;
    color: var(--right-text-secondary);
    border: 1px solid var(--card-border);
    border-radius: 100px;
    cursor: pointer;
    transition: all var(--transition-speed);
    margin-left: 0.75rem;
    vertical-align: middle;
}

.collapse-all-btn:hover {
    background: #e5e7eb;
    color: var(--heading-color);
}

.collapse-all-btn-wrapper {
    margin-bottom: 0.75rem;
}

.image-scroll-container {
    display: flex;
    gap: 0.75rem;
    padding: 1rem 1.5rem;
    overflow-x: auto;
    scroll-snap-type: x mandatory;
    -webkit-overflow-scrolling: touch;
}

.image-scroll-container::-webkit-scrollbar {
    height: 6px;
}

.image-scroll-container::-webkit-scrollbar-track {
    background: #f0f0f0;
    border-radius: 3px;
}

.image-scroll-container::-webkit-scrollbar-thumb {
    background: #ccc;
    border-radius: 3px;
}

.image-scroll-container img {
    flex: 0 0 auto;
    height: 160px;
    width: auto;
    border-radius: var(--radius-sm);
    object-fit: cover;
    scroll-snap-align: start;
    cursor: pointer;
    transition: transform var(--transition-speed);
    border: 1px solid var(--card-border);
}

.image-scroll-container img:hover {
    transform: scale(1.03);
}

/* =============================================
   EDUCATION & CAREER CARDS
   ============================================= */
.edu-card {
    display: flex;
    gap: 1.25rem;
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: var(--radius);
    padding: 1.75rem;
    margin-bottom: 1.25rem;
    transition: transform var(--transition-speed);
}

.edu-card:hover {
    transform: translateY(-2px);
}

.edu-card-icon {
    flex-shrink: 0;
    width: 48px;
    height: 48px;
    background: var(--keyword-bg);
    color: var(--accent);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.2rem;
}

.edu-card-content {
    flex: 1;
    min-width: 0;
}

.edu-card-header {
    display: flex;
    justify-content: space-between;
    align-items: baseline;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-bottom: 0.35rem;
}

.edu-card-header h3 {
    font-size: 1.15rem;
    margin: 0;
}

.edu-year {
    font-size: 0.78rem;
    font-weight: 600;
    color: var(--accent);
    white-space: nowrap;
}

.edu-degree {
    font-size: 0.92rem;
    color: var(--right-text-secondary);
    margin-bottom: 0.75rem;
}

.edu-card-content ul {
    padding-left: 1.25rem;
    list-style: disc;
}

.edu-card-content li {
    font-size: 0.92rem;
    color: var(--right-text-secondary);
    margin-bottom: 0.5rem;
    line-height: 1.65;
}

.edu-card-content li a {
    font-weight: 500;
}

/* Education media (photo + map) */
.edu-media {
    display: flex;
    gap: 1rem;
    margin-top: 1rem;
    border-top: 1px solid var(--card-border);
    padding-top: 1rem;
}

.edu-photo {
    width: 50%;
    max-height: 200px;
    object-fit: cover;
    border-radius: var(--radius-sm);
}

.edu-map {
    width: 50%;
    height: 200px;
    border: 0;
    border-radius: var(--radius-sm);
}

@media (max-width: 600px) {
    .edu-media {
        flex-direction: column;
    }
    .edu-photo,
    .edu-map {
        width: 100%;
    }
}

/* =============================================
   MISCELLANEOUS SECTION
   ============================================= */
.misc-block {
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: var(--radius);
    padding: 1.75rem;
    margin-bottom: 1.5rem;
}

.misc-block h3 {
    margin-top: 0;
    margin-bottom: 1.25rem;
}

.misc-block h3 i {
    margin-right: 8px;
    color: var(--accent);
}

/* Skills Grid */
.skills-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 1.25rem;
    margin-bottom: 1.5rem;
}

.skill-group {
    padding: 1rem;
    background: #fff;
    border: 1px solid var(--card-border);
    border-radius: var(--radius-sm);
}

.skill-group h4 {
    font-size: 0.85rem;
    text-transform: uppercase;
    letter-spacing: 0.04em;
    color: var(--right-text-secondary);
    margin-bottom: 0.6rem;
}

.skill-group p {
    margin-bottom: 0;
    display: flex;
    flex-wrap: wrap;
    gap: 0.35rem;
}

.skill-group .keyword {
    font-size: inherit;
    padding: 0;
}

/* Certifications */
.cert-list {
    padding-left: 0;
    list-style: none;
}

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

.cert-list a {
    display: inline-flex;
    align-items: center;
    gap: 0.4rem;
    font-size: 0.9rem;
    font-weight: 500;
}

.cert-list i {
    color: #d97706;
}

/* Hobbies Grid */
.hobbies-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1rem;
}

.hobby-card {
    text-align: center;
    padding: 1.25rem;
    background: #fff;
    border: 1px solid var(--card-border);
    border-radius: var(--radius-sm);
    transition: transform var(--transition-speed);
}

.hobby-card:hover {
    transform: translateY(-1px);
}

.hobby-icon {
    font-size: 2rem;
    color: var(--accent);
    margin-bottom: 0.65rem;
}

.hobby-card p {
    font-size: 0.9rem;
    margin-bottom: 0;
}

/* =============================================
   LIGHTBOX
   ============================================= */
.lightbox-overlay {
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.85);
    z-index: 1000;
    display: none;
    align-items: center;
    justify-content: center;
    backdrop-filter: blur(4px);
}

.lightbox-overlay.active {
    display: flex;
}

.lightbox-content {
    position: relative;
    max-width: 80vw;
    max-height: 80vh;
    display: flex;
    flex-direction: column;
    align-items: center;
}

.lightbox-img {
    max-width: 100%;
    max-height: 70vh;
    border-radius: var(--radius);
    object-fit: contain;
}

.lightbox-close,
.lightbox-prev,
.lightbox-next {
    position: absolute;
    background: rgba(255, 255, 255, 0.15);
    border: none;
    color: #fff;
    width: 44px;
    height: 44px;
    border-radius: 50%;
    font-size: 1.1rem;
    cursor: pointer;
    transition: background var(--transition-speed);
    display: flex;
    align-items: center;
    justify-content: center;
}

.lightbox-close:hover,
.lightbox-prev:hover,
.lightbox-next:hover {
    background: rgba(255, 255, 255, 0.3);
}

.lightbox-close {
    top: -20px;
    right: -20px;
}

.lightbox-prev {
    left: -60px;
    top: 50%;
    transform: translateY(-50%);
}

.lightbox-next {
    right: -60px;
    top: 50%;
    transform: translateY(-50%);
}

.lightbox-dots {
    display: flex;
    gap: 8px;
    margin-top: 1rem;
}

.lightbox-dot {
    width: 10px;
    height: 10px;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.35);
    border: none;
    cursor: pointer;
    transition: background var(--transition-speed);
}

.lightbox-dot.active {
    background: #fff;
}

/* =============================================
   RESPONSIVE
   ============================================= */
@media (max-width: 1024px) {
    .right-panel {
        padding: 2.5rem 2rem;
    }
}

@media (max-width: 768px) {
    :root {
        --left-panel-width: 0px;
    }

    .left-panel {
        position: fixed;
        transform: translateX(-100%);
        width: 280px;
        transition: transform 0.35s ease;
        z-index: 200;
    }

    .left-panel.open {
        transform: translateX(0);
    }

    .right-panel {
        margin-left: 0;
        width: 100%;
        padding: 1.5rem 1.25rem;
        padding-top: 4rem;
    }

    .mobile-menu-btn {
        display: flex !important;
    }

    .mobile-overlay {
        display: block !important;
    }

    .content-section h2 {
        font-size: 1.7rem;
    }

    .edu-card {
        flex-direction: column;
    }

    .edu-card-header {
        flex-direction: column;
    }

    .lightbox-prev { left: -10px; }
    .lightbox-next { right: -10px; }
    .lightbox-close { top: -50px; right: 0; }
}

/* Mobile menu button (hidden on desktop) */
.mobile-menu-btn {
    display: none;
    position: fixed;
    top: 1rem;
    left: 1rem;
    z-index: 300;
    width: 44px;
    height: 44px;
    border-radius: 50%;
    background: var(--left-bg);
    color: #fff;
    border: none;
    font-size: 1.2rem;
    cursor: pointer;
    align-items: center;
    justify-content: center;
}

.mobile-menu-btn.attention-ping {
    animation: mobileBtnPulse 1.2s ease-in-out infinite, mobileBtnNudge 0.7s ease-in-out infinite;
    box-shadow: 0 0 0 0 rgba(37, 99, 235, 0.5);
}

.mobile-menu-hint {
    display: none;
    position: fixed;
    top: 1.55rem;
    left: 3.95rem;
    z-index: 305;
    padding: 0.28rem 0.6rem;
    border-radius: 999px;
    background: rgba(17, 24, 39, 0.9);
    color: #f9fafb;
    font-size: 0.72rem;
    font-weight: 600;
    letter-spacing: 0.01em;
    opacity: 0;
    transform: translateX(-6px);
    transition: opacity 0.28s ease, transform 0.28s ease;
    pointer-events: none;
}

.mobile-menu-hint.active {
    opacity: 1;
    transform: translateX(0);
}

@keyframes mobileBtnPulse {
    0% {
        transform: scale(1);
        box-shadow: 0 0 0 0 rgba(37, 99, 235, 0.5);
    }
    70% {
        transform: scale(1.06);
        box-shadow: 0 0 0 12px rgba(37, 99, 235, 0);
    }
    100% {
        transform: scale(1);
        box-shadow: 0 0 0 0 rgba(37, 99, 235, 0);
    }
}

@keyframes mobileBtnNudge {
    0%,
    100% {
        margin-left: 0;
    }
    25% {
        margin-left: -2px;
    }
    75% {
        margin-left: 2px;
    }
}

@media (prefers-reduced-motion: reduce) {
    .mobile-menu-btn.attention-ping {
        animation: none;
    }

    .mobile-menu-hint {
        transition: none;
    }
}

@media (max-width: 768px) {
    .mobile-menu-hint {
        display: block;
    }
}

.mobile-overlay {
    display: none;
    position: fixed;
    inset: 0;
    background: rgba(0,0,0,0.4);
    z-index: 150;
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.3s;
}

.mobile-overlay.active {
    opacity: 1;
    pointer-events: auto;
}