/* ===================================
   VASKAR CHAKMA - ACADEMIC PORTFOLIO
   Redesigned with Clean Academic Style
   =================================== */

/* Reset and Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Helvetica Neue', Arial, sans-serif;
    line-height: 1.6;
    color: #333;
    background-color: #ffffff;
    overflow-x: hidden;
}

/* Container */
.container {
    max-width: 980px;
    margin: 0 auto;
    padding: 40px 20px;
}

/* ========== PROFILE HEADER ========== */
.profile-header {
    display: flex;
    gap: 30px;
    margin-bottom: 50px;
    align-items: flex-start;
}

.profile-photo {
    flex-shrink: 0;
    width: 200px;
    height: 200px;
    border-radius: 50%;
    overflow: hidden;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 72px;
    color: white;
    font-weight: 600;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
}

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

.profile-info {
    flex: 1;
}

.profile-info h1 {
    font-size: 2em;
    font-weight: 600;
    color: #000;
    margin-bottom: 8px;
    line-height: 1.3;
}

.profile-info .subtitle {
    font-size: 1em;
    color: #666;
    margin-bottom: 5px;
    font-weight: 400;
}

.profile-info .affiliation {
    font-size: 0.9em;
    color: #666;
    margin-bottom: 3px;
    line-height: 1.4;
}

.profile-contact {
    margin-top: 15px;
    font-size: 0.9em;
    color: #666;
}

.profile-contact a {
    color: #1a73e8;
    text-decoration: none;
    margin-left: 15px;
}

.profile-contact a:hover {
    text-decoration: underline;
}

/* ========== NAVIGATION ========== */
nav {
    border-bottom: 1px solid #e0e0e0;
    margin-bottom: 40px;
    position: sticky;
    top: 0;
    background: white;
    z-index: 100;
    padding: 12px 0;
}

.nav-links {
    display: flex;
    gap: 25px;
    flex-wrap: wrap;
}

.nav-links a {
    color: #333;
    text-decoration: none;
    font-size: 0.95em;
    font-weight: 500;
    padding: 5px 0;
    transition: color 0.2s;
}

.nav-links a:hover,
.nav-links a.active {
    color: #1a73e8;
}

/* ========== MOBILE MENU TOGGLE ========== */
.mobile-menu-toggle {
    display: none;
    position: fixed;
    top: 15px;
    right: 15px;
    z-index: 1000;
    background-color: #1a73e8;
    border: none;
    border-radius: 5px;
    padding: 10px;
    cursor: pointer;
    flex-direction: column;
    gap: 4px;
}

.mobile-menu-toggle span {
    width: 25px;
    height: 3px;
    background-color: white;
    transition: all 0.3s;
    border-radius: 2px;
}

.mobile-menu-toggle.active span:nth-child(1) {
    transform: rotate(45deg) translate(5px, 5px);
}

.mobile-menu-toggle.active span:nth-child(2) {
    opacity: 0;
}

.mobile-menu-toggle.active span:nth-child(3) {
    transform: rotate(-45deg) translate(7px, -6px);
}

/* ========== SECTION STYLES ========== */
section {
    margin-bottom: 50px;
}

section h2 {
    font-size: 1.6em;
    font-weight: 600;
    color: #000;
    margin-bottom: 25px;
    padding-bottom: 10px;
    border-bottom: 1px solid #e0e0e0;
}

section h3 {
    font-size: 1.2em;
    font-weight: 600;
    color: #333;
    margin: 25px 0 15px 0;
}

section p {
    color: #555;
    font-size: 0.95em;
    line-height: 1.7;
    margin-bottom: 15px;
}

section a {
    color: #1a73e8;
    text-decoration: none;
}

section a:hover {
    text-decoration: underline;
}

/* ========== RESEARCH INTERESTS ========== */
.interests {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    margin-top: 15px;
}

.interest-tag {
    background-color: #f1f3f4;
    color: #333;
    padding: 6px 14px;
    border-radius: 16px;
    font-size: 0.85em;
    font-weight: 500;
}

/* ========== EDUCATION ========== */
.education-item {
    margin-bottom: 25px;
    padding-bottom: 20px;
    border-bottom: 1px solid #f0f0f0;
}

.education-item:last-child {
    border-bottom: none;
}

.edu-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    gap: 20px;
}

.edu-content {
    flex: 1;
}

.edu-degree {
    font-weight: 600;
    color: #000;
    font-size: 1em;
    margin-bottom: 5px;
}

.edu-school {
    color: #666;
    font-size: 0.9em;
    margin-bottom: 8px;
}

.edu-detail {
    color: #666;
    font-size: 0.85em;
    margin-top: 5px;
    line-height: 1.5;
}

.edu-year {
    color: #999;
    font-size: 0.9em;
    white-space: nowrap;
    font-weight: 500;
}

/* ========== PUBLICATIONS ========== */
.publication-item {
    margin-bottom: 25px;
    padding-bottom: 20px;
    border-bottom: 1px solid #f0f0f0;
    opacity: 0;
    transform: translateY(20px);
    transition: opacity 0.6s ease, transform 0.6s ease;
}

.publication-item.visible {
    opacity: 1;
    transform: translateY(0);
}

.publication-item:last-child {
    border-bottom: none;
}

.pub-content {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.pub-title {
    font-weight: 600;
    color: #1a73e8;
    font-size: 1em;
    line-height: 1.4;
    cursor: pointer;
}

.pub-title:hover {
    text-decoration: underline;
}

.pub-authors {
    color: #666;
    font-size: 0.9em;
    line-height: 1.4;
}

.pub-authors strong {
    color: #333;
    font-weight: 600;
}

.pub-venue {
    color: #666;
    font-size: 0.85em;
    font-style: italic;
}

.pub-links {
    display: flex;
    gap: 12px;
    margin-top: 5px;
}

.pub-links a {
    color: #1a73e8;
    text-decoration: none;
    font-size: 0.85em;
}

.pub-links a:hover {
    text-decoration: underline;
}

/* ========== EXPERIENCE ========== */
.experience-item {
    margin-bottom: 20px;
    padding-bottom: 15px;
    border-bottom: 1px solid #f0f0f0;
}

.experience-item:last-child {
    border-bottom: none;
}

.exp-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    gap: 20px;
}

.exp-content {
    flex: 1;
}

.exp-title {
    font-weight: 600;
    color: #000;
    font-size: 1em;
    margin-bottom: 4px;
}

.exp-org {
    color: #666;
    font-size: 0.9em;
    margin-bottom: 6px;
}

.exp-desc {
    color: #666;
    font-size: 0.85em;
    line-height: 1.5;
}

.exp-year {
    color: #999;
    font-size: 0.9em;
    white-space: nowrap;
    font-weight: 500;
}

/* ========== SKILLS & HONORS ========== */
.honors-list {
    list-style-position: inside;
    color: #666;
    font-size: 0.9em;
    line-height: 1.8;
}

.honors-list li {
    margin-bottom: 8px;
}

/* ========== FOOTER ========== */
footer {
    margin-top: 60px;
    padding-top: 20px;
    border-top: 1px solid #e0e0e0;
    text-align: center;
    color: #999;
    font-size: 0.85em;
}

/* ========== SCROLL TO TOP ========== */
#scrollToTop {
    display: none;
    position: fixed;
    bottom: 30px;
    right: 30px;
    z-index: 99;
    border: none;
    outline: none;
    background-color: #1a73e8;
    color: white;
    cursor: pointer;
    padding: 12px;
    border-radius: 50%;
    font-size: 18px;
    width: 50px;
    height: 50px;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.2);
    transition: all 0.3s;
}

#scrollToTop:hover {
    background-color: #1557b0;
    transform: translateY(-3px);
}

/* ========================================
   RESPONSIVE DESIGN
   ======================================== */

/* Mobile Devices (up to 768px) */
@media (max-width: 768px) {
    .container {
        padding: 20px 15px;
    }

    .profile-header {
        flex-direction: column;
        align-items: center;
        text-align: center;
        gap: 20px;
    }

    .profile-photo {
        width: 160px;
        height: 160px;
        font-size: 60px;
    }

    .profile-info h1 {
        font-size: 1.6em;
    }

    .profile-contact {
        display: flex;
        flex-direction: column;
        gap: 10px;
    }

    .profile-contact a {
        margin-left: 0;
    }

    .mobile-menu-toggle {
        display: flex;
    }

    nav {
        position: fixed;
        top: 0;
        left: -100%;
        width: 75%;
        height: 100vh;
        background-color: white;
        box-shadow: 2px 0 10px rgba(0,0,0,0.1);
        transition: left 0.3s;
        padding: 80px 20px 20px;
    }

    nav.active {
        left: 0;
    }

    .nav-links {
        flex-direction: column;
        gap: 0;
    }

    .nav-links a {
        padding: 15px 0;
        border-bottom: 1px solid #f0f0f0;
        font-size: 1em;
    }

    section h2 {
        font-size: 1.4em;
    }

    section h3 {
        font-size: 1.1em;
    }

    .edu-header,
    .exp-header {
        flex-direction: column;
        gap: 10px;
    }

    .edu-year,
    .exp-year {
        align-self: flex-start;
    }

    #scrollToTop {
        width: 45px;
        height: 45px;
        bottom: 20px;
        right: 20px;
    }
}

/* Tablets (768px - 1024px) */
@media (min-width: 768px) and (max-width: 1024px) {
    .container {
        padding: 30px 30px;
    }

    .profile-photo {
        width: 180px;
        height: 180px;
        font-size: 64px;
    }
}

/* Desktop (1024px+) */
@media (min-width: 1024px) {
    .container {
        padding: 50px 40px;
    }
}

/* Print Styles */
@media print {
    body {
        background-color: white;
    }

    .container {
        max-width: 100%;
        padding: 0;
    }

    nav,
    #scrollToTop,
    .mobile-menu-toggle {
        display: none;
    }

    .profile-header {
        page-break-after: avoid;
    }

    section {
        page-break-inside: avoid;
    }

    .publication-item,
    .education-item,
    .experience-item {
        page-break-inside: avoid;
    }

    a {
        color: #000;
        text-decoration: none;
    }

    a[href]:after {
        content: " (" attr(href) ")";
        font-size: 0.8em;
        color: #666;
    }
}