:root {
    --accent: #00bcd4;
    --accent-dark: #0097a7;
    --bg-main: #f5f6fa;
    --text-main: #2d3436;
    --card-bg: #fff;
    --card-shadow: 0 4px 24px rgba(0, 188, 212, 0.08), 0 1.5px 6px rgba(0, 188, 212, 0.08);
}

body {
    font-family: Poppins, Inter, sans-serif;
    margin: 0;
    line-height: 1.6;
    color: var(--text-main);
    background: var(--bg-main);
    transition: background-color .3s, color .3s;
}

body.dark-mode {
    background: #121212 !important;
    color: #e0e0e0 !important;
    /* Subtle neon effect */
    box-shadow: 0 0 40px 0 rgba(0,188,212,0.08) inset;
}

body.dark-mode header {
    background: rgba(20, 30, 40, 0.95) !important;
    box-shadow: 0 0 24px 0 rgba(0,188,212,0.12), 0 2px 8px rgba(0,188,212,0.10);
    border: 1.5px solid rgba(0,188,212,0.18);
}

body.dark-mode .logo-text {
    color: #00bcd4 !important;
    text-shadow: 0 0 8px #00bcd4, 0 0 2px #fff2;
}

body.dark-mode .nav-link {
    color: #e0e0e0 !important;
    text-shadow: 0 0 4px #00bcd433;
}

body.dark-mode .nav-link:hover {
    color: #00bcd4 !important;
    box-shadow: 0 0 18px #00bcd4cc, 0 0 2px #fff2;
    background: rgba(0, 188, 212, 0.08);
}

body.dark-mode .card,
body.dark-mode .achievement-card,
body.dark-mode .project-card,
body.dark-mode #paper-details,
body.dark-mode .research-papers-row,
body.dark-mode .research-paper-details-row {
    background: #181c22 !important;
    color: #e0e0e0 !important;
    border-color: #00bcd4 !important;
    box-shadow: 0 0 24px 0 #00bcd455, 0 2px 8px #00bcd422;
}

body.dark-mode .footer, body.dark-mode footer {
    background: #181c22 !important;
    color: #00bcd4 !important;
    text-shadow: 0 0 8px #00bcd4cc;
}

body.dark-mode a,
body.dark-mode a:visited {
    color: #00bcd4;
    text-shadow: 0 0 4px #00bcd4cc;
}

body.dark-mode .skill-icon-3d {
    background: #232b36;
    box-shadow: 0 0 18px #00bcd455, 0 2px 8px #00bcd422;
}

body.dark-mode .skill-icon-3d[data-tooltip]:hover::after {
    background: #00bcd4;
    color: #181c22;
    box-shadow: 0 0 12px #00bcd4cc;
}

body.dark-mode .paper-card {
    background: #232b36;
    color: #00bcd4;
    border-color: #00bcd4;
    box-shadow: 0 0 12px #00bcd4cc;
}

body.dark-mode .paper-card.active, body.dark-mode .paper-card:hover {
    color: #fff;
    background: #00bcd4;
    box-shadow: 0 0 24px #00bcd4cc, 0 2px 8px #00bcd422;
}

body.dark-mode h1,
body.dark-mode h2,
body.dark-mode h3,
body.dark-mode h4,
body.dark-mode h5,
body.dark-mode h6,
body.dark-mode .center-heading,
body.dark-mode .text-content,
body.dark-mode .typed-intro,
body.dark-mode #typed-text,
body.dark-mode .achievement-card,
body.dark-mode .achievement-card p,
body.dark-mode .project-card,
body.dark-mode .card,
body.dark-mode .main-content,
body.dark-mode section,
body.dark-mode .paper-abstract-text,
body.dark-mode .footer,
body.dark-mode footer,
body.dark-mode .btn,
body.dark-mode .btn-outline-dark,
body.dark-mode .btn-outline-primary {
    color: #fff !important;
}

body.dark-mode .achievement-card p,
body.dark-mode .skills-icons .skill-icon-3d p,
body.dark-mode .skills-icons .skill-icon-3d h5 {
    color: #fff !important;
}

body.dark-mode .text-dark,
body.dark-mode .text-primary {
    color: #fff !important;
}

body.dark-mode .paper-card-inner {
    color: #fff !important;
}

body.dark-mode .nav-link {
    color: #e0e0e0 !important;
}

body.dark-mode .btn-outline-dark,
body.dark-mode .btn-outline-primary {
    border-color: #00bcd4 !important;
    color: #fff !important;
    background: transparent !important;
}
body.dark-mode .btn-outline-dark:hover,
body.dark-mode .btn-outline-primary:hover {
    background: #00bcd4 !important;
    color: #181c22 !important;
}

header {
    position: fixed;
    top: 20px;
    left: 50%;
    transform: translateX(-50%);
    width: 95%;
    max-width: 1400px;
    z-index: 1000;
    border-radius: 50px;
    padding: .8rem 2rem;
    border: 1px solid rgba(200, 200, 200, .18);
    display: flex;
    justify-content: space-between;
    align-items: center;
    box-shadow: 0 4px 12px rgba(0, 0, 0, .1);
    background: rgba(245, 245, 245, .85) !important;
    color: #2d3436 !important;
    transition: .3s;
}

nav {
    padding: 0;
    background: none;
}

.logo-text {
    color: #0097a7 !important; /* softer accent */
    /* No text-shadow in light mode for logo */
    transition: color .3s;
}

header .nav-link {
    color: #2d3436 !important;
    font-weight: 500;
    transition: .3s;
    padding: .5rem 1.2rem;
    border-radius: 25px;
    margin: 0 .2rem;
}

header .nav-link:hover {
    color: #00bcd4 !important;
    box-shadow: 0 0 15px rgba(0, 188, 212, .3);
    background: rgba(0, 188, 212, .1);
}

header .nav-link::after {
    content: none;
}

.hero {
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    padding: 80px 1rem 2rem;
    background: linear-gradient(135deg, var(--bg-main) 50%, #dfe6e9 50%);
    min-height: 100vh;
    position: relative;
    overflow: hidden;
    animation: 1.5s ease-in-out fadeInUp;
    color: var(--text-main);
    text-align: center;
}

body.dark-mode .hero {
    background: linear-gradient(135deg, #121212 50%, #1e1e1e 50%);
}

.hero .text-content {
    max-width: 800px;
    margin: 0 auto;
    z-index: 1;
}

.hero .illustration {
    display: none;
}

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

.hero::before,
.hero::after {
    content: '';
    z-index: 0;
    position: absolute;
    background: rgba(255, 255, 255, .1);
    border-radius: 50%;
}

.hero::before {
    top: -50px;
    left: -50px;
    width: 200px;
    height: 200px;
}

.hero::after {
    bottom: -50px;
    right: -50px;
    width: 300px;
    height: 300px;
}

.hero .text-primary {
    color: #0097a7 !important; /* softer accent */
    text-shadow: 0 0 3px #00bcd433, 0 0 1px #fff1; /* much softer neon */
}

body.dark-mode .hero .text-primary {
    color: #00bcd4 !important;
    text-shadow: 0 0 8px #00bcd4, 0 0 2px #fff2;
}

h1, h2, h3, h4, h5, h6 {
    font-family: Poppins, sans-serif;
    font-weight: 600;
    color: #2d3436;
}

h1 {
    font-size: 3.5rem;
    letter-spacing: -1px;
}

.center-heading {
    text-align: center;
}

.main-content {
    padding: 2rem;
    max-width: 1200px;
    margin: auto;
}

.section {
    margin-bottom: 3rem;
}

section {
    margin: 3rem 0;
    padding-top: 6rem;
    padding-bottom: 4rem;
}

.project-card {
    background: rgba(255, 255, 255, .9);
    cursor: pointer;
    transition: .3s;
    border-radius: 12px;
    overflow: hidden;
}

.project-card:hover {
    transform: translateY(-10px);
    box-shadow: 0 10px 30px rgba(0, 0, 0, .1);
}

.card {
    background: rgba(255, 255, 255, .9);
    border-radius: 8px;
    color: #2d3436;
    box-shadow: 0 5px 15px rgba(0, 0, 0, .05);
    transition: transform .3s, box-shadow .3s;
    padding: 1.5rem;
    border: none;
}

.card:hover {
    transform: translateY(-5px);
    box-shadow: 0 4px 10px rgba(0, 0, 0, .4);
}

.footer {
    padding: 1rem 0;
    background: #182848;
    color: #fff;
    font-size: .9rem;
    margin-top: 3rem;
    text-align: center;
}

footer {
    background: rgba(30, 30, 30, .95);
    color: #f5f6fa;
    padding: 2rem 0;
}

.footer p {
    margin: 0;
}

.social-icons {
    display: flex;
    justify-content: center;
    gap: 1rem;
    margin-top: 2rem;
    animation: 2s ease-in-out fadeIn;
}

.social-icons a {
    text-decoration: none;
    font-size: 2.2rem;
    color: #2d3436;
    transition: .3s;
    padding: .5rem;
    border-radius: 50%;
    background: rgba(255, 255, 255, .2);
    width: 3.2rem;
    height: 3.2rem;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 .5rem;
}

.social-icons a:hover {
    transform: translateY(-3px);
    background: rgba(255, 255, 255, .3);
    box-shadow: 0 5px 15px rgba(0, 0, 0, .1);
}

.social-icons a.github:hover { color: #fff; }
.social-icons a.linkedin:hover { color: #0077b5; }
.social-icons a.email:hover { color: #ea4335; }
.social-icons a.leetcode:hover { color: #ffa116; }
.social-icons a.kaggle:hover { color: #20beff; }

@keyframes fadeIn {
    0%, 100% { opacity: 0; }
    50% { opacity: 1; }
}

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

[data-aos] {
    transition-property: opacity, transform;
    transition-duration: .8s;
    transition-timing-function: cubic-bezier(0.16, 1, 0.3, 1);
}

.skills-icons {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 2.5em !important;
    padding: 2.5em 0;
    min-height: 200px;
}

.skill-icon-3d {
    width: 6rem;
    height: 6rem;
    font-size: 2rem;
    display: flex;
    align-items: center;
    justify-content: center;
    background: #fff;
    border-radius: 1.5em;
    box-shadow: 0 8px 28px rgba(0, 0, 0, .18), 0 2px 8px rgba(0, 188, 212, .12);
    margin: 1em;
    position: relative;
    text-align: center;
    flex-direction: column;
    transition: transform 0.3s;
}

.skill-icon-3d i,
.skill-icon-3d img {
    width: 60px;
    height: 60px;
    object-fit: contain;
    pointer-events: none;
    display: block;
    margin: 0;
    padding: 0;
}

.skill-icon-3d[data-tooltip]:hover::after,
.skill-icon-3d[data-tooltip]:focus::after {
    content: attr(data-tooltip);
    position: absolute;
    bottom: -45px;
    left: 50%;
    transform: translateX(-50%);
    background: #222;
    color: #fff;
    padding: 7px 16px;
    border-radius: 8px;
    white-space: nowrap;
    font-size: 1rem;
    font-family: Poppins, sans-serif;
    box-shadow: 0 4px 16px rgba(0, 0, 0, 0.18);
    opacity: 1;
    pointer-events: none;
    z-index: 10;
    transition: opacity .2s, transform .2s;
}

.skill-icon-3d[data-tooltip]:hover::before,
.skill-icon-3d[data-tooltip]:focus::before {
    content: '';
    position: absolute;
    bottom: -13px;
    left: 50%;
    transform: translateX(-50%);
    border-width: 7px 7px 0;
    border-style: solid;
    border-color: #222 transparent transparent;
    z-index: 11;
    opacity: 1;
}

.skills-icons .skill-icon-3d h5 {
    font-size: 1.2em;
    margin-top: 0.5em;
    color: var(--text-main);
}

.skills-icons .skill-icon-3d p {
    font-size: 0.9em;
    margin-top: 0.3em;
    color: #555;
}

.achievement-card {
    background: var(--card-bg);
    box-shadow: var(--card-shadow);
    min-width: 270px;
    flex: 1 1 270px;
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    border: 1.5px solid var(--accent);
    border-radius: 8px;
    padding: 1.5rem;
    max-width: 300px;
    text-align: left;
    transition: transform .3s, box-shadow .3s;
}

.achievement-card:hover {
    transform: translateY(-8px) scale(1.03);
    box-shadow: 0 6px 12px rgba(0, 0, 0, .2);
}

.achievement-card h5 {
    font-weight: 600;
    color: var(--accent);
    display: flex;
    align-items: center;
    gap: .5rem;
    font-size: 1.2rem;
    margin-bottom: .5rem;
}

.achievement-card ul {
    padding-left: 1.2rem;
}

.achievement-card li {
    margin-bottom: .5rem;
    line-height: 1.6;
}

.achievement-card a {
    color: var(--accent-dark);
    text-decoration: underline;
    font-weight: 500;
}

.achievement-card a:hover,
.achievement-card h5 {
    color: var(--accent);
}

.achievement-card p {
    margin-bottom: 0;
    font-size: 1rem;
    color: #555;
}

.achievements-cards {
    gap: 2rem;
    margin-top: 2rem;
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
}

#research-papers .row {
    display: flex;
    flex-wrap: nowrap;
    gap: 3rem;
    align-items: flex-start;
}

#paper-list {
    min-width: 220px;
    margin-right: 0;
}

#paper-details {
    border-radius: 12px;
    padding: 1.5rem;
    min-width: 0;
    flex: 1;
    background: var(--card-bg);
    box-shadow: var(--card-shadow);
}

.btn-outline-dark {
    border-color: var(--accent) !important;
    color: var(--accent) !important;
}

.btn-outline-dark:hover {
    background: var(--accent) !important;
    color: #fff !important;
}

@media (max-width:991px) {
    #research-papers .row {
        flex-wrap: wrap;
        gap: 1.5rem;
    }
    #paper-details,
    #paper-list {
        min-width: 0;
        width: 100%;
    }
}

@media (max-width:768px) {
    .achievements-cards {
        flex-direction: column;
        align-items: center;
    }
    .achievement-card {
        width: 100%;
        max-width: 100%;
    }
}

@media (max-width:767px) {
    .main-content {
        padding: 1rem;
    }
    .card-title {
        font-size: 1.3rem;
    }
}

@media (max-width: 767px) {
    .skill-icon-3d {
        width: 6rem;
        height: 6rem;
        font-size: 2.5rem;
    }
    .skill-icon-3d i,
    .skill-icon-3d img {
        width: 60px;
        height: 60px;
    }
    .skills-icons {
        gap: 1.5em;
        padding: 1.5em 0;
    }
}

@media (max-width:600px) {
    .skills-icons {
        gap: 1em !important;
    }
    .skill-icon-3d {
        width: 6rem;
        height: 6rem;
        font-size: 3rem;
    }
}

#projects-container {
    display: flex;
    flex-direction: column;
    align-items: center;
    width: 100%;
    margin: 0 auto;
    max-width: 1000px;
}

.project-card-wrapper {
    flex: 1 1 0;
    min-width: 270px;
    max-width: 300px;
    display: flex;
    justify-content: center;
}

@media (max-width: 991px) {
    #projects-container .d-flex.flex-row {
        flex-direction: column !important;
        align-items: center;
        gap: 1.5rem !important;
    }
    .project-card-wrapper {
        max-width: 100%;
        width: 100%;
    }
}

.research-papers-row {
    display: flex;
    justify-content: center;
    align-items: center;
    background: var(--card-bg);
    box-shadow: var(--card-shadow);
    border-radius: 16px;
    margin-top: 2.5rem;
    margin-bottom: 2.5rem;
    padding: 2rem 1rem;
    gap: 2rem;
}

.paper-card {
    background: var(--card-bg);
    color: var(--text-main);
    border: 2px solid var(--accent);
    border-radius: 10px;
    box-shadow: 0 2px 8px rgba(0,188,212,0.08);
    padding: 0.6rem 0.8rem; /* smaller padding */
    min-width: 120px; /* smaller min width */
    max-width: 180px; /* smaller max width */
    cursor: pointer;
    transition: box-shadow .2s, border-color .2s, transform .2s;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    font-weight: 500;
    font-size: 0.85rem; /* smaller font size */
}

.paper-card-inner {
    width: 100%;
    word-break: break-word;
    font-size: 0.92em; /* slightly smaller text */
}

.paper-card.active, .paper-card:hover {
    border-color: var(--accent-dark);
    box-shadow: 0 6px 18px rgba(0,188,212,0.18);
    color: var(--accent-dark);
    transform: translateY(-4px) scale(1.04);
}

.research-paper-details-row {
    margin: 2.5rem auto;
    background: var(--card-bg);
    box-shadow: var(--card-shadow);
    border-radius: 16px;
    padding: 2.5rem;
    display: flex;
    justify-content: space-between;
    gap: 2.5rem;
    align-items: flex-start;
    max-width: 1200px;
}

#paper-abstract {
    flex: 0 0 45%;
    max-width: 45%;
}

#paper-pdf {
    flex: 0 0 50%;
    max-width: 50%;
    height: 500px;
    border-radius: 8px;
    overflow: hidden;
}

#paper-pdf iframe {
    width: 100%;
    height: 100%;
    border: none;
    border-radius: 8px;
}

.paper-abstract-text {
    color: #555;
    font-size: 1.08rem;
    margin-top: 1.2rem;
}

@media (max-width: 991px) {
    .research-papers-row {
        flex-direction: column;
        gap: 1.2rem;
        padding: 1.2rem 0.5rem;
    }
    .research-paper-details-row {
        flex-direction: column;
        gap: 1.2rem;
        padding: 1.2rem 0.5rem;
    }
    .paper-card {
        min-width: 180px;
        max-width: 100%;
        font-size: 0.98rem;
    }
    #paper-abstract,
    #paper-pdf {
        flex: 0 0 100%;
        max-width: 100%;
    }
    #paper-pdf {
        height: 400px;
        margin-top: 1.5rem;
    }
}

@media (max-width: 600px) {
    .research-papers-row {
        padding: 0.5rem 0.2rem;
    }
    .research-paper-details-row {
        padding: 0.5rem 0.2rem;
    }
    .paper-card {
        padding: 0.7rem 0.5rem;
        font-size: 0.92rem;
    }
    .paper-abstract-text {
        font-size: 0.95rem;
    }
}

/* --- Responsive header and dark mode toggle --- */
#dark-mode-toggle {
  margin-left: 32px;
  font-size: 1.6rem;
  background: none;
  border: none;
  cursor: pointer;
  color: #0097a7;
  transition: color 0.3s, transform 0.2s;
  z-index: 1100;
}
#dark-mode-toggle:focus {
  outline: 2px solid #00bcd4;
}
body.dark-mode #dark-mode-toggle {
  color: #00bcd4;
}

@media (max-width: 991px) {
  header {
    flex-direction: column;
    align-items: stretch;
    padding: 0.8rem 0.5rem;
    top: 0;
    left: 0;
    transform: none;
    width: 100%;
    border-radius: 0 0 24px 24px;
  }
  #dark-mode-toggle {
    align-self: flex-end;
    margin-left: auto;
    margin-right: 0;
    margin-top: 0.5rem;
    margin-bottom: 0.5rem;
  }
}
@media (max-width: 600px) {
  header {
    padding: 0.5rem 0.2rem;
  }
  #dark-mode-toggle {
    font-size: 2rem;
    margin-top: 0.3rem;
    margin-bottom: 0.3rem;
  }
}

/* --- Responsive hero section --- */
.hero {
  padding: 100px 0.5rem 2rem;
  min-height: 80vh;
}
@media (max-width: 600px) {
  .hero {
    padding: 80px 0.2rem 1rem;
    min-height: 60vh;
  }
  .hero .text-content {
    padding: 0.5rem;
  }
  h1 {
    font-size: 2.1rem;
  }
}

/* --- Responsive skills section --- */
.skills-icons {
  gap: 1.2em !important;
  padding: 1.2em 0;
}
@media (max-width: 600px) {
  .skills-icons {
    gap: 0.5em !important;
    padding: 0.5em 0;
  }
  .skill-icon-3d {
    width: 4.2rem;
    height: 4.2rem;
    font-size: 1.2rem;
  }
  .skill-icon-3d i,
  .skill-icon-3d img {
    width: 38px;
    height: 38px;
  }
}

/* --- Responsive project cards --- */
#projects-container {
  max-width: 100%;
  padding: 0 0.5rem;
}
.project-card-wrapper {
  min-width: 220px;
  max-width: 100%;
}
@media (max-width: 991px) {
  #projects-container .d-flex.flex-row {
    flex-direction: column !important;
    align-items: center;
    gap: 1rem !important;
  }
  .project-card-wrapper {
    max-width: 100%;
    width: 100%;
    min-width: 0;
  }
}
@media (max-width: 600px) {
  .project-card-wrapper {
    min-width: 0;
    max-width: 100%;
    margin-bottom: 1rem;
  }
}

/* --- Responsive achievements section --- */
.achievements-cards {
  gap: 1rem;
}
.achievement-card {
  min-width: 180px;
  max-width: 100%;
  padding: 1rem;
}
@media (max-width: 600px) {
  .achievement-card {
    padding: 0.7rem;
    font-size: 0.95rem;
  }
}

/* --- Responsive research papers section --- */
.research-papers-row,
.research-paper-details-row {
  padding: 1rem 0.2rem;
  gap: 1rem;
}
@media (max-width: 991px) {
  .research-papers-row,
  .research-paper-details-row {
    flex-direction: column;
    gap: 0.7rem;
    padding: 0.7rem 0.2rem;
  }
}
@media (max-width: 600px) {
  .paper-card {
    min-width: 100px;
    max-width: 100%;
    font-size: 0.85rem;
    padding: 0.4rem 0.2rem;
  }
  .paper-abstract-text {
    font-size: 0.95rem;
  }
}

/* --- Responsive footer --- */
footer, .footer {
  padding: 1rem 0.2rem;
  font-size: 0.9rem;
}
@media (max-width: 600px) {
  footer, .footer {
    font-size: 0.8rem;
    padding: 0.5rem 0.1rem;
  }
}

/* --- Responsive social icons --- */
.social-icons a {
  font-size: 1.5rem;
  width: 2.2rem;
  height: 2.2rem;
  margin: 0 0.2rem;
}
@media (max-width: 600px) {
  .social-icons {
    gap: 0.3rem;
  }
  .social-icons a {
    font-size: 1.2rem;
    width: 1.7rem;
    height: 1.7rem;
    margin: 0 0.1rem;
  }
}

.research-paper-details-row {
    margin: 2.5rem auto;
    background: var(--card-bg);
    box-shadow: var(--card-shadow);
    border-radius: 16px;
    padding: 2.5rem;
    gap: 2.5rem;
    align-items: flex-start;
    max-width: 1200px;
    overflow: hidden;
}

#paper-pdf {
    position: relative;
    width: 100%;
    height: 600px;
    overflow: hidden;
    border-radius: 8px;
}

#paper-pdf iframe {
    width: 100%;
    height: 100%;
    border: none;
    border-radius: 8px;
}

.paper-abstract-text {
    color: var(--text-main);
    font-size: 1rem;
    line-height: 1.6;
    margin-top: 1.2rem;
    overflow-wrap: break-word;
    word-wrap: break-word;
    hyphens: auto;
}