/******************************************************
 * style.css — Aohua Tian Academic Portfolio
 * Theme: Apple-style glassmorphism design
 * Palette: Translucent blues, soft blur, smooth motion
 ******************************************************/

/* ====================================================
   Root Variables & Global Defaults
==================================================== */
:root {
    --primary-color: #1e88e5;
    --accent-color: #64b5f6;
    --text-color: #2b3a42;
    --bg-color: #e6f0ff;
    --glass-bg: rgba(255, 255, 255, 0.25);
    --border-radius: 18px;
    --transition: all 0.35s ease;
    --backdrop-blur: blur(18px);
}

*,
*::before,
*::after {
    box-sizing: border-box;
}

html,
body {
    margin: 0;
    padding: 0;
    font-family: "Poppins", "Segoe UI", Arial, sans-serif;
    color: var(--text-color);
    background: linear-gradient(120deg, #cfdffb 0%, #e8f3ff 100%);
    scroll-behavior: smooth;
}

/* ====================================================
   Accessibility — Skip Link
==================================================== */
.skip {
    position: absolute;
    top: -1000px;
    left: 0;
    background-color: var(--accent-color);
    color: #fff;
    padding: 10px 20px;
    border-radius: var(--border-radius);
    text-decoration: none;
    z-index: 999;
    transition: var(--transition);
}

.skip:focus {
    top: 20px;
}

/* ====================================================
   Header & Navigation
==================================================== */
header {
    position: sticky;
    top: 0;
    z-index: 1000;
    backdrop-filter: var(--backdrop-blur);
    background: rgba(255, 255, 255, 0.45);
    border-bottom: 1px solid rgba(255, 255, 255, 0.25);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.05);
}

nav {
    max-width: 1100px;
    margin: 0 auto;
    padding: 0.75rem 1rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.logo {
    font-size: 1.6rem;
    font-weight: 600;
    color: var(--primary-color);
    margin: 0;
    letter-spacing: 0.5px;
    transition: var(--transition);
}

.logo:hover {
    transform: scale(1.05);
}

.nav-links {
    list-style: none;
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
    margin: 0;
    padding: 0;
}

.nav-links a {
    text-decoration: none;
    color: var(--text-color);
    padding: 0.6rem 1rem;
    border-radius: var(--border-radius);
    transition: var(--transition);
    font-weight: 500;
    backdrop-filter: var(--backdrop-blur);
}

.nav-links a:hover,
.nav-links a:focus,
.nav-links a[aria-current="page"] {
    background: rgba(30, 136, 229, 0.25);
    color: #fff;
    box-shadow: 0 0 15px rgba(30, 136, 229, 0.3);
}

/* ===== Scroll Hide Navbar (for mobile) ===== */
header {
    position: fixed;
    top: 0;
    width: 100%;
    transition: transform 0.4s ease;
}

header.hidden {
    transform: translateY(-100%);
}



/* ====================================================
   Hero Section
==================================================== */
.hero {
    padding: 5rem 1rem;
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    justify-content: center;
    gap: 3rem;
    background: linear-gradient(135deg,
            rgba(227, 242, 253, 0.9) 0%,
            rgba(255, 255, 255, 0.8) 100%);
}

.profile {
    width: 220px;
    height: 220px;
    border-radius: 50%;
    object-fit: cover;
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.15);
    transition: var(--transition);
    backdrop-filter: var(--backdrop-blur);
}

.profile:hover {
    transform: scale(1.06);
}

.intro-text {
    max-width: 560px;
    background: var(--glass-bg);
    border-radius: var(--border-radius);
    backdrop-filter: var(--backdrop-blur);
    padding: 1.5rem 2rem;
    box-shadow: 0 6px 20px rgba(0, 0, 0, 0.08);
}

.intro-text h2 {
    color: var(--primary-color);
    font-size: 2rem;
    font-weight: 600;
}

.intro-text p {
    font-size: 1.05rem;
    margin-top: 0.75rem;
    line-height: 1.6;
}

.hero-buttons .btn {
    margin-top: 1rem;
    margin-right: 0.5rem;
    border-radius: var(--border-radius);
    transition: var(--transition);
    backdrop-filter: var(--backdrop-blur);
}

/* Buttons */
.btn-primary {
    background: rgba(30, 136, 229, 0.75);
    border: 1px solid rgba(255, 255, 255, 0.3);
    color: #fff;
}

.btn-primary:hover {
    background: rgba(100, 181, 246, 0.85);
    box-shadow: 0 4px 16px rgba(30, 136, 229, 0.35);
}

.btn-dark {
    background: rgba(43, 58, 66, 0.8);
    color: #fff;
    border: 1px solid rgba(255, 255, 255, 0.25);
}

.btn-dark:hover {
    background: rgba(100, 181, 246, 0.9);
}

/* ====================================================
   Research Interests
==================================================== */
.research-interests {
    text-align: center;
    padding: 4rem 1rem;
}

.research-interests h2 {
    color: var(--primary-color);
    font-weight: 600;
    margin-bottom: 1rem;
}

.section-desc {
    max-width: 700px;
    margin: 0 auto 2.5rem;
    font-size: 1.05rem;
    color: #444;
}

.interest-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
    gap: 2rem;
    max-width: 1100px;
    margin: 0 auto;
}

.interest-grid figure {
    background: var(--glass-bg);
    border-radius: var(--border-radius);
    backdrop-filter: var(--backdrop-blur);
    box-shadow: 0 8px 22px rgba(0, 0, 0, 0.1);
    overflow: hidden;
    transition: var(--transition);
}

.interest-grid figure:hover {
    transform: translateY(-8px);
    box-shadow: 0 12px 28px rgba(0, 0, 0, 0.15);
}

.interest-grid img {
    width: 100%;
    height: auto;
    display: block;
    opacity: 0.9;
}

.interest-grid figcaption {
    padding: 1rem;
    font-weight: 600;
    color: var(--text-color);
}

/* ====================================================
   Quick Links
==================================================== */
.quick-links {
    background: rgba(227, 242, 253, 0.6);
    backdrop-filter: var(--backdrop-blur);
    text-align: center;
    padding: 3rem 1rem;
}

.link-buttons {
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    gap: 1rem;
}

.link-buttons .btn {
    border-radius: var(--border-radius);
    padding: 0.8rem 1.6rem;
    transition: var(--transition);
}

/* ====================================================
   Footer
==================================================== */
footer {
    background: rgba(30, 136, 229, 0.75);
    backdrop-filter: var(--backdrop-blur);
    color: #fff;
    text-align: center;
    padding: 2rem 1rem;
    border-top: 1px solid rgba(255, 255, 255, 0.25);
}

footer p {
    margin: 0 0 1rem;
    font-size: 0.95rem;
}

footer .social {
    list-style: none;
    display: flex;
    justify-content: center;
    gap: 1rem;
    padding: 0;
    margin: 0;
}

footer .social img {
    width: 28px;
    height: 28px;
    filter: brightness(0) invert(1);
    transition: var(--transition);
}

footer .social img:hover {
    transform: scale(1.15);
}

/* ====================================================
   Responsive Layout — Tablet & Mobile
==================================================== */
/* Tablet (≤768px) */
@media screen and (max-width: 768px) {
    .hero {
        flex-direction: column;
        text-align: center;
    }

    .hide-mobile {
        display: none;
    }

    .profile {
        width: 170px;
        height: 170px;
    }

    .intro-text h2 {
        font-size: 1.6rem;
    }
}

/* Mobile (≤600px) */
@media screen and (max-width: 600px) {
    .logo {
        font-size: 1.4rem;
    }

    .hide-mobile {
        display: none;
    }

    nav {
        flex-direction: column;
        align-items: center;
        gap: 0.5rem;
    }

    .nav-links {
        flex-direction: column;
        align-items: center;
        width: 100%;
    }

    .nav-links a {
        display: block;
        width: 100%;
        text-align: center;
        padding: 0.75rem;
    }

    .hero {
        flex-direction: column;
        text-align: center;
        padding: 2rem 1rem;
        gap: 1.5rem;
    }

    .profile {
        width: 140px;
        height: 140px;
    }

    .intro-text {
        max-width: 95%;
        padding: 1rem;
    }

    .intro-text h2 {
        font-size: 1.4rem;
    }

    .intro-text p {
        font-size: 0.95rem;
    }

    .hero-buttons .btn,
    .link-buttons .btn {
        display: block;
        width: 80%;
        margin: 0.5rem auto;
    }

    .interest-grid {
        grid-template-columns: 1fr;
        gap: 1.2rem;
    }

    footer {
        padding: 1.5rem 0.5rem;
    }

    footer p {
        font-size: 0.85rem;
    }

    footer .social img {
        width: 24px;
        height: 24px;
    }
}

/* ====================================================
   Modal (Project Preview)
==================================================== */
.modal {
    display: none;
    position: fixed;
    z-index: 2000;
    inset: 0;
    overflow: auto;
    background: rgba(0, 0, 0, 0.85);
    backdrop-filter: blur(10px);
    animation: fadeIn 0.3s ease-in-out;
}

@keyframes fadeIn {
    from {
        opacity: 0;
    }

    to {
        opacity: 1;
    }
}

.modal-content {
    display: block;
    margin: 4rem auto 1rem;
    max-width: 85%;
    max-height: 70vh;
    border-radius: 12px;
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.4);
    transition: transform 0.3s ease;
}

.modal-content:hover {
    transform: scale(1.02);
}

.modal-caption {
    color: #fff;
    max-width: 80%;
    margin: 1rem auto 2rem;
    font-size: 1.05rem;
    line-height: 1.6;
    text-align: center;
    background: rgba(255, 255, 255, 0.1);
    border-radius: 12px;
    padding: 1.2rem;
    backdrop-filter: blur(12px);
}

.close-modal {
    position: fixed;
    top: 20px;
    right: 35px;
    color: #fff;
    font-size: 40px;
    font-weight: bold;
    cursor: pointer;
    transition: 0.2s;
    z-index: 2100;
}

.close-modal:hover {
    color: var(--accent-color);
}

figure {
    cursor: pointer;
    transition: transform 0.2s ease;
}

figure:hover {
    transform: translateY(-3px);
}

/* Modal responsive tweak */
@media screen and (max-width: 600px) {
    .modal-content {
        max-width: 95%;
        max-height: 60vh;
    }
}

/* ====================================================
   Publications, Experience, Contact Pages
==================================================== */
/* Publications */
.pub-list {
    list-style: decimal inside;
    padding-left: 0;
    margin: 1.5rem auto;
    max-width: 950px;
}

.pub-list li {
    margin: 1rem 0;
    line-height: 1.8;
    color: #1e2b38;
    background: rgba(240, 250, 255, 0.6);
    border-radius: 12px;
    padding: 1rem 1.25rem;
    box-shadow: 0 2px 8px rgba(0, 50, 100, 0.05);
    transition: all 0.2s ease-in-out;
}

.pub-list a {
    text-decoration: none;
    color: #004e9a;
}

.pub-list a:hover {
    color: #0078d4;
    text-decoration: underline;
}

.under-review li {
    background: rgba(240, 240, 240, 0.8);
    color: #555;
    border-left: 4px solid #bbb;
}

.under-review li em {
    color: #333;
}

/* Experience */
.experience-entry {
    background: rgba(240, 250, 255, 0.6);
    border-radius: 12px;
    padding: 1.25rem 1.75rem;
    margin: 1.5rem auto;
    max-width: 950px;
    box-shadow: 0 2px 10px rgba(0, 80, 150, 0.05);
    transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.experience-entry:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 15px rgba(0, 80, 150, 0.1);
}

.experience-entry h3 {
    color: #004e9a;
    margin-bottom: 0.4rem;
}

.experience-entry p {
    margin: 0.2rem 0 0.8rem;
    line-height: 1.7;
    color: #1e2b38;
}

.experience-entry ul {
    margin: 0.5rem 0 0.5rem 1.2rem;
    list-style: disc;
}

.experience-entry li {
    margin: 0.25rem 0;
    color: #333;
    line-height: 1.6;
}

/* Layout corrections for Experience page */
body.experience-page main,
body.experience-page .hero,
body.experience-page .research-interests,
body.experience-page .experience-entry,
body.experience-page p,
body.experience-page ul,
body.experience-page h2,
body.experience-page h3 {
    text-align: left !important;
}

body.experience-page h2 {
    text-align: center !important;
}

.logo-layout {
    display: flex;
    align-items: flex-start;
    gap: 1.2rem;
    padding: 1.2rem 1.5rem;
}

.org-logo {
    width: 70px;
    height: 70px;
    object-fit: contain;
    border-radius: 10px;
    flex-shrink: 0;
    background: rgba(255, 255, 255, 0.5);
    box-shadow: 0 2px 6px rgba(0, 0, 0, 0.1);
}

.exp-text {
    flex: 1;
}

@media screen and (max-width: 700px) {
    .logo-layout {
        flex-direction: column;
        align-items: center;
        text-align: center;
    }

    .org-logo {
        width: 60px;
        height: 60px;
        margin-bottom: 0.5rem;
    }

    .exp-text {
        text-align: left;
        width: 100%;
    }
}

/* Contact */
body.contact-page .contact-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
    gap: 1.5rem;
    max-width: 900px;
    margin: 0 auto;
    text-align: left;
}

body.contact-page .contact-card {
    background: var(--glass-bg);
    border-radius: var(--border-radius);
    backdrop-filter: var(--backdrop-blur);
    box-shadow: 0 6px 15px rgba(0, 0, 0, 0.1);
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 1rem 1.2rem;
    transition: var(--transition);
}

body.contact-page .contact-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.15);
}

.contact-icon {
    width: 40px;
    height: 40px;
    filter: brightness(0.4);
    flex-shrink: 0;
}

.contact-card a {
    color: var(--primary-color);
    text-decoration: none;
}

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

/* Contact Form */
.contact-form {
    max-width: 600px;
    margin: 2rem auto;
    display: flex;
    flex-direction: column;
    gap: 1rem;
    text-align: left;
}

.contact-form input,
.contact-form textarea {
    width: 100%;
    padding: 0.8rem 1rem;
    border: 1px solid rgba(30, 136, 229, 0.3);
    border-radius: var(--border-radius);
    background: rgba(255, 255, 255, 0.7);
    font-family: inherit;
    font-size: 1rem;
    transition: var(--transition);
}

.contact-form input:focus,
.contact-form textarea:focus {
    outline: none;
    border-color: var(--primary-color);
    background: rgba(255, 255, 255, 0.95);
    box-shadow: 0 0 8px rgba(30, 136, 229, 0.3);
}

.contact-form button {
    align-self: center;
    padding: 0.8rem 2rem;
    border: none;
    border-radius: var(--border-radius);
    cursor: pointer;
    background: var(--primary-color);
    color: white;
    font-size: 1rem;
    transition: var(--transition);
}

.contact-form button:hover {
    background: var(--accent-color);
}