/* === INTRO SECTION === */
.intro-section {
    width: 100%;
    background: transparent;
    backdrop-filter: blur(20px);
    border: var(--border-1) solid var(--glass-border);
    border-radius: var(--radius-2xl);
    padding: var(--space-3xl);
    box-shadow: var(--shadow-light);
    text-align: center;
    position: relative;
    overflow: hidden;
}

.intro-section h1 {
    font-size: clamp(var(--font-size-3xl), 5vw, var(--font-size-6xl));
    font-weight: 300;
    line-height: var(--space-2xl);
    margin-bottom: var(--space-sm);
    background: var(--gradient-primary-secondary);
    background-clip: text;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    text-shadow: 0 0 30px var(--primary-opacity-50);
    animation: glow 3s ease-in-out infinite alternate;
}

.intro-text {
    font-size: clamp(var(--font-size-lg), 3vw, var(--font-size-2xl));
    color: var(--text-secondary);
    line-height: var(--line-height-loose);
}

.intro-section::after {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: 
        radial-gradient(circle, var(--tertiary) 1px, transparent 1px);
    background-size: 50px 50px;
    animation: moveStars 20s linear infinite;
    z-index: -1;
}

@keyframes moveStars {
    0% { transform: translate(0, 0); }
    100% { transform: translate(-50px, -50px); }
}

/* === RESEARCH SECTIONS === */
.research-section {
    background: 
        radial-gradient(circle at 20% 80%, var(--quaternary-opacity-10) 0%, transparent 50%),
        radial-gradient(circle at 80% 20%, var(--tertiary-opacity-10) 0%, transparent 50%);
    backdrop-filter: blur(20px);
    border: var(--border-1) solid var(--glass-border);
    border-radius: var(--radius-2xl);
    padding: var(--space-3xl);
    box-shadow: var(--shadow-light);
    position: relative;
    overflow: hidden;
}

/* === SECTION HEADERS === */
.section-title {
    font-size: var(--font-size-3xl);
    font-weight: var(--font-weight-bold);
    color: var(--text-primary);
    margin-bottom: var(--space-xl);
    position: relative;
    display: flex;
    align-items: center;
    gap: var(--space-md);
}

.section-title svg {
    fill: var(--tertiary);
    width: 60px;
    height: auto;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: var(--font-size-2xl);
}

.section-title::after {
    content: '';
    flex-grow: 1;
    height: var(--border-2);
    background: var(--gradient-tertiary);
    border-radius: var(--radius-xl);
    margin-left: var(--space-lg);
}

/* === SUBSECTION TITLES === */
.subsection-title {
    font-size: var(--font-size-2xl);
    font-weight: var(--font-weight-semibold);
    color: var(--text-primary);
    margin: 0 0 var(--space-lg) 0;
    padding: var(--space-sm) var(--space-lg);
    background: linear-gradient(135deg, var(--quaternary), var(--tertiary));
    border-radius: var(--radius-xl);
    display: inline-block;
}

/* === RESEARCH LINKS === */
.research-links {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: var(--space-lg);
    margin-bottom: var(--space-xl);
}

.research-links a {
    display: flex;
    align-items: center;
    gap: var(--space-lg);
    background: var(--bg-card);
    color: var(--text-secondary);
    text-decoration: none;
    padding: var(--space-lg);
    border-radius: var(--radius-lg);
    border: var(--border-1) solid var(--glass-border);
    transition: var(--transition);
    position: relative;
    overflow: hidden;
}

.research-links a::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, var(--tertiary-opacity-10), transparent);
    transition: left 0.5s ease;
}

.research-links a:hover::before {
    left: 100%;
}

.research-links a:hover {
    background: var(--bg-card-hover);
    color: var(--text-primary);
    transform: translateY(-2px);
    box-shadow: var(--shadow-card);
    border-color: var(--tertiary-opacity-20);
}

/* === PDF ICON === */
.research-links img {
    width: 50px;
    height: auto;
    flex-shrink: 0;
    filter: drop-shadow(0 2px 4px var(--black-opacity-20));
}

/* === RESEARCH INFO === */
.research-info {
    flex-grow: 1;
}

.research-title {
    font-size: var(--font-size-lg);
    font-weight: var(--font-weight-semibold);
    color: inherit;
    margin-bottom: var(--space-xs);
    line-height: var(--line-height-relaxed);
}

.research-date {
    font-size: var(--font-size-sm);
    color: var(--text-muted);
    font-style: italic;
}

/* === ARROW ICON === */
.research-links svg {
    width: 24px;
    height: auto;
    fill: var(--tertiary);
    flex-shrink: 0;
    transition: var(--transition);
}

.research-links a:hover svg {
    transform: translateX(5px);
}

/* === RESPONSIVE === */
@media (max-width: 768px) {
    .section-title {
        flex-direction: column;
        align-items: flex-start;
        text-align: left;
    }

    .section-title::after {
        width: 100%;
        margin-left: 0;
        margin-top: var(--space-sm);
    }

    .intro-section,
    .research-section {
        padding: var(--space-xl);
    }

    .research-links {
        grid-template-columns: 1fr;
    }

    .research-links a {
        flex-direction: column;
        text-align: center;
        gap: var(--space-md);
    }

    .research-info {
        text-align: center;
    }
}

@media (max-width: 480px) {
    .intro-section,
    .research-section {
        padding: var(--space-lg);
    }

    .intro-section h1 {
        font-size: var(--font-size-3xl);
    }

    .section-title {
        font-size: var(--font-size-2xl);
    }

    .subsection-title {
        font-size: var(--font-size-xl);
    }
}

/* === ANIMACIONS === */
.intro-section { animation: slideInUp 0.8s ease-out; }
.youth-research { animation: slideInUp 1s ease-out 0.2s both; }
.phd-research { animation: slideInUp 1s ease-out 0.4s both; }

@keyframes slideInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}