/* ============================================================
   NABILA TABASSUM — PORTFOLIO
   Design System: Dark theme, Inter font, green accent
   ============================================================ */

/* === DESIGN TOKENS === */
:root {
    --font: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;

    /* Backgrounds */
    --bg-base: #050505;
    --bg-elevated: #0a0a0a;
    --bg-card: #0f0f0f;
    --bg-card-hover: #161616;
    --bg-subtle: #1a1a1a;

    /* Text */
    --text-primary: #fafafa;
    --text-secondary: #a1a1a1;
    --text-muted: #525252;

    /* Accent — Nature Green */
    --accent: #22c55e;
    --accent-hover: #16a34a;
    --accent-soft: rgba(34, 197, 94, 0.1);
    --accent-glow: rgba(34, 197, 94, 0.25);

    /* Borders */
    --border: rgba(255, 255, 255, 0.06);
    --border-hover: rgba(255, 255, 255, 0.12);

    /* Radii */
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 20px;
    --radius-xl: 24px;
    --radius-full: 999px;

    /* Shadows */
    --shadow-card: 0 0 0 1px var(--border);
    --shadow-card-hover: 0 0 0 1px var(--border-hover), 0 16px 48px rgba(0, 0, 0, 0.5);
    --shadow-glow: 0 0 60px var(--accent-glow);

    /* Transitions */
    --ease-out: cubic-bezier(0.16, 1, 0.3, 1);
    --ease-spring: cubic-bezier(0.34, 1.56, 0.64, 1);
    --duration-fast: 150ms;
    --duration-base: 300ms;
    --duration-slow: 600ms;
}

/* === RESET & BASE === */
*,
*::before,
*::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
    scroll-padding-top: 80px;
}

body {
    font-family: var(--font);
    background-color: var(--bg-base);
    color: var(--text-primary);
    line-height: 1.7;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    overflow-x: hidden;
}

::selection {
    background: var(--accent);
    color: var(--bg-base);
}

img {
    max-width: 100%;
    display: block;
}

a {
    color: inherit;
    text-decoration: none;
}

/* === LAYOUT === */
.container {
    max-width: 1080px;
    margin: 0 auto;
    padding: 0 24px;
}

section {
    padding: 120px 0;
    position: relative;
}

/* === REVEAL ANIMATIONS === */
.reveal {
    opacity: 0;
    transform: translateY(32px);
    transition: opacity 0.8s var(--ease-out), transform 0.8s var(--ease-out);
}

.reveal.visible {
    opacity: 1;
    transform: translateY(0);
}

.reveal-delay-1 { transition-delay: 0.1s; }
.reveal-delay-2 { transition-delay: 0.2s; }
.reveal-delay-3 { transition-delay: 0.3s; }
.reveal-delay-4 { transition-delay: 0.4s; }
.reveal-delay-5 { transition-delay: 0.5s; }

/* ============================================================
   NAVIGATION
   ============================================================ */
#header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background: rgba(5, 5, 5, 0.6);
    backdrop-filter: blur(20px) saturate(180%);
    -webkit-backdrop-filter: blur(20px) saturate(180%);
    border-bottom: 1px solid var(--border);
    transition: background var(--duration-base) ease, border-color var(--duration-base) ease;
}

#header.scrolled {
    background: rgba(5, 5, 5, 0.85);
    border-bottom-color: var(--border-hover);
}

#navbar {
    max-width: 1080px;
    margin: 0 auto;
    padding: 0 24px;
    height: 72px;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

/* Logo */
.logo {
    font-size: 1.5rem;
    font-weight: 800;
    letter-spacing: -0.02em;
    color: var(--text-primary);
    transition: opacity var(--duration-fast) ease;
}

.logo:hover {
    opacity: 0.8;
}

.logo-dot {
    color: var(--accent);
}

/* Nav Links */
.nav-links {
    list-style: none;
    display: flex;
    align-items: center;
    gap: 8px;
}

.nav-link {
    display: inline-block;
    padding: 8px 16px;
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--text-secondary);
    border-radius: var(--radius-full);
    transition: color var(--duration-fast) ease, background var(--duration-fast) ease;
}

.nav-link:hover {
    color: var(--text-primary);
    background: rgba(255, 255, 255, 0.06);
}

.nav-link.active {
    color: var(--accent);
}

/* Mobile Toggle */
.mobile-toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 8px;
    z-index: 1001;
}

.mobile-toggle .bar {
    display: block;
    width: 22px;
    height: 2px;
    background: var(--text-primary);
    border-radius: 2px;
    transition: transform var(--duration-base) var(--ease-out), opacity var(--duration-fast) ease;
}

.mobile-toggle.active .bar:nth-child(1) {
    transform: translateY(7px) rotate(45deg);
}

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

.mobile-toggle.active .bar:nth-child(3) {
    transform: translateY(-7px) rotate(-45deg);
}

/* ============================================================
   HERO SECTION
   ============================================================ */
#hero {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    text-align: center;
    position: relative;
    overflow: hidden;
    padding: 120px 24px 60px;
}

/* Ambient Glow */
.hero-glow {
    position: absolute;
    border-radius: 50%;
    filter: blur(120px);
    pointer-events: none;
    opacity: 0.4;
}

.hero-glow-1 {
    width: 500px;
    height: 500px;
    background: var(--accent);
    top: -150px;
    right: -100px;
    opacity: 0.08;
    animation: glowFloat 8s ease-in-out infinite;
}

.hero-glow-2 {
    width: 400px;
    height: 400px;
    background: #10b981;
    bottom: -100px;
    left: -100px;
    opacity: 0.06;
    animation: glowFloat 10s ease-in-out infinite reverse;
}

@keyframes glowFloat {
    0%, 100% { transform: translate(0, 0) scale(1); }
    50% { transform: translate(30px, -20px) scale(1.1); }
}

/* Hero Content */
.hero-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 40px;
    position: relative;
    z-index: 1;
}

/* Profile Image */
.hero-image-wrapper {
    position: relative;
}

.hero-image-ring {
    width: 180px;
    height: 180px;
    border-radius: 50%;
    padding: 3px;
    background: linear-gradient(135deg, var(--accent), #10b981, var(--accent-hover));
    animation: ringRotate 6s linear infinite;
    position: relative;
}

@keyframes ringRotate {
    0% { background: linear-gradient(0deg, var(--accent), #10b981, var(--accent-hover)); }
    25% { background: linear-gradient(90deg, var(--accent), #10b981, var(--accent-hover)); }
    50% { background: linear-gradient(180deg, var(--accent), #10b981, var(--accent-hover)); }
    75% { background: linear-gradient(270deg, var(--accent), #10b981, var(--accent-hover)); }
    100% { background: linear-gradient(360deg, var(--accent), #10b981, var(--accent-hover)); }
}

.hero-image {
    width: 100%;
    height: 100%;
    border-radius: 50%;
    object-fit: cover;
    border: 3px solid var(--bg-base);
}

.hero-image-wrapper::after {
    content: '';
    position: absolute;
    inset: -12px;
    border-radius: 50%;
    background: var(--accent);
    opacity: 0.08;
    filter: blur(24px);
    z-index: -1;
    animation: pulseGlow 3s ease-in-out infinite;
}

@keyframes pulseGlow {
    0%, 100% { opacity: 0.06; transform: scale(1); }
    50% { opacity: 0.12; transform: scale(1.05); }
}

/* Hero Typography */
.hero-greeting {
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--accent);
    letter-spacing: 0.15em;
    text-transform: uppercase;
    margin-bottom: 8px;
}

.hero-name {
    font-size: clamp(2.5rem, 6vw, 4rem);
    font-weight: 800;
    letter-spacing: -0.03em;
    line-height: 1.1;
    margin-bottom: 12px;
    background: linear-gradient(135deg, var(--text-primary) 0%, var(--text-secondary) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-subtitle {
    font-size: 1.15rem;
    font-weight: 400;
    color: var(--text-secondary);
    margin-bottom: 4px;
}

.hero-university {
    font-size: 0.95rem;
    font-weight: 500;
    color: var(--text-muted);
    margin-bottom: 32px;
}

/* Buttons */
.hero-actions {
    display: flex;
    gap: 12px;
    flex-wrap: wrap;
    justify-content: center;
}

.btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 12px 28px;
    font-family: var(--font);
    font-size: 0.875rem;
    font-weight: 600;
    border-radius: var(--radius-full);
    border: none;
    cursor: pointer;
    transition: all var(--duration-base) var(--ease-out);
}

.btn-primary {
    background: var(--accent);
    color: var(--bg-base);
}

.btn-primary:hover {
    background: var(--accent-hover);
    transform: translateY(-2px);
    box-shadow: 0 8px 30px var(--accent-glow);
}

.btn-ghost {
    background: transparent;
    color: var(--text-secondary);
    border: 1px solid var(--border-hover);
}

.btn-ghost:hover {
    color: var(--text-primary);
    background: rgba(255, 255, 255, 0.04);
    border-color: var(--text-muted);
    transform: translateY(-2px);
}

/* Scroll Indicator */
.scroll-indicator {
    position: absolute;
    bottom: 40px;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 8px;
}

.scroll-text {
    font-size: 0.7rem;
    font-weight: 500;
    color: var(--text-muted);
    letter-spacing: 0.15em;
    text-transform: uppercase;
}

.scroll-line {
    width: 1px;
    height: 40px;
    background: linear-gradient(to bottom, var(--text-muted), transparent);
    animation: scrollPulse 2s ease-in-out infinite;
}

@keyframes scrollPulse {
    0%, 100% { opacity: 0.3; transform: scaleY(0.6); }
    50% { opacity: 1; transform: scaleY(1); }
}

/* ============================================================
   SECTION HEADERS
   ============================================================ */
.section-header {
    display: flex;
    align-items: center;
    gap: 16px;
    margin-bottom: 56px;
}

.section-number {
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--accent);
    font-variant-numeric: tabular-nums;
}

.section-title {
    font-size: 1.75rem;
    font-weight: 700;
    letter-spacing: -0.02em;
    white-space: nowrap;
}

.section-line {
    flex: 1;
    height: 1px;
    background: var(--border);
}

/* ============================================================
   ABOUT SECTION
   ============================================================ */
#about {
    background: var(--bg-base);
}

.about-text {
    font-size: 1.1rem;
    line-height: 1.85;
    color: var(--text-secondary);
    max-width: 720px;
    margin-bottom: 56px;
}

.about-focus-areas {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 16px;
}

.focus-card {
    padding: 28px 24px;
    border-radius: var(--radius-lg);
    background: var(--bg-card);
    box-shadow: var(--shadow-card);
    transition: all var(--duration-base) var(--ease-out);
    position: relative;
    overflow: hidden;
}

.focus-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 2px;
    background: linear-gradient(90deg, var(--accent), transparent);
    opacity: 0;
    transition: opacity var(--duration-base) ease;
}

.focus-card:hover {
    background: var(--bg-card-hover);
    box-shadow: var(--shadow-card-hover);
    transform: translateY(-4px);
}

.focus-card:hover::before {
    opacity: 1;
}

.focus-icon {
    width: 48px;
    height: 48px;
    border-radius: var(--radius-md);
    background: var(--accent-soft);
    color: var(--accent);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 20px;
    transition: background var(--duration-base) ease;
}

.focus-card:hover .focus-icon {
    background: var(--accent-glow);
}

.focus-title {
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: 8px;
    color: var(--text-primary);
}

.focus-desc {
    font-size: 0.85rem;
    color: var(--text-muted);
    line-height: 1.6;
}

/* ============================================================
   EDUCATION SECTION
   ============================================================ */
#education {
    background: var(--bg-elevated);
}

.edu-card {
    background: var(--bg-card);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-card);
    padding: 40px;
    transition: box-shadow var(--duration-base) ease;
}

.edu-card:hover {
    box-shadow: var(--shadow-card-hover);
}

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

.edu-degree {
    font-size: 1.25rem;
    font-weight: 700;
    letter-spacing: -0.01em;
    margin-bottom: 6px;
}

.edu-university {
    font-size: 0.95rem;
    color: var(--text-secondary);
}

.edu-badge {
    font-size: 0.75rem;
    font-weight: 600;
    color: var(--accent);
    background: var(--accent-soft);
    padding: 6px 14px;
    border-radius: var(--radius-full);
    white-space: nowrap;
    border: 1px solid rgba(34, 197, 94, 0.15);
}

.edu-divider {
    height: 1px;
    background: var(--border);
    margin: 28px 0;
}

.coursework-heading {
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.1em;
    margin-bottom: 16px;
}

.coursework-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
}

.course-tag {
    font-size: 0.8rem;
    font-weight: 500;
    color: var(--text-secondary);
    padding: 6px 14px;
    border-radius: var(--radius-full);
    background: var(--bg-subtle);
    border: 1px solid var(--border);
    transition: all var(--duration-fast) ease;
}

.course-tag:hover {
    color: var(--text-primary);
    border-color: var(--border-hover);
    background: var(--bg-card-hover);
    transform: translateY(-1px);
}

/* ============================================================
   SKILLS SECTION
   ============================================================ */
#skills {
    background: var(--bg-base);
}

.skills-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
    gap: 16px;
}

.skill-card {
    padding: 28px 20px;
    border-radius: var(--radius-lg);
    background: var(--bg-card);
    box-shadow: var(--shadow-card);
    text-align: center;
    transition: all var(--duration-base) var(--ease-out);
    cursor: default;
    position: relative;
    overflow: hidden;
}

.skill-card::after {
    content: '';
    position: absolute;
    inset: 0;
    border-radius: var(--radius-lg);
    background: radial-gradient(circle at 50% 0%, var(--accent-soft), transparent 70%);
    opacity: 0;
    transition: opacity var(--duration-base) ease;
}

.skill-card:hover {
    background: var(--bg-card-hover);
    box-shadow: var(--shadow-card-hover);
    transform: translateY(-6px);
}

.skill-card:hover::after {
    opacity: 1;
}

.skill-icon-wrapper {
    width: 56px;
    height: 56px;
    border-radius: var(--radius-md);
    background: var(--accent-soft);
    color: var(--accent);
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 16px;
    transition: all var(--duration-base) ease;
    position: relative;
    z-index: 1;
}

.skill-card:hover .skill-icon-wrapper {
    background: var(--accent-glow);
    transform: scale(1.08);
}

.skill-name {
    display: block;
    font-size: 0.95rem;
    font-weight: 600;
    margin-bottom: 4px;
    position: relative;
    z-index: 1;
}

.skill-category {
    display: block;
    font-size: 0.75rem;
    font-weight: 500;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.08em;
    position: relative;
    z-index: 1;
}

/* ============================================================
   CONTACT SECTION
   ============================================================ */
#contact {
    background: var(--bg-elevated);
}

.contact-intro {
    font-size: 1.05rem;
    color: var(--text-secondary);
    max-width: 560px;
    margin-bottom: 40px;
    line-height: 1.7;
}

.contact-cards {
    display: flex;
    flex-direction: column;
    gap: 12px;
    max-width: 560px;
}

.contact-card {
    display: flex;
    align-items: center;
    gap: 16px;
    padding: 20px 24px;
    border-radius: var(--radius-lg);
    background: var(--bg-card);
    box-shadow: var(--shadow-card);
    transition: all var(--duration-base) var(--ease-out);
}

.contact-card:hover {
    background: var(--bg-card-hover);
    box-shadow: var(--shadow-card-hover);
    transform: translateX(6px);
}

.contact-icon {
    width: 44px;
    height: 44px;
    border-radius: var(--radius-md);
    background: var(--accent-soft);
    color: var(--accent);
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
    transition: background var(--duration-base) ease;
}

.contact-card:hover .contact-icon {
    background: var(--accent-glow);
}

.contact-details {
    flex: 1;
    min-width: 0;
}

.contact-label {
    display: block;
    font-size: 0.75rem;
    font-weight: 600;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.08em;
    margin-bottom: 2px;
}

.contact-value {
    display: block;
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--text-primary);
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.contact-arrow {
    color: var(--text-muted);
    transition: all var(--duration-fast) ease;
    flex-shrink: 0;
}

.contact-card:hover .contact-arrow {
    color: var(--accent);
    transform: translate(2px, -2px);
}

/* ============================================================
   FOOTER
   ============================================================ */
#footer {
    border-top: 1px solid var(--border);
    padding: 32px 0;
    background: var(--bg-base);
}

.footer-content {
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.footer-logo {
    font-size: 1.25rem;
    font-weight: 800;
    color: var(--text-primary);
    transition: opacity var(--duration-fast) ease;
}

.footer-logo:hover {
    opacity: 0.7;
}

.footer-text {
    font-size: 0.8rem;
    color: var(--text-muted);
}

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

/* Tablet */
@media (max-width: 768px) {
    section {
        padding: 80px 0;
    }

    /* Mobile Navigation */
    .mobile-toggle {
        display: flex;
    }

    .nav-links {
        position: fixed;
        top: 0;
        right: 0;
        width: 280px;
        height: 100vh;
        flex-direction: column;
        background: var(--bg-elevated);
        border-left: 1px solid var(--border);
        padding: 100px 32px 40px;
        gap: 4px;
        transform: translateX(100%);
        transition: transform var(--duration-base) var(--ease-out);
        z-index: 999;
    }

    .nav-links.open {
        transform: translateX(0);
    }

    .nav-link {
        font-size: 1rem;
        padding: 12px 16px;
        width: 100%;
    }

    /* Hero */
    #hero {
        padding: 100px 24px 60px;
    }

    .hero-image-ring {
        width: 140px;
        height: 140px;
    }

    .hero-name {
        font-size: 2.25rem;
    }

    .hero-subtitle {
        font-size: 1rem;
    }

    /* About */
    .about-focus-areas {
        grid-template-columns: 1fr;
    }

    /* Education */
    .edu-card {
        padding: 24px;
    }

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

    .edu-badge {
        align-self: flex-start;
    }

    /* Skills */
    .skills-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    /* Contact */
    .contact-value {
        font-size: 0.8rem;
    }

    /* Footer */
    .footer-content {
        flex-direction: column;
        gap: 12px;
        text-align: center;
    }
}

/* Mobile */
@media (max-width: 480px) {
    .section-title {
        font-size: 1.4rem;
    }

    .hero-name {
        font-size: 1.85rem;
    }

    .hero-actions {
        flex-direction: column;
        width: 100%;
    }

    .btn {
        justify-content: center;
        width: 100%;
    }

    .skills-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 10px;
    }

    .skill-card {
        padding: 20px 12px;
    }

    .skill-icon-wrapper {
        width: 44px;
        height: 44px;
    }

    .scroll-indicator {
        display: none;
    }
}