/* ============================================
   PORTFOLIO WEBSITE STYLES
   Mobile-First Responsive Design
   ============================================ */

/* CSS Custom Properties (Variables) */
:root {
    /* Colors - WCAG 2.2 Compliant */
    --color-primary: #2D7A9B;
    --color-primary-dark: #1F5A75;
    --color-accent: #00CED1;
    --color-text: #2C3E50;
    --color-text-light: #5A6C7D;
    --color-background: #FFFFFF;
    --color-background-alt: #F5F5F5;
    --color-border: #E0E0E0;

    /* Typography */
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif;
    --font-size-base: 16px;
    --font-size-sm: 0.875rem;
    --font-size-md: 1rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.25rem;
    --font-size-2xl: 1.5rem;
    --font-size-3xl: 2rem;
    --font-size-4xl: 2.5rem;
    --font-size-5xl: 3rem;

    /* Spacing (8px grid system) */
    --spacing-xs: 0.25rem;   /* 4px */
    --spacing-sm: 0.5rem;    /* 8px */
    --spacing-md: 1rem;      /* 16px */
    --spacing-lg: 1.5rem;    /* 24px */
    --spacing-xl: 2rem;      /* 32px */
    --spacing-2xl: 3rem;     /* 48px */
    --spacing-3xl: 4rem;     /* 64px */
    --spacing-4xl: 6rem;     /* 96px */

    /* Shadows */
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.1);
    --shadow-xl: 0 20px 25px rgba(0, 0, 0, 0.15);

    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-base: 300ms ease;
    --transition-slow: 500ms ease;

    /* Border Radius */
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-xl: 16px;
    --radius-full: 9999px;

    /* Layout */
    --container-max: 1200px;
    --nav-height: 70px;
}

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

html {
    font-size: var(--font-size-base);
    scroll-behavior: smooth;
    -webkit-text-size-adjust: 100%;
}

body {
    font-family: var(--font-family);
    font-size: var(--font-size-lg);
    line-height: 1.6;
    color: var(--color-text);
    background-color: var(--color-background);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

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

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

ul, ol {
    list-style: none;
}

button {
    font-family: inherit;
    font-size: inherit;
    border: none;
    background: none;
    cursor: pointer;
}

/* ============================================
   LAYOUT
   ============================================ */
.container {
    width: 100%;
    max-width: var(--container-max);
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

section {
    padding: var(--spacing-2xl) 0;
}

/* ============================================
   TYPOGRAPHY
   ============================================ */
h1, h2, h3, h4, h5, h6 {
    font-weight: 700;
    line-height: 1.2;
    color: var(--color-text);
}

h1 { font-size: var(--font-size-3xl); }
h2 { font-size: var(--font-size-2xl); }
h3 { font-size: var(--font-size-xl); }
h4 { font-size: var(--font-size-lg); }

.section-title {
    text-align: center;
    margin-bottom: var(--spacing-md);
}

.section-subtitle {
    text-align: center;
    color: var(--color-text);
    margin-bottom: var(--spacing-2xl);
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.highlight {
    color: var(--color-primary);
}

/* ============================================
   BUTTONS
   ============================================ */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-sm) var(--spacing-lg);
    font-size: var(--font-size-md);
    font-weight: 600;
    border-radius: var(--radius-md);
    transition: all var(--transition-base);
    text-align: center;
}

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

.btn-primary:hover {
    background-color: var(--color-primary-dark);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.btn-secondary {
    background-color: transparent;
    color: var(--color-primary);
    border: 2px solid var(--color-primary);
}

.btn-secondary:hover {
    background-color: var(--color-primary);
    color: var(--color-background);
}

/* ============================================
   NAVIGATION
   ============================================ */
.nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: var(--nav-height);
    background-color: var(--color-background);
    box-shadow: var(--shadow-sm);
    z-index: 1000;
    transition: box-shadow var(--transition-base);
}

.nav.scrolled {
    box-shadow: var(--shadow-md);
}

.nav-container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 100%;
    max-width: var(--container-max);
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

.nav-logo {
    font-size: var(--font-size-xl);
    font-weight: 700;
    color: var(--color-primary);
}

.nav-menu {
    display: flex;
    gap: var(--spacing-xl);
}

.nav-link {
    font-weight: 500;
    color: var(--color-text);
    transition: color var(--transition-fast);
    position: relative;
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 0;
    height: 2px;
    background-color: var(--color-primary);
    transition: width var(--transition-base);
}

.nav-link:hover,
.nav-link.active {
    color: var(--color-primary);
}

.nav-link:hover::after,
.nav-link.active::after {
    width: 100%;
}

/* Mobile Navigation Toggle */
.nav-toggle {
    display: none;
    width: 40px;
    height: 40px;
    padding: var(--spacing-sm);
    z-index: 1001;
}

.hamburger {
    display: block;
    width: 24px;
    height: 2px;
    background-color: var(--color-text);
    position: relative;
    transition: background-color var(--transition-fast);
}

.hamburger::before,
.hamburger::after {
    content: '';
    position: absolute;
    left: 0;
    width: 24px;
    height: 2px;
    background-color: var(--color-text);
    transition: transform var(--transition-base);
}

.hamburger::before { top: -8px; }
.hamburger::after { top: 8px; }

.nav-toggle.active .hamburger {
    background-color: transparent;
}

.nav-toggle.active .hamburger::before {
    transform: rotate(45deg) translate(5px, 6px);
}

.nav-toggle.active .hamburger::after {
    transform: rotate(-45deg) translate(5px, -6px);
}

/* ============================================
   HERO SECTION
   ============================================ */
.hero {
    padding-top: calc(var(--nav-height) + var(--spacing-3xl));
    padding-bottom: var(--spacing-3xl);
    min-height: 100vh;
    display: flex;
    align-items: center;
}

.hero-content {
    display: flex;
    flex-direction: column-reverse;
    align-items: center;
    gap: var(--spacing-2xl);
}

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

.hero-title {
    font-size: var(--font-size-3xl);
    margin-bottom: var(--spacing-sm);
}

.hero-subtitle {
    font-size: var(--font-size-xl);
    color: var(--color-text-light);
    font-weight: 500;
    margin-bottom: var(--spacing-lg);
}

.hero-description {
    color: var(--color-text);
    margin-bottom: var(--spacing-xl);
    max-width: 500px;
    margin-left: auto;
    margin-right: auto;
}

.hero-cta {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
    align-items: center;
}

.hero-image {
    flex-shrink: 0;
}

.profile-photo {
    width: 250px;
    height: 250px;
    border-radius: 50%;
    object-fit: cover;
    object-position: center center;
    box-shadow: var(--shadow-lg);
    border: 4px solid var(--color-background);
    image-rendering: -webkit-optimize-contrast;
    transform: translateZ(0);
    -webkit-backface-visibility: hidden;
    backface-visibility: hidden;
}

/* ============================================
   SKILLS TICKER
   ============================================ */
.ticker-section {
    background-color: var(--color-accent);
    padding: var(--spacing-lg) 0;
    overflow: hidden;
}

.ticker-wrapper {
    position: relative;
}

.ticker {
    display: flex;
    overflow: hidden;
}

.ticker-content {
    display: flex;
    animation: ticker 30s linear infinite;
}

.ticker-item {
    flex-shrink: 0;
    padding: 0 var(--spacing-xl);
    font-weight: 600;
    color: var(--color-text);
    white-space: nowrap;
    font-size: var(--font-size-md);
}

@keyframes ticker {
    0% {
        transform: translateX(0);
    }
    100% {
        transform: translateX(-50%);
    }
}

/* Pause on hover */
.ticker-section:hover .ticker-content {
    animation-play-state: paused;
}

/* ============================================
   PROJECTS SECTION
   ============================================ */
.projects {
    background-color: var(--color-background-alt);
}

.projects-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: var(--spacing-lg);
}

.project-card {
    background-color: var(--color-background);
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-md);
    transition: transform var(--transition-base), box-shadow var(--transition-base);
    display: block;
}

.project-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-xl);
}

.project-header {
    padding: var(--spacing-lg);
    min-height: 100px;
    display: flex;
    align-items: center;
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-dark) 100%);
}

.project-header-title {
    font-size: var(--font-size-lg);
    font-weight: 700;
    line-height: 1.3;
    margin: 0;
    color: #FFFFFF;
}

.project-content {
    padding: var(--spacing-lg);
    padding-bottom: 18px;
}

.project-description {
    color: var(--color-text);
    font-size: var(--font-size-md);
    margin-bottom: var(--spacing-md);
    line-height: 1.5;
}

.project-tags {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-md);
}

.tag {
    display: inline-block;
    padding: var(--spacing-xs) var(--spacing-sm);
    background-color: var(--color-background-alt);
    color: var(--color-primary);
    font-size: var(--font-size-sm);
    font-weight: 500;
    border-radius: var(--radius-full);
}

.tag::before {
    content: '#';
}

.project-cta {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    font-size: var(--font-size-sm);
    font-weight: 600;
    color: var(--color-primary);
    transition: gap var(--transition-base);
}

.project-card:hover .project-cta {
    gap: var(--spacing-sm);
}

.project-cta-arrow {
    transition: transform var(--transition-base);
}

.project-card:hover .project-cta-arrow {
    transform: translateX(4px);
}

/* ============================================
   PERSONAL AI PROJECTS SECTION
   ============================================ */
.personal-projects {
    background-color: var(--color-background);
}

.personal-projects-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: var(--spacing-lg);
}

.personal-projects .project-header {
    background: linear-gradient(135deg, #14532D 0%, #1a6b3a 100%);
}

/* ============================================
   ABOUT SECTION
   ============================================ */
.about {
    background-color: var(--color-background);
}

.about-content {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-2xl);
}

.about-bio {
    max-width: 840px;
    margin: 0 auto;
    text-align: center;
}

.about-bio p {
    margin-bottom: var(--spacing-md);
    color: var(--color-text);
}

.about-details {
    display: grid;
    grid-template-columns: 1fr;
    gap: var(--spacing-xl);
}

.about-section h3 {
    font-size: var(--font-size-lg);
    margin-bottom: var(--spacing-md);
    color: var(--color-primary);
    padding-bottom: var(--spacing-sm);
    border-bottom: 2px solid var(--color-border);
}

.education-item {
    margin-bottom: var(--spacing-md);
}

.education-degree {
    font-weight: 600;
    color: var(--color-text);
}

.education-school {
    color: var(--color-text);
}

.education-year {
    font-size: var(--font-size-sm);
    color: var(--color-text);
}

.skills-list {
    display: grid;
    grid-template-columns: 1fr;
    gap: var(--spacing-lg);
}

.skill-category h4 {
    font-size: var(--font-size-md);
    margin-bottom: var(--spacing-sm);
    color: var(--color-text);
}

.skill-category ul {
    list-style: disc;
    padding-left: var(--spacing-lg);
}

.skill-category li {
    color: var(--color-text);
    margin-bottom: var(--spacing-xs);
    font-size: var(--font-size-md);
}

/* Two Column Layout for About Section */
.about-details.two-column {
    display: grid;
    grid-template-columns: 1fr;
    gap: var(--spacing-xl);
}

/* Credential Items (Education & Certifications) */
.credential-item {
    margin-bottom: var(--spacing-lg);
    padding-bottom: var(--spacing-md);
    border-bottom: 1px solid var(--color-border);
}

.credential-item:last-child {
    border-bottom: none;
    margin-bottom: 0;
    padding-bottom: 0;
}

.credential-title {
    font-weight: 600;
    color: var(--color-text);
    margin-bottom: var(--spacing-xs);
}

.credential-org {
    color: var(--color-text);
    font-size: var(--font-size-md);
    margin-bottom: var(--spacing-xs);
}

.credential-year {
    font-size: var(--font-size-sm);
    color: var(--color-primary);
    font-weight: 500;
}

/* Placeholder Items */
.credential-item.placeholder {
    opacity: 0.5;
    border-style: dashed;
}

.credential-item.placeholder .credential-title {
    color: var(--color-text-light);
}

.certifications-list {
    list-style: disc;
    padding-left: var(--spacing-lg);
}

.certifications-list li {
    color: var(--color-text);
    margin-bottom: var(--spacing-sm);
}

/* ============================================
   CONTACT SECTION
   ============================================ */
.contact {
    background-color: var(--color-background-alt);
    padding: var(--spacing-2xl) 0;
}

.contact .section-title {
    margin-bottom: var(--spacing-sm);
}

.contact .section-subtitle {
    margin-bottom: var(--spacing-xl);
}

.contact-content {
    max-width: 800px;
    margin: 0 auto;
}

.contact-methods {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: var(--spacing-lg);
    max-width: 560px;
    margin: 0 auto;
}

.contact-card {
    display: flex;
    flex-direction: column;
    align-items: center;
    text-align: center;
    padding: var(--spacing-xl) var(--spacing-lg);
    background-color: var(--color-background);
    border-radius: var(--radius-lg);
    transition: all var(--transition-base);
    box-shadow: var(--shadow-sm);
}

.contact-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.contact-card-icon {
    width: 48px;
    height: 48px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: var(--spacing-md);
    color: var(--color-primary);
}

.contact-card-icon svg {
    width: 32px;
    height: 32px;
}

.contact-card-label {
    font-size: var(--font-size-sm);
    font-weight: 600;
    color: var(--color-text);
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin-bottom: var(--spacing-sm);
}

.contact-card-divider {
    width: 40px;
    height: 2px;
    background-color: var(--color-border);
    margin-bottom: var(--spacing-sm);
}

.contact-card-value {
    font-size: var(--font-size-sm);
    color: var(--color-text-light);
    word-break: break-word;
}

/* Responsive contact cards */
@media (max-width: 767px) {
    .contact-methods {
        grid-template-columns: 1fr;
    }
}

/* ============================================
   FOOTER
   ============================================ */
.footer {
    background-color: var(--color-text);
    color: var(--color-background);
    padding: var(--spacing-xl) 0;
}

.footer-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-md);
}

.footer-social {
    display: flex;
    gap: var(--spacing-md);
}

.footer-social a {
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-full);
    color: var(--color-background);
    transition: all var(--transition-base);
}

.footer-social a:hover {
    background-color: var(--color-primary);
    transform: translateY(-2px);
}

.footer-copyright {
    font-size: var(--font-size-sm);
    color: rgba(255, 255, 255, 0.7);
}

/* ============================================
   RESPONSIVE STYLES
   ============================================ */

/* Tablet (768px and up) */
@media (min-width: 768px) {
    :root {
        --font-size-base: 18px;
    }

    h1 { font-size: var(--font-size-4xl); }
    h2 { font-size: var(--font-size-3xl); }

    .container {
        padding: 0 var(--spacing-xl);
    }

    section {
        padding: var(--spacing-3xl) 0;
    }

    .hero-title {
        font-size: var(--font-size-4xl);
    }

    .hero-cta {
        flex-direction: row;
    }

    .profile-photo {
        width: 280px;
        height: 280px;
    }

    .projects-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .personal-projects-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .skills-list {
        grid-template-columns: repeat(3, 1fr);
    }

    .about-details.two-column {
        grid-template-columns: repeat(2, 1fr);
    }

    .about-details.two-column .about-section {
        grid-column: span 1;
    }

    .skills-list {
        grid-template-columns: 1fr;
    }
}

/* Desktop (1024px and up) */
@media (min-width: 1024px) {
    .hero-content {
        flex-direction: row;
        justify-content: space-between;
        text-align: left;
    }

    .hero-text {
        text-align: left;
        flex: 1;
    }

    .hero-description {
        margin-left: 0;
        margin-right: 0;
    }

    .hero-cta {
        justify-content: flex-start;
    }

    .profile-photo {
        width: 320px;
        height: 320px;
    }

    .projects-grid {
        grid-template-columns: repeat(3, 1fr);
    }

    /* 3+2 grid layout for 5 cards */
    .project-card:nth-child(4),
    .project-card:nth-child(5) {
        max-width: calc(50% - var(--spacing-lg) / 2);
    }

    .projects-grid {
        display: flex;
        flex-wrap: wrap;
        justify-content: center;
    }

    .project-card {
        flex: 0 0 calc(33.333% - var(--spacing-lg));
    }

    .project-card:nth-child(4),
    .project-card:nth-child(5) {
        flex: 0 0 calc(33.333% - var(--spacing-lg));
    }
}

/* Large Desktop (1200px and up) */
@media (min-width: 1200px) {
    h1 { font-size: var(--font-size-5xl); }

    .hero-title {
        font-size: var(--font-size-5xl);
    }

    .profile-photo {
        width: 350px;
        height: 350px;
    }
}

/* Mobile Navigation Styles */
@media (max-width: 767px) {
    .nav-toggle {
        display: flex;
        align-items: center;
        justify-content: center;
    }

    .nav-menu {
        position: fixed;
        top: 0;
        right: -100%;
        width: 80%;
        max-width: 300px;
        height: 100vh;
        background-color: var(--color-background);
        flex-direction: column;
        justify-content: center;
        align-items: center;
        gap: var(--spacing-xl);
        box-shadow: var(--shadow-xl);
        transition: right var(--transition-base);
        z-index: 999;
    }

    .nav-menu.active {
        right: 0;
    }

    .nav-link {
        font-size: var(--font-size-xl);
    }

    /* Mobile overlay */
    .nav-menu::before {
        content: '';
        position: fixed;
        top: 0;
        left: -100vw;
        width: 100vw;
        height: 100vh;
        background-color: rgba(0, 0, 0, 0.5);
        opacity: 0;
        transition: opacity var(--transition-base);
        pointer-events: none;
    }

    .nav-menu.active::before {
        opacity: 1;
        pointer-events: auto;
    }
}

/* ============================================
   UTILITY CLASSES
   ============================================ */
.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

/* Focus styles for accessibility */
a:focus-visible,
button:focus-visible {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
}

/* Reduced motion preference */
@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }

    html {
        scroll-behavior: auto;
    }
}