/* ============================================================
   Portfolio — Riyad Bin Islam
   Dark/Light theme with CSS custom properties
   ============================================================ */

/* --- Reset & Base --- */
*, *::before, *::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --font-body: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    --font-mono: 'JetBrains Mono', monospace;
    --radius: 12px;
    --radius-sm: 8px;
    --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    --max-width: 1100px;
    --nav-height: 64px;
}

/* --- Dark Theme (Default) --- */
[data-theme="dark"] {
    --bg-primary: #0a0a0f;
    --bg-secondary: #12121a;
    --bg-card: #1a1a25;
    --bg-card-hover: #22222f;
    --bg-nav: rgba(10, 10, 15, 0.85);
    --text-primary: #f0f0f5;
    --text-secondary: #a0a0b0;
    --text-muted: #6a6a7a;
    --accent: #6c63ff;
    --accent-hover: #7f78ff;
    --accent-glow: rgba(108, 99, 255, 0.15);
    --border: #2a2a3a;
    --border-hover: #3a3a4a;
    --tag-bg: #1e1e2e;
    --tag-text: #b0b0c0;
    --shadow-card: 0 4px 24px rgba(0, 0, 0, 0.3);
    --shadow-nav: 0 1px 12px rgba(0, 0, 0, 0.4);
}

/* --- Light Theme --- */
[data-theme="light"] {
    --bg-primary: #ffffff;
    --bg-secondary: #f8f9fc;
    --bg-card: #ffffff;
    --bg-card-hover: #f0f2f8;
    --bg-nav: rgba(255, 255, 255, 0.9);
    --text-primary: #1a1a2e;
    --text-secondary: #4a4a5a;
    --text-muted: #8a8a9a;
    --accent: #5046e5;
    --accent-hover: #4338ca;
    --accent-glow: rgba(80, 70, 229, 0.1);
    --border: #e2e4ea;
    --border-hover: #d0d2da;
    --tag-bg: #f0f2f8;
    --tag-text: #4a4a5a;
    --shadow-card: 0 4px 24px rgba(0, 0, 0, 0.06);
    --shadow-nav: 0 1px 12px rgba(0, 0, 0, 0.06);
}

html {
    scroll-behavior: smooth;
    scroll-padding-top: var(--nav-height);
}

body {
    font-family: var(--font-body);
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    transition: background var(--transition), color var(--transition);
    -webkit-font-smoothing: antialiased;
}

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

ul { list-style: none; }
img { max-width: 100%; display: block; }

.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 24px;
}

/* --- Navigation --- */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: var(--nav-height);
    background: var(--bg-nav);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--border);
    z-index: 1000;
    transition: background var(--transition), border-color var(--transition);
    box-shadow: var(--shadow-nav);
}

.nav-container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 24px;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.nav-logo {
    font-weight: 700;
    font-size: 1.25rem;
    letter-spacing: -0.5px;
    color: var(--accent);
}

.nav-links {
    display: flex;
    gap: 32px;
}

.nav-links a {
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--text-secondary);
    transition: color var(--transition);
    position: relative;
}

.nav-links a::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--accent);
    transition: width var(--transition);
}

.nav-links a:hover {
    color: var(--text-primary);
}

.nav-links a:hover::after {
    width: 100%;
}

.nav-actions {
    display: flex;
    align-items: center;
    gap: 12px;
}

/* Theme Toggle */
.theme-toggle {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    border: 1px solid var(--border);
    border-radius: 50%;
    background: var(--bg-card);
    cursor: pointer;
    transition: all var(--transition);
    color: var(--text-secondary);
}

.theme-toggle:hover {
    border-color: var(--accent);
    color: var(--accent);
    background: var(--accent-glow);
}

[data-theme="dark"] .icon-sun { display: block; }
[data-theme="dark"] .icon-moon { display: none; }
[data-theme="light"] .icon-sun { display: none; }
[data-theme="light"] .icon-moon { display: block; }

/* Mobile Menu Button */
.mobile-menu-btn {
    display: none;
    flex-direction: column;
    justify-content: center;
    gap: 5px;
    width: 36px;
    height: 36px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 6px;
}

.mobile-menu-btn span {
    display: block;
    width: 100%;
    height: 2px;
    background: var(--text-primary);
    border-radius: 2px;
    transition: all var(--transition);
}

.mobile-menu-btn.active span:nth-child(1) {
    transform: rotate(45deg) translate(5px, 5px);
}

.mobile-menu-btn.active span:nth-child(2) {
    opacity: 0;
}

.mobile-menu-btn.active span:nth-child(3) {
    transform: rotate(-45deg) translate(5px, -5px);
}

/* --- Hero --- */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    padding-top: var(--nav-height);
}

.hero-container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 80px 24px;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 60px;
    align-items: center;
}

.hero-greeting {
    font-size: 1rem;
    color: var(--accent);
    font-weight: 500;
    margin-bottom: 8px;
}

.hero-name {
    font-size: clamp(2.5rem, 5vw, 3.5rem);
    font-weight: 700;
    letter-spacing: -1.5px;
    line-height: 1.1;
    margin-bottom: 12px;
}

.hero-title {
    font-size: 1.3rem;
    color: var(--text-secondary);
    font-weight: 400;
    margin-bottom: 20px;
}

.hero-description {
    font-size: 1rem;
    color: var(--text-muted);
    max-width: 480px;
    margin-bottom: 32px;
    line-height: 1.7;
}

.hero-cta {
    display: flex;
    gap: 16px;
    flex-wrap: wrap;
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 12px 28px;
    font-size: 0.9rem;
    font-weight: 500;
    border-radius: var(--radius-sm);
    transition: all var(--transition);
    cursor: pointer;
    border: none;
}

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

.btn-primary:hover {
    background: var(--accent-hover);
    transform: translateY(-2px);
    box-shadow: 0 8px 24px rgba(108, 99, 255, 0.3);
}

.btn-outline {
    background: transparent;
    border: 1px solid var(--border);
    color: var(--text-primary);
}

.btn-outline:hover {
    border-color: var(--accent);
    color: var(--accent);
    background: var(--accent-glow);
}

/* Hero Visual */
.hero-visual {
    display: flex;
    align-items: center;
    justify-content: center;
}

.hero-graphic {
    position: relative;
    width: 320px;
    height: 320px;
}

.orbit {
    position: absolute;
    border-radius: 50%;
    border: 1px solid var(--border);
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    animation: spin 20s linear infinite;
}

.orbit::after {
    content: '';
    position: absolute;
    width: 8px;
    height: 8px;
    background: var(--accent);
    border-radius: 50%;
    top: -4px;
    left: 50%;
    transform: translateX(-50%);
    box-shadow: 0 0 12px var(--accent);
}

.orbit-1 {
    width: 160px;
    height: 160px;
    animation-duration: 8s;
}

.orbit-2 {
    width: 240px;
    height: 240px;
    animation-duration: 14s;
    animation-direction: reverse;
}

.orbit-3 {
    width: 320px;
    height: 320px;
    animation-duration: 20s;
}

.core-node {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 48px;
    height: 48px;
    background: var(--accent);
    border-radius: 50%;
    box-shadow: 0 0 40px var(--accent), 0 0 80px rgba(108, 99, 255, 0.3);
    animation: pulse 3s ease-in-out infinite;
}

@keyframes spin {
    from { transform: translate(-50%, -50%) rotate(0deg); }
    to { transform: translate(-50%, -50%) rotate(360deg); }
}

@keyframes pulse {
    0%, 100% { transform: translate(-50%, -50%) scale(1); opacity: 1; }
    50% { transform: translate(-50%, -50%) scale(1.1); opacity: 0.8; }
}

/* --- Sections --- */
.section {
    padding: 100px 0;
}

.section-alt {
    background: var(--bg-secondary);
    transition: background var(--transition);
}

.section-title {
    font-size: 2rem;
    font-weight: 700;
    letter-spacing: -0.5px;
    margin-bottom: 48px;
    position: relative;
    display: inline-block;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: -8px;
    left: 0;
    width: 48px;
    height: 3px;
    background: var(--accent);
    border-radius: 2px;
}

/* --- About --- */
.about-grid {
    display: grid;
    grid-template-columns: 2fr 1fr;
    gap: 48px;
    align-items: start;
}

.about-text p {
    color: var(--text-secondary);
    margin-bottom: 16px;
    line-height: 1.8;
}

.about-stats {
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.stat-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    padding: 20px 24px;
    text-align: center;
    transition: all var(--transition);
}

.stat-card:hover {
    border-color: var(--accent);
    background: var(--accent-glow);
}

.stat-number {
    display: block;
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--accent);
    margin-bottom: 4px;
}

.stat-label {
    font-size: 0.8rem;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 1px;
}

/* --- Projects --- */
.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 24px;
}

.project-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 32px;
    transition: all var(--transition);
    position: relative;
    overflow: hidden;
}

.project-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: linear-gradient(90deg, var(--accent), transparent);
    opacity: 0;
    transition: opacity var(--transition);
}

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

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

.project-icon {
    width: 56px;
    height: 56px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--accent-glow);
    border-radius: var(--radius-sm);
    color: var(--accent);
    margin-bottom: 20px;
}

.project-name {
    font-size: 1.3rem;
    font-weight: 600;
    margin-bottom: 4px;
}

.project-tagline {
    font-size: 0.85rem;
    color: var(--accent);
    font-weight: 500;
    margin-bottom: 12px;
}

.project-description {
    color: var(--text-secondary);
    font-size: 0.9rem;
    line-height: 1.7;
    margin-bottom: 20px;
}

.project-tech {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin-bottom: 20px;
}

.project-tech li {
    font-size: 0.75rem;
    padding: 4px 10px;
    background: var(--tag-bg);
    color: var(--tag-text);
    border-radius: 4px;
    font-family: var(--font-mono);
}

.project-links {
    display: flex;
    gap: 16px;
}

.project-link {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    font-size: 0.85rem;
    color: var(--text-muted);
    font-weight: 500;
    transition: color var(--transition);
}

.project-link:hover {
    color: var(--accent);
}

.project-badge {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    font-size: 0.8rem;
    font-weight: 500;
    color: var(--text-muted);
    padding: 6px 12px;
    background: var(--tag-bg);
    border: 1px solid var(--border);
    border-radius: 20px;
}

.project-card-coming {
    border-style: dashed;
}

.coming-soon-badge {
    display: inline-block;
    padding: 6px 14px;
    background: var(--accent-glow);
    color: var(--accent);
    font-size: 0.8rem;
    font-weight: 500;
    border-radius: 20px;
    margin-top: 12px;
}

/* --- Skills --- */
.skills-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: 24px;
}

.skill-category {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 28px;
    transition: all var(--transition);
}

.skill-category:hover {
    border-color: var(--border-hover);
}

.skill-category h3 {
    font-size: 0.9rem;
    font-weight: 600;
    margin-bottom: 16px;
    color: var(--text-primary);
}

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

.skill-tag {
    font-size: 0.8rem;
    padding: 6px 12px;
    background: var(--tag-bg);
    color: var(--tag-text);
    border-radius: 6px;
    border: 1px solid var(--border);
    transition: all var(--transition);
}

.skill-tag:hover {
    border-color: var(--accent);
    color: var(--accent);
    background: var(--accent-glow);
}

/* --- Contact --- */
.contact-content {
    text-align: center;
    max-width: 600px;
    margin: 0 auto;
}

.contact-text {
    font-size: 1.1rem;
    color: var(--text-secondary);
    margin-bottom: 32px;
}

.contact-links {
    display: flex;
    justify-content: center;
    gap: 16px;
    flex-wrap: wrap;
}

.contact-card {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    padding: 14px 24px;
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    color: var(--text-secondary);
    font-size: 0.9rem;
    transition: all var(--transition);
}

.contact-card:hover {
    border-color: var(--accent);
    color: var(--accent);
    background: var(--accent-glow);
    transform: translateY(-2px);
}

/* --- Footer --- */
.footer {
    padding: 32px 0;
    text-align: center;
    border-top: 1px solid var(--border);
    transition: border-color var(--transition);
}

.footer p {
    font-size: 0.85rem;
    color: var(--text-muted);
}

/* --- Responsive --- */
@media (max-width: 768px) {
    .nav-links {
        display: none;
        position: absolute;
        top: var(--nav-height);
        left: 0;
        right: 0;
        background: var(--bg-nav);
        backdrop-filter: blur(12px);
        -webkit-backdrop-filter: blur(12px);
        flex-direction: column;
        padding: 24px;
        gap: 20px;
        border-bottom: 1px solid var(--border);
    }

    .nav-links.active {
        display: flex;
    }

    .mobile-menu-btn {
        display: flex;
    }

    .hero-container {
        grid-template-columns: 1fr;
        gap: 40px;
        padding: 40px 24px;
    }

    .hero-visual {
        order: -1;
    }

    .hero-graphic {
        width: 220px;
        height: 220px;
    }

    .orbit-1 { width: 110px; height: 110px; }
    .orbit-2 { width: 165px; height: 165px; }
    .orbit-3 { width: 220px; height: 220px; }

    .hero-name {
        font-size: 2.2rem;
    }

    .about-grid {
        grid-template-columns: 1fr;
        gap: 32px;
    }

    .about-stats {
        flex-direction: row;
        flex-wrap: wrap;
    }

    .stat-card {
        flex: 1;
        min-width: 120px;
    }

    .projects-grid {
        grid-template-columns: 1fr;
    }

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

    .contact-links {
        flex-direction: column;
        align-items: center;
    }

    .section {
        padding: 60px 0;
    }
}

@media (max-width: 480px) {
    .hero-cta {
        flex-direction: column;
    }

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

    .hero-graphic {
        width: 180px;
        height: 180px;
    }

    .orbit-1 { width: 90px; height: 90px; }
    .orbit-2 { width: 135px; height: 135px; }
    .orbit-3 { width: 180px; height: 180px; }
}