/* ===================== Senthil — Portfolio Styles ===================== */

:root {
    --bg-color: #050505;
    --bg-elevated: #0c0c0f;
    --text-main: #f3f4f6;
    --text-muted: #9ca3af;
    --surface: rgba(255, 255, 255, 0.03);
    --surface-hover: rgba(255, 255, 255, 0.06);
    --border-color: rgba(255, 255, 255, 0.08);
    --font-display: 'Space Grotesk', sans-serif;
    --font-body: 'Manrope', sans-serif;
    --transition: all 0.4s cubic-bezier(0.16, 1, 0.3, 1);
    --accent: #8b5cf6;
    --accent-glow: rgba(139, 92, 246, 0.5);
    --danger: #f87171;
    --success: #34d399;
}

/* Light mode overrides */
body.light-mode {
    --bg-color: #f7f7fb;
    --bg-elevated: #ffffff;
    --text-main: #16161a;
    --text-muted: #5b5b66;
    --surface: rgba(0, 0, 0, 0.03);
    --surface-hover: rgba(0, 0, 0, 0.06);
    --border-color: rgba(0, 0, 0, 0.09);
}

/* Accent themes (click logo to cycle) */
body.theme-violet { --accent: #8b5cf6; --accent-glow: rgba(139, 92, 246, 0.5); }
body.theme-cyan   { --accent: #06b6d4; --accent-glow: rgba(6, 182, 212, 0.5); }
body.theme-green  { --accent: #10b981; --accent-glow: rgba(16, 185, 129, 0.5); }
body.theme-orange { --accent: #f97316; --accent-glow: rgba(249, 115, 22, 0.5); }

* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }

body {
    font-family: var(--font-body);
    background-color: var(--bg-color);
    color: var(--text-main);
    overflow-x: hidden;
    line-height: 1.6;
    transition: background-color 0.4s ease, color 0.4s ease;
}

/* Background Noise & Gradients */
.noise {
    position: fixed;
    top: 0; left: 0; width: 100vw; height: 100vh;
    pointer-events: none;
    z-index: 3;
    opacity: 0.035;
    background: url('data:image/svg+xml;utf8,%3Csvg viewBox="0 0 200 200" xmlns="http://www.w3.org/2000/svg"%3E%3Cfilter id="noiseFilter"%3E%3CfeTurbulence type="fractalNoise" baseFrequency="0.65" numOctaves="3" stitchTiles="stitch"/%3E%3C/filter%3E%3Crect width="100%25" height="100%25" filter="url(%23noiseFilter)"/%3E%3C/svg%3E');
}
body.light-mode .noise { opacity: 0.015; }

.gradient-mesh {
    position: fixed;
    top: 0; left: 0; width: 100vw; height: 100vh;
    pointer-events: none;
    z-index: -1;
    background:
        radial-gradient(circle at 15% 50%, var(--accent-glow), transparent 25%),
        radial-gradient(circle at 85% 30%, rgba(255,255,255,0.02), transparent 25%);
    filter: blur(80px);
    opacity: 0.4;
    transition: var(--transition);
}
body.light-mode .gradient-mesh { opacity: 0.18; }

/* Typography */
h1, h2, h3, h4, .font-display {
    font-family: var(--font-display);
    font-weight: 700;
    line-height: 1.1;
}
.text-accent { color: var(--accent); transition: color 0.4s ease; }
.text-muted { color: var(--text-muted); }
a { color: inherit; }

/* Custom Cursor */
.cursor-dot, .cursor-ring {
    position: fixed;
    top: 0; left: 0;
    pointer-events: none;
    z-index: 10000;
    transform: translate(-50%, -50%);
    border-radius: 50%;
}
.cursor-dot {
    width: 8px; height: 8px;
    background-color: var(--accent);
    transition: width 0.2s, height 0.2s, background-color 0.4s ease;
}
.cursor-ring {
    width: 40px; height: 40px;
    border: 1px solid var(--accent-glow);
    transition: width 0.3s, height 0.3s, transform 0.1s, border-color 0.4s ease;
}
@media (hover: none) and (pointer: coarse) {
    .cursor-dot, .cursor-ring { display: none; }
}

/* Scroll Progress */
.scroll-progress-h {
    position: fixed;
    top: 0; left: 0; height: 3px; width: 0%;
    background: linear-gradient(to right, transparent, var(--accent));
    z-index: 9998;
}
.scroll-progress-h::after {
    content: '';
    position: absolute;
    right: 0; top: -2px; width: 7px; height: 7px;
    background: white;
    box-shadow: 0 0 10px var(--accent), 0 0 20px var(--accent);
    border-radius: 50%;
}

/* Navigation */
nav {
    position: fixed;
    top: 0; left: 0; width: 100%;
    padding: 1.5rem 4%;
    display: flex;
    justify-content: space-between;
    align-items: center;
    z-index: 100;
    backdrop-filter: blur(10px);
    background: color-mix(in srgb, var(--bg-color) 55%, transparent);
    border-bottom: 1px solid transparent;
    transition: var(--transition);
}
nav.scrolled {
    border-bottom-color: var(--border-color);
    background: color-mix(in srgb, var(--bg-color) 80%, transparent);
}

.logo {
    font-family: var(--font-display);
    font-size: 1.5rem;
    font-weight: 800;
    cursor: pointer;
    position: relative;
    z-index: 101;
}
.logo-hint {
    position: absolute;
    top: 130%; left: 0;
    font-size: 0.7rem;
    font-family: var(--font-body);
    background: var(--bg-elevated);
    padding: 4px 10px;
    border-radius: 4px;
    border: 1px solid var(--border-color);
    opacity: 0;
    transform: translateY(10px);
    transition: var(--transition);
    pointer-events: none;
    white-space: nowrap;
}
.logo:hover .logo-hint { opacity: 1; transform: translateY(0); }

.nav-right { display: flex; align-items: center; gap: 1.5rem; }

.nav-links { display: flex; gap: 2rem; }
.nav-links a {
    color: var(--text-main);
    text-decoration: none;
    font-size: 0.85rem;
    text-transform: uppercase;
    letter-spacing: 1px;
    position: relative;
    font-weight: 500;
}
.nav-links a::after {
    content: '';
    position: absolute;
    bottom: -6px; left: 0;
    width: 0%; height: 2px;
    background: var(--accent);
    transition: var(--transition);
}
.nav-links a:hover::after, .nav-links a.active-link::after { width: 100%; }
.nav-links a.active-link { color: var(--accent); }

/* Theme toggle button */
.theme-toggle-btn {
    width: 42px; height: 42px;
    border-radius: 50%;
    border: 1px solid var(--border-color);
    background: var(--surface);
    color: var(--text-main);
    display: flex; align-items: center; justify-content: center;
    cursor: pointer;
    font-size: 1rem;
    transition: var(--transition);
    z-index: 101;
}
.theme-toggle-btn:hover { border-color: var(--accent); color: var(--accent); background: var(--surface-hover); }
.theme-toggle-btn .fa-sun { display: none; }
body.light-mode .theme-toggle-btn .fa-moon { display: none; }
body.light-mode .theme-toggle-btn .fa-sun { display: inline; }

/* Hamburger */
.hamburger {
    display: none;
    flex-direction: column;
    justify-content: center;
    gap: 5px;
    width: 30px; height: 24px;
    cursor: pointer;
    z-index: 101;
    background: none;
    border: none;
}
.hamburger span {
    display: block;
    width: 100%; height: 2px;
    background: var(--text-main);
    border-radius: 2px;
    transition: var(--transition);
}
.hamburger.active span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.hamburger.active span:nth-child(2) { opacity: 0; }
.hamburger.active span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

@media (max-width: 850px) {
    .nav-links {
        position: fixed;
        top: 0; right: 0;
        width: min(75vw, 320px); height: 100vh;
        background: var(--bg-elevated);
        border-left: 1px solid var(--border-color);
        flex-direction: column;
        justify-content: center;
        align-items: flex-start;
        padding: 3rem;
        gap: 2rem;
        transform: translateX(100%);
        transition: transform 0.45s cubic-bezier(0.16, 1, 0.3, 1);
        z-index: 100;
    }
    .nav-links.open { transform: translateX(0); }
    .nav-links a { font-size: 1.1rem; }
    .hamburger { display: flex; }
    .nav-overlay {
        position: fixed; inset: 0;
        background: rgba(0,0,0,0.5);
        z-index: 99;
        opacity: 0; pointer-events: none;
        transition: opacity 0.4s ease;
    }
    .nav-overlay.open { opacity: 1; pointer-events: auto; }
}

/* Layout & Container */
.container { max-width: 1200px; margin: 0 auto; padding: 0 1.5rem; }
section { padding: 7rem 0; position: relative; }

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.6rem;
    padding: 1rem 2rem;
    font-family: var(--font-display);
    font-weight: 600;
    font-size: 0.95rem;
    text-decoration: none;
    border-radius: 100px;
    transition: var(--transition);
    cursor: pointer;
    position: relative;
    overflow: hidden;
    border: 1px solid var(--border-color);
    background: var(--surface);
    color: var(--text-main);
}
.btn-primary {
    background: var(--accent);
    color: #fff;
    border-color: var(--accent);
    box-shadow: 0 0 20px var(--accent-glow);
}
.btn-primary:hover { box-shadow: 0 0 40px var(--accent-glow); transform: translateY(-2px); }
.btn-secondary:hover { background: var(--surface-hover); border-color: var(--accent); color: var(--accent); }
.btn:disabled { opacity: 0.6; cursor: not-allowed; }

/* Bento Grid */
.bento-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 1.25rem; grid-auto-rows: minmax(180px, auto); }
.bento-cell {
    background: var(--surface);
    border: 1px solid var(--border-color);
    border-radius: 22px;
    padding: 2.2rem;
    position: relative;
    overflow: hidden;
    backdrop-filter: blur(10px);
    transition: transform 0.3s ease, border-color 0.3s ease;
    transform-style: preserve-3d;
}
.bento-cell::before {
    content: '';
    position: absolute;
    top: 0; left: 0; right: 0; bottom: 0;
    background: radial-gradient(700px circle at var(--mouse-x, -100%) var(--mouse-y, -100%), var(--accent-glow), transparent 40%);
    z-index: 0; opacity: 0; transition: opacity 0.3s; pointer-events: none;
}
.bento-cell:hover::before { opacity: 0.5; }
.bento-cell > * { position: relative; z-index: 1; }

@media (max-width: 992px) { .bento-grid { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 576px) { .bento-grid { grid-template-columns: 1fr; } }

/* Hero */
#hero { min-height: 100vh; display: flex; align-items: center; justify-content: center; text-align: center; padding-top: 6rem; }
.hero-content { display: flex; flex-direction: column; align-items: center; z-index: 10; }
.avatar-slot {
    width: 84px; height: 84px;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--bg-color), var(--surface));
    border: 1px solid var(--accent);
    display: flex; align-items: center; justify-content: center;
    font-family: var(--font-display);
    font-size: 2rem; font-weight: 700;
    margin-bottom: 2rem;
    box-shadow: 0 0 30px var(--accent-glow);
}
.hero-eyebrow {
    font-family: var(--font-display);
    letter-spacing: 3px;
    text-transform: uppercase;
    font-size: 0.85rem;
    color: var(--accent);
    margin-bottom: 1rem;
}
.hero-title { font-size: clamp(3rem, 9vw, 7rem); letter-spacing: -0.03em; margin-bottom: 0.5rem; }
.scramble-text { display: inline-block; min-width: 10px; }
.hero-subtitle { font-size: clamp(1.05rem, 2.4vw, 1.4rem); color: var(--text-muted); margin: 0 auto 2rem; max-width: 780px; }
.hero-btns { display: flex; gap: 1rem; margin-top: 1rem; flex-wrap: wrap; justify-content: center; }
.hero-meta { display: flex; gap: 1.5rem; margin-top: 3rem; flex-wrap: wrap; justify-content: center; color: var(--text-muted); font-size: 0.9rem; }
.hero-meta span { display: flex; align-items: center; gap: 0.5rem; }
.scroll-cue {
    position: absolute; bottom: 2rem; left: 50%; transform: translateX(-50%);
    display: flex; flex-direction: column; align-items: center; gap: 0.5rem;
    color: var(--text-muted); font-size: 0.75rem; letter-spacing: 2px; text-transform: uppercase;
    animation: bob 2.4s ease-in-out infinite;
}
@keyframes bob { 0%,100% { transform: translate(-50%, 0); } 50% { transform: translate(-50%, 10px); } }

/* About */
.about-cell-main { grid-column: span 2; grid-row: span 2; }
.about-cell-stat { display: flex; flex-direction: column; justify-content: center; align-items: center; text-align: center; }
.stat-num { font-size: 3.5rem; font-family: var(--font-display); font-weight: 700; color: var(--accent); line-height: 1; margin-bottom: 0.5rem; }

/* Marquee */
.marquee-wrapper {
    position: relative; width: 100%; overflow: hidden;
    background: var(--surface);
    border-top: 1px solid var(--border-color);
    border-bottom: 1px solid var(--border-color);
    padding: 1.4rem 0; display: flex;
}
.marquee { display: flex; white-space: nowrap; animation: marquee 28s linear infinite; }
.marquee:hover { animation-play-state: paused; }
.marquee-item {
    font-family: var(--font-display); font-size: 1.3rem; font-weight: 600;
    padding: 0 2rem; display: flex; align-items: center; gap: 0.8rem;
    color: var(--text-muted); transition: var(--transition);
}
.marquee-item:hover { color: var(--accent); }
@keyframes marquee { 0% { transform: translateX(0); } 100% { transform: translateX(-50%); } }

/* Skills */
.tag-list { display: flex; flex-wrap: wrap; gap: 0.7rem; margin-top: 1.4rem; }
.tag {
    background: var(--surface-hover);
    border: 1px solid var(--border-color);
    padding: 0.5rem 1rem; border-radius: 100px; font-size: 0.88rem;
    transition: var(--transition);
}
.tag:hover { border-color: var(--accent); background: var(--accent-glow); color: #fff; }

.skill-bar-block { margin-bottom: 1.3rem; }
.skill-bar-head { display: flex; justify-content: space-between; margin-bottom: 0.4rem; font-size: 0.92rem; }
.skill-bar-track { width: 100%; height: 8px; border-radius: 10px; background: var(--surface-hover); overflow: hidden; }
.skill-bar-fill {
    height: 100%; border-radius: 10px;
    background: linear-gradient(90deg, var(--accent), var(--accent-glow));
    width: 0%;
    transition: width 1.4s cubic-bezier(0.16, 1, 0.3, 1);
}

/* Projects */
.project-card { display: flex; flex-direction: column; justify-content: space-between; grid-column: span 2; min-height: 260px; }
.project-header { display: flex; justify-content: space-between; align-items: flex-start; margin-bottom: 1rem; }
.project-index { font-family: var(--font-display); font-size: 1.4rem; color: var(--text-muted); opacity: 0.5; }
.project-links a { color: var(--text-main); font-size: 1.15rem; margin-left: 1rem; transition: var(--transition); }
.project-links a:hover { color: var(--accent); transform: scale(1.1); }
.project-title { font-size: 1.55rem; margin-bottom: 0.9rem; }
.project-desc { color: var(--text-muted); margin-bottom: 1.6rem; font-size: 0.95rem; }
.project-status {
    position: absolute; top: 1.6rem; right: 1.6rem;
    font-size: 0.68rem; text-transform: uppercase; letter-spacing: 1px;
    padding: 0.25rem 0.7rem; border-radius: 100px;
    border: 1px solid var(--border-color); color: var(--text-muted);
}
.project-status.ongoing { color: var(--accent); border-color: var(--accent); }

/* Timeline */
.timeline { position: relative; max-width: 800px; margin: 0 auto; }
.timeline::before { content: ''; position: absolute; top: 0; left: 30px; width: 1px; height: 100%; background: var(--border-color); }
.timeline-item { position: relative; padding-left: 80px; margin-bottom: 3rem; }
.timeline-dot {
    position: absolute; top: 5px; left: 24px; width: 13px; height: 13px; border-radius: 50%;
    background: var(--bg-color); border: 2px solid var(--accent); box-shadow: 0 0 10px var(--accent-glow);
}
.timeline-date { font-family: var(--font-display); color: var(--accent); font-size: 0.85rem; margin-bottom: 0.4rem; letter-spacing: 1px; text-transform: uppercase; }
.timeline-title { font-size: 1.4rem; margin-bottom: 0.2rem; }
.timeline-org { color: var(--text-muted); font-weight: 500; margin-bottom: 1rem; font-size: 1.05rem; }
.timeline-content ul { list-style: none; }
.timeline-content li { position: relative; padding-left: 1.5rem; margin-bottom: 0.5rem; color: var(--text-muted); font-size: 0.95rem; }
.timeline-content li::before { content: '▹'; position: absolute; left: 0; top: 0; color: var(--accent); }

/* Two column (Education / Achievements) */
.two-col-layout { display: grid; grid-template-columns: 1fr 1fr; gap: 3.5rem; }
.list-block { margin-bottom: 1.8rem; padding-bottom: 1.8rem; border-bottom: 1px solid var(--border-color); }
.list-block:last-child { border-bottom: none; margin-bottom: 0; padding-bottom: 0; }
.list-title { font-size: 1.2rem; margin-bottom: 0.4rem; }
.list-meta { display: flex; justify-content: space-between; color: var(--text-muted); font-size: 0.9rem; gap: 1rem; flex-wrap: wrap; }
@media (max-width: 768px) { .two-col-layout { grid-template-columns: 1fr; gap: 2rem; } }

/* Achievements grid */
.achieve-item {
    display: flex; align-items: flex-start; gap: 0.9rem;
    padding: 1.1rem 0; border-bottom: 1px solid var(--border-color);
}
.achieve-item:last-child { border-bottom: none; }
.achieve-item i { color: var(--accent); margin-top: 0.2rem; }

/* Section header */
.section-header { margin-bottom: 3.5rem; }
.section-tag { font-family: var(--font-display); color: var(--accent); letter-spacing: 3px; text-transform: uppercase; font-size: 0.8rem; margin-bottom: 0.7rem; display: block; }
.section-title { font-size: 2.6rem; display: flex; align-items: center; gap: 1rem; }
.section-title::before { content: ''; width: 46px; height: 2px; background: var(--accent); }
.section-sub { color: var(--text-muted); max-width: 600px; margin-top: 1rem; }

/* Contact */
#contact { padding: 8rem 0 5rem; }
.contact-grid { display: grid; grid-template-columns: 1fr 1.1fr; gap: 3rem; align-items: flex-start; }
@media (max-width: 900px) { .contact-grid { grid-template-columns: 1fr; } }

.contact-title { font-size: clamp(2.4rem, 5vw, 3.6rem); margin-bottom: 1.2rem; }
.contact-links { display: flex; gap: 1rem; margin-top: 2.5rem; flex-wrap: wrap; }
.contact-links a {
    color: var(--text-main); font-size: 1.4rem; transition: var(--transition);
    width: 52px; height: 52px; border-radius: 50%;
    border: 1px solid var(--border-color);
    display: flex; align-items: center; justify-content: center;
    background: var(--surface);
}
.contact-links a:hover { color: var(--accent); border-color: var(--accent); background: var(--accent-glow); transform: translateY(-4px); }

.contact-info-item { display: flex; align-items: center; gap: 1rem; margin-bottom: 1.4rem; color: var(--text-muted); }
.contact-info-item i { width: 40px; height: 40px; border-radius: 50%; background: var(--surface); border: 1px solid var(--border-color); display: flex; align-items: center; justify-content: center; color: var(--accent); }
.contact-info-item a { color: var(--text-main); text-decoration: none; }
.contact-info-item a:hover { color: var(--accent); }

/* Form */
.contact-form { background: var(--surface); border: 1px solid var(--border-color); border-radius: 22px; padding: 2.2rem; backdrop-filter: blur(10px); }
.form-row { display: grid; grid-template-columns: 1fr 1fr; gap: 1rem; }
@media (max-width: 560px) { .form-row { grid-template-columns: 1fr; } }
.form-group { margin-bottom: 1.3rem; position: relative; }
.form-group label { display: block; font-size: 0.85rem; margin-bottom: 0.5rem; color: var(--text-muted); font-weight: 600; }
.form-group input, .form-group textarea {
    width: 100%; padding: 0.85rem 1rem;
    background: var(--bg-elevated); border: 1px solid var(--border-color);
    border-radius: 10px; color: var(--text-main); font-family: var(--font-body);
    font-size: 0.95rem; transition: var(--transition);
}
.form-group textarea { resize: vertical; min-height: 120px; }
.form-group input:focus, .form-group textarea:focus { outline: none; border-color: var(--accent); box-shadow: 0 0 0 3px var(--accent-glow); }
.form-group input.invalid, .form-group textarea.invalid { border-color: var(--danger); }
.form-error {
    color: var(--danger); font-size: 0.8rem; margin-top: 0.4rem; min-height: 1rem;
    opacity: 0; transform: translateY(-4px); transition: var(--transition);
}
.form-error.show { opacity: 1; transform: translateY(0); }
.form-status {
    margin-top: 1.2rem; padding: 0.9rem 1rem; border-radius: 10px; font-size: 0.9rem;
    display: none; align-items: center; gap: 0.6rem;
}
.form-status.success { display: flex; background: rgba(52, 211, 153, 0.12); color: var(--success); border: 1px solid rgba(52, 211, 153, 0.3); }
.form-status.error { display: flex; background: rgba(248, 113, 113, 0.12); color: var(--danger); border: 1px solid rgba(248, 113, 113, 0.3); }
.char-count { font-size: 0.75rem; color: var(--text-muted); text-align: right; margin-top: 0.3rem; }

footer {
    text-align: center; padding: 2.5rem 0; color: var(--text-muted);
    border-top: 1px solid var(--border-color); margin-top: 2rem; font-size: 0.88rem;
}
footer .footer-links { display: flex; gap: 1.2rem; justify-content: center; margin-top: 1rem; }
footer .footer-links a { color: var(--text-muted); }
footer .footer-links a:hover { color: var(--accent); }

/* Reveal animations */
.reveal { opacity: 0; transform: translateY(28px); transition: all 0.8s cubic-bezier(0.16, 1, 0.3, 1); }
.reveal.active { opacity: 1; transform: translateY(0); }

/* Back to top */
.back-to-top {
    position: fixed; bottom: 2rem; right: 2rem; z-index: 90;
    width: 48px; height: 48px; border-radius: 50%;
    background: var(--accent); color: #fff; border: none;
    display: flex; align-items: center; justify-content: center;
    box-shadow: 0 0 20px var(--accent-glow); cursor: pointer;
    opacity: 0; pointer-events: none; transform: translateY(10px);
    transition: var(--transition);
}
.back-to-top.show { opacity: 1; pointer-events: auto; transform: translateY(0); }

@media (max-width: 768px) {
    section { padding: 5rem 0; }
    .contact-form { padding: 1.6rem; }
}