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

:root {
    --bg-primary: #060611;
    --bg-secondary: #0d1025;
    --bg-card: #0f1328;
    --bg-input: #161a35;
    --bg-tag: #0d1025;
    --bg-glass: rgba(0, 0, 0, 0.3);
    --border-card: rgba(99, 102, 241, 0.15);
    --border-glow: rgba(99, 102, 241, 0.25);
    --border-tag: rgba(99, 102, 241, 0.15);

    --text-primary: #f0f0f8;
    --text-secondary: #8b8fa3;
    --text-muted: #6b7089;

    --accent-purple: #a855f7;
    --accent-cyan: #22d3ee;
    --accent-green: #34d399;
    --accent-orange: #fb923c;
    --accent-blue: #6366f1;

    --gradient-name: linear-gradient(135deg, #a855f7 0%, #6366f1 40%, #22d3ee 100%);
    --gradient-btn: linear-gradient(135deg, #6366f1 0%, #a855f7 50%, #ec4899 100%);

    --font-main: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --radius-lg: 32px;
    --radius-md: 20px;
    --radius-sm: 12px;
    --radius: 16px;
}

[data-theme="light"] {
    --bg-primary: #ffffff;
    --bg-secondary: #f1f5f9;
    --bg-card: #f8fafc;
    --bg-input: #ffffff;
    --bg-tag: #f1f5f9;
    --bg-glass: rgba(255, 255, 255, 0.9);
    --border-card: rgba(0, 0, 0, 0.08);
    --border-glow: rgba(99, 102, 241, 0.3);
    --border-tag: rgba(0, 0, 0, 0.1);

    --text-primary: #0f172a;
    --text-secondary: #1e293b;
    --text-muted: #475569;

    --accent-purple: #7c3aed;
    --accent-cyan: #0e7490;
    --accent-green: #047857;
    --accent-orange: #c2410c;
    --accent-blue: #4338ca;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-main);
    background-color: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    overflow-x: hidden;
    transition: background-color 0.3s ease, color 0.3s ease;
}

/* Theme Toggle - Integrated into "i" dot */
.name-i {
    position: relative;
    display: inline-block;
    /* Stable box for coordinate system */
    vertical-align: baseline;
    background: inherit;
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
}

.i-dot-toggle {
    position: absolute;
    top: 0.15em;
    /* Optical placement for larger size */
    left: 55%;
    /* Shifted clearly to the right of the stem */
    transform: translateX(-50%);
    width: 1.35em;
    /* Prominent "normal toggle" size */
    height: 1.35em;
    padding: 0;
    border: 1px solid var(--accent-cyan);
    background: var(--bg-primary);
    color: var(--accent-purple);
    cursor: pointer;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    z-index: 2;
    transition: all 0.3s cubic-bezier(0.175, 0.885, 0.32, 1.275);
    border-radius: 50%;
}

.i-dot-toggle svg {
    width: 55%;
    height: 55%;
    stroke-width: 5;
    /* More robust icon stroke */
}

.i-dot-toggle:hover {
    transform: translateX(-50%) scale(1.15);
    box-shadow: 0 0 15px var(--accent-purple);
}

[data-theme="light"] .i-dot-toggle {
    color: var(--accent-blue);
    background: var(--bg-primary);
}

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

[data-theme="light"] .moon-icon {
    display: block !important;
}

/* ===== HERO SECTION ===== */
.hero {
    min-height: 70vh;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    padding: 100px 24px 60px;
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: -50%;
    left: 50%;
    transform: translateX(-50%);
    width: 800px;
    height: 800px;
    background: radial-gradient(circle, rgba(99, 102, 241, 0.08) 0%, transparent 70%);
    pointer-events: none;
}

.hero-content {
    max-width: 700px;
    position: relative;
    z-index: 1;
}

.hero-name {
    font-size: clamp(3rem, 8vw, 5.5rem);
    font-weight: 900;
    background: var(--gradient-name);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    line-height: 1.1;
    margin-bottom: 8px;
    letter-spacing: -2px;
}

.hero-title {
    font-size: clamp(1.2rem, 3vw, 1.75rem);
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 24px;
}

.hero-bio {
    font-size: 1rem;
    color: var(--text-secondary);
    max-width: 540px;
    margin: 0 auto 16px;
    line-height: 1.7;
}

.hero-previous {
    font-size: 0.9rem;
    color: var(--text-muted);
    margin-bottom: 32px;
}

.highlight-green {
    color: var(--accent-green);
    font-weight: 600;
}

.highlight-purple {
    color: var(--accent-purple);
    font-weight: 600;
}

a.highlight-green,
a.highlight-purple {
    text-decoration: none;
    transition: opacity 0.3s ease;
}

a.highlight-green:hover,
a.highlight-purple:hover {
    text-decoration: underline;
    opacity: 0.85;
}

/* Tech Pills */
.tech-pills {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 10px;
    transition: opacity 0.3s ease, max-height 0.4s ease;
    max-height: 200px;
    overflow: hidden;
}

.tech-pills.hidden {
    opacity: 0;
    max-height: 0;
    margin: 0;
    pointer-events: none;
}

.pill {
    padding: 6px 16px;
    border-radius: var(--radius-sm);
    font-size: 0.8rem;
    font-weight: 500;
    color: var(--text-secondary);
    border: 1px solid var(--border-tag);
    background: var(--bg-tag);
    transition: all 0.3s ease;
}

.pill:hover {
    border-color: var(--accent-purple);
    color: var(--text-primary);
    box-shadow: 0 0 15px rgba(168, 85, 247, 0.15);
}

/* ===== SKILLS TOGGLE BUTTON ===== */
.skills-toggle {
    display: flex;
    align-items: center;
    gap: 8px;
    margin: 28px auto 0;
    padding: 10px 24px;
    border-radius: var(--radius-sm);
    border: 1px solid var(--border-card);
    background: transparent;
    color: var(--text-muted);
    font-family: var(--font-main);
    font-size: 0.82rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s ease;
}

.skills-toggle:hover {
    border-color: var(--accent-purple);
    color: var(--text-primary);
    box-shadow: 0 0 15px rgba(168, 85, 247, 0.12);
}

.skills-toggle-chevron {
    transition: transform 0.4s cubic-bezier(0.4, 0, 0.2, 1);
}

.skills-toggle.active .skills-toggle-chevron {
    transform: rotate(180deg);
}

.skills-toggle.active {
    border-color: var(--accent-purple);
    color: var(--text-primary);
}

/* ===== SKILLS PANEL (collapsible) ===== */
.skills-panel {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.6s cubic-bezier(0.4, 0, 0.2, 1),
        opacity 0.4s ease,
        visibility 0s 0.6s;
    opacity: 0;
    visibility: hidden;
}

.skills-panel.open {
    opacity: 1;
    visibility: visible;
    transition: max-height 0.6s cubic-bezier(0.4, 0, 0.2, 1),
        opacity 0.4s ease,
        visibility 0s 0s;
}

.skills-panel-inner {
    max-width: 900px;
    margin: 0 auto;
    padding: 12px 24px 48px;
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 28px 32px;
}

.skills-category {
    text-align: left;
}

.category-title {
    font-size: 0.8rem;
    font-weight: 700;
    color: var(--accent-cyan);
    margin-bottom: 10px;
    text-transform: uppercase;
    letter-spacing: 1px;
}

.category-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 6px;
}

/* Skill Tag Pills (reused) */
.skill-tag {
    display: inline-block;
    padding: 5px 12px;
    border-radius: var(--radius-sm);
    font-size: 0.72rem;
    font-weight: 500;
    color: var(--text-secondary);
    background: var(--bg-tag);
    border: 1px solid var(--border-tag);
    transition: all 0.3s ease;
}

.skill-tag:hover {
    border-color: var(--accent-cyan);
    color: var(--text-primary);
    box-shadow: 0 0 10px rgba(34, 211, 238, 0.15);
}


/* ===== PROJECTS SECTION ===== */
.projects {
    padding: 60px 24px 80px;
    max-width: 1000px;
    margin: 0 auto;
}

.section-title {
    font-size: clamp(1.5rem, 3vw, 2rem);
    font-weight: 800;
    text-align: center;
    margin-bottom: 48px;
    color: var(--text-primary);
}

.gradient-title {
    background: var(--gradient-name);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.project-card {
    background: var(--bg-card);
    border: 1px solid var(--border-card);
    border-radius: var(--radius-md);
    padding: 40px;
    margin-bottom: 32px;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 40px;
    transition: all 0.4s ease;
    position: relative;
    overflow: hidden;
}

.project-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 2px;
    background: var(--gradient-btn);
    opacity: 0;
    transition: opacity 0.4s ease;
}

.project-card:hover {
    border-color: var(--border-glow);
    box-shadow: 0 8px 40px rgba(99, 102, 241, 0.08);
}

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

.project-name {
    font-size: 1.35rem;
    font-weight: 800;
    margin-bottom: 12px;
    color: var(--text-primary);
}

.project-desc {
    font-size: 0.9rem;
    color: var(--text-secondary);
    line-height: 1.7;
    margin-bottom: 28px;
}

.project-columns {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 24px;
    margin-bottom: 24px;
}

.project-col ul {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.project-col li {
    font-size: 0.825rem;
    color: var(--text-secondary);
}

.col-title {
    font-size: 0.85rem;
    font-weight: 700;
    margin-bottom: 12px;
}

.col-cyan {
    color: var(--accent-cyan);
}

.col-purple {
    color: var(--accent-purple);
}

.col-green {
    color: var(--accent-green);
}

.project-achievements {
    margin-top: 24px;
    padding-top: 20px;
    border-top: 1px solid rgba(255, 255, 255, 0.05);
}

.project-achievements ul {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.project-achievements li {
    font-size: 0.825rem;
    color: var(--text-secondary);
}

/* AI Knowledge Section */
.expertise-section {
    padding: 80px 2rem;
    max-width: 1200px;
    margin: 0 auto;
}

.expertise-container {
    background: #0b1120;
    border-radius: var(--radius-lg);
    padding: 50px;
    border: 1px solid rgba(255, 255, 255, 0.05);
}

.expertise-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
}

.expertise-card {
    background: #0f172a;
    border: 1.5px solid rgba(255, 255, 255, 0.03);
    border-radius: var(--radius-md);
    padding: 32px;
    transition: transform 0.3s ease, border-color 0.3s ease, box-shadow 0.3s ease;
}

.expertise-card:hover {
    transform: translateY(-5px);
    border-color: rgba(255, 255, 255, 0.1);
}

.expertise-card h3 {
    font-size: 1.15rem;
    margin-bottom: 24px;
    font-weight: 700;
}

.expertise-card ul {
    list-style: none;
    padding: 0;
    display: flex;
    flex-direction: column;
    gap: 14px;
}

.expertise-card li {
    font-size: 0.875rem;
    color: var(--text-secondary);
    display: flex;
    align-items: center;
    gap: 12px;
}

.expertise-card li::before {
    content: '';
    width: 4px;
    height: 4px;
    border-radius: 50%;
    flex-shrink: 0;
}

/* Accent Colors & "Active" State (from reference) */
.card-cyan {
    border-color: rgba(56, 189, 248, 0.15);
}

.card-cyan:hover {
    border-color: rgba(56, 189, 248, 0.4);
    box-shadow: 0 0 20px rgba(56, 189, 248, 0.1);
}

.card-cyan h3 {
    color: var(--accent-cyan);
}

.card-cyan li::before {
    background: var(--accent-cyan);
}

.card-purple {
    border-color: rgba(168, 85, 247, 0.15);
}

.card-purple:hover {
    border-color: rgba(168, 85, 247, 0.4);
    box-shadow: 0 0 20px rgba(168, 85, 247, 0.1);
}

.card-purple h3 {
    color: var(--accent-purple);
}

.card-purple li::before {
    background: var(--accent-purple);
}

.card-green {
    border-color: rgba(52, 211, 153, 0.15);
}

.card-green:hover {
    border-color: rgba(52, 211, 153, 0.4);
    box-shadow: 0 0 20px rgba(52, 211, 153, 0.1);
}

.card-green h3 {
    color: var(--accent-green);
}

.card-green li::before {
    background: var(--accent-green);
}

@media (max-width: 1024px) {
    .expertise-grid {
        grid-template-columns: 1fr 1fr;
    }
}

@media (max-width: 768px) {
    .expertise-grid {
        grid-template-columns: 1fr;
    }

    .expertise-section {
        padding: 60px 1.5rem;
    }

    .expertise-container {
        padding: 30px 20px;
    }
}

/* ===== ARCHITECTURE DIAGRAMS ===== */
.project-diagram {
    display: flex;
    flex-direction: column;
}

.diagram-title {
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--text-secondary);
    margin-bottom: 20px;
}

.arch-diagram {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0;
    flex: 1;
}

.arch-row {
    display: flex;
    gap: 16px;
    justify-content: center;
    width: 100%;
}

.arch-box {
    padding: 10px 12px;
    border-radius: var(--radius-sm);
    font-size: 0.72rem;
    font-weight: 500;
    text-align: center;
    border: 1.5px solid;
    width: 150px;
    flex-shrink: 0;
    color: var(--text-primary);
    background: var(--bg-glass);
}

.arch-box.wide {
    width: 316px;
}

.box-purple {
    border-color: var(--accent-purple);
}

.box-cyan {
    border-color: var(--accent-cyan);
}

.box-green {
    border-color: var(--accent-green);
}

.box-orange {
    border-color: var(--accent-orange);
}

.arch-connector {
    width: 2px;
    height: 30px;
    background: rgba(168, 85, 247, 0.6);
    position: relative;
    margin: 2px auto;
}

.arch-connector.branch-out::after,
.arch-connector.branch-in::before {
    content: '';
    position: absolute;
    left: 50%;
    transform: translateX(-50%);
    width: 166px;
    height: 2px;
    background: inherit;
}

.arch-connector.branch-out::after {
    bottom: 0;
}

.arch-connector.branch-in::before {
    top: 0;
}

/* Wide branch for row with 3 boxes */
.arch-connector.wide-branch-out::after,
.arch-connector.wide-branch-in::before {
    width: 332px !important;
}

.arch-connector.branch-double::after,
.arch-connector.branch-double::before {
    content: '';
    position: absolute;
    left: 50%;
    transform: translateX(-50%);
    width: 166px;
    height: 2px;
    background: inherit;
}

.arch-connector.branch-double::after {
    bottom: 0;
}

.arch-connector.branch-double::before {
    top: 0;
}

/* ===== CONTACT SECTION ===== */
.contact {
    padding: 80px 24px 60px;
    max-width: 600px;
    margin: 0 auto;
    text-align: center;
}

.contact-subtitle {
    font-size: 0.9rem;
    color: var(--text-secondary);
    margin-bottom: 16px;
    line-height: 1.7;
}

.contact-location {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 6px;
    font-size: 0.85rem;
    color: var(--text-muted);
    margin-bottom: 40px;
}

.icon-location {
    width: 16px;
    height: 16px;
}

.contact-form {
    text-align: left;
}

.form-group {
    margin-bottom: 20px;
}

.form-group label {
    display: block;
    font-size: 0.85rem;
    font-weight: 500;
    color: var(--text-primary);
    margin-bottom: 8px;
}

.form-group input,
.form-group textarea {
    width: 100%;
    padding: 14px 16px;
    border-radius: var(--radius-sm);
    border: 1px solid var(--border-card);
    background: var(--bg-input);
    color: var(--text-primary);
    font-family: var(--font-main);
    font-size: 0.9rem;
    outline: none;
    transition: border-color 0.3s ease, box-shadow 0.3s ease;
}

.form-group input:focus,
.form-group textarea:focus {
    border-color: var(--accent-blue);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.15);
}

.form-group textarea {
    resize: vertical;
    min-height: 120px;
}

.btn-gradient {
    width: 100%;
    padding: 16px;
    border: none;
    border-radius: var(--radius-sm);
    background: var(--gradient-btn);
    color: white;
    font-family: var(--font-main);
    font-size: 0.95rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
}

.btn-gradient::before {
    content: '';
    position: absolute;
    inset: 0;
    background: linear-gradient(135deg, rgba(255, 255, 255, 0.1), transparent);
    opacity: 0;
    transition: opacity 0.3s ease;
}

.btn-gradient:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 30px rgba(99, 102, 241, 0.3);
}

.btn-gradient:hover::before {
    opacity: 1;
}

.btn-gradient:active {
    transform: translateY(0);
}

/* ===== FOOTER ===== */
.footer {
    padding: 60px 24px 40px;
    text-align: center;
    background: var(--bg-primary);
}

.btn-resume {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 12px 28px;
    border-radius: var(--radius-sm);
    border: 1px solid var(--border-card);
    background: transparent;
    color: var(--text-primary);
    font-family: var(--font-main);
    font-size: 0.9rem;
    font-weight: 500;
    text-decoration: none;
    transition: all 0.3s ease;
    margin-bottom: 28px;
}

.btn-resume:hover {
    border-color: var(--accent-purple);
    box-shadow: 0 0 20px rgba(168, 85, 247, 0.15);
    transform: translateY(-2px);
}

.social-links {
    display: flex;
    justify-content: center;
    gap: 20px;
    margin-bottom: 32px;
}

.social-links a {
    color: var(--text-muted);
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
}

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

.footer-copy {
    font-size: 0.75rem;
    color: var(--text-muted);
}

/* ===== ANIMATIONS ===== */
.fade-in {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.7s ease, transform 0.7s ease;
}

.fade-in.visible {
    opacity: 1;
    transform: translateY(0);
}

/* ===== RESPONSIVE ===== */
@media (max-width: 900px) {
    .skills-panel-inner {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 768px) {
    .skills-panel-inner {
        grid-template-columns: 1fr;
        gap: 24px;
    }

    .project-card {
        grid-template-columns: 1fr;
        padding: 28px;
    }

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

    .hero {
        padding: 80px 20px 40px;
        min-height: 60vh;
    }

    .arch-box {
        min-width: 80px;
        font-size: 0.65rem;
        padding: 8px 10px;
    }

    .arch-row {
        flex-wrap: wrap;
    }
}

@media (max-width: 480px) {
    .hero-name {
        font-size: 2.5rem;
    }

    .name-i {
        margin-right: 0.1em;
    }

    .i-dot-toggle {
        top: -0.1em !important;
        /* Lifted higher for more breathing room */
        left: 50% !important;
        transform: translateX(-50%) !important;
        width: 1.15em !important;
        height: 1.15em !important;
    }

    .i-dot-toggle svg {
        width: 50% !important;
        height: 50% !important;
    }

    .tech-pills {
        gap: 8px;
    }

    .pill {
        font-size: 0.72rem;
        padding: 5px 12px;
    }
}

@media (max-width: 350px) {
    .i-dot-toggle {
        top: -0.15em !important;
        /* Higher on ultra-narrow */
        left: 50% !important;
        transform: translateX(-50%) !important;
        width: 1.05em !important;
        height: 1.05em !important;
    }
}

/* ===== TOAST ===== */
.toast {
    position: fixed;
    bottom: 40px;
    left: 50%;
    transform: translateX(-50%) translateY(20px);
    background: #1e293b;
    color: #f1f5f9;
    border: 1px solid rgba(56, 189, 248, 0.3);
    padding: 14px 28px;
    border-radius: 12px;
    font-size: 0.9rem;
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.3s ease, transform 0.3s ease, visibility 0.3s ease;
    z-index: 9999;
    pointer-events: none;
    box-shadow: 0 4px 24px rgba(0, 0, 0, 0.4);
}

.toast.show {
    opacity: 1;
    visibility: visible;
    transform: translateX(-50%) translateY(0);
}