/* =========================================
    1. CSS VARIABLES
   ========================================= */
:root {
    --primary-color: #2563EB;
    --primary-hover: #1d4ed8;
    --primary-alpha-10: rgba(37, 99, 235, 0.1);
    --primary-alpha-20: rgba(37, 99, 235, 0.2);
    --bg-color: #f9fbfd;
    --bg-secondary: #f8f9fa;
    --text-main: #1f2937;
    --text-secondary: #4b5563;
    --card-bg: #ffffff;
    --border-color: #e5e7eb;
    --modal-overlay: rgba(0, 0, 0, 0.7);
    --shadow-sm: 0 3px 10px rgba(0, 0, 0, 0.08);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.05);
    --shadow-lg: 0 4px 20px rgba(0, 0, 0, 0.05);
    --shadow-hover: 0 8px 30px rgba(0, 0, 0, 0.12);
    --section-padding: 100px 0;
    --card-padding: 25px;
    --radius-sm: 6px;
    --radius-md: 10px;
    --radius-lg: 12px;
    --radius-xl: 16px;
    --radius-full: 20px;
    --transition-base: 0.3s ease;
    --transition-slow: 0.4s ease;
}

body.dark-mode {
    --primary-color: #60a5fa;
    --primary-hover: #93c5fd;
    --bg-color: #111827;
    --bg-secondary: #1f2937;
    --text-main: #f3f4f6;
    --text-secondary: #9ca3af;
    --card-bg: #1f2937;
    --border-color: #374151;
    --shadow-lg: 0 4px 20px rgba(0, 0, 0, 0.3);
    --modal-overlay: rgba(0, 0, 0, 0.85);
}

/* =========================================
    2. RESET & BASE STYLES
   ========================================= */
*, *::before, *::after { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
    font-family: 'Inter', sans-serif;
    color: var(--text-main);
    background-color: var(--bg-color);
    line-height: 1.6;
    overflow-x: hidden;
    transition: background-color var(--transition-base), color var(--transition-base);
}
a { text-decoration: none; color: inherit; transition: all var(--transition-base); }
ul { list-style: none; }
img { max-width: 100%; display: block; }
button { font-family: inherit; cursor: pointer; border: none; background: none; }

/* =========================================
    3. UTILITY CLASSES
   ========================================= */
.container { width: 100%; max-width: 1200px; margin: 0 auto; padding: 0 5%; }
.highlight { color: var(--primary-color); font-weight: 600; }

.section-header { text-align: center; max-width: 700px; margin: 0 auto 60px; }
.section-label {
    display: inline-block; color: var(--primary-color); font-weight: 600;
    font-size: 0.9rem; text-transform: uppercase; letter-spacing: 1.5px; margin-bottom: 15px;
}
.section-title { font-size: 2.5rem; font-weight: 700; color: var(--text-main); margin-bottom: 10px; text-align: center; }
.section-subtitle { font-size: 1.1rem; color: var(--text-secondary); margin-top: 15px; font-style: italic; text-align: center; }

.card-base, .pillar-card, .project-card, .education-card, .cert-card, .skill-category {
    background: var(--card-bg);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
    border: 1px solid var(--border-color);
}

/* =========================================
    4. BUTTONS
   ========================================= */
.btn {
    display: inline-block; padding: 12px 30px; border-radius: var(--radius-sm);
    font-weight: 600; font-size: 1rem; border: 2px solid transparent; transition: all var(--transition-base);
}
.btn-primary { background-color: var(--primary-color); color: #fff; border-color: var(--primary-color); }
.btn-primary:hover { background-color: var(--primary-hover); border-color: var(--primary-hover); transform: translateY(-2px); }
.btn-secondary { background-color: transparent; color: var(--primary-color); border-color: var(--primary-color); }
.btn-secondary:hover { background-color: var(--primary-alpha-10); transform: translateY(-2px); }
.btn-text, .view-details {
    color: var(--primary-color); font-weight: 600; display: inline-flex; align-items: center; gap: 8px; cursor: pointer;
}
.btn-text:hover i, .project-card:hover .view-details i { transform: translateX(5px); }

/* =========================================
    5. NAVIGATION
   ========================================= */
.navbar {
    display: flex; justify-content: space-between; align-items: center;
    padding: 20px 5%; background: var(--bg-color); position: fixed;
    width: 100%; top: 0; z-index: 100; box-shadow: 0 2px 10px rgba(0,0,0,0.05);
}
.logo { font-weight: 700; font-size: 1.2rem; color: var(--primary-color); }
.nav-links { display: flex; gap: 30px; }
.nav-links a { font-size: 0.95rem; color: var(--text-secondary); font-weight: 500; }
.nav-links a:hover, .nav-links a.active { color: var(--primary-color); }
.nav-controls { display: flex; align-items: center; gap: 20px; }
.theme-toggle, .menu-btn { cursor: pointer; font-size: 1.2rem; color: var(--text-main); }
.menu-btn { display: none; }

/* =========================================
    6. HERO SECTION
   ========================================= */
.hero { min-height: 100vh; display: flex; align-items: center; position: relative; padding-top: 80px; }
.hero .container { display: flex; align-items: center; justify-content: space-between; }
.hero-content { flex: 1; max-width: 600px; z-index: 2; }
.headline { font-size: 4rem; font-weight: 700; color: var(--primary-color); line-height: 1.1; margin-bottom: 10px; }
.subheadline { font-size: 1.5rem; font-weight: 400; margin-bottom: 25px; }
.bio-text { font-size: 1rem; color: var(--text-secondary); margin-bottom: 40px; max-width: 90%; }
.cta-group { display: flex; gap: 20px; margin-bottom: 40px; }

.stats-bar {
    display: flex; align-items: center; padding: 15px 25px;
    width: fit-content; margin-bottom: 40px; background: var(--card-bg); border-radius: var(--radius-lg);
}
.stat-item { display: flex; align-items: center; gap: 12px; }
.stat-icon { font-size: 1.2rem; color: var(--primary-color); }
.stat-info { display: flex; flex-direction: column; line-height: 1.2; }
.stat-number { font-weight: 700; font-size: 1.1rem; }
.stat-label { font-size: 0.8rem; color: var(--text-secondary); }
.stat-divider { width: 1px; height: 30px; background-color: var(--border-color); margin: 0 25px; }

.tech-stack { display: flex; gap: 20px; }
.tech-stack img { height: 35px; opacity: 0.8; transition: opacity var(--transition-base), transform var(--transition-base); }
.tech-stack img:hover { opacity: 1; transform: scale(1.1); }

.hero-visual { flex: 1; display: flex; justify-content: flex-end; position: relative; }
.network-img { max-width: 120%; height: auto; opacity: 0.8; transform: translateX(10%); }
.hero-visual::before {
    content: ''; position: absolute; top: 0; bottom: 0; left: -20%; right: 0;
    background: linear-gradient(to right, var(--bg-color) 0%, transparent 60%);
    pointer-events: none; z-index: 1;
}
body.dark-mode .network-img { opacity: 0.3; filter: brightness(0.6) contrast(0.9); }
body.dark-mode .hero-visual::before {
    background: linear-gradient(to right, var(--bg-color) 0%, var(--bg-color) 20%, transparent 70%);
}

/* =========================================
    7. ABOUT SECTION
   ========================================= */
.about-section { padding: var(--section-padding); border-top: 1px solid var(--border-color); }
.about-flex { display: flex; gap: 80px; align-items: flex-start; }
.about-narrative { flex: 1; }
.lead-text { font-size: 1.5rem; font-weight: 600; margin-bottom: 25px; line-height: 1.3; }
.about-narrative p { margin-bottom: 20px; color: var(--text-secondary); font-size: 1.05rem; }

.value-pillars { flex: 1; display: flex; flex-direction: column; gap: 20px; }
.pillar-card { padding: var(--card-padding); border-left: 4px solid var(--primary-color); transition: transform var(--transition-base); }
.pillar-card:hover { transform: translateX(10px); }
.pillar-icon { font-size: 1.5rem; color: var(--primary-color); margin-bottom: 15px; }
.pillar-card h4 { margin-bottom: 10px; font-size: 1.1rem; }
.pillar-card p { font-size: 0.9rem; color: var(--text-secondary); }

/* =========================================
    8. PORTFOLIO SECTION
   ========================================= */
.portfolio-section { padding: var(--section-padding); }
.portfolio-grid {
    display: grid; grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 30px; max-width: 1200px; margin: 0 auto;
}
.project-card { overflow: hidden; transition: transform var(--transition-base), box-shadow var(--transition-base); cursor: pointer; }
.project-card:hover { transform: translateY(-5px); box-shadow: var(--shadow-hover); }
.project-image { width: 100%; overflow: hidden; background: var(--card-bg); display: flex; justify-content: center; align-items: center; }
.project-img { width: 100%; height: auto; object-fit: contain; transition: transform var(--transition-base); }
.project-card:hover .project-img { transform: scale(1.05); }
.project-content { padding: var(--card-padding); }
.project-title { font-size: 1.3rem; font-weight: 700; margin-bottom: 12px; }
.project-description { font-size: 0.95rem; color: var(--text-secondary); margin-bottom: 20px; }

.project-tags, .skill-tags { display: flex; flex-wrap: wrap; gap: 8px; margin-bottom: 15px; }
.tag, .skill-tag, .experience-duration {
    background: var(--primary-alpha-10); color: var(--primary-color);
    padding: 5px 12px; border-radius: var(--radius-full); font-size: 0.8rem; font-weight: 600;
}
.skill-tags { gap: 10px; }
.skill-tag { padding: 8px 15px; font-size: 0.9rem; transition: all var(--transition-base); }
.skill-tag:hover { background: var(--primary-alpha-20); transform: translateY(-2px); }

/* =========================================
    9. EXPERIENCE SECTION
   ========================================= */
.experience-section { padding: 80px 0; background: var(--bg-secondary); }
.experience-timeline { position: relative; }
.experience-timeline::before {
    content: ''; position: absolute; left: 30px; top: 0; bottom: 0;
    width: 2px; background: var(--primary-color); opacity: 0.3;
}
.experience-item { position: relative; margin-bottom: 40px; padding-left: 60px; }
.experience-item::before {
    content: ''; position: absolute; left: 24px; top: 10px; width: 12px; height: 12px;
    border-radius: 50%; background: var(--primary-color); border: 3px solid var(--bg-secondary); z-index: 1;
}
.experience-header {
    display: flex; justify-content: space-between; align-items: flex-start;
    margin-bottom: 15px; flex-wrap: wrap; gap: 15px;
}
.experience-title { font-size: 1.3rem; color: var(--text-main); font-weight: 700; margin-bottom: 5px; }
.experience-company { color: var(--primary-color); font-weight: 600; font-size: 1.1rem; }
.experience-duration { font-size: 0.9rem; white-space: nowrap; }
.experience-list li { margin-bottom: 12px; padding-left: 25px; position: relative; color: var(--text-secondary); line-height: 1.6; }
.experience-list li::before { content: "▸"; position: absolute; left: 0; color: var(--primary-color); font-weight: bold; }
.experience-list strong { color: var(--text-main); }

/* =========================================
    10. EDUCATION & SKILLS SECTION
   ========================================= */
.education-skills-section { padding: 80px 0; }
.education-card { padding: 30px; border-left: 4px solid var(--primary-color); }
.education-header { margin-bottom: 20px; }
.education-header h3 { font-size: 1.4rem; color: var(--text-main); margin-bottom: 5px; }
.education-institution { color: var(--primary-color); font-weight: 600; font-size: 1.1rem; }
.education-content p { color: var(--text-secondary); margin-bottom: 10px; line-height: 1.6; }

.cert-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(250px, 1fr)); gap: 25px; }
.cert-card {
    padding: var(--card-padding); box-shadow: var(--shadow-sm);
    transition: transform var(--transition-base), box-shadow var(--transition-base);
    border-top: 3px solid var(--primary-color); border: 1px solid var(--border-color);
}
.cert-card:hover { transform: translateY(-5px); box-shadow: var(--shadow-hover); }
.cert-header { display: flex; align-items: center; gap: 15px; margin-bottom: 15px; }
.cert-icon { font-size: 1.5rem; color: var(--primary-color); }
.cert-header h4 { font-size: 1.1rem; color: var(--text-main); margin: 0; }
.cert-issuer { color: var(--text-secondary); font-size: 0.95rem; margin-bottom: 15px; }

.skills-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); gap: 30px; }
.skill-category { padding: var(--card-padding); }
.skill-category h3 { font-size: 1.2rem; color: var(--text-main); margin-bottom: 20px; display: flex; align-items: center; gap: 10px; }
.skill-category h3 i { color: var(--primary-color); }

/* =========================================
    11. MODAL
   ========================================= */
.modal-overlay {
    display: none; position: fixed; inset: 0; background: var(--modal-overlay);
    z-index: 1000; align-items: center; justify-content: center; padding: 20px;
    opacity: 0; transition: opacity var(--transition-base);
}
.modal-overlay.active { display: flex; opacity: 1; }
.modal-content {
    background: var(--card-bg); border-radius: var(--radius-xl);
    max-width: 900px; width: 100%; max-height: 90vh; overflow-y: auto;
    position: relative; transform: scale(0.9); transition: transform var(--transition-base);
}
.modal-overlay.active .modal-content { transform: scale(1); }
.modal-header {
    padding: 30px; border-bottom: 1px solid var(--border-color);
    position: sticky; top: 0; background: var(--card-bg); z-index: 10;
    display: flex; justify-content: space-between; align-items: start;
}
.modal-title { font-size: 2rem; font-weight: 700; margin-bottom: 10px; }
#modalTags { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 10px; }
.close-modal {
    font-size: 1.8rem; color: var(--text-secondary); padding: 5px;
    width: 40px; height: 40px; display: flex; align-items: center;
    justify-content: center; border-radius: 50%; transition: all var(--transition-base);
}
.close-modal:hover { background: rgba(0,0,0,0.05); color: var(--text-main); }
.modal-body { padding: 30px; }

.image-gallery { margin-bottom: 30px; }
.main-image { width: 100%; height: auto; border-radius: var(--radius-md); margin-bottom: 15px; box-shadow: var(--shadow-md); }
.thumbnail-gallery { display: flex; gap: 10px; flex-wrap: wrap; }
.thumbnail {
    width: 100px; height: 60px; object-fit: cover; border-radius: var(--radius-sm);
    cursor: pointer; opacity: 0.6; border: 2px solid transparent; transition: all var(--transition-base);
}
.thumbnail:hover { opacity: 0.9; transform: scale(1.05); }
.thumbnail.active { opacity: 1; border-color: var(--primary-color); }

.detail-section { margin-bottom: 30px; }
.detail-section h3 { font-size: 1.5rem; color: var(--text-main); margin-bottom: 15px; padding-bottom: 10px; border-bottom: 2px solid var(--border-color); }
.detail-section p { color: var(--text-secondary); line-height: 1.8; margin-bottom: 15px; }
.detail-section ul { list-style: none; padding: 0; }
.detail-section li { color: var(--text-secondary); line-height: 1.8; margin-bottom: 12px; padding-left: 25px; position: relative; }
.detail-section li::before { content: "▸"; position: absolute; left: 0; color: var(--primary-color); font-weight: bold; }

.project-links-section {
    display: flex; gap: 15px; margin: 30px 0; padding: 25px;
    background: rgba(0,0,0,0.03); border-radius: var(--radius-md); flex-wrap: wrap;
}
body.dark-mode .project-links-section { background: rgba(255,255,255,0.05); }
.github-link, .demo-link {
    display: inline-flex; align-items: center; gap: 10px; padding: 12px 24px;
    border-radius: var(--radius-sm); font-weight: 600; text-decoration: none; transition: all var(--transition-base);
}
.github-link { background: #24292e; color: #fff; border: 2px solid #24292e; }
.github-link:hover { background: #1a1e22; border-color: #1a1e22; transform: translateY(-2px); box-shadow: 0 4px 12px rgba(0,0,0,0.15); }
body.dark-mode .github-link { background: #ffffff; color: #24292e; border-color: #ffffff; }
body.dark-mode .github-link:hover { background: #e6e6e6; border-color: #e6e6e6; }
.demo-link { background: var(--primary-color); color: #fff; border: 2px solid var(--primary-color); }
.demo-link:hover { background: var(--primary-hover); border-color: var(--primary-hover); transform: translateY(-2px); }

.modal-content::-webkit-scrollbar { width: 8px; }
.modal-content::-webkit-scrollbar-track { background: var(--bg-color); }
.modal-content::-webkit-scrollbar-thumb { background: var(--primary-color); border-radius: 4px; }

/* =========================================
    12. CONTACT SECTION
   ========================================= */
.contact-section { padding: 50px 0; background-color: var(--bg-color); }
.contact-header-content { text-align: center; max-width: 700px; margin: 0 auto 60px auto; }
.contact-subtitle { font-size: 1.1rem; color: var(--text-secondary); line-height: 1.6; margin-top: 15px; }
.contact-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); gap: 30px; max-width: 1100px; margin: 0 auto; }
.contact-card {
    background: var(--card-bg); padding: 40px 30px; border-radius: 16px;
    text-align: center; text-decoration: none; box-shadow: var(--shadow-md);
    border: 1px solid var(--border-color); transition: all 0.3s ease;
    display: flex; flex-direction: column; align-items: center; justify-content: center;
}
.contact-card:hover { transform: translateY(-8px); box-shadow: var(--shadow-hover); border-color: var(--primary-color); }
.icon-box {
    width: 70px; height: 70px; background: rgba(37,99,235,0.08); border-radius: 50%;
    display: flex; align-items: center; justify-content: center; margin-bottom: 20px; transition: background 0.3s ease;
}
.icon-box i { font-size: 1.8rem; color: var(--primary-color); }
.contact-card:hover .icon-box { background: var(--primary-color); }
.contact-card:hover .icon-box i { color: #ffffff; }
.contact-card h3 { font-size: 1.3rem; color: var(--text-main); margin-bottom: 10px; font-weight: 700; }
.contact-card p { color: var(--text-secondary); font-size: 0.95rem; margin-bottom: 25px; }
.card-action { color: var(--primary-color); font-weight: 600; font-size: 0.9rem; display: flex; align-items: center; gap: 8px; }

/* =========================================
    13. FOOTER
   ========================================= */
.footer { padding: 20px 0; text-align: center; background-color: var(--bg-color); border-top: 1px solid var(--border-color); margin-top: auto; }
.footer p { color: var(--text-secondary); font-size: 0.9rem; margin: 0; }

/* =========================================
    14. LOADING STATES
   ========================================= */
.loading-container { display: flex; flex-direction: column; align-items: center; justify-content: center; padding: 60px 20px; min-height: 300px; }
.loading-spinner {
    width: 50px; height: 50px; border: 4px solid var(--border-color);
    border-top: 4px solid var(--primary-color); border-radius: 50%;
    animation: spin 1s linear infinite; margin-bottom: 20px;
}
@keyframes spin { 0% { transform: rotate(0deg); } 100% { transform: rotate(360deg); } }
.loading-container p { color: var(--text-secondary); font-size: 1rem; }
img[loading="lazy"] { opacity: 0; transition: opacity 0.3s ease-in; }
img[loading="lazy"].loaded { opacity: 1; }

/* =========================================
    15. BACK TO TOP BUTTON
   ========================================= */
.back-to-top {
    position: fixed; bottom: 30px; right: 30px; width: 50px; height: 50px;
    background: var(--primary-color); color: #fff; border-radius: 50%;
    display: flex; align-items: center; justify-content: center; font-size: 1.2rem;
    box-shadow: 0 4px 12px rgba(37,99,235,0.3); cursor: pointer;
    opacity: 0; visibility: hidden; transform: translateY(20px); transition: all 0.3s ease; z-index: 999;
}
.back-to-top.show { opacity: 1; visibility: visible; transform: translateY(0); }
.back-to-top:hover { background: var(--primary-hover); transform: translateY(-5px); box-shadow: 0 6px 20px rgba(37,99,235,0.4); }

/* =========================================
    16. SMOOTH SCROLL
   ========================================= */
html { scroll-padding-top: 80px; }

/* =========================================
    17. IMAGE ERROR STATE
   ========================================= */
.project-img[src*="data:image/svg"], .main-image[src*="data:image/svg"], .thumbnail[src*="data:image/svg"] {
    background-color: var(--bg-secondary); border: 2px dashed var(--border-color);
}

/* =========================================
    18. RESPONSIVE DESIGN
   ========================================= */
@media (max-width: 900px) {
    .menu-btn { display: flex; align-items: center; justify-content: center; width: 44px; height: 44px; border-radius: 8px; transition: background-color 0.3s ease; }
    .menu-btn:hover { background-color: var(--primary-alpha-10); }
    .nav-links {
        position: absolute; top: 70px; left: 0; width: 100%; background-color: var(--card-bg);
        flex-direction: column; align-items: center; padding: 20px 0;
        border-bottom: 1px solid var(--border-color); box-shadow: 0 10px 10px rgba(0,0,0,0.05);
        transform: translateY(-150%); opacity: 0; transition: all var(--transition-slow); z-index: -1;
    }
    .nav-links.active { transform: translateY(0); opacity: 1; z-index: 90; }
    .hero .container { flex-direction: column; text-align: center; justify-content: center; }
    .hero-content { margin-top: 40px; }
    .stats-bar { margin: 0 auto 30px; justify-content: center; flex-wrap: wrap; }
    .stat-divider { display: none; }
    .stat-item { margin: 10px; }
    .cta-group, .tech-stack { justify-content: center; }
    .hero-visual { display: none; }
    .headline { font-size: 3rem; }
    .about-flex { flex-direction: column; gap: 40px; }
}

@media (max-width: 768px) {
    .section-title { font-size: 2rem; }
    .portfolio-grid { grid-template-columns: 1fr; }
    .modal-content { margin: 10px; max-width: calc(100% - 20px); }
    .modal-header, .modal-body { padding: 20px; }
    .education-card { padding: 20px; }
    .skills-grid, .cert-grid { grid-template-columns: 1fr; }
    .back-to-top { bottom: 20px; right: 20px; width: 45px; height: 45px; font-size: 1.1rem; }
}

@media (max-width: 480px) {
    .headline { font-size: 2.5rem; }
    .cta-group { flex-direction: column; }
    .btn { width: 100%; text-align: center; }
    .back-to-top { bottom: 15px; right: 15px; width: 40px; height: 40px; font-size: 1rem; }
}

/* =========================================
    19. SQL PROJECT CARD
   ========================================= */
.retail-sql-card {
    background: #1e1e2e;
    padding: 0;
    border-radius: var(--radius-lg) var(--radius-lg) 0 0;
    overflow: hidden;
    max-height: 220px;
}

.retail-sql-card .project-img {
    width: 100%;
    height: 220px;
    object-fit: cover;
    object-position: top;
}

.project-card[data-project="retail"] { cursor: default; }
.project-card[data-project="retail"] .view-details { display: inline-flex; cursor: pointer; }

/* =========================================
    20. KEY ACHIEVEMENTS BLOCK
   ========================================= */
.achievements-block {
    margin-top: 20px; padding: 16px 20px;
    background: var(--primary-alpha-10);
    border-left: 4px solid var(--primary-color);
    border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
}

.achievements-title {
    font-weight: 700; color: var(--primary-color);
    margin-bottom: 10px; font-size: 0.95rem;
    display: flex; align-items: center; gap: 8px;
}