/* ===== Reset & Variables ===== */
:root {
    --blue: #2563eb;
    --blue-light: #3b82f6;
    --green: #16a34a;
    --red: #dc2626;
    --purple: #7c3aed;
    --dark: #1e293b;
    --text: #374151;
    --text-light: #6b7280;
    --bg: #f3f4f6;
    --white: #ffffff;
    --border: #e5e7eb;
    --radius: 10px;
    --shadow: 0 1px 3px rgba(0,0,0,0.08), 0 1px 2px rgba(0,0,0,0.06);
}

*, *::before, *::after { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }
body { font-family: 'Segoe UI', system-ui, -apple-system, sans-serif; line-height: 1.65; color: var(--text); background: var(--bg); }
a { text-decoration: none; color: inherit; }
ul { list-style: none; }
img { max-width: 100%; }

/* ===== Layout ===== */
.container { max-width: 1060px; margin: 0 auto; padding: 0 20px; }

/* ===== Navbar ===== */
.navbar {
    background: var(--dark);
    padding: 0.7rem 0;
    position: sticky;
    top: 0;
    z-index: 100;
    box-shadow: 0 2px 8px rgba(0,0,0,0.15);
}
.navbar .container { display: flex; justify-content: space-between; align-items: center; }
.nav-brand { display: flex; align-items: center; gap: 8px; color: #fff; font-size: 1.2rem; font-weight: 700; }
.nav-brand i { color: var(--green); }
.nav-menu { display: flex; gap: 4px; }
.nav-menu a { color: rgba(255,255,255,0.8); padding: 0.45rem 0.9rem; border-radius: 6px; font-size: 0.9rem; transition: 0.2s; }
.nav-menu a:hover, .nav-menu a.active { background: var(--blue); color: #fff; }
.hamburger { display: none; flex-direction: column; cursor: pointer; gap: 5px; }
.hamburger span { width: 22px; height: 2px; background: #fff; transition: 0.3s; }

/* ===== Hero ===== */
.hero {
    background: linear-gradient(135deg, #0f172a 0%, var(--dark) 100%);
    color: #fff;
    text-align: center;
    padding: 3.5rem 20px;
}
.hero h1 { font-size: 1.8rem; margin-bottom: 0.6rem; line-height: 1.35; max-width: 700px; margin-left: auto; margin-right: auto; }
.hero p { opacity: 0.8; font-size: 1.05rem; margin-bottom: 1.2rem; }
.btn { display: inline-block; background: var(--blue); color: #fff; padding: 0.65rem 1.6rem; border-radius: 6px; font-size: 0.95rem; border: none; cursor: pointer; transition: 0.2s; }
.btn:hover { background: var(--blue-light); transform: translateY(-1px); }

/* ===== Page Header ===== */
.page-header {
    background: linear-gradient(135deg, var(--blue), var(--green));
    color: #fff;
    text-align: center;
    padding: 2rem 20px;
}
.page-header h1 { font-size: 1.6rem; margin-bottom: 0.3rem; }
.page-header p { opacity: 0.9; }

/* ===== Section ===== */
.section { padding: 2.5rem 0; }
.section-title {
    font-size: 1.4rem;
    margin-bottom: 1.2rem;
    color: var(--dark);
    display: flex;
    align-items: center;
    gap: 10px;
    padding-bottom: 0.5rem;
    border-bottom: 2px solid var(--border);
}
.section-title i { color: var(--blue); }

/* ===== Card ===== */
.card {
    background: var(--white);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: 1.4rem;
    margin-bottom: 1.2rem;
}
.card h3 { font-size: 1.1rem; margin-bottom: 0.6rem; color: var(--dark); }

/* ===== Grid ===== */
.grid-2 { display: grid; grid-template-columns: repeat(2, 1fr); gap: 1.2rem; margin: 1.2rem 0; }
.grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 1.2rem; margin: 1.2rem 0; }


/* ===== Mini Card (for grids) ===== */
.mini-card {
    background: var(--white);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: 1.2rem;
    text-align: center;
    transition: transform 0.2s;
}
.mini-card:hover { transform: translateY(-2px); }
.mini-card i { font-size: 1.8rem; color: var(--blue); margin-bottom: 0.5rem; display: block; }
.mini-card h4 { font-size: 0.95rem; margin-bottom: 0.3rem; color: var(--dark); }
.mini-card p { font-size: 0.85rem; color: var(--text-light); }

/* ===== Comparison ===== */
.comparison { display: grid; grid-template-columns: 1fr 1fr; gap: 1.2rem; margin: 1.2rem 0; }
.comparison-box {
    background: var(--white);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    overflow: hidden;
}
.comparison-box .header {
    padding: 0.8rem 1.2rem;
    color: #fff;
    font-weight: 600;
    font-size: 1.05rem;
    display: flex;
    align-items: center;
    gap: 8px;
}
.comparison-box.cli .header { background: var(--green); }
.comparison-box.gui .header { background: var(--red); }
.comparison-box .body { padding: 1rem 1.2rem; }
.comparison-box .body li { padding: 0.25rem 0; display: flex; align-items: center; gap: 8px; font-size: 0.92rem; }
.comparison-box .body li i { color: var(--green); font-size: 0.8rem; }
.comparison-box .example { background: var(--bg); padding: 0.8rem 1.2rem; font-size: 0.88rem; border-top: 1px solid var(--border); }
.comparison-box .example code { background: var(--dark); color: var(--green); padding: 0.5rem 0.8rem; display: block; border-radius: 4px; font-family: monospace; margin-top: 0.3rem; font-size: 0.82rem; }

/* ===== Table ===== */
.table-wrap { overflow-x: auto; margin: 1.2rem 0; }
table {
    width: 100%;
    background: var(--white);
    border-radius: var(--radius);
    overflow: hidden;
    border-collapse: collapse;
    box-shadow: var(--shadow);
}
thead { background: var(--dark); color: #fff; }
th, td { padding: 0.7rem 1rem; text-align: left; font-size: 0.9rem; border-bottom: 1px solid var(--border); }
tbody tr:hover { background: var(--bg); }
tbody tr:last-child td { border-bottom: none; }









/* ===== References ===== */
.ref-list { padding-left: 1.5rem; }
.ref-list li { list-style: disc; margin-bottom: 0.5rem; font-size: 0.9rem; line-height: 1.5; }
.ref-list a { color: var(--blue); }
.ref-list a:hover { color: var(--green); }

/* ===== Charts Page ===== */
.charts-page { padding: 2rem 0; }
.chart-card {
    background: var(--white);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: 1.4rem;
    margin-bottom: 1.5rem;
}
.chart-card h3 { font-size: 1.1rem; margin-bottom: 0.2rem; color: var(--dark); display: flex; align-items: center; gap: 8px; }
.chart-card h3 i { color: var(--blue); }
.chart-card .subtitle { color: var(--text-light); font-size: 0.88rem; margin-bottom: 1rem; }
.chart-box { position: relative; height: 320px; }
.chart-row { display: grid; grid-template-columns: 1fr 1fr; gap: 1.2rem; }
.chart-row .chart-box { height: 260px; }

/* Stats */
.stats-row { display: grid; grid-template-columns: repeat(3, 1fr); gap: 1rem; margin: 1.5rem 0; }
.stat-box {
    background: var(--white);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: 1.2rem;
    text-align: center;
}
.stat-box i { font-size: 1.5rem; color: var(--blue); margin-bottom: 0.4rem; display: block; }
.stat-box .num { font-size: 1.5rem; font-weight: 700; color: var(--dark); }
.stat-box .label { font-size: 0.82rem; color: var(--text-light); margin-top: 0.2rem; }

/* ===== Contacts Page ===== */
.contacts-page { padding: 2rem 0; }
.contacts-grid { display: grid; grid-template-columns: 1fr 1.2fr; gap: 1.5rem; margin-bottom: 2rem; }

.contact-info {
    background: var(--white);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: 1.5rem;
}
.contact-info h2 { font-size: 1.2rem; margin-bottom: 1rem; color: var(--dark); }
.info-item { display: flex; gap: 0.8rem; margin-bottom: 1rem; align-items: flex-start; }
.info-item i { color: var(--blue); font-size: 1.1rem; margin-top: 3px; width: 20px; text-align: center; }
.info-item strong { display: block; font-size: 0.9rem; color: var(--dark); }
.info-item p { font-size: 0.88rem; color: var(--text-light); margin: 0; }
.social-links { display: flex; gap: 0.6rem; margin-top: 1rem; padding-top: 1rem; border-top: 1px solid var(--border); }
.social-links a {
    width: 36px; height: 36px; background: var(--bg); border-radius: 50%;
    display: flex; align-items: center; justify-content: center;
    color: var(--text); font-size: 1rem; transition: 0.2s;
}
.social-links a:hover { background: var(--blue); color: #fff; }

.contact-form-wrapper {
    background: var(--white);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: 1.5rem;
}
.contact-form-wrapper h2 { font-size: 1.2rem; margin-bottom: 1rem; color: var(--dark); }
.contact-form { display: flex; flex-direction: column; gap: 1rem; }
.form-group { display: flex; flex-direction: column; }
.form-group label { font-weight: 500; font-size: 0.88rem; margin-bottom: 0.3rem; }
.form-group input,
.form-group select,
.form-group textarea {
    padding: 0.6rem 0.75rem;
    border: 1.5px solid var(--border);
    border-radius: 6px;
    font-size: 0.9rem;
    font-family: inherit;
    transition: border-color 0.2s;
    background: var(--white);
}
.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus { outline: none; border-color: var(--blue); }
.form-group input.error,
.form-group select.error,
.form-group textarea.error { border-color: var(--red); }
.form-error { color: var(--red); font-size: 0.78rem; margin-top: 0.2rem; }





/* ===== Author Page ===== */
.author-page { padding: 2rem 0; }

.profile-card {
    background: var(--white);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: 2rem;
    text-align: center;
    margin-bottom: 1.5rem;
}
.profile-avatar {
    width: 100px; height: 100px;
    background: linear-gradient(135deg, var(--blue), var(--green));
    border-radius: 50%;
    display: flex; align-items: center; justify-content: center;
    margin: 0 auto 1rem;
    font-size: 2.5rem;
    color: #fff;
}
.profile-card h2 { font-size: 1.4rem; margin-bottom: 0.2rem; }
.profile-title { color: var(--text-light); font-size: 0.95rem; margin-bottom: 0.6rem; }
.profile-bio { font-size: 0.9rem; color: var(--text); max-width: 560px; margin: 0 auto 1rem; line-height: 1.6; }
.profile-links { display: flex; gap: 0.6rem; justify-content: center; }
.profile-links a {
    width: 38px; height: 38px; background: var(--bg); border-radius: 50%;
    display: flex; align-items: center; justify-content: center;
    color: var(--text); font-size: 1.1rem; transition: 0.2s;
}
.profile-links a:hover { background: var(--blue); color: #fff; }

.author-section { margin-bottom: 1.5rem; }
.author-section h2 { font-size: 1.2rem; margin-bottom: 1rem; display: flex; align-items: center; gap: 8px; color: var(--dark); }
.author-section h2 i { color: var(--blue); }



/* Timeline Simple */
.timeline-simple .timeline-item { margin-bottom: 1rem; padding-left: 1rem; border-left: 3px solid var(--blue); }
.timeline-simple .timeline-date { font-size: 0.82rem; color: var(--blue); font-weight: 600; }
.timeline-simple .timeline-item h3 { font-size: 0.95rem; margin: 0.2rem 0; }
.timeline-simple .timeline-item p { font-size: 0.85rem; color: var(--text-light); }





/* ===== Footer ===== */
.footer {
    background: var(--dark);
    color: #fff;
    padding: 2rem 0 1rem;
    margin-top: 2.5rem;
}
.footer-grid { display: grid; grid-template-columns: 2fr 1fr 1fr; gap: 2rem; margin-bottom: 1.5rem; }
.footer h3 { font-size: 1rem; margin-bottom: 0.6rem; display: flex; align-items: center; gap: 6px; }
.footer p, .footer li { font-size: 0.88rem; opacity: 0.8; }
.footer li { margin-bottom: 0.3rem; }
.footer a { color: rgba(255,255,255,0.75); transition: color 0.2s; }
.footer a:hover { color: var(--green); }
.footer-bottom { text-align: center; padding-top: 1rem; border-top: 1px solid rgba(255,255,255,0.1); font-size: 0.82rem; opacity: 0.6; }

/* ===== Scroll Top ===== */
.scroll-top {
    position: fixed; bottom: 20px; right: 20px;
    width: 40px; height: 40px;
    background: var(--blue); color: #fff; border: none;
    border-radius: 50%; cursor: pointer; font-size: 1rem;
    opacity: 0; pointer-events: none; transition: 0.3s;
    box-shadow: 0 2px 8px rgba(0,0,0,0.2);
    z-index: 50;
}
.scroll-top.visible { opacity: 1; pointer-events: auto; }
.scroll-top:hover { background: var(--blue-light); transform: translateY(-2px); }

/* ===== Responsive ===== */
@media (max-width: 768px) {
    .hamburger { display: flex; }
    .nav-menu {
        position: fixed; top: 52px; left: 0; right: 0;
        background: var(--dark); flex-direction: column; padding: 0.8rem;
        transform: translateY(-100%); opacity: 0; transition: 0.3s; pointer-events: none;
    }
    .nav-menu.active { transform: translateY(0); opacity: 1; pointer-events: auto; }
    .hero h1 { font-size: 1.4rem; }
    .grid-2, .comparison, .contacts-grid, .skills-grid, .chart-row { grid-template-columns: 1fr; }
    .grid-3, .stats-row { grid-template-columns: 1fr 1fr; }

    .footer-grid { grid-template-columns: 1fr; }
    .chart-box { height: 260px; }
}

@media (max-width: 480px) {
    .grid-3, .stats-row { grid-template-columns: 1fr; }
    .hero h1 { font-size: 1.2rem; }
    .chart-box { height: 220px; }
}

@media print {
    .navbar, .scroll-top { display: none !important; }
    body { background: #fff; }
}