/* =====================================================
   OmixCalculator — Shared Base Stylesheet
   Covers: Reset, Variables, Layout, Header, Nav, Footer
   All page-specific styles remain inline per page.
   ===================================================== */

/* --- CSS Variables --- */
:root {
    --primary: #2563EB;
    --primary-dark: #1D4ED8;
    --navy: #0F172A;
    --accent: #0EA5A5;
    --col-math: #4F46E5;
    --col-finance: #059669;
    --col-health: #E11D48;
    --col-time: #D97706;
    --col-biz: #334155;
    --bg-body: #ffffff;
    --bg-card: #ffffff;
    --text-main: #334155;
    --text-heading: #0F172A;
    --border: #E2E8F0;
    --container-width: 1100px;
    --nav-height: 70px;
    --space-md: 2rem;
    --space-lg: 5rem;
    --radius-lg: 16px;
    --shadow-subtle: 0 1px 3px rgba(0,0,0,0.05);
    --shadow-float: 0 20px 25px -5px rgba(0,0,0,0.05), 0 8px 10px -6px rgba(0,0,0,0.01);
    --font-stack: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
}

/* --- Reset & Base --- */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
body { font-family: var(--font-stack); background-color: var(--bg-body); color: var(--text-main); line-height: 1.6; -webkit-font-smoothing: antialiased; text-rendering: optimizeLegibility; display: flex; flex-direction: column; min-height: 100vh; }
main { flex-grow: 1; }
a { text-decoration: none; color: inherit; cursor: pointer; transition: all 0.3s cubic-bezier(0.4,0,0.2,1); }

/* --- Accessibility --- */
.sr-only { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0,0,0,0); white-space: nowrap; border-width: 0; }

/* --- Layout --- */
.container { max-width: var(--container-width); margin: 0 auto; padding: 0 20px; width: 100%; }
.section-wrapper { padding-top: var(--space-lg); padding-bottom: var(--space-lg); border-bottom: 1px solid var(--border); }
.section-wrapper:last-child { border-bottom: none; }

/* --- Typography --- */
.section-label { font-size: 0.75rem; text-transform: uppercase; letter-spacing: 0.08em; font-weight: 700; color: var(--primary); margin-bottom: 0.5rem; display: block; }
p { color: var(--text-main); font-size: 1.05rem; }

/* --- Header --- */
header { background-color: rgba(255,255,255,0.90); height: var(--nav-height); display: flex; align-items: center; position: sticky; top: 0; z-index: 100; backdrop-filter: blur(12px); -webkit-backdrop-filter: blur(12px); will-change: transform; border-bottom: 1px solid var(--border); }
.header-inner { display: flex; align-items: center; width: 100%; }
.logo { display: flex; align-items: center; gap: 12px; }
.logo:focus { outline: none; }
.logo-mark { display: block; width: 36px; height: 36px; flex-shrink: 0; }
.logo-text { display: flex; align-items: baseline; line-height: 1; }
.brand-name { font-weight: 800; font-size: 1.35rem; color: var(--primary); letter-spacing: -0.03em; }
.brand-suffix { font-weight: 600; font-size: 1.35rem; color: var(--navy); letter-spacing: -0.02em; }

/* --- Navigation --- */
#mainNav { margin-left: auto; }
.nav-actions { display: flex; align-items: center; gap: 1rem; }
nav ul { display: flex; gap: 0.5rem; list-style: none; }
nav a { font-weight: 600; font-size: 0.95rem; color: var(--navy); padding: 10px 16px; border-radius: 8px; }
nav a:hover, nav a.nav-active { color: var(--primary); background-color: #EFF6FF; }
.mobile-menu-btn { display: none; background: none; border: none; cursor: pointer; padding: 12px; z-index: 102; margin-right: -12px; }
.hamburger-line { display: block; width: 24px; height: 2px; background-color: var(--primary); margin: 5px 0; transition: all 0.3s ease; border-radius: 2px; }

/* --- Footer --- */
footer { background-color: var(--navy); color: #F8FAFC; padding: 4rem 0 0; border-top: 1px solid #1E293B; }
.footer-grid { display: grid; grid-template-columns: 1.5fr 1fr 1fr; gap: 4rem; padding-bottom: 4rem; }
.footer-brand .logo-text { font-size: 1.5rem; margin-bottom: 1.25rem; display: inline-block; }
.footer-brand .brand-name { color: #60A5FA; }
.footer-brand .brand-suffix { color: white; }
.footer-brand p { color: #CBD5E1; font-size: 0.95rem; line-height: 1.6; max-width: 320px; }
.footer-col h3 { color: #E2E8F0; font-size: 0.85rem; text-transform: uppercase; letter-spacing: 0.05em; margin-bottom: 1.5rem; font-weight: 700; }
.footer-col ul { list-style: none; }
.footer-col li { margin-bottom: 0; }
.footer-col a { color: #CBD5E1; transition: color 0.2s, padding-left 0.2s; display: block; padding: 8px 0; }
.footer-col a:hover { color: white; padding-left: 4px; }
.footer-bottom { background-color: #020617; padding: 1.5rem 0; text-align: center; border-top: 1px solid #1E293B; color: #94A3B8; font-size: 0.85rem; }
.footer-bottom p { font-size: 0.85rem; margin: 0; color: inherit; }

/* --- Mobile --- */
@media (max-width: 768px) {
    .header-inner { justify-content: space-between; }
    .mobile-menu-btn { display: block; }
    nav {
        position: absolute; top: 100%; left: 0; right: 0;
        background: rgba(255,255,255,0.98);
        border-bottom: 1px solid var(--border);
        padding: 1.5rem; opacity: 0; transform: translateY(-10px); visibility: hidden;
        transition: all 0.3s cubic-bezier(0.4,0,0.2,1);
        box-shadow: var(--shadow-float);
        backdrop-filter: blur(10px); -webkit-backdrop-filter: blur(10px);
        text-align: center; margin: 0;
    }
    nav.is-active { opacity: 1; transform: translateY(0); visibility: visible; }
    nav ul { flex-direction: column; gap: 0.5rem; align-items: center; }
    nav a { display: block; width: 100%; padding: 16px; font-size: 1.05rem; }
    .section-wrapper { padding-top: 3rem; padding-bottom: 3rem; }
    .brand-name, .brand-suffix { font-size: 1.15rem; }
    .footer-grid { grid-template-columns: 1fr; gap: 2.5rem; text-align: center; }
    .footer-brand p { margin: 0 auto; }
    .footer-brand .logo-text { justify-content: center; }
}