/* 
  Nexus Code Studio — Shared Design System
  Phase 2: Premium foundation
  Option C approach: shared base + page-specific overrides
*/

:root {
    /* Core Colors — Refined Premium Dark */
    --primary: #06b6d4;
    --primary-bright: #22d3ee;
    --primary-muted: #0891b2;
    --primary-rgb: 6, 182, 212;

    --bg: #0a0e14;
    --bg-subtle: #0f1419;
    --surface: #1a1f26;
    --surface-elevated: #1f2630;
    --surface-hover: #242b35;

    --text: #e8eaed;
    --text-muted: #9ca3af;
    --text-dim: #6b7280;

    --border: rgba(255, 255, 255, 0.06);
    --border-subtle: rgba(255, 255, 255, 0.03);
    --border-strong: rgba(255, 255, 255, 0.12);

    --glow: rgba(6, 182, 212, 0.18);
    --ring: rgba(6, 182, 212, 0.4);

    /* Spacing Scale (premium, generous) */
    --space-xs: 4px;
    --space-sm: 8px;
    --space-md: 16px;
    --space-lg: 24px;
    --space-xl: 32px;
    --space-2xl: 48px;
    --space-3xl: 64px;

    /* Typography */
    --font-display: 'Plus Jakarta Sans', -apple-system, BlinkMacSystemFont, sans-serif;
    --font-body: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
}

/* Base */
*, *::before, *::after {
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-body);
    background: var(--bg);
    color: var(--text);
    line-height: 1.65;
    margin: 0;
    overflow-x: hidden;
}

/* Typography — More Premium */
h1, h2, h3, h4 {
    font-family: var(--font-display);
    font-weight: 800;
    line-height: 1.1;
    letter-spacing: -0.025em;
}

h1 { font-size: clamp(2.4rem, 5.5vw, 3.6rem); }
h2 { font-size: clamp(1.8rem, 4vw, 2.6rem); }
h3 { font-size: 1.25rem; }

.section-label {
    font-size: 0.75rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--primary);
    margin-bottom: var(--space-sm);
}

/* Navigation — Explicit Tabs Feel */
nav {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    padding: 18px 0;
    z-index: 100;
    background: rgba(10, 14, 20, 0.96);
    border-bottom: 1px solid var(--border);
    backdrop-filter: blur(14px);
}

.nav-container {
    max-width: 1100px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 24px;
}

.logo {
    font-family: var(--font-display);
    font-weight: 800;
    font-size: 1.1rem;
    color: var(--text);
    text-decoration: none;
    letter-spacing: -0.02em;
}

.logo span {
    color: var(--primary);
}

.nav-links {
    display: flex;
    gap: 28px;
    align-items: center;
}

.nav-links a {
    color: var(--text-muted);
    text-decoration: none;
    font-size: 0.875rem;
    font-weight: 500;
    letter-spacing: 0.04em;
    text-transform: uppercase;
    padding: 6px 0;
    position: relative;
    transition: color 0.2s ease;
}

.nav-links a:hover {
    color: var(--primary-bright);
}

.nav-links a.active {
    color: var(--primary-bright);
}

.nav-links a.active::after {
    content: '';
    position: absolute;
    bottom: -2px;
    left: 0;
    width: 100%;
    height: 2px;
    background: var(--primary);
    border-radius: 2px;
}

/* Buttons — Premium */
.btn,
a.btn {
    display: inline-block;
    padding: 14px 28px;
    font-size: 0.95rem;
    font-weight: 600;
    border-radius: 8px;
    text-decoration: none;
    transition: all 0.2s ease;
    cursor: pointer;
    border: none;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary), var(--primary-bright));
    color: #fff;
    box-shadow: 0 4px 20px var(--glow);
}

.btn-primary:hover {
    transform: translateY(-1px);
    box-shadow: 0 10px 25px var(--glow);
}

.btn-secondary {
    background: rgba(255,255,255,0.05);
    color: var(--text);
    border: 1px solid var(--border);
}

.btn-secondary:hover {
    background: var(--surface-hover);
    border-color: var(--primary);
    color: var(--text);
}

/* Cards & Surfaces */
.card {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 16px;
    padding: var(--space-xl);
    transition: transform 0.2s ease, border-color 0.2s ease;
}

.card:hover {
    border-color: var(--border-strong);
    transform: translateY(-2px);
}

/* Sections */
.section {
    padding: var(--space-3xl) var(--space-xl);
    max-width: 1100px;
    margin: 0 auto;
}

/* Forms */
input, textarea {
    width: 100%;
    background: var(--bg-subtle);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 14px 16px;
    color: var(--text);
    font-size: 1rem;
    font-family: inherit;
    transition: border-color 0.2s ease;
}

input:focus, textarea:focus {
    outline: none;
    border-color: var(--primary);
}

input::placeholder, textarea::placeholder {
    color: var(--text-dim);
}

/* Footer */
footer {
    padding: var(--space-xl) var(--space-md);
    text-align: center;
    border-top: 1px solid var(--border);
    color: var(--text-dim);
    font-size: 0.85rem;
}

footer a {
    color: var(--text-muted);
    text-decoration: none;
}

footer a:hover {
    color: var(--primary-bright);
}

/* Utilities */
.text-muted { color: var(--text-muted); }
.text-dim { color: var(--text-dim); }
.text-center { text-align: center; }

/* Responsive */
@media (max-width: 700px) {
    .nav-links {
        gap: 18px;
    }
    .nav-links a {
        font-size: 0.8rem;
    }
}
/* Shared mobile base improvements */
@media (max-width: 768px) {
    nav {
        padding: 14px 0;
    }
    .nav-container {
        padding: 0 16px;
    }
    h1 { font-size: clamp(1.8rem, 6vw, 2.8rem); }
    h2 { font-size: clamp(1.5rem, 5vw, 2.1rem); }
    section {
        padding-left: 16px;
        padding-right: 16px;
    }
}