/* 
 * TelecomByte - Base Styles
 * Reset, Variables, and Foundation
 */
:root {
    /* Color Palette */
    --primary: #0056D2;
    --accent: #ff6b00;
    --bg-color: #f5f7fb;
    --text-color: #111827;
    --muted-color: #64748b;
    --card-bg: #ffffff;
    --border-color: #e5e7eb;

    /* Typography Scale */
    --font-main: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    --fs-base: 1rem; /* 16px */
    --fs-h1: clamp(2rem, 5vw, 3rem);
    --fs-h2: clamp(1.5rem, 3vw, 2rem);
    --fs-h3: clamp(1.25rem, 2vw, 1.5rem);
    
    /* Spacing */
    --space-xs: 0.5rem;
    --space-md: 1rem;
    --space-lg: 2rem;
    --container-width: 1200px;
}

/* Dark Mode Overrides */
body.dark-mode {
    --bg-color: #0f172a;
    --text-color: #f8fafc;
    --card-bg: #1e293b;
    --border-color: #334155;
    --muted-color: #94a3b8;
}

/* Global Reset */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    font-family: var(--font-main);
    background-color: var(--bg-color);
    color: var(--text-color);
    font-size: var(--fs-base);
    line-height: 1.6;
    transition: background-color 0.3s ease, color 0.3s ease;
}

/* Layout Foundation */
.container {
    width: min(var(--container-width), 92%);
    margin: 0 auto;
}

/* Accessibility: Skip Link */
.skip-link {
    position: absolute;
    top: -40px;
    left: 0;
    background: var(--primary);
    color: white;
    padding: 8px;
    z-index: 9999;
}
.skip-link:focus { top: 0; }

/* Responsive Images */
img {
    max-width: 100%;
    height: auto;
    display: block;
}

/* Links & Buttons */
a {
    color: var(--primary);
    text-decoration: none;
    transition: opacity 0.2s;
}

a:hover { opacity: 0.8; }

button, .btn {
    cursor: pointer;
    font-family: inherit;
    border: none;
    padding: 0.75rem 1.5rem;
    border-radius: 6px;
    font-weight: 600;
}

/* Typography Hierarchy */
h1, h2, h3, h4 {
    line-height: 1.2;
    margin-bottom: var(--space-md);
    color: var(--text-color);
}

h1 { font-size: var(--fs-h1); }
h2 { font-size: var(--fs-h2); }
h3 { font-size: var(--fs-h3); }

p { margin-bottom: var(--space-md); }