/* ==========================================================================
   Base Styles — Merged: reset + design-tokens + typography + utilities + icons
   Single file replaces 4 separate CSS files + Font Awesome.
   ========================================================================== */

/* ---------- RESET ---------- */

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

body, h1, h2, h3, h4, h5, h6, p, figure, blockquote, dl, dd {
    margin: 0;
}

html {
    scroll-behavior: smooth;
}

@media (prefers-reduced-motion: reduce) {
    html {
        scroll-behavior: auto;
    }
}

body {
    min-height: 100vh;
    line-height: 1.5;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

img, picture, video, canvas, svg {
    display: block;
    max-width: 100%;
}

input, button, textarea, select {
    font: inherit;
}

p, h1, h2, h3, h4, h5, h6 {
    overflow-wrap: break-word;
}

ul[role="list"], ol[role="list"] {
    list-style: none;
    padding: 0;
    margin: 0;
}

a {
    text-decoration-skip-ink: auto;
}

/* ---------- DESIGN TOKENS ---------- */

:root {
    /* Colors */
    --color-primary: #0055FF;
    --color-primary-dark: #0042CC;
    --color-primary-light: #3377FF;
    --color-primary-soft: #E8F0FF;
    --color-accent: #FF6B35;
    --color-heading: #1A1A2E;
    --color-body: #4A4A68;
    --color-muted: #8E8EA0;
    --color-bg: #FFFFFF;
    --color-surface: #F8F9FC;
    --color-border: #E2E4EA;
    --color-success: #10B981;
    --color-warning: #F59E0B;
    --color-error: #EF4444;

    /* Typography */
    --font-primary: 'Urbanist', 'Noto Sans Bengali', system-ui, -apple-system, sans-serif;
    --font-heading: var(--font-primary);
    
    --font-size-xs: 0.75rem; /* 12px */
    --font-size-sm: 0.875rem; /* 14px */
    --font-size-base: 1rem; /* 16px */
    --font-size-lg: 1.125rem; /* 18px */
    --font-size-xl: 1.25rem; /* 20px */
    --font-size-2xl: 1.5rem; /* 24px */
    --font-size-3xl: 1.875rem; /* 30px */
    --font-size-4xl: 2.25rem; /* 36px */
    --font-size-5xl: 3rem; /* 48px */
    --font-size-6xl: 3.75rem; /* 60px */
    
    --line-height-tight: 1.2;
    --line-height-normal: 1.5;
    --line-height-relaxed: 1.75;
    
    --font-weight-light: 300;
    --font-weight-regular: 400;
    --font-weight-medium: 500;
    --font-weight-semibold: 600;
    --font-weight-bold: 700;

    /* Spacing */
    --space-xs: 0.25rem;
    --space-sm: 0.5rem;
    --space-md: 1rem;
    --space-lg: 1.5rem;
    --space-xl: 2rem;
    --space-2xl: 3rem;
    --space-3xl: 4rem;
    --space-4xl: 6rem;
    --space-5xl: 8rem;

    /* Layout */
    --container-max: 1200px;
    --container-padding: 1rem;
    --header-height: 80px;
    
    /* Border Radius */
    --border-radius-sm: 4px;
    --border-radius-md: 8px;
    --border-radius-lg: 12px;
    --border-radius-full: 9999px;

    /* Effects */
    --shadow-sm: 0 1px 2px rgba(0,0,0,0.05);
    --shadow-md: 0 4px 6px rgba(0,0,0,0.07);
    --shadow-lg: 0 10px 25px rgba(0,0,0,0.1);
    
    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-base: 250ms ease;
    --transition-slow: 350ms ease;
}

/* ---------- TYPOGRAPHY ---------- */

@font-face {
    font-family: 'Urbanist';
    src: url('../fonts/Urbanist-Light.woff2') format('woff2'),
         url('../fonts/Urbanist-Light.ttf') format('truetype');
    font-weight: 300;
    font-style: normal;
    font-display: swap;
}

@font-face {
    font-family: 'Urbanist';
    src: url('../fonts/Urbanist-Regular.woff2') format('woff2'),
         url('../fonts/Urbanist-Regular.ttf') format('truetype');
    font-weight: 400;
    font-style: normal;
    font-display: swap;
}

@font-face {
    font-family: 'Urbanist';
    src: url('../fonts/Urbanist-Medium.woff2') format('woff2'),
         url('../fonts/Urbanist-Medium.ttf') format('truetype');
    font-weight: 500;
    font-style: normal;
    font-display: swap;
}

@font-face {
    font-family: 'Urbanist';
    src: url('../fonts/Urbanist-SemiBold.woff2') format('woff2'),
         url('../fonts/Urbanist-SemiBold.ttf') format('truetype');
    font-weight: 600;
    font-style: normal;
    font-display: swap;
}

@font-face {
    font-family: 'Urbanist';
    src: url('../fonts/Urbanist-Bold.woff2') format('woff2'),
         url('../fonts/Urbanist-Bold.ttf') format('truetype');
    font-weight: 700;
    font-style: normal;
    font-display: swap;
}

/* Base typography styles */
body {
    font-family: var(--font-primary);
    color: var(--color-body);
    font-size: var(--font-size-base);
    line-height: var(--line-height-normal);
    font-weight: var(--font-weight-regular);
}

h1, h2, h3, h4, h5, h6 {
    font-family: var(--font-heading);
    color: var(--color-heading);
    line-height: var(--line-height-tight);
    font-weight: var(--font-weight-bold);
}

h1 {
    font-size: var(--font-size-3xl);
}

h2 {
    font-size: var(--font-size-2xl);
}

h3 {
    font-size: var(--font-size-3xl);
}

h4 {
    font-size: var(--font-size-2xl);
}

h5 {
    font-size: var(--font-size-xl);
}

h6 {
    font-size: var(--font-size-lg);
}

@media (min-width: 768px) {
    h1 {
        font-size: var(--font-size-4xl);
    }
    h2 {
        font-size: var(--font-size-3xl);
    }
}

@media (min-width: 1024px) {
    h1 {
        font-size: var(--font-size-5xl);
    }
    h2 {
        font-size: var(--font-size-4xl);
    }
}

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

a {
    color: var(--color-primary);
    text-decoration: none;
    transition: color var(--transition-fast);
}

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

strong {
    font-weight: var(--font-weight-semibold);
}

small {
    font-size: var(--font-size-sm);
}

/* ---------- UTILITIES ---------- */

.container {
    width: 100%;
    max-width: var(--container-max);
    margin: 0 auto;
    padding: 0 var(--container-padding);
}

@media (min-width: 768px) {
    .container {
        --container-padding: 1.5rem;
    }
}

@media (min-width: 1024px) {
    .container {
        --container-padding: 2rem;
    }
}

/* Screen reader only */
.sr-only,
.screen-reader-text {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    clip-path: inset(50%);
    white-space: nowrap;
    border-width: 0;
}

/* Skip link: visible on keyboard focus */
.skip-link.screen-reader-text:focus {
    clip: auto;
    clip-path: none;
    width: auto;
    height: auto;
    margin: 0;
    overflow: visible;
    display: block;
    position: fixed;
    top: 0;
    left: 0;
    z-index: 100000;
    padding: 0.75rem 1.5rem;
    background: var(--color-primary, #0055FF);
    color: #fff;
    font-size: var(--font-size-base, 1rem);
    font-weight: var(--font-weight-semibold, 600);
    text-decoration: none;
    outline: 2px solid #fff;
    outline-offset: -2px;
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.875rem 2rem;
    font-family: var(--font-primary);
    font-size: var(--font-size-base);
    font-weight: var(--font-weight-semibold);
    border-radius: var(--border-radius-md);
    border: 2px solid transparent;
    cursor: pointer;
    transition: all var(--transition-base);
    text-decoration: none;
    line-height: 1;
}

.btn-primary {
    background: var(--color-primary);
    color: #fff;
}

.btn-primary:hover {
    background: var(--color-primary-dark);
    color: #fff;
}

.btn-primary:focus-visible {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
}

.btn-outline {
    background: transparent;
    color: var(--color-primary);
    border-color: var(--color-primary);
}

.btn-outline:hover {
    background: var(--color-primary);
    color: #fff;
}

.btn-sm {
    padding: 0.5rem 1rem;
    font-size: var(--font-size-sm);
}

.btn-lg {
    padding: 1rem 2.5rem;
    font-size: var(--font-size-lg);
}

/* Text alignment */
.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }

/* Flexbox */
.flex { display: flex; }
.flex-col { flex-direction: column; }
.items-center { align-items: center; }
.justify-between { justify-content: space-between; }
.gap-md { gap: var(--space-md); }
.gap-lg { gap: var(--space-lg); }

/* Responsive display */
.hide-mobile {
    display: none;
}

@media (min-width: 768px) {
    .hide-mobile {
        display: block;
    }
    
    .flex.hide-mobile {
        display: flex;
    }
}

@media (min-width: 768px) {
    .hide-desktop {
        display: none !important;
    }
}

.show-mobile {
    display: block;
}

@media (min-width: 768px) {
    .show-mobile {
        display: none !important;
    }
}

/* ---------- INLINE SVG ICON STYLES ---------- */

.adv-icon {
    display: inline-block;
    width: 1em;
    height: 1em;
    vertical-align: -0.125em;
    fill: currentColor;
    flex-shrink: 0;
}

/* ---------- ENTRANCE SCROLL ANIMATIONS (Universal) ---------- */
.home-reveal,
.site-reveal {
    opacity: 0;
    transform: translateY(24px);
    transition: opacity 0.7s cubic-bezier(0.16, 1, 0.3, 1), transform 0.7s cubic-bezier(0.16, 1, 0.3, 1);
    will-change: opacity, transform;
}

.home-reveal.is-revealed,
.site-reveal.is-revealed {
    opacity: 1;
    transform: translateY(0);
}

.reveal-delay-1 { transition-delay: 0.1s; }
.reveal-delay-2 { transition-delay: 0.2s; }
.reveal-delay-3 { transition-delay: 0.3s; }
.reveal-delay-4 { transition-delay: 0.4s; }
.reveal-delay-5 { transition-delay: 0.5s; }
.reveal-delay-6 { transition-delay: 0.6s; }

@media (prefers-reduced-motion: reduce) {
    .home-reveal,
    .site-reveal {
        opacity: 1 !important;
        transform: none !important;
        transition: none !important;
    }
}

@media (max-width: 767px) {
    :root {
        --header-height: 70px;
    }
}

@media (max-width: 480px) {
    :root {
        --header-height: 70px;
    }
}