/* ============================================
   DIGITAL SEBA (ডিজিটাল সেবা প্ল্যাটফর্ম) - Core Design System
   Phase 0: Theme Configuration & Branding
   ============================================ */

/* --------------------------------------------
   1. CSS Variables & Theming
   -------------------------------------------- */
:root {
  /* Primary Theme Colors */
  --primary-blue: #2563EB; /* Modern Trust Blue */
  --primary-blue-hover: #1D4ED8;
  --primary-blue-light: #3B82F6;

  /* Slate Gray Palette */
  --slate-50: #F8FAFC;
  --slate-100: #F1F5F9;
  --slate-200: #E2E8F0;
  --slate-300: #CBD5E1;
  --slate-400: #94A3B8;
  --slate-500: #64748B;
  --slate-600: #475569;
  --slate-700: #334155;
  --slate-800: #1E293B;
  --slate-900: #0F172A;

  /* Surfaces & Backgrounds (Default: Light Mode) */
  --bg-body: var(--slate-50);
  --bg-surface: #FFFFFF;
  --bg-surface-hover: var(--slate-50);
  --border-color: var(--slate-200);

  /* Typography Colors */
  --text-primary: var(--slate-900);
  --text-secondary: var(--slate-600);
  --text-muted: var(--slate-400);

  /* Typography Setup */
  --font-sans: 'Inter', system-ui, -apple-system, sans-serif;
  --font-bengali: 'SolaimanLipi', 'Noto Sans Bengali', sans-serif;
  
  /* Utilities */
  --theme-transition: background-color 0.3s ease, color 0.3s ease, border-color 0.3s ease, box-shadow 0.3s ease;
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
  --shadow-card: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
}

/* Dark Theme Overrides */
[data-theme="dark"] {
  --bg-body: var(--slate-900);
  --bg-surface: var(--slate-800);
  --bg-surface-hover: var(--slate-700);
  --border-color: var(--slate-700);

  --text-primary: var(--slate-50);
  --text-secondary: var(--slate-300);
  --text-muted: var(--slate-500);
  
  --shadow-card: 0 10px 15px -3px rgba(0, 0, 0, 0.5), 0 4px 6px -2px rgba(0, 0, 0, 0.3);
}

/* --------------------------------------------
   2. Resets & Base Typography
   -------------------------------------------- */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: var(--font-sans);
  background-color: var(--bg-body);
  color: var(--text-primary);
  transition: var(--theme-transition);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* Bengali Typography Utility */
.font-bn {
  font-family: var(--font-bengali);
}

/* --------------------------------------------
   3. Branding Elements & Logo
   -------------------------------------------- */
.brand-logo {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-family: var(--font-sans);
  font-weight: 700;
  font-size: 1.5rem;
  color: var(--text-primary);
  text-decoration: none;
  transition: var(--theme-transition);
}

.brand-logo:hover {
  opacity: 0.9;
}

/* Lightning / Digital Motif Icon */
.brand-icon-lightning {
  color: var(--primary-blue);
  display: flex;
  align-items: center;
  justify-content: center;
  width: 2rem;
  height: 2rem;
}

.brand-icon-lightning svg {
  width: 100%;
  height: 100%;
  fill: currentColor;
  filter: drop-shadow(0 0 8px rgba(37, 99, 235, 0.4));
}

/* --------------------------------------------
   4. Modular Architecture (Phase Imports)
   -------------------------------------------- */
/* 
  Digital Seba Individual Pages (Upcoming phases):
  @import url('pages/home.css');
  @import url('pages/services.css');
  @import url('pages/tools.css');
  @import url('pages/resources.css');
  @import url('pages/live-tv.css');
  @import url('pages/focus-mode.css');
  @import url('pages/about.css');
*/

/* --------------------------------------------
   5. Back to Top Button
   -------------------------------------------- */
#backToTop {
  position: fixed !important;
  bottom: 90px !important; /* Above WhatsApp icon */
  right: 24px !important;
  width: 48px !important;
  height: 48px !important;
  border: 1px solid var(--border-color) !important;
  border-radius: 50% !important;
  background: var(--bg-surface) !important;
  color: var(--primary-blue) !important;
  font-size: 20px !important;
  cursor: pointer !important;
  z-index: 9999 !important;
  box-shadow: var(--shadow-md) !important;
  transition: var(--theme-transition) !important;
  backdrop-filter: blur(8px) !important;
  -webkit-backdrop-filter: blur(8px) !important;
  text-align: center !important;
  line-height: 46px !important;
}
#backToTop:hover {
  transform: translateY(-5px) !important;
  background: var(--primary-blue) !important;
  color: #fff !important;
  box-shadow: var(--shadow-card) !important;
}