/* =========================================
   1. GLOBAL VARIABLES
   ========================================= */
:root {
    /* Colors */
    --primary-color: #3a7bd5;
    --secondary-color: #00d2ff;
    --accent-color: #ff6b6b;
    --success-color: #4CAF50;
    --warning-color: #ff9f43;
    --dark-color: #2c3e50;
    --light-color: #f8f9fa;
    --text-color: #2d3436;
    --text-light: #ffffff;
    
    /* Backgrounds & Gradients */
    --bg-gradient: linear-gradient(to bottom right, #F8F9FA, #E1F5C4);
    --gradient-primary: linear-gradient(135deg, #4b6d91, #3c5774);
    --gradient-secondary: linear-gradient(135deg, #82bcfa, #426589);
    --nav-bg: #7aacde93;
    --glass-bg: rgba(255, 255, 255, 0.518);
    
    /* Shadows & Transitions */
    --shadow: 0 4px 20px rgba(0, 0, 0, 0.1);
    --transition: all 0.3s cubic-bezier(0.25, 0.8, 0.25, 1);
}

/* =========================================
   2. BASE RESETS & TYPOGRAPHY
   ========================================= */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Montserrat', sans-serif;
    background: var(--bg-gradient);
    min-height: 100vh;
    margin: 0;
    color: #4A4A4A;
    display: flex;
    flex-direction: column;
    font-size: 16px;
    line-height: 1.6;
    overflow-x: hidden;
}

main {
    flex: 1;
    margin-bottom: 6rem;
}

/* =========================================
   3. CUSTOM SCROLLBAR
   ========================================= */
html::-webkit-scrollbar {
    width: 1rem;
}

html::-webkit-scrollbar-track {
    background: var(--bg-gradient);
    border-radius: 10px;
}

html::-webkit-scrollbar-thumb {
    background: #426589;
    border-radius: 10px;
    border: 2px solid transparent;
    background-clip: content-box;
    box-shadow: 0 2px 6px rgba(0, 0, 0, 0.25);
    transition: background 0.3s ease, box-shadow 0.3s ease;
}

html::-webkit-scrollbar-thumb:hover {
    background: #2e4663;
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.35);
}

html::-webkit-scrollbar-corner {
    background: transparent;
}

/* =========================================
   4. TOP NAVIGATION BAR (GLASSMORPHISM)
   ========================================= */
.navbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0.8rem 1.5rem;
    width: 90%;
    height: 9vh;
    max-width: 1100px;
    margin: 1rem auto;
    position: sticky;
    top: 10px;
    z-index: 1000;
    background: var(--nav-bg);
    backdrop-filter: blur(15px);
    -webkit-backdrop-filter: blur(15px);
    border: 1px solid rgba(255, 255, 255, 0.25);
    border-radius: 1.5rem;
    box-shadow: 0 8px 30px rgba(0, 0, 0, 0.1);
    transition: all 0.3s ease;
}

.navbar:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 35px rgba(0, 0, 0, 0.15);
}

.navbar .logo {
    font-size: 1.5rem;
    font-weight: bold;
    color: white;
    text-decoration: none;
    display: flex;
    align-items: center;
    gap: 10px;
}

.hamburger {
    display: flex;
    flex-direction: column;
    cursor: pointer;
    gap: 5px;
    z-index: 2100;
    padding: 8px;
    border-radius: 5px;
    transition: background 0.3s;
}

.hamburger:hover {
    background: rgba(255, 255, 255, 0.1);
}

.hamburger span {
    width: 35px;
    height: 3px;
    background: rgb(0, 0, 0);
    border-radius: 2px;
    transition: all 0.3s ease;
}

.hamburger.active span:nth-child(1) {
    transform: translateY(8px) rotate(45deg);
}

.hamburger.active span:nth-child(2) {
    opacity: 0;
}

.hamburger.active span:nth-child(3) {
    transform: translateY(-8px) rotate(-45deg);
}
 
/* =========================================
   5. SIDEBAR MENU & OVERLAY
   ========================================= */
.calculator-nav {
    position: fixed;
    top: 0;
    right: -400px;
    width: 350px;
    height: 100%;
    background: linear-gradient(135deg, #3c4a59, #34495e);
    padding: 80px 20px 20px 20px;
    overflow-y: auto;
    transition: right 0.4s cubic-bezier(0.23, 1, 0.32, 1);
    z-index: 1500;
    box-shadow: -4px 0 25px rgba(0, 0, 0, 0.2);
}

.calculator-nav.active {
    right: 0;
}

.close-btn {
    position: absolute;
    top: 20px;
    right: 20px;
    background: rgba(255, 255, 255, 0.1);
    border: none;
    width: 40px;
    height: 40px;
    border-radius: 50%;
    color: white;
    font-size: 2rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.3s ease;
}

.close-btn:hover {
    background: rgba(255, 255, 255, 0.2);
    transform: rotate(90deg);
}

.nav-category {
    margin-bottom: 10px;
    border-radius: 10px;
    overflow: hidden;
    background: rgba(0, 0, 0, 0.05);
}

.category-btn {
    width: 100%;
    background: none;
    border: none;
    color: white;
    font-size: 1rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 15px;
    cursor: pointer;
    transition: all 0.3s ease;
}

.category-btn:hover {
    background: rgba(255, 255, 255, 0.1);
}

.category-btn i {
    margin-right: 10px;
    width: 20px;
    text-align: center;
}

.category-btn .arrow {
    transition: transform 0.3s ease;
}

.category-btn.active .arrow {
    transform: rotate(180deg);
}

.submenu {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.4s ease;
    background: rgba(0, 0, 0, 0.2);
}

.submenu.active {
    max-height: 500px;
}

.submenu .nav-btn {
    background: none;
    border: none;
    text-align: left;
    color: #ddd;
    padding: 12px 20px 12px 50px;
    cursor: pointer;
    font-size: 0.9rem;
    transition: all 0.2s ease;
    display: flex;
    align-items: center;
    width: 100%;
}

.submenu .nav-btn:hover {
    background: rgba(255, 255, 255, 0.08);
    color: #fff;
    padding-left: 55px;
}

.nav-btn.active {
    color: #60a5fa;
    background: rgba(96, 165, 250, 0.1);
}

.nav-icon {
    margin-right: 12px;
    width: 20px;
    text-align: center;
}

.nav-category.always-open .submenu {
    max-height: none !important;
    background: rgba(0, 0, 0, 0.2);
}

.nav-category.always-open .category-btn {
    cursor: default;
    justify-content: flex-start;
}

.nav-category.always-open .arrow {
    display: none;
}

.mobile-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
    opacity: 0;
    visibility: hidden;
    transition: all 0.3s ease;
    z-index: 1200;
}

.mobile-overlay.active {
    opacity: 1;
    visibility: visible;
}

/* =========================================
   6. FOOTER
   ========================================= */
footer {
    background: var(--gradient-primary);
    color: #fff;
    text-align: center;
    padding: 40px 20px 20px;
    font-family: Arial, sans-serif;
}

.footer-container {
    max-width: 1200px;
    margin: 0 auto;
}

.footer-social {
    margin-bottom: 20px;
}

.footer-social a {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 45px;
    text-decoration: none;
    height: 45px;
    margin: 0 8px;
    background: #fff;
    color: #000;
    border-radius: 50%;
    font-size: 20px;
    transition: all 0.3s ease;
}

.footer-social a:hover {
    transform: translateY(-4px);
    background: #7777778f;
    color: #000;
}

.footer-links {
    margin: 20px 0;
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    gap: 20px;
}

.footer-links a, .popular-links a {
    color: #fff;
    text-decoration: none;
    font-size: 15px;
    transition: color 0.3s ease;
    position: relative;
}

.footer-links a:hover, .popular-links a:hover {
    color: #c4c1c1f0;
}

.popular-links a:hover {
    text-decoration: underline;
}

.footer-links a::after {
    content: attr(data-desc);
    position: absolute;
    bottom: -30px;
    left: 50%;
    transform: translateX(-50%) scale(0.9);
    background: rgba(255, 255, 255, 0.9);
    color: #333;
    padding: 5px 10px;
    border-radius: 4px;
    font-size: 12px;
    opacity: 0;
    transition: all 0.3s ease;
    pointer-events: none;
    white-space: nowrap;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
}

.footer-links a:hover::after {
    opacity: 1;
    transform: translateX(-50%) scale(1);
    bottom: -35px;
}

.footer-bottom {
    border-top: 1px solid rgba(255, 255, 255, 0.4);
    margin-top: 20px;
    padding-top: 15px;
}

.footer-bottom p {
    font-size: 14px;
    opacity: 0.9;
    color: white;
}

.footer-bottom span {
    font-weight: bold;
}

/* =========================================
   7. PRELOADER
   ========================================= */
.preloaderBg {
    position: fixed;
    inset: 0;
    z-index: 9999;
    background: linear-gradient(135deg, #439af6, #8fb4da);
    width: 100vw;
    height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    transition: opacity 0.8s ease, visibility 0.8s ease;
    overflow: hidden;
}

.loader {
    width: clamp(100px, 30vw, 200px);
    height: clamp(100px, 30vw, 200px);
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
}

.preloader {
    background: url("../logo/logo.png") no-repeat center;
    background-size: contain;
    width: 60%;
    height: 60%;
    position: absolute;
    animation: pulse 1s ease-in-out infinite;
}

.preloader2 {
    border: 5px solid rgba(255, 255, 255, 0.3);
    border-top: 5px solid #000;
    border-radius: 50%;
    width: 100%;
    height: 100%;
    animation: spin 1s linear infinite;
    position: absolute;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

@keyframes pulse {
    0%, 100% { transform: scale(1); }
    50% { transform: scale(1.1); }
}

.preloaderBg.hide {
    opacity: 0;
    visibility: hidden;
}

/* =========================================
   8. GLOBAL RESPONSIVE ADJUSTMENTS
   ========================================= */
@media (max-width: 768px) {
    .navbar { padding: 1rem; }
    .calculator-nav { width: 300px; right: -300px; }
    .submenu .nav-btn { padding: 10px 15px 10px 45px; }
    .submenu .nav-btn:hover { padding-left: 50px; }
    
    footer { padding: 2rem 1rem; }
    .footer-links { gap: 15px; }
    .footer-links a { font-size: 14px; }
    .footer-links a::after { display: none; }
    .footer-social a { width: 36px; height: 36px; font-size: 16px; }
}

@media (max-width: 480px) {
    .calculator-nav { width: 280px; right: -280px; padding: 70px 15px 15px 15px; }
    .footer-links { flex-direction: column; align-items: center; gap: 10px; }
    .footer-bottom p { font-size: 12px; }
    .popular-links a { font-size: 12px; }
}