/* ===================================
   Global Styles & Reset
   =================================== */

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --primary-color: #000000;
    --secondary-color: #ffffff;
    --gray-light: #f5f5f5;
    --gray-medium: #cccccc;
    --gray-dark: #666666;
    --border-color: #e0e0e0;
    --shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
    --shadow-hover: 0 4px 16px rgba(0, 0, 0, 0.15);
    --transition: all 0.3s ease;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    line-height: 1.6;
    color: var(--primary-color);
    background-color: var(--secondary-color);
    overflow-x: hidden;
}

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

a:hover {
    opacity: 0.8;
}

img {
    max-width: 100%;
    height: auto;
    display: block;
}

button {
    cursor: pointer;
    border: none;
    background: none;
    font-family: inherit;
}

/* ===================================
   Container & Layout
   =================================== */

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

.section {
    padding: 60px 0;
}

/* ===================================
   Header Styles
   =================================== */

header {
    background-color: var(--secondary-color);
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 1000;
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 15px 20px;
    max-width: 1200px;
    margin: 0 auto;
}

.logo {
    display: flex;
    align-items: center;
    font-size: 24px;
    font-weight: bold;
}

.logo img {
    height: 40px;
    width: auto;
}

/* Navigation */
nav ul {
    display: flex;
    list-style: none;
    gap: 30px;
}

nav a {
    font-weight: 500;
    padding: 8px 16px;
    border-radius: 4px;
    transition: var(--transition);
}

nav a:hover,
nav a.active {
    background-color: var(--gray-light);
}

/* Mobile Menu Toggle */
.menu-toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    padding: 10px;
}

.menu-toggle span {
    width: 25px;
    height: 3px;
    background-color: var(--primary-color);
    transition: var(--transition);
}

/* ===================================
   Footer Styles
   =================================== */

footer {
    background-color: var(--primary-color);
    color: var(--secondary-color);
    padding: 40px 0 20px;
    margin-top: 60px;
}

.footer-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

.footer-top {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr;
    gap: 40px;
    padding-bottom: 30px;
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

.footer-about .footer-logo {
    margin-bottom: 15px;
}

.footer-about .footer-logo img {
    height: 35px;
    width: auto;
    filter: invert(1);
}

.footer-description {
    color: rgba(255, 255, 255, 0.8);
    line-height: 1.6;
    margin-top: 10px;
}

.footer-section h3 {
    font-size: 16px;
    margin-bottom: 15px;
    font-weight: 600;
}

.footer-section ul {
    list-style: none;
}

.footer-section ul li {
    margin-bottom: 10px;
}

.footer-section a {
    color: rgba(255, 255, 255, 0.8);
    transition: var(--transition);
}

.footer-section a:hover {
    color: var(--secondary-color);
}

.footer-bottom {
    text-align: center;
    padding-top: 20px;
    color: rgba(255, 255, 255, 0.6);
    font-size: 14px;
}

/* ===================================
   Back to Top Button
   =================================== */

#backToTop {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 50px;
    height: 50px;
    background-color: var(--primary-color);
    color: var(--secondary-color);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 20px;
    opacity: 0;
    visibility: hidden;
    transition: var(--transition);
    z-index: 999;
    box-shadow: var(--shadow);
}

#backToTop.show {
    opacity: 1;
    visibility: visible;
}

#backToTop:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-hover);
}

/* ===================================
   Common Components
   =================================== */

/* Buttons */
.btn {
    padding: 12px 24px;
    border-radius: 4px;
    font-weight: 500;
    transition: var(--transition);
    display: inline-block;
    text-align: center;
}

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

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

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

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

/* Cards */
.card {
    background-color: var(--secondary-color);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    overflow: hidden;
    transition: var(--transition);
}

.card:hover {
    box-shadow: var(--shadow-hover);
    transform: translateY(-2px);
}

/* Loading Spinner */
.loading {
    display: inline-block;
    width: 40px;
    height: 40px;
    border: 4px solid var(--gray-light);
    border-top-color: var(--primary-color);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    to {
        transform: rotate(360deg);
    }
}

/* ===================================
   Responsive Design - Tablet
   =================================== */

@media (max-width: 768px) {
    .section {
        padding: 40px 0;
    }

    /* Header */
    .menu-toggle {
        display: flex;
    }

    nav {
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background-color: var(--secondary-color);
        border-top: 1px solid var(--border-color);
        max-height: 0;
        overflow: hidden;
        transition: max-height 0.3s ease;
    }

    nav.active {
        height: 100vh;
        max-height: 100vh;
    }

    nav ul {
        flex-direction: column;
        gap: 0;
        padding: 10px 0;
    }

    nav a {
        display: block;
        padding: 15px 20px;
    }

    /* Footer */
    .footer-top {
        grid-template-columns: 1fr;
        gap: 30px;
    }

    #backToTop {
        width: 45px;
        height: 45px;
        bottom: 20px;
        right: 20px;
    }
}

/* ===================================
   Responsive Design - Mobile
   =================================== */

@media (max-width: 480px) {
    .container {
        padding: 0 15px;
    }

    .section {
        padding: 30px 0;
    }

    .header-content {
        padding: 12px 15px;
    }

    .logo img {
        height: 32px;
    }

    footer {
        padding: 30px 0 15px;
    }

    .footer-content {
        padding: 0 15px;
    }

    #backToTop {
        width: 40px;
        height: 40px;
        font-size: 18px;
    }
}