/* =========================================================================
   Dong Feng Motor - Core Stylesheet
   Modern Clean-Tech, Minimalist, Premium Technology Aesthetic
   ========================================================================= */

:root {
    /* Color Palette */
    --clr-primary: #0A2A43; /* Deep Blue */
    --clr-secondary: #1FAF73; /* Emerald Green */
    --clr-white: #FFFFFF;
    --clr-dark: #051524;
    --clr-light-bg: #f8fafc;
    --clr-text: #334155;
    --clr-text-light: #94a3b8;
    
    /* Typography */
    --font-heading: 'Outfit', sans-serif;
    --font-body: 'Inter', sans-serif;
    
    /* Transitions */
    --transition-fast: 0.2s ease;
    --transition-base: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    --transition-slow: 0.6s cubic-bezier(0.4, 0, 0.2, 1);
    
    /* Layout */
    --container-max: 1280px;
    --section-pad: 5rem 1rem;
    --box-shadow: 0 10px 30px rgba(10, 42, 67, 0.08);
    --glass-bg: rgba(255, 255, 255, 0.85);
    --dark-glass-bg: rgba(10, 42, 67, 0.7);
    --border-radius: 12px;
}

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

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    font-family: var(--font-body);
    color: var(--clr-text);
    background-color: var(--clr-white);
    line-height: 1.6;
    overflow-x: hidden;
}

h1, h2, h3, h4, h5, h6 {
    font-family: var(--font-heading);
    color: var(--clr-primary);
    line-height: 1.2;
    margin-bottom: 1rem;
}

a {
    text-decoration: none;
    color: inherit;
}

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

.container {
    max-width: var(--container-max);
    margin: 0 auto;
    width: 100%;
    padding: 0 1rem;
}

/* Text Utilities */
.text-center { text-align: center; }
.text-white { color: var(--clr-white); }
.text-green { color: var(--clr-secondary); }
.text-blue-light { color: #82a8c9; }
.max-w { max-width: 800px; margin-left: auto; margin-right: auto; }
.highlight-text { font-size: 1.25rem; font-weight: 600; color: var(--clr-primary); margin-top: 1.5rem; }
.text-gradient { 
    background: linear-gradient(135deg, var(--clr-primary), var(--clr-secondary));
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
}

/* Backgrounds */
.bg-dark {
    background-color: var(--clr-dark);
    color: var(--clr-white);
}
.bg-dark h1, .bg-dark h2, .bg-dark h3, .bg-dark h4 {
    color: var(--clr-white);
}
.bg-dark p {
    color: var(--clr-text-light);
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0.875rem 2rem;
    border-radius: 50px;
    font-family: var(--font-heading);
    font-weight: 600;
    font-size: 1rem;
    transition: var(--transition-base);
    cursor: pointer;
    border: none;
    position: relative;
    overflow: hidden;
}

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

.btn-primary:hover {
    background-color: #17905c;
    transform: translateY(-2px);
    box-shadow: 0 8px 20px rgba(31, 175, 115, 0.3);
}

.btn-secondary {
    background-color: transparent;
    color: var(--clr-white);
    border: 2px solid var(--clr-white);
}

.btn-secondary:hover {
    background-color: var(--clr-white);
    color: var(--clr-primary);
    transform: translateY(-2px);
}

.btn-contact {
    background-color: var(--clr-primary);
    color: var(--clr-white) !important;
    padding: 0.5rem 1.25rem;
    border-radius: 50px;
}
.btn-contact:hover {
    background-color: var(--clr-secondary);
}

/* Components */
.glass-frame {
    background: var(--glass-bg);
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255,255,255,0.2);
    overflow: hidden;
    box-shadow: var(--box-shadow);
}
.border-radius {
    border-radius: var(--border-radius);
}

/* Layout Grids */
.section-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
    align-items: center;
    padding: var(--section-pad);
}

/* Header & Navigation */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    z-index: 1000;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid rgba(0,0,0,0.05);
    transition: var(--transition-base);
}

.navbar.scrolled {
    box-shadow: 0 4px 20px rgba(0,0,0,0.05);
}

.nav-container {
    max-width: var(--container-max);
    margin: 0 auto;
    padding: 1rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-links {
    display: flex;
    gap: 2rem;
    align-items: center;
}

.brand-logo {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.brand-logo img {
    height: 45px;
    width: auto;
    object-fit: contain;
}

.brand-text {
    display: flex;
    flex-direction: column;
    text-align: left;
}

.brand-title {
    font-family: var(--font-heading);
    font-weight: 800;
    color: var(--clr-primary);
    font-size: 1.25rem;
    line-height: 1;
    letter-spacing: 0.5px;
}

.brand-subtitle {
    font-size: 0.65rem;
    color: var(--clr-secondary);
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin-top: 4px;
}

.nav-link {
    font-weight: 500;
    color: var(--clr-primary);
    font-size: 0.95rem;
    transition: var(--transition-fast);
}

.nav-link:hover:not(.btn-contact) {
    color: var(--clr-secondary);
}

/* Hamburger */
.hamburger {
    display: none;
    flex-direction: column;
    gap: 5px;
    cursor: pointer;
    z-index: 1001;
}

.hamburger span {
    display: block;
    width: 25px;
    height: 3px;
    background-color: var(--clr-primary);
    transition: var(--transition-base);
    border-radius: 2px;
}

.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);
}

/* 1. Hero Section */
.hero-section {
    position: relative;
    height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 0 1rem;
    overflow: hidden;
}

.hero-bg, .hero-bg img {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
    z-index: -2;
}

.hero-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(to right, rgba(10, 42, 67, 0.8), rgba(10, 42, 67, 0.3));
    z-index: -1;
}

.dark-glass {
    background: rgba(5, 21, 36, 0.7);
}

.hero-content {
    max-width: 900px;
    color: var(--clr-white);
    text-align: left;
    margin-top: 7rem;
}

.hero-title {
    font-size: clamp(3rem, 5vw, 5rem);
    color: var(--clr-white);
    margin-bottom: 0.5rem;
    font-weight: 800;
}

.hero-subtitle {
    font-size: clamp(1.2rem, 2vw, 1.8rem);
    font-weight: 400;
    color: #e2e8f0;
    margin-bottom: 2rem;
}

.hero-text {
    font-size: 1.1rem;
    max-width: 800px;
    margin-bottom: 3rem;
    color: rgba(255,255,255,0.9);
}

.hero-buttons {
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
}

/* 2. About Section */
.about-section {
    background-color: var(--clr-light-bg);
}

.section-title {
    font-size: 2.5rem;
    margin-bottom: 1.5rem;
}

/* 3. Technology Section */
.technology-section {
    padding: var(--section-pad);
}
.tech-intro {
    margin-bottom: 4rem;
}
.tech-grid {
    display: flex;
    flex-direction: column;
    gap: 4rem;
}
.tech-card {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 3rem;
    align-items: center;
}
.reverse-layout {
    direction: rtl;
}
.reverse-layout > * {
    direction: ltr;
}
.card-title {
    font-size: 2rem;
    margin-bottom: 1rem;
    color: var(--clr-secondary);
}

.tech-card-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform 0.8s ease;
}
.tech-card-image:hover img {
    transform: scale(1.05);
}

/* 4. Projects */
.projects-section {
    position: relative;
    padding: 8rem 1rem;
    text-align: center;
}
.center-content {
    margin: 0 auto;
    text-align: center;
    position: relative;
    z-index: 10;
}

/* 5. Impact & 6. Research */
.box-padding {
    padding: 2rem 0;
}

/* 7. Contact / CTA */
.cta-section {
    background-color: var(--clr-light-bg);
    padding: var(--section-pad);
}

.contact-box {
    margin-top: 3rem;
    background: var(--clr-white);
    padding: 2rem;
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
}
.contact-title {
    margin-bottom: 1.5rem;
    font-size: 1.25rem;
}

.form-group {
    margin-bottom: 1.5rem;
}
.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 500;
    font-size: 0.9rem;
    color: var(--clr-primary);
}
.form-group input[type="text"],
.form-group input[type="email"],
.form-group textarea {
    width: 100%;
    padding: 0.75rem 1rem;
    border: 1px solid #e2e8f0;
    border-radius: 8px;
    font-family: inherit;
    font-size: 1rem;
    transition: var(--transition-base);
}
.form-group input:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--clr-secondary);
    box-shadow: 0 0 0 3px rgba(31,175,115,0.1);
}
.checkbox-group {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}
.checkbox-group input {
    width: auto;
}
.btn-submit {
    width: 100%;
}
.full-height img {
    height: 100%;
    min-height: 500px;
}
.object-cover {
    object-fit: cover;
}

/* Footer */
.footer {
    padding: 4rem 1rem 2rem;
}
.footer-logo {
    display: flex;
    justify-content: center;
    margin-bottom: 1.5rem;
}
.footer-brand {
    text-align: left;
}
.footer-brand .brand-title {
    color: var(--clr-white);
}
.footer-tagline {
    font-size: 1.1rem;
    color: var(--clr-white);
    margin-bottom: 1.5rem;
}
.footer-links {
    margin-bottom: 2rem;
    font-size: 0.9rem;
}
.footer-link {
    color: var(--clr-text-light);
    transition: var(--transition-fast);
}
.footer-link:hover {
    color: var(--clr-secondary);
}
.footer-copyright {
    font-size: 0.85rem;
    color: var(--clr-text-light);
    border-top: 1px solid rgba(255,255,255,0.1);
    padding-top: 2rem;
}

/* Legal Pages */
.legal-section {
    padding: 10rem 1rem 5rem;
    background-color: var(--clr-light-bg);
}
.legal-content {
    background: var(--clr-white);
    padding: 4rem 3rem;
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
}
.legal-content h1 {
    font-size: 2.5rem;
    margin-bottom: 2rem;
    text-align: center;
}
.legal-content h2 {
    font-size: 1.5rem;
    margin-top: 2rem;
    margin-bottom: 1rem;
    color: var(--clr-primary);
}
.legal-content p {
    margin-bottom: 1rem;
}
.legal-content ul {
    margin-left: 2rem;
    margin-bottom: 1rem;
}

/* Animations */
.animate-up {
    opacity: 0;
    transform: translateY(30px);
    animation: fadeUp 0.8s forwards cubic-bezier(0.4, 0, 0.2, 1);
}
.delay-1 { animation-delay: 0.2s; }
.delay-2 { animation-delay: 0.4s; }
.delay-3 { animation-delay: 0.6s; }

@keyframes fadeUp {
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.scroll-reveal {
    opacity: 0;
    transform: translateY(40px);
    transition: opacity 0.8s ease, transform 0.8s ease;
}

.scroll-reveal.visible {
    opacity: 1;
    transform: translateY(0);
}

/* Responsive */
@media screen and (max-width: 992px) {
    .section-grid {
        grid-template-columns: 1fr;
        gap: 3rem;
    }
    .tech-card {
        grid-template-columns: 1fr;
        gap: 2rem;
    }
    .reverse-mobile {
        display: flex;
        flex-direction: column-reverse;
    }
    .hero-content {
        text-align: center;
        margin-top: 3rem;
    }
    .hero-overlay {
        background: linear-gradient(to bottom, rgba(10, 42, 67, 0.6), rgba(10, 42, 67, 0.9));
    }
    .hero-buttons {
        justify-content: center;
    }
}

@media screen and (max-width: 768px) {
    .hamburger {
        display: flex;
    }
    .nav-links {
        position: fixed;
        top: 70px;
        right: -100%;
        background: var(--clr-white);
        width: 100%;
        height: calc(100vh - 70px);
        flex-direction: column;
        justify-content: center;
        transition: var(--transition-base);
        padding: 2rem;
    }
    .nav-links.active {
        right: 0;
    }
    .hero-title {
        font-size: 2.5rem;
    }
}