/* ==========================================================================
   CSS VARIABLES
   ========================================================================== */
:root {
    --primary: #d11212;
    --primary-dark: #8b0a0a;
    --secondary: #007bff;
    --secondary-dark: #0056b3;
    --accent: #ffd100;
    --background: #f8f9fa;
    --surface: #ffffff;
    --text: #1a1a2e;
    --text-muted: #6c757d;
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.08);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.12);
    --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.16);
    --radius-sm: 6px;
    --radius-md: 12px;
    --radius-lg: 20px;
    --transition: 0.3s ease;
    --nav-height: 72px;
}

/* ==========================================================================
   GLOBAL STYLES
   ========================================================================== */
*,
*::before,
*::after {
    box-sizing: border-box;
}

body {
    margin: 0;
    padding-top: var(--nav-height);
    font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
    background-color: var(--background);
    color: var(--text);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
}

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

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

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

/* ==========================================================================
   NAVIGATION BAR (HEADER) - Fixed top
   ========================================================================== */
.site-nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background-color: var(--surface);
    border-bottom: 1px solid rgba(0, 0, 0, 0.08);
    padding: 0 1.5rem;
    height: var(--nav-height);
    box-shadow: var(--shadow-sm);
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 100%;
}

.nav-logo {
    max-height: 56px;
    width: auto;
    display: block;
    transition: transform var(--transition);
}

.nav-logo:hover {
    transform: scale(1.04);
}

.nav-actions {
    display: flex;
    align-items: center;
    gap: 16px;
}

/* ==========================================================================
   HERO SECTION
   ========================================================================== */
.hero-section {
    display: flex;
    max-width: 1200px;
    margin: 60px auto;
    gap: 50px;
    padding: 0 20px;
    align-items: center;
}

.hero-left {
    flex: 1;
}

.hero-right {
    flex: 1.2;
}

.hero-title {
    font-size: 2.8rem;
    font-weight: 800;
    line-height: 1.15;
    margin: 0 0 12px 0;
    color: var(--text);
}

.hero-subtitle {
    font-size: 1.15rem;
    color: var(--text-muted);
    margin: 0 0 24px 0;
    line-height: 1.6;
}

.hero-description {
    margin-top: 40px;
    font-size: 1.3rem;
    color: var(--primary);
    font-weight: 900;
    text-transform: uppercase;
    letter-spacing: 1px;
    text-align: center;
}

/* ==========================================================================
   COMPARISON SLIDER
   ========================================================================== */
.comparison-slider {
    position: relative;
    width: 100%;
    height: 480px;
    border-radius: var(--radius-lg);
    overflow: hidden;
    --slider-pos: 50%;
    background-color: #333;
    box-shadow: var(--shadow-lg);
}

.comparison-slider::before {
    content: "";
    position: absolute;
    top: 0;
    bottom: 0;
    left: var(--slider-pos, 50%);
    width: 4px;
    background: var(--accent);
    z-index: 5;
    transform: translateX(-50%);
    pointer-events: none;
}

.comparison-slider::after {
    content: "";
    position: absolute;
    top: 0;
    bottom: 0;
    left: var(--slider-pos);
    width: 4px;
    background: var(--accent);
    z-index: 3;
    transform: translateX(-50%);
    pointer-events: none;
}

.img-original,
.img-mosaic {
    position: absolute;
    top: 0;
    left: 0;
    height: 100%;
    width: 100%;
    background-size: cover;
    background-position: center;
    z-index: 1;
}

.img-mosaic {
    z-index: 2;
    clip-path: inset(0 calc(100% - var(--slider-pos)) 0 0);
}

.img-original {
    z-index: 1;
}

.slider-handle {
    position: absolute;
    -webkit-appearance: none;
    appearance: none;
    width: 100%;
    height: 100%;
    background: transparent;
    outline: none;
    margin: 0;
    z-index: 10;
    cursor: ew-resize;
}

.slider-handle::-webkit-slider-thumb {
    -webkit-appearance: none;
    width: 40px;
    height: 40px;
    background: var(--accent);
    border: 4px solid var(--surface);
    border-radius: 50%;
    cursor: pointer;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.35);
}

.slider-handle::-moz-range-thumb {
    width: 40px;
    height: 40px;
    background: var(--accent);
    border: 4px solid var(--surface);
    border-radius: 50%;
    cursor: pointer;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.35);
}

/* ==========================================================================
   UPLOAD FORM & DROP ZONE
   ========================================================================== */
.upload-container {
    background: var(--surface);
    padding: 30px;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-sm);
}

.drop-zone {
    background-color: var(--secondary);
    background-image: radial-gradient(var(--secondary-dark) 20%, transparent 20%);
    background-size: 30px 30px;
    border: 4px solid var(--secondary-dark);
    padding: 60px;
    border-radius: var(--radius-md);
    text-align: center;
    cursor: pointer;
    transition: transform var(--transition), background-color var(--transition), border-color var(--transition);
    margin-bottom: 25px;
    color: white;
}

.drop-zone:hover {
    transform: scale(1.01);
    background-color: #0069d9;
}

.drop-zone.highlight {
    border-color: var(--accent);
    transform: scale(1.02);
}

.drop-title {
    font-size: 1.5rem;
    font-weight: 900;
    text-transform: uppercase;
    text-shadow: 2px 2px 0px var(--secondary-dark);
    margin-bottom: 10px;
}

.drop-hint {
    font-weight: 600;
    opacity: 0.9;
}

.highlight-text {
    color: var(--accent);
}

/* ==========================================================================
   SUPPORTED FORMATS
   ========================================================================== */
.supported-formats {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    flex-wrap: wrap;
    margin-top: 12px;
    font-size: 0.85rem;
    color: var(--text-muted);
}

.supported-formats span {
    background: var(--background);
    padding: 3px 10px;
    border-radius: var(--radius-sm);
    font-weight: 600;
    font-size: 0.8rem;
    color: var(--text);
    border: 1px solid rgba(0, 0, 0, 0.08);
}

/* ==========================================================================
   ERROR LIST
   ========================================================================== */
.error-list {
    list-style: none;
    padding: 0;
    margin: 16px 0;
}

.error-list li {
    background: #fff5f5;
    border-left: 4px solid var(--primary);
    padding: 10px 16px;
    margin-bottom: 8px;
    border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
    font-size: 0.9rem;
    color: var(--primary-dark);
}

/* ==========================================================================
   BUTTONS
   ========================================================================== */
.main-btn {
    width: 100%;
    padding: 18px;
    background-color: var(--primary);
    color: white;
    border: none;
    border-radius: var(--radius-sm);
    font-size: 1.2rem;
    font-weight: 800;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    cursor: pointer;
    box-shadow: 0 5px 0 var(--primary-dark);
    transition: all 0.1s ease;
    margin-bottom: 20px;
}

.main-btn:hover {
    background-color: #e61919;
    transform: translateY(-2px);
    box-shadow: 0 7px 0 var(--primary-dark);
}

.main-btn:active {
    transform: translateY(3px);
    box-shadow: 0 2px 0 var(--primary-dark);
}

.nav-btn {
    padding: 9px 18px;
    border-radius: var(--radius-sm);
    font-size: 0.875rem;
    font-weight: 600;
    cursor: pointer;
    border: 1px solid transparent;
    transition: all var(--transition);
    display: inline-flex;
    align-items: center;
    gap: 6px;
}

.nav-btn.active {
    background-color: var(--primary);
    color: white;
    border-color: var(--primary);
    box-shadow: 0 3px 0 var(--primary-dark);
}

.nav-btn.active:hover {
    background-color: #e61919;
}

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

.btn-primary:hover {
    background-color: #0069d9;
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(0, 123, 255, 0.3);
}

.btn-secondary {
    background-color: var(--background);
    color: var(--text);
    border-color: #ddd;
}

.btn-secondary:hover {
    background-color: #e9ecef;
    transform: translateY(-1px);
}

.btn-danger {
    background-color: #dc3545;
    color: white;
    border-color: #dc3545;
}

.btn-danger:hover {
    background-color: #c82333;
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(220, 53, 69, 0.3);
}

/* ==========================================================================
   CART & BADGE
   ========================================================================== */
.cart-section {
    display: flex;
    align-items: center;
}

.cart-link {
    position: relative;
    display: flex;
    transition: transform var(--transition);
}

.cart-link:hover {
    transform: scale(1.08);
}

.cart-icon {
    width: 44px;
    height: 44px;
    object-fit: contain;
}

.cart-badge {
    position: absolute;
    top: -4px;
    right: -4px;
    background-color: var(--primary);
    color: white;
    font-size: 11px;
    font-weight: 700;
    border-radius: 50%;
    width: 22px;
    height: 22px;
    display: flex;
    justify-content: center;
    align-items: center;
    border: 2px solid var(--surface);
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.2);
}

/* ==========================================================================
   LANG SELECT
   ========================================================================== */
.lang-select {
    padding: 6px 10px;
    border-radius: var(--radius-sm);
    border: 1px solid #ddd;
    background: var(--surface);
    font-size: 0.875rem;
    color: var(--text);
    cursor: pointer;
    transition: border-color var(--transition);
}

.lang-select:hover,
.lang-select:focus {
    border-color: var(--secondary);
    outline: none;
}

/* ==========================================================================
   ACCOUNT ACTIONS
   ========================================================================== */
.account-actions {
    display: flex;
    gap: 10px;
    align-items: center;
}

/* ==========================================================================
   HOW IT WORKS SECTION
   ========================================================================== */
.how-it-works {
    max-width: 1200px;
    margin: 0 auto;
    padding: 80px 20px;
    text-align: center;
}

.how-it-works h2 {
    font-size: 2.2rem;
    font-weight: 800;
    margin-bottom: 12px;
    color: var(--text);
}

.how-it-works p {
    color: var(--text-muted);
    font-size: 1.05rem;
    margin-bottom: 48px;
    max-width: 560px;
    margin-left: auto;
    margin-right: auto;
}

.steps-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 32px;
}

.step-card {
    background: var(--surface);
    border-radius: var(--radius-lg);
    padding: 40px 28px 36px;
    box-shadow: var(--shadow-sm);
    transition: transform var(--transition), box-shadow var(--transition);
    position: relative;
}

.step-card:hover {
    transform: translateY(-6px);
    box-shadow: var(--shadow-md);
}

.step-number {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 48px;
    height: 48px;
    border-radius: 50%;
    background-color: var(--primary);
    color: white;
    font-size: 1.25rem;
    font-weight: 800;
    margin-bottom: 20px;
    box-shadow: 0 4px 0 var(--primary-dark);
}

.step-card .step-icon {
    font-size: 2.5rem;
    display: block;
    margin-bottom: 16px;
}

.step-card h3 {
    font-size: 1.15rem;
    font-weight: 700;
    margin: 0 0 10px 0;
    color: var(--text);
}

.step-card p {
    font-size: 0.95rem;
    color: var(--text-muted);
    margin: 0;
    line-height: 1.6;
}

/* ==========================================================================
   FEATURES SECTION
   ========================================================================== */
.features-section {
    background: var(--surface);
    padding: 80px 20px;
}

.features-section .section-inner {
    max-width: 1200px;
    margin: 0 auto;
    text-align: center;
}

.features-section h2 {
    font-size: 2.2rem;
    font-weight: 800;
    margin-bottom: 12px;
    color: var(--text);
}

.features-section > p,
.features-section .section-inner > p {
    color: var(--text-muted);
    font-size: 1.05rem;
    margin-bottom: 48px;
    max-width: 560px;
    margin-left: auto;
    margin-right: auto;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 32px;
}

.feature-card {
    background: var(--background);
    border-radius: var(--radius-md);
    padding: 32px 24px;
    text-align: center;
    transition: transform var(--transition), box-shadow var(--transition);
    border: 1px solid rgba(0, 0, 0, 0.05);
}

.feature-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-md);
    border-color: transparent;
}

.feature-card .feature-icon {
    font-size: 2.5rem;
    margin-bottom: 16px;
    display: block;
}

.feature-card h3 {
    font-size: 1.1rem;
    font-weight: 700;
    margin: 0 0 10px 0;
    color: var(--text);
}

.feature-card p {
    font-size: 0.9rem;
    color: var(--text-muted);
    margin: 0;
    line-height: 1.6;
}

/* ==========================================================================
   CTA SECTION
   ========================================================================== */
.cta-section {
    max-width: 1200px;
    margin: 0 auto;
    padding: 80px 20px;
    text-align: center;
}

.cta-inner {
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
    border-radius: var(--radius-lg);
    padding: 64px 40px;
    color: white;
    box-shadow: var(--shadow-lg);
}

.cta-inner h2 {
    font-size: 2rem;
    font-weight: 800;
    margin: 0 0 16px 0;
}

.cta-inner p {
    font-size: 1.1rem;
    opacity: 0.9;
    margin: 0 0 32px 0;
    max-width: 500px;
    margin-left: auto;
    margin-right: auto;
}

.cta-inner .cta-btn {
    display: inline-block;
    padding: 16px 40px;
    background: var(--accent);
    color: var(--text);
    font-size: 1.1rem;
    font-weight: 800;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    border: none;
    border-radius: var(--radius-sm);
    cursor: pointer;
    box-shadow: 0 4px 0 #b89500;
    transition: all 0.15s ease;
}

.cta-inner .cta-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 0 #b89500;
    color: var(--text);
}

.cta-inner .cta-btn:active {
    transform: translateY(2px);
    box-shadow: 0 2px 0 #b89500;
}

/* ==========================================================================
   FOOTER
   ========================================================================== */
.site-footer {
    background-color: var(--text);
    color: rgba(255, 255, 255, 0.7);
    padding: 48px 20px 24px;
    margin-top: 0;
}

.footer-container {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    flex-wrap: wrap;
    gap: 32px;
}

.footer-col {
    flex: 1;
    min-width: 180px;
}

.footer-col h4 {
    color: white;
    font-size: 0.95rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin: 0 0 16px 0;
}

.footer-col ul {
    list-style: none;
    padding: 0;
    margin: 0;
}

.footer-col ul li {
    margin-bottom: 8px;
}

.footer-col ul li a {
    color: rgba(255, 255, 255, 0.6);
    font-size: 0.9rem;
    transition: color var(--transition);
}

.footer-col ul li a:hover {
    color: var(--accent);
}

.footer-bottom {
    max-width: 1200px;
    margin: 32px auto 0;
    padding-top: 20px;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    text-align: center;
    font-size: 0.85rem;
    color: rgba(255, 255, 255, 0.4);
}

/* ==========================================================================
   RESPONSIVE - Tablet (max-width: 992px)
   ========================================================================== */
@media (max-width: 992px) {
    .hero-section {
        flex-direction: column;
        margin: 40px auto;
        gap: 32px;
    }

    .hero-left,
    .hero-right {
        flex: none;
        width: 100%;
    }

    .hero-title {
        font-size: 2.2rem;
    }

    .steps-grid,
    .features-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .comparison-slider {
        height: 360px;
    }

    .footer-container {
        gap: 24px;
    }
}

/* ==========================================================================
   RESPONSIVE - Mobile (max-width: 600px)
   ========================================================================== */
@media (max-width: 600px) {
    :root {
        --nav-height: 60px;
    }

    .site-nav {
        padding: 0 12px;
    }

    .nav-logo {
        max-height: 42px;
    }

    .nav-actions {
        gap: 8px;
    }

    .nav-btn {
        padding: 6px 10px;
        font-size: 0.8rem;
    }

    .hero-section {
        margin: 24px auto;
        padding: 0 16px;
        gap: 24px;
    }

    .hero-title {
        font-size: 1.7rem;
    }

    .hero-subtitle {
        font-size: 1rem;
    }

    .hero-description {
        font-size: 1.05rem;
    }

    .comparison-slider {
        height: 260px;
        border-radius: var(--radius-md);
    }

    .drop-zone {
        padding: 36px 20px;
    }

    .drop-title {
        font-size: 1.2rem;
    }

    .upload-container {
        padding: 16px;
    }

    .steps-grid,
    .features-grid {
        grid-template-columns: 1fr;
        gap: 20px;
    }

    .step-card,
    .feature-card {
        padding: 28px 20px;
    }

    .how-it-works,
    .features-section,
    .cta-section {
        padding: 48px 16px;
    }

    .how-it-works h2,
    .features-section h2 {
        font-size: 1.6rem;
    }

    .cta-inner {
        padding: 40px 20px;
    }

    .cta-inner h2 {
        font-size: 1.5rem;
    }

    .cta-inner .cta-btn {
        padding: 14px 28px;
        font-size: 1rem;
    }

    .footer-container {
        flex-direction: column;
        gap: 28px;
    }

    .footer-col {
        min-width: 100%;
    }

    .main-btn {
        padding: 14px;
        font-size: 1.05rem;
    }

    .cart-icon {
        width: 36px;
        height: 36px;
    }

    .lang-select {
        padding: 4px 6px;
        font-size: 0.8rem;
    }

    .account-actions {
        gap: 6px;
    }
}