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

:root {
    --primary-gradient: linear-gradient(135deg, #2d3748 0%, #4a5568 100%);
    --secondary-gradient: linear-gradient(135deg, #718096 0%, #a0aec0 100%);
    --success-gradient: linear-gradient(135deg, #38a169 0%, #48bb78 100%);
    --accent-gradient: linear-gradient(135deg, #ed8936 0%, #dd6b20 100%);
    --metallic-gradient: linear-gradient(135deg, #718096 0%, #a0aec0 50%, #cbd5e0 100%);
    --steel-gradient: linear-gradient(135deg, #4a5568 0%, #2d3748 50%, #1a202c 100%);
    --background-dark: linear-gradient(135deg, #0f0f0f 0%, #1a1a1a 50%, #0d1117 100%);
    --glass-dark: rgba(45, 55, 72, 0.15);
    --glass-border: rgba(160, 174, 192, 0.15);
    --shadow-dark: 0 8px 32px rgba(0, 0, 0, 0.4);
    --shadow-medium: 0 15px 35px rgba(0, 0, 0, 0.3);
    --shadow-heavy: 0 25px 50px rgba(0, 0, 0, 0.5);
    --shadow-inset: inset 0 1px 3px rgba(0, 0, 0, 0.3);
    --text-primary: #f7fafc;
    --text-secondary: #a0aec0;
    --text-muted: #718096;
    --border-radius: 24px;
    --border-radius-small: 16px;
    --transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
}

body {
    font-family: 'Inter', 'SF Pro Display', system-ui, -apple-system, sans-serif;
    background: var(--background-dark);
    min-height: 100vh;
    color: var(--text-primary);
    font-weight: 400;
    line-height: 1.6;
    overflow-x: hidden;
    position: relative;
}

body::before {
    content: '';
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: 
        radial-gradient(circle at 25% 25%, rgba(113, 128, 150, 0.1) 0%, transparent 50%),
        radial-gradient(circle at 75% 75%, rgba(74, 85, 104, 0.1) 0%, transparent 50%),
        radial-gradient(circle at 50% 50%, rgba(45, 55, 72, 0.05) 0%, transparent 50%);
    pointer-events: none;
    z-index: -1;
}

/* Effet de grain métallique */
body::after {
    content: '';
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-image: 
        repeating-linear-gradient(
            0deg,
            transparent,
            transparent 2px,
            rgba(160, 174, 192, 0.02) 2px,
            rgba(160, 174, 192, 0.02) 4px
        ),
        repeating-linear-gradient(
            90deg,
            transparent,
            transparent 2px,
            rgba(160, 174, 192, 0.02) 2px,
            rgba(160, 174, 192, 0.02) 4px
        );
    pointer-events: none;
    z-index: -1;
}

.container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 40px 20px;
    position: relative;
    z-index: 1;
}

.header {
    text-align: center;
    margin-bottom: 60px;
    color: var(--text-primary);
    position: relative;
}

.header::before {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 300px;
    height: 300px;
    background: radial-gradient(circle, rgba(113, 128, 150, 0.1) 0%, transparent 70%);
    border-radius: 50%;
    z-index: -1;
}

.header h1 {
    font-size: clamp(2.5rem, 5vw, 4rem);
    font-weight: 900;
    margin-bottom: 20px;
    text-shadow: 
        0 2px 4px rgba(0, 0, 0, 0.8),
        0 4px 8px rgba(0, 0, 0, 0.6),
        0 8px 16px rgba(0, 0, 0, 0.4);
    background: var(--metallic-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    animation: metallicGlow 4s ease-in-out infinite alternate;
    position: relative;
}

.header h1::after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(45deg, transparent 30%, rgba(255, 255, 255, 0.1) 50%, transparent 70%);
    animation: steelShine 3s linear infinite;
    pointer-events: none;
}

@keyframes metallicGlow {
    0% { 
        filter: drop-shadow(0 0 20px rgba(113, 128, 150, 0.3));
        transform: scale(1);
    }
    100% { 
        filter: drop-shadow(0 0 40px rgba(160, 174, 192, 0.5));
        transform: scale(1.02);
    }
}

@keyframes steelShine {
    0% { transform: translateX(-100%) skewX(-45deg); }
    100% { transform: translateX(200%) skewX(-45deg); }
}

.header p {
    font-size: 1.3rem;
    color: var(--text-secondary);
    font-weight: 300;
    letter-spacing: 0.5px;
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.5);
}

.progress-bar {
    width: 100%;
    height: 10px;
    background: var(--glass-dark);
    backdrop-filter: blur(15px);
    border-radius: 50px;
    margin: 40px 0 60px;
    overflow: hidden;
    border: 1px solid var(--glass-border);
    box-shadow: var(--shadow-inset), var(--shadow-dark);
    position: relative;
}

.progress-bar::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(90deg, transparent, rgba(160, 174, 192, 0.2), transparent);
    animation: progressShimmer 2s infinite;
}

@keyframes progressShimmer {
    0% { transform: translateX(-100%); }
    100% { transform: translateX(100%); }
}

.progress-fill {
    height: 100%;
    background: var(--steel-gradient);
    transition: width 0.8s cubic-bezier(0.4, 0, 0.2, 1);
    border-radius: 50px;
    position: relative;
    overflow: hidden;
    box-shadow: 0 0 20px rgba(74, 85, 104, 0.5);
}

.progress-fill::after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.3), transparent);
    animation: progressGlow 2s infinite;
}

@keyframes progressGlow {
    0% { transform: translateX(-100%); opacity: 0; }
    50% { opacity: 1; }
    100% { transform: translateX(100%); opacity: 0; }
}

.form-container {
    background: var(--glass-dark);
    backdrop-filter: blur(25px);
    border-radius: var(--border-radius);
    padding: 50px;
    box-shadow: var(--shadow-heavy);
    margin-bottom: 40px;
    border: 1px solid var(--glass-border);
    position: relative;
    overflow: hidden;
}

.form-container::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 2px;
    background: var(--metallic-gradient);
    opacity: 0.6;
}

.form-container::after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: 
        radial-gradient(circle at 10% 20%, rgba(113, 128, 150, 0.05) 0%, transparent 50%),
        radial-gradient(circle at 90% 80%, rgba(74, 85, 104, 0.05) 0%, transparent 50%);
    pointer-events: none;
}

.step {
    display: none;
    animation: steelSlideIn 0.6s cubic-bezier(0.4, 0, 0.2, 1);
}

.step.active {
    display: block;
}

@keyframes steelSlideIn {
    from { 
        opacity: 0; 
        transform: translateY(30px) scale(0.98);
        filter: blur(5px);
    }
    to { 
        opacity: 1; 
        transform: translateY(0) scale(1);
        filter: blur(0);
    }
}

.step-header {
    background: var(--steel-gradient);
    color: var(--text-primary);
    padding: 40px 30px;
    border-radius: var(--border-radius);
    margin-bottom: 40px;
    text-align: center;
    position: relative;
    overflow: hidden;
    box-shadow: var(--shadow-medium), var(--shadow-inset);
    border: 1px solid rgba(160, 174, 192, 0.1);
}

.step-header::before {
    content: '';
    position: absolute;
    top: -100%;
    left: -100%;
    width: 300%;
    height: 300%;
    background: conic-gradient(from 0deg, transparent, rgba(160, 174, 192, 0.1), transparent);
    animation: steelRotate 8s linear infinite;
}

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

.step-header h2 {
    font-size: 2.2rem;
    font-weight: 800;
    margin-bottom: 15px;
    position: relative;
    z-index: 1;
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.5);
}

.step-header p {
    font-size: 1.1rem;
    color: var(--text-secondary);
    font-weight: 300;
    position: relative;
    z-index: 1;
}

.form-group {
    margin-bottom: 35px;
    position: relative;
}

.form-group label {
    display: block;
    font-weight: 700;
    margin-bottom: 12px;
    color: var(--text-primary);
    font-size: 1.1rem;
    position: relative;
    padding-left: 25px;
    text-shadow: 0 1px 2px rgba(0, 0, 0, 0.3);
}

.form-group label::before {
    content: '';
    position: absolute;
    left: 0;
    top: 50%;
    transform: translateY(-50%);
    width: 6px;
    height: 6px;
    background: var(--metallic-gradient);
    border-radius: 50%;
    box-shadow: 0 0 15px rgba(113, 128, 150, 0.6);
}

.form-group input,
.form-group select,
.form-group textarea {
    width: 100%;
    padding: 18px 24px;
    border: 2px solid rgba(74, 85, 104, 0.3);
    border-radius: var(--border-radius-small);
    font-size: 1rem;
    transition: var(--transition);
    background: rgba(26, 32, 44, 0.8);
    backdrop-filter: blur(10px);
    color: var(--text-primary);
    font-weight: 500;
    box-shadow: var(--shadow-inset);
}

.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
    outline: none;
    border-color: #a0aec0;
    background: rgba(26, 32, 44, 0.95);
    box-shadow: 
        0 0 0 4px rgba(160, 174, 192, 0.15),
        0 8px 25px rgba(0, 0, 0, 0.3),
        var(--shadow-inset);
    transform: translateY(-2px);
}

.file-upload {
    position: relative;
    display: inline-block;
    width: 100%;
}

.file-upload input[type=file] {
    position: absolute;
    opacity: 0;
    width: 100%;
    height: 100%;
    cursor: pointer;
    z-index: 2;
}

.file-upload-label {
    display: block;
    padding: 30px;
    border: 2px dashed rgba(160, 174, 192, 0.4);
    border-radius: var(--border-radius-small);
    text-align: center;
    cursor: pointer;
    transition: var(--transition);
    background: var(--glass-dark);
    backdrop-filter: blur(15px);
    position: relative;
    overflow: hidden;
    box-shadow: var(--shadow-inset);
}

.file-upload-label::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(160, 174, 192, 0.1), transparent);
    transition: var(--transition);
}

.file-upload-label:hover {
    background: rgba(45, 55, 72, 0.3);
    border-color: #a0aec0;
    transform: translateY(-3px);
    box-shadow: var(--shadow-medium), var(--shadow-inset);
}

.file-upload-label:hover::before {
    left: 100%;
}

.file-list {
    margin-top: 20px;
    padding: 20px;
    background: rgba(26, 32, 44, 0.6);
    backdrop-filter: blur(15px);
    border-radius: var(--border-radius-small);
    border: 1px solid rgba(74, 85, 104, 0.3);
    box-shadow: var(--shadow-inset);
}

.file-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 12px 0;
    border-bottom: 1px solid rgba(74, 85, 104, 0.3);
    animation: steelFadeIn 0.4s ease;
    color: var(--text-secondary);
}

.file-item:last-child {
    border-bottom: none;
}

@keyframes steelFadeIn {
    from { opacity: 0; transform: translateX(-20px); }
    to { opacity: 1; transform: translateX(0); }
}

.btn {
    padding: 18px 36px;
    border: none;
    border-radius: var(--border-radius-small);
    font-size: 1.1rem;
    font-weight: 700;
    cursor: pointer;
    transition: var(--transition);
    text-transform: uppercase;
    letter-spacing: 1.5px;
    text-decoration: none;
    display: inline-block;
    text-align: center;
    position: relative;
    overflow: hidden;
    box-shadow: var(--shadow-dark);
    border: 1px solid rgba(160, 174, 192, 0.2);
}

.btn::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.1), transparent);
    transition: var(--transition);
}

.btn:hover::before {
    left: 100%;
}

.btn-primary {
    background: var(--steel-gradient);
    color: var(--text-primary);
    text-shadow: 0 1px 2px rgba(0, 0, 0, 0.5);
}

.btn-primary:hover {
    background: linear-gradient(135deg, #4a5568 0%, #2d3748 50%, #1a202c 100%);
    transform: translateY(-3px) scale(1.02);
    box-shadow: 
        0 15px 35px rgba(0, 0, 0, 0.4),
        0 5px 15px rgba(74, 85, 104, 0.3);
}

.btn-secondary {
    background: linear-gradient(135deg, #718096 0%, #4a5568 100%);
    color: var(--text-primary);
    margin-right: 20px;
    text-shadow: 0 1px 2px rgba(0, 0, 0, 0.5);
}

.btn-secondary:hover {
    background: linear-gradient(135deg, #a0aec0 0%, #718096 100%);
    transform: translateY(-2px);
    box-shadow: var(--shadow-medium);
}

.btn-success {
    background: var(--success-gradient);
    color: white;
    text-shadow: 0 1px 2px rgba(0, 0, 0, 0.5);
}

.btn-success:hover {
    background: linear-gradient(135deg, #48bb78 0%, #38a169 100%);
    transform: translateY(-3px) scale(1.02);
    box-shadow: 
        0 15px 35px rgba(56, 161, 105, 0.4),
        0 5px 15px rgba(0, 0, 0, 0.2);
}

.grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 30px;
}

.help-text {
    font-size: 0.9rem;
    color: var(--text-muted);
    margin-top: 8px;
    font-style: italic;
    font-weight: 400;
}

.success-message {
    background: var(--success-gradient);
    color: white;
    padding: 50px 40px;
    border-radius: var(--border-radius);
    text-align: center;
    margin-bottom: 40px;
    position: relative;
    overflow: hidden;
    box-shadow: var(--shadow-heavy);
    border: 1px solid rgba(72, 187, 120, 0.3);
}

.success-message::before {
    content: '';
    position: absolute;
    top: -100%;
    left: -100%;
    width: 300%;
    height: 300%;
    background: conic-gradient(from 0deg, transparent, rgba(255, 255, 255, 0.1), transparent);
    animation: successRotate 4s linear infinite;
}

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

.success-message h2 {
    font-size: 2.5rem;
    font-weight: 800;
    margin-bottom: 20px;
    position: relative;
    z-index: 1;
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.3);
}

.success-message p {
    font-size: 1.2rem;
    opacity: 0.95;
    position: relative;
    z-index: 1;
}

.download-btn {
    display: inline-block;
    margin: 25px 15px;
    text-decoration: none;
    transition: var(--transition);
}

.download-btn:hover {
    transform: scale(1.05);
}

.tutorial-link {
    background: var(--glass-dark);
    backdrop-filter: blur(20px);
    border-left: 5px solid var(--metallic-gradient);
    padding: 40px;
    margin: 40px 0;
    border-radius: var(--border-radius);
    text-align: center;
    box-shadow: var(--shadow-dark);
    border: 1px solid var(--glass-border);
    position: relative;
    overflow: hidden;
}

.tutorial-link::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 5px;
    height: 100%;
    background: var(--metallic-gradient);
}

.tutorial-link h3 {
    color: var(--text-primary);
    margin-bottom: 20px;
    font-size: 1.5rem;
    font-weight: 800;
    text-shadow: 0 1px 2px rgba(0, 0, 0, 0.3);
}

.tutorial-link p {
    margin-bottom: 25px;
    line-height: 1.7;
    color: var(--text-secondary);
    font-size: 1.1rem;
}

/* Effets de particules métalliques */
.metallic-particles {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    z-index: -1;
}

.metallic-particles::before,
.metallic-particles::after {
    content: '';
    position: absolute;
    background: radial-gradient(circle, rgba(160, 174, 192, 0.1), transparent);
    border-radius: 50%;
    animation: metallicFloat 8s ease-in-out infinite;
}

.metallic-particles::before {
    width: 100px;
    height: 100px;
    top: 20%;
    left: 15%;
    animation-delay: 0s;
}

.metallic-particles::after {
    width: 150px;
    height: 150px;
    top: 70%;
    right: 20%;
    animation-delay: 4s;
}

@keyframes metallicFloat {
    0%, 100% { transform: translateY(0px) rotate(0deg) scale(1); opacity: 0.3; }
    25% { transform: translateY(-30px) rotate(90deg) scale(1.1); opacity: 0.6; }
    50% { transform: translateY(-10px) rotate(180deg) scale(0.9); opacity: 0.8; }
    75% { transform: translateY(20px) rotate(270deg) scale(1.05); opacity: 0.4; }
}

/* Scrollbar sombre personnalisée */
::-webkit-scrollbar {
    width: 12px;
}

::-webkit-scrollbar-track {
    background: rgba(26, 32, 44, 0.8);
    border-radius: 10px;
    box-shadow: inset 0 0 5px rgba(0, 0, 0, 0.3);
}

::-webkit-scrollbar-thumb {
    background: var(--steel-gradient);
    border-radius: 10px;
    border: 2px solid rgba(26, 32, 44, 0.8);
}

::-webkit-scrollbar-thumb:hover {
    background: var(--metallic-gradient);
}

/* Responsive Design Sombre */
@media (max-width: 1200px) {
    .container {
        max-width: 100%;
        padding: 30px 15px;
    }
    
    .form-container {
        padding: 40px 30px;
    }
}

@media (max-width: 768px) {
    .container {
        padding: 20px 10px;
    }
    
    .form-container {
        padding: 30px 20px;
        border-radius: 20px;
    }
    
    .header h1 {
        font-size: 2.5rem;
    }
    
    .step-header {
        padding: 30px 20px;
    }
    
    .step-header h2 {
        font-size: 1.8rem;
    }
    
    .grid {
        grid-template-columns: 1fr;
        gap: 20px;
    }
    
    .btn {
        padding: 16px 28px;
        font-size: 1rem;
        width: 100%;
        margin-bottom: 15px;
    }
    
    .btn-secondary {
        margin-right: 0;
    }
}

@media (max-width: 480px) {
    .header h1 {
        font-size: 2rem;
    }
    
    .form-container {
        padding: 25px 15px;
    }
    
    .step-header {
        padding: 25px 15px;
    }
    
    .success-message {
        padding: 40px 25px;
    }
    
    .tutorial-link {
        padding: 30px 20px;
    }
}

/* Animations d'entrée spéciales */
.animate-steel {
    animation: steelEntry 0.8s cubic-bezier(0.4, 0, 0.2, 1);
}

@keyframes steelEntry {
    0% {
        opacity: 0;
        transform: scale(0.8) rotateY(-90deg);
        filter: blur(10px);
    }
    50% {
        opacity: 0.7;
        transform: scale(1.05) rotateY(-20deg);
        filter: blur(2px);
    }
    100% {
        opacity: 1;
        transform: scale(1) rotateY(0deg);
        filter: blur(0);
    }
}