<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 800 450" width="800" height="450">  <defs>    <linearGradient id="bg" x1="0%" y1="0%" x2="100%" y2="100%">      <stop offset="0%" style="stop-color:#060a18"/>      <stop offset="100%" style="stop-color:#121f4a"/>    </linearGradient>    <linearGradient id="down" x1="0%" y1="0%" x2="0%" y2="100%">      <stop offset="0%" style="stop-color:#e93a3a;stop-opacity:0.3"/>      <stop offset="100%" style="stop-color:#e93a3a;stop-opacity:0"/>    </linearGradient>  </defs>  <rect width="800" height="450" fill="url(#bg)"/>  <!-- Grid -->  <g stroke="rgba(255,255,255,0.04)" stroke-width="1">    <line x1="0" y1="100" x2="800" y2="100"/>    <line x1="0" y1="200" x2="800" y2="200"/>    <line x1="0" y1="300" x2="800" y2="300"/>    <line x1="0" y1="400" x2="800" y2="400"/>  </g>  <!-- Declining CPA curve -->  <polyline points="80,120 200,160 320,200 440,240 560,260 680,290 760,310" fill="none" stroke="rgba(255,255,255,0.15)" stroke-width="1" stroke-dasharray="4,3"/>  <!-- Optimized CPA curve -->  <polyline points="80,120 200,100 320,85 440,72 560,60 680,52 760,48" fill="none" stroke="#e93a3a" stroke-width="2.5"/>  <!-- Area fill -->  <polygon points="80,120 200,100 320,85 440,72 560,60 680,52 760,48 760,400 80,400" fill="url(#down)" opacity="0.5"/>  <!-- Arrow down indicator -->  <g transform="translate(580,160)">    <circle r="28" fill="rgba(233,58,58,0.15)" stroke="rgba(233,58,58,0.4)" stroke-width="1.5"/>    <text text-anchor="middle" dy="6" font-family="Arial, sans-serif" font-size="18" font-weight="700" fill="#e93a3a">↓</text>  </g>  <text x="580" y="210" text-anchor="middle" font-family="Arial, sans-serif" font-size="12" font-weight="700" fill="#e93a3a">−42% CPA</text>  <!-- Axis labels -->  <text x="80" y="430" font-family="Arial, sans-serif" font-size="11" fill="rgba(255,255,255,0.25)">J0</text>  <text x="310" y="430" font-family="Arial, sans-serif" font-size="11" fill="rgba(255,255,255,0.25)">30 j</text>  <text x="540" y="430" font-family="Arial, sans-serif" font-size="11" fill="rgba(255,255,255,0.25)">60 j</text>  <text x="740" y="430" font-family="Arial, sans-serif" font-size="11" fill="rgba(255,255,255,0.25)">90 j</text>  <text x="40" y="445" font-family="Arial, sans-serif" font-size="11" fill="rgba(255,255,255,0.25)" letter-spacing="2">RÉDUCTION CPA · ACQUISITION PARE-BRISE</text></svg>