:root {
     --bg: #0b1020;
     --panel: #121a2d;
     --text: #e6ecff;
     --muted: #95a2c2;
     --primary: #4da3ff;
     --success: #2ecc71;
     --error: #ff6b6b;
     --warn: #f1c40f;
     --code: #0e1426;
     --accent: #f7931a;
     --glass: rgba(24, 31, 54, 0.82);
     --glass-border: rgba(77, 163, 255, 0.13);
}
 * {
     box-sizing: border-box;
     margin: 0;
     padding: 0;
}
 html, body {
     height: 100%;
     overflow-x: hidden;
     font-family: 'Inter', ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, Ubuntu, Cantarell, Noto Sans, Helvetica, Arial, sans-serif;
     color: var(--text);
}
 body {
     min-height: 100vh;
     background: linear-gradient(135deg, #0b1020 0%, #181f36 60%, #101938 100%);
     position: relative;
}
 .bg-animated {
     position: fixed;
     top: 0;
     left: 0;
     width: 100vw;
     height: 100vh;
     z-index: 0;
     overflow: hidden;
}
 .floating-shapes {
     position: absolute;
     width: 100%;
     height: 100%;
}
 .shape {
     position: absolute;
     border-radius: 50%;
     background: rgba(77, 163, 255, 0.05);
}
 .shape:nth-child(1) {
     width: 80px;
     height: 80px;
     top: 10%;
     left: 10%;
}
 .shape:nth-child(2) {
     width: 120px;
     height: 120px;
     top: 70%;
     left: 80%;
}
 .shape:nth-child(3) {
     width: 60px;
     height: 60px;
     top: 20%;
     left: 85%;
}
 .shape:nth-child(4) {
     width: 100px;
     height: 100px;
     top: 80%;
     left: 15%;
}
 .main-centered {
     min-height: 100vh;
     display: flex;
     flex-direction: column;
     align-items: center;
     justify-content: flex-start;
     padding-top: 2vh;
     padding-bottom: 2vh;
     position: relative;
     z-index: 1;
}
 .container {
     max-width: 900px;
     margin: 0 auto;
     padding: 1.5rem;
     display: flex;
     flex-direction: column;
     align-items: center;
}
 .main-title {
     text-align: center;
     font-size: 2.5rem;
     font-weight: 800;
     margin-top: 0.5rem;
     margin-bottom: 0.5rem;
     letter-spacing: 0.01em;
     color: #fff;
     text-shadow: 0 2px 16px rgba(77, 163, 255, 0.4);
}
 .mathslover {
     color: var(--primary);
     text-shadow: 0 2px 12px rgba(77, 163, 255, 0.6);
     position: relative;
}
 .mathslover::after {
     content: '';
     position: absolute;
     bottom: -5px;
     left: 0;
     width: 100%;
     height: 2px;
     background: linear-gradient(90deg, transparent, var(--primary), transparent);
}
 .main-desc {
     text-align: center;
     color: #b3c6e6;
     font-size: 1.2rem;
     margin-bottom: 1.5rem;
     max-width: 600px;
     line-height: 1.5;
}
 .sats {
     color: var(--accent);
     font-weight: 600;
}
 .card-glass {
     background: var(--glass);
     border-radius: 20px;
     box-shadow: 0 8px 32px rgba(0, 0, 0, 0.2), 0 2px 8px rgba(0, 0, 0, 0.1);
     backdrop-filter: blur(12px) saturate(1.2);
     border: 1.5px solid var(--glass-border);
     transition: all 0.3s ease;
}
 .card-glass:hover {
     box-shadow: 0 12px 40px rgba(0, 0, 0, 0.3), 0 4px 16px rgba(0, 0, 0, 0.15);
     transform: translateY(-2px);
}
 .controls {
     display: flex;
     flex-direction: column;
     gap: 0.8rem;
     margin: 1rem 0;
     align-items: center;
     padding: 1.5rem;
     width: 100%;
     max-width: 400px;
}
 .input-label {
     color: #b3c6e6;
     font-size: 1.1rem;
     margin-bottom: 0.2rem;
     align-self: flex-start;
     font-weight: 500;
}
 .input-amount {
     padding: 0.8rem 1rem;
     border-radius: 12px;
     border: 1px solid rgba(255, 255, 255, 0.15);
     background: rgba(24, 31, 54, 0.7);
     color: #e6ecff;
     font-size: 1.1rem;
     outline: none;
     transition: all 0.3s ease;
     width: 100%;
     margin-bottom: 0.5rem;
}
 .input-amount:focus {
     border-color: var(--primary);
     box-shadow: 0 0 0 3px rgba(77, 163, 255, 0.2);
}
 .btn-row {
     display: flex;
     gap: 0.8rem;
     width: 100%;
     justify-content: center;
}
 .btn-primary, .btn-pay {
     padding: 0.8rem 1.5rem;
     border-radius: 12px;
     border: none;
     background: linear-gradient(135deg, var(--primary), #3578c7);
     color: #fff;
     font-weight: 600;
     font-size: 1.1rem;
     cursor: pointer;
     box-shadow: 0 4px 12px rgba(77, 163, 255, 0.3);
     transition: all 0.3s ease;
     display: flex;
     align-items: center;
     justify-content: center;
     gap: 0.5rem;
     flex: 1;
     position: relative;
     overflow: hidden;
}
 .btn-primary::before, .btn-pay::before {
     content: '';
     position: absolute;
     top: 0;
     left: -100%;
     width: 100%;
     height: 100%;
     background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
     transition: left 0.5s;
}
 .btn-primary:hover::before, .btn-pay:hover::before {
     left: 100%;
}
 .btn-primary:hover, .btn-pay:hover {
     transform: translateY(-2px);
     box-shadow: 0 6px 16px rgba(77, 163, 255, 0.4);
}
 .btn-primary:active, .btn-pay:active {
     transform: translateY(0);
}
 .btn-pay {
     padding: 0.7rem 1.2rem;
     font-size: 1rem;
     border-radius: 10px;
     gap: 0.4rem;
}
 .btn-pay .lightning-emoji {
     font-size: 1.2rem;
     filter: drop-shadow(0 0 6px rgba(255, 247, 0, 0.8));
}
 .btn-primary:disabled, .btn-pay:disabled {
     opacity: 0.6;
     cursor: not-allowed;
     transform: none;
}
 .btn-primary:disabled:hover, .btn-pay:disabled:hover {
     transform: none;
     box-shadow: 0 4px 12px rgba(77, 163, 255, 0.3);
}
 .btn-secondary {
     padding: 0.5rem 1rem;
     border-radius: 10px;
     background: rgba(35, 43, 74, 0.7);
     color: var(--primary);
     border: 1px solid var(--primary);
     cursor: pointer;
     font-size: 0.9rem;
     font-weight: 500;
     transition: all 0.3s ease;
}
 .btn-secondary:hover {
     background: var(--primary);
     color: #fff;
}
 .invoice-area {
     margin-top: 1rem;
     margin-bottom: 1.5rem;
     width: 100%;
     max-width: 400px;
     padding: 1.5rem;
     opacity: 0;
     transform: translateY(20px);
     transition: all 0.5s ease;
}
 .invoice-area.show {
     opacity: 1;
     transform: translateY(0);
}
 .invoice-header {
     display: flex;
     align-items: center;
     justify-content: space-between;
     margin-bottom: 1rem;
     width: 100%;
}
 .invoice-label {
     font-weight: 600;
     color: var(--primary);
     font-size: 1.2rem;
}
 .invoice-string {
     display: none !important;
}
 .qrcode {
     display: flex;
     justify-content: center;
     align-items: center;
     margin-bottom: 1rem;
     width: 100%;
     padding: 1rem;
     background: #ffffff;
     border-radius: 12px;
}
 .qrcode canvas {
     box-shadow: 0 4px 12px rgba(0, 0, 0, 0.2);
}
 .loading-buffer {
     display: flex;
     align-items: center;
     justify-content: center;
     gap: 0.8rem;
     color: var(--primary);
     font-weight: bold;
     margin-bottom: 1rem;
     width: 100%;
     max-width: 400px;
     padding: 1.5rem;
     opacity: 0;
     transition: opacity 0.3s ease;
}
 .loading-buffer.show {
     opacity: 1;
}
 .paid-status {
     width: 100%;
     text-align: center;
     font-weight: 700;
     margin: 0.5rem 0 1rem 0;
     padding: 0.8rem 1rem;
     border-radius: 12px;
     background: rgba(255, 255, 255, 0.05);
     border: 1px solid rgba(255, 255, 255, 0.12);
     color: #b3c6e6;
     transition: all 0.3s ease;
}
 .spinner {
     border: 3px solid rgba(230, 236, 255, 0.3);
     border-top: 3px solid var(--primary);
     border-radius: 50%;
     width: 24px;
     height: 24px;
     animation: spin 1s linear infinite;
     box-sizing: border-box;
     display: inline-block;
}
 @keyframes spin {
     0% {
         transform: rotate(0deg);
    }
     100% {
         transform: rotate(360deg);
    }
}
 .code-block {
     background: rgba(24, 31, 54, 0.7);
     border: 1px solid rgba(255, 255, 255, 0.08);
     border-radius: 12px;
     padding: 1.2rem;
     overflow: auto;
     line-height: 1.4;
     white-space: pre-wrap;
     word-break: break-word;
     margin-top: 1rem;
     margin-bottom: 1rem;
     width: 100%;
     max-width: 400px;
     transition: all 0.3s ease;
}
 .btc-sent-modal {
     display: none;
     position: fixed;
     top: 0;
     left: 0;
     width: 100vw;
     height: 100vh;
     background: rgba(15, 17, 48, 0.95);
     z-index: 9999;
     justify-content: center;
     align-items: center;
     flex-direction: column;
     backdrop-filter: blur(5px);
}
 .btc-sent-card {
     background: rgba(24, 31, 54, 0.98);
     border-radius: 24px;
     box-shadow: 0 12px 40px rgba(0, 0, 0, 0.4);
     padding: 2.5rem 2rem 2rem 2rem;
     display: flex;
     flex-direction: column;
     align-items: center;
     min-width: 300px;
     max-width: 90vw;
     animation: btc-card-pop 0.7s cubic-bezier(0.5, 1.8, 0.5, 1) forwards;
     border: 1px solid rgba(247, 147, 26, 0.3);
}
 .btc-sent-graphic {
     position: relative;
     width: 140px;
     height: 140px;
     margin-bottom: 1.5rem;
}
 .btc-svg-main {
     width: 140px;
     height: 140px;
     animation: btc-pop 0.7s cubic-bezier(0.5, 1.8, 0.5, 1) forwards;
}
 .btc-svg-bolt {
     position: absolute;
     left: 50%;
     top: 15px;
     width: 50px;
     height: 50px;
     transform: translateX(-50%);
     animation: bolt-flash 1.1s cubic-bezier(0.5, 1.8, 0.5, 1) 0.1s forwards;
     opacity: 0;
     z-index: 2;
}
 .btc-svg-tick {
     position: absolute;
     left: 50%;
     bottom: 10px;
     width: 42px;
     height: 42px;
     transform: translateX(-50%);
     animation: tick-bounce 1.1s cubic-bezier(0.5, 1.8, 0.5, 1) 0.5s forwards;
     opacity: 0;
     z-index: 2;
}
 .btc-sent-msg {
     margin-top: 1rem;
     font-size: 1.6rem;
     font-weight: bold;
     color: #fff;
     text-shadow: 0 2px 12px var(--accent);
     letter-spacing: 0.02em;
     text-align: center;
     animation: text-glow 2s infinite alternate;
}
 @keyframes text-glow {
     0% {
         text-shadow: 0 2px 12px var(--accent);
    }
     100% {
         text-shadow: 0 2px 20px var(--accent), 0 0 30px rgba(247, 147, 26, 0.5);
    }
}
 @keyframes btc-card-pop {
     0% {
         transform: scale(0.7);
         opacity: 0;
    }
     60% {
         transform: scale(1.08);
         opacity: 1;
    }
     100% {
         transform: scale(1);
         opacity: 1;
    }
}
 @keyframes btc-pop {
     0% {
         transform: scale(0.5);
         opacity: 0;
    }
     60% {
         transform: scale(1.15);
         opacity: 1;
    }
     100% {
         transform: scale(1);
         opacity: 1;
    }
}
 @keyframes bolt-flash {
     0% {
         opacity: 0;
         transform: scale(0.5) rotate(-20deg);
    }
     40% {
         opacity: 1;
         transform: scale(1.1) rotate(0deg);
    }
     100% {
         opacity: 1;
         transform: scale(1) rotate(0deg);
    }
}
 @keyframes tick-bounce {
     0% {
         opacity: 0;
         transform: scale(0.5) translateY(10px);
    }
     60% {
         opacity: 1;
         transform: scale(1.1) translateY(-4px);
    }
     100% {
         opacity: 1;
         transform: scale(1) translateY(0);
    }
}
 @media (max-width: 768px) {
     .floating-shapes {
         display: none;
    }
     .main-title {
         font-size: 2rem;
    }
     .main-desc {
         font-size: 1.1rem;
    }
     .controls, .invoice-area, .loading-buffer, .code-block {
         max-width: 95vw;
         padding-left: 1rem;
         padding-right: 1rem;
    }
     .card-glass {
         border-radius: 16px;
    }
     .btc-sent-card {
         min-width: 0;
         width: 95vw;
         padding: 2rem 1rem 1.5rem 1rem;
    }
     .btc-sent-graphic {
         width: 120px;
         height: 120px;
    }
     .btc-svg-main {
         width: 120px;
         height: 120px;
    }
     .btc-svg-bolt {
         top: 12px;
         width: 45px;
         height: 45px;
    }
     .btc-svg-tick {
         bottom: 8px;
         width: 38px;
         height: 38px;
    }
     .btc-sent-msg {
         font-size: 1.4rem;
    }
}
 @media (max-width: 480px) {
     .main-title {
         font-size: 1.7rem;
    }
     .btn-row {
         flex-direction: column;
    }
     .btn-primary, .btn-pay {
         width: 100%;
    }
}
 .success-pulse {
     animation: success-pulse 0.5s ease;
}
 @keyframes success-pulse {
     0% {
         transform: scale(1);
    }
     50% {
         transform: scale(1.05);
    }
     100% {
         transform: scale(1);
    }
}