/* style.css */
* { box-sizing: border-box; }
body {
    font-family: 'Prompt', sans-serif;
    background-color: #f4f7f6;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
    padding: 20px;
}
.invoice-card {
    background: white;
    padding: 2.5rem;
    border-radius: 20px;
    box-shadow: 0 15px 35px rgba(0,0,0,0.1);
    width: 100%;
    max-width: 400px;
    text-align: center;
}
h2 { color: #333; margin-bottom: 1.5rem; }

input {
    width: 100%;
    padding: 15px;
    margin: 10px 0;
    border: 2px solid #e2e8f0;
    border-radius: 12px;
    font-family: 'Prompt', sans-serif;
    font-size: 1rem;
    transition: border-color 0.3s;
}
input:focus {
    border-color: #2563eb;
    outline: none;
}

button {
    width: 100%;
    padding: 15px;
    margin-top: 15px;
    background-color: #2563eb;
    color: white;
    border: none;
    border-radius: 12px;
    font-size: 1rem;
    font-weight: 500;
    font-family: 'Prompt', sans-serif;
    cursor: pointer;
    transition: background 0.3s;
}
button:hover { background-color: #1d4ed8; }
button:disabled { background-color: #94a3b8; cursor: not-allowed; }

.spinner {
    display: none;
    width: 30px;
    height: 30px;
    border: 4px solid #f3f3f3;
    border-top: 4px solid #2563eb;
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin: 20px auto 0 auto;
}
@keyframes spin { 0% { transform: rotate(0deg); } 100% { transform: rotate(360deg); } }