* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

body {
    background-color: #f4f7f6;
    color: #333;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
}

.container {
    width: 100%;
    max-width: 400px;
    padding: 20px;
}

.title {
    text-align: center;
    font-size: 24px;
    color: #2c3e50;
}

.subtitle {
    text-align: center;
    font-size: 14px;
    color: #7f8c8d;
    margin-bottom: 30px;
}

.card {
    background: white;
    padding: 30px;
    border-radius: 15px;
    box-shadow: 0 10px 20px rgba(0,0,0,0.05);
}

label {
    display: block;
    margin-bottom: 8px;
    font-weight: 600;
    font-size: 14px;
    color: #34495e;
}

input[type="text"], input[type="number"] {
    width: 100%;
    padding: 12px;
    border: 1px solid #ddd;
    border-radius: 8px;
    margin-bottom: 20px;
    font-size: 16px;
    outline: none;
    transition: border 0.3s;
}

input:focus {
    border-color: #e74c3c;
}

.input-group {
    display: flex;
    align-items: center;
    position: relative;
}

.currency {
    position: absolute;
    left: 15px;
    top: 12px;
    font-size: 16px;
    color: #7f8c8d;
}

.input-group input {
    padding-left: 30px;
}

.btn-gasto {
    width: 100%;
    background-color: #e74c3c;
    color: white;
    border: none;
    padding: 15px;
    border-radius: 8px;
    font-size: 16px;
    font-weight: bold;
    cursor: pointer;
    box-shadow: 0 4px 6px rgba(231, 76, 60, 0.3);
    transition: background 0.3s;
}

.btn-gasto:hover {
    background-color: #c0392b;
}

.oculto {
    display: none;
}

#mensaje-exito {
    text-align: center;
    color: #27ae60;
    margin-top: 15px;
    font-weight: 600;
}