body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: #e2e8f0;
    color: #1e293b;
    margin: 0;
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}
header {
    background-color: #1e293b;
    color: white;
    padding: 1.5rem;
    text-align: center;
    box-shadow: 0 4px 6px rgba(0,0,0,0.15);
}
h1 {
    margin: 0;
    font-size: 1.8rem;
}
main {
    flex: 1;
    padding: 2rem;
    max-width: 1600px;
    margin: 0 auto;
    width: 100%;
    box-sizing: border-box;
}
.container {
    display: grid;
    grid-template-columns: 1fr;
    gap: 2rem;
}
@media (min-width: 992px) {
    .container {
        grid-template-columns: 300px 1fr;
    }
}
.card {
    background: white;
    padding: 1.5rem;
    border-radius: 8px;
    box-shadow: 0 4px 12px rgba(0,0,0,0.1);
}
.form-group {
    margin-bottom: 1.2rem;
}
label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 600;
    color: #1e293b;
}
input, select {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid #94a3b8;
    border-radius: 6px;
    box-sizing: border-box;
    font-size: 1rem;
    transition: border-color 0.2s;
}
input:focus, select:focus {
    outline: none;
    border-color: #4f46e5;
    box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.2);
}
button {
    background-color: #4f46e5;
    color: white;
    border: none;
    padding: 1rem;
    font-size: 1.1rem;
    font-weight: bold;
    border-radius: 6px;
    cursor: pointer;
    width: 100%;
    transition: background 0.3s, transform 0.1s;
    margin-top: 1rem;
}
button:hover {
    background-color: #4338ca;
}
button:active {
    transform: scale(0.98);
}
#btn-export {
    background-color: #059669;
    margin-top: 0.5rem;
}
#btn-export:hover:not(:disabled) {
    background-color: #047857;
}
#btn-export:active:not(:disabled) {
    transform: scale(0.98);
}
#btn-export:disabled {
    background-color: #cbd5e1;
    color: #64748b;
    cursor: not-allowed;
    transform: none;
}
.table-responsive {
    overflow-x: auto;
}
table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.9rem;
    background: white;
    border-radius: 8px;
    overflow: hidden;
}
th, td {
    border: 1px solid #cbd5e1;
    padding: 0.75rem 0.5rem;
    text-align: right;
    word-wrap: break-word;
}
th {
    background-color: #f1f5f9;
    color: #0f172a;
    text-align: center;
    font-weight: 600;
}
td:first-child {
    text-align: center;
    font-weight: bold;
    background-color: #f1f5f9;
}
tfoot th {
    background-color: #cbd5e1;
    color: #0f172a;
    font-weight: bold;
}
footer {
    background-color: #1e293b;
    color: white;
    text-align: center;
    padding: 1.5rem;
    margin-top: auto;
}
.error {
    color: #e74c3c;
    background: #fadbd8;
    padding: 1rem;
    border-radius: 6px;
    text-align: center;
    font-weight: bold;
}