/* Variables y paleta de colores moderna */
:root {
    --primary: #4F46E5;
    --primary-hover: #4338CA;
    --bg-color: #F3F4F6;
    --card-bg: #FFFFFF;
    --text-main: #1F2937;
    --text-muted: #6B7280;
    --border-color: #E5E7EB;
    --success: #10B981;
    --error: #EF4444;
    --radius: 12px;
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    font-family: 'Inter', sans-serif;
    background-color: var(--bg-color);
    color: var(--text-main);
    line-height: 1.6;
    display: flex;
    justify-content: center;
    padding: 2rem;
}

.app-container {
    width: 100%;
    max-width: 800px;
    display: flex;
    flex-direction: column;
    gap: 2rem;
}

header {
    text-align: center;
}

header h1 {
    font-size: 2.5rem;
    color: var(--primary);
    margin-bottom: 0.5rem;
}

.card {
    background-color: var(--card-bg);
    border-radius: var(--radius);
    padding: 1.5rem;
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    margin-bottom: 1.5rem;
    border: 1px solid var(--border-color);
}

.card h2 {
    font-size: 1.25rem;
    margin-bottom: 1rem;
    border-bottom: 2px solid var(--bg-color);
    padding-bottom: 0.5rem;
}

.file-drop-area {
    position: relative;
    display: flex;
    align-items: center;
    justify-content: center;
    width: 100%;
    max-width: 100%;
    padding: 2rem;
    border: 2px dashed var(--primary);
    border-radius: var(--radius);
    background-color: #EEF2FF;
    transition: 0.2s;
    text-align: center;
    cursor: pointer;
}

.file-drop-area:hover, .file-drop-area.dragover {
    background-color: #E0E7FF;
}

.file-msg {
    font-weight: 500;
    color: var(--primary);
}

.file-drop-area input {
    position: absolute;
    left: 0;
    top: 0;
    height: 100%;
    width: 100%;
    cursor: pointer;
    opacity: 0;
}

.form-group {
    margin-bottom: 1rem;
    display: flex;
    flex-direction: column;
}

.form-row {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
}

label {
    font-weight: 600;
    margin-bottom: 0.5rem;
    font-size: 0.9rem;
}

select, input[type="text"], input[type="number"] {
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    font-size: 1rem;
    outline: none;
    transition: border-color 0.2s;
}

select:focus, input:focus {
    border-color: var(--primary);
}

.actions {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 1rem;
}

.btn-primary {
    background-color: var(--primary);
    color: white;
    font-weight: 600;
    font-size: 1.1rem;
    padding: 1rem 2rem;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    transition: background-color 0.2s, transform 0.1s;
    width: 100%;
    box-shadow: 0 4px 6px rgba(79, 70, 229, 0.3);
}

.btn-primary:hover {
    background-color: var(--primary-hover);
    transform: translateY(-2px);
}

.btn-primary:disabled {
    background-color: var(--text-muted);
    cursor: not-allowed;
    transform: none;
}

.status-message {
    text-align: center;
    margin-top: 1rem;
    font-weight: 500;
    padding: 1rem;
    border-radius: 8px;
    display: none;
}

.status-message.success {
    background-color: #D1FAE5;
    color: var(--success);
    display: block;
}

.status-message.error {
    background-color: #FEE2E2;
    color: var(--error);
    display: block;
}

/* Spinner animado */
.spinner {
    border: 4px solid rgba(0, 0, 0, 0.1);
    width: 36px;
    height: 36px;
    border-radius: 50%;
    border-left-color: var(--primary);
    animation: spin 1s linear infinite;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

footer {
    text-align: center;
    color: var(--text-muted);
    font-size: 0.9rem;
    margin-top: 2rem;
    padding-top: 1rem;
    border-top: 1px solid var(--border-color);
}