:root {
    --color-primary: #001b48;
    --color-secondary: #004581;
    --color-tertiary: #018abd;
    --color-quaternary: #97cbdc;
    --color-quinary: #dde8f0;
    --text-color: #333;
    --text-light: #fff;
}

body {
    font-family: 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
    background-color: var(--color-quinary);
    margin: 0;
    padding: 0;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
}

.container {
    background-color: var(--text-light);
    width: 100%;
    max-width: 600px;
    border-radius: 12px;
    box-shadow: 0 8px 30px rgba(0, 27, 72, 0.1);
    overflow: hidden;
}

header {
    background: linear-gradient(135deg, var(--color-primary), var(--color-secondary));
    color: var(--text-light);
    padding: 30px;
    text-align: center;
}

header h1 {
    margin: 0;
    font-size: 24px;
    font-weight: 600;
}

header p {
    margin: 10px 0 0;
    font-size: 14px;
    opacity: 0.9;
}

main {
    padding: 40px;
}

.upload-area {
    border: 2px dashed var(--color-tertiary);
    border-radius: 8px;
    padding: 40px 20px;
    text-align: center;
    background-color: rgba(1, 138, 189, 0.03);
    cursor: pointer;
    transition: all 0.3s ease;
}

.upload-area:hover, .upload-area.dragover {
    background-color: rgba(1, 138, 189, 0.1);
    border-color: var(--color-secondary);
}

.upload-area .icon {
    font-size: 48px;
    margin-bottom: 15px;
}

.upload-area h3 {
    margin: 0;
    color: var(--color-secondary);
    font-weight: 500;
}

.upload-area p {
    color: #666;
    margin-bottom: 20px;
}

button {
    border: none;
    padding: 10px 20px;
    border-radius: 6px;
    font-size: 16px;
    font-weight: 500;
    cursor: pointer;
    transition: background-color 0.3s;
}

.btn-select {
    background-color: var(--color-tertiary);
    color: var(--text-light);
}
.btn-select:hover { background-color: var(--color-secondary); }

.btn-upload {
    background-color: var(--color-primary);
    color: var(--text-light);
    width: 100%;
    padding: 15px;
    font-size: 18px;
    margin-top: 15px;
}
.btn-upload:hover { background-color: #001233; }

#file-info {
    margin-top: 25px;
    text-align: center;
}

.hidden { display: none !important; }

#status-message {
    margin-top: 20px;
    padding: 15px;
    border-radius: 6px;
    text-align: center;
    font-weight: 500;
}
.success { background-color: #d4edda; color: #155724; border: 1px solid #c3e6cb; }
.error { background-color: #f8d7da; color: #721c24; border: 1px solid #f5c6cb; }

#loader {
    margin-top: 20px;
    text-align: center;
    color: var(--color-secondary);
    font-weight: 500;
}

.spinner {
    display: inline-block;
    width: 20px; height: 20px;
    border: 3px solid rgba(0, 69, 129, 0.3);
    border-radius: 50%;
    border-top-color: var(--color-secondary);
    animation: spin 1s ease-in-out infinite;
    vertical-align: middle;
    margin-right: 10px;
}

@keyframes spin { to { transform: rotate(360deg); } }