:root {
    --primary-color: #6366f1;
    --primary-hover: #4f46e5;
    --bg-color: #f8fafc;
    --card-bg: #ffffff;
    --text-main: #1e293b;
    --text-muted: #64748b;
    --border-color: #e2e8f0;
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
}

* {
    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: 1.5;
    min-height: 100vh;
    display: flex;
    justify-content: center;
    padding: 2rem;
}

.container {
    width: 100%;
    max-width: 800px;
    background: var(--card-bg);
    border-radius: 1rem;
    box-shadow: var(--shadow-md);
    padding: 2.5rem;
    display: flex;
    flex-direction: column;
    gap: 2rem;
    height: fit-content;
}

header {
    text-align: center;
}

header h1 {
    font-size: 2rem;
    font-weight: 700;
    color: var(--text-main);
    margin-bottom: 0.5rem;
}

header p {
    color: var(--text-muted);
}

.drop-zone {
    border: 2px dashed var(--border-color);
    border-radius: 0.75rem;
    padding: 3rem;
    text-align: center;
    transition: all 0.2s ease;
    cursor: pointer;
    background: #fdfdfe;
}

.drop-zone:hover, .drop-zone.drag-over {
    border-color: var(--primary-color);
    background-color: #eff6ff;
}

.drop-message svg {
    color: var(--text-muted);
    margin-bottom: 1rem;
}

.drop-message p {
    font-weight: 500;
    color: var(--text-muted);
}

.drop-message span {
    color: var(--primary-color);
    text-decoration: underline;
}

.file-list {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
    min-height: 50px; /* To allow dropping into empty list if implemented */
}

.file-item {
    display: flex;
    align-items: center;
    background: white;
    border: 1px solid var(--border-color);
    border-radius: 0.5rem;
    padding: 0.75rem 1rem;
    gap: 1rem;
    cursor: grab;
    transition: box-shadow 0.2s;
}

.file-item:active {
    cursor: grabbing;
    box-shadow: var(--shadow-sm);
}

.file-icon {
    width: 24px;
    height: 24px;
    color: #ef4444; /* PDF Red */
}

.file-info {
    flex: 1;
    overflow: hidden;
}

.file-name {
    font-weight: 500;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.file-size {
    font-size: 0.875rem;
    color: var(--text-muted);
}

.remove-btn {
    background: none;
    border: none;
    color: var(--text-muted);
    cursor: pointer;
    padding: 0.25rem;
    border-radius: 0.25rem;
    transition: color 0.2s;
}

.remove-btn:hover {
    color: #ef4444;
    background-color: #fef2f2;
}

.actions {
    display: flex;
    justify-content: flex-end;
    padding-top: 1rem;
    border-top: 1px solid var(--border-color);
}

.btn {
    padding: 0.75rem 1.5rem;
    border-radius: 0.5rem;
    border: none;
    font-weight: 600;
    cursor: pointer;
    transition: background-color 0.2s;
    font-family: inherit;
    font-size: 1rem;
}

.btn-primary {
    background-color: var(--primary-color);
    color: white;
}

.btn-primary:hover:not(:disabled) {
    background-color: var(--primary-hover);
}

.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    background-color: var(--text-muted);
}