/* CSS Variables */
:root {
    --primary-color: #2563eb;
    --primary-hover: #1d4ed8;
    --secondary-color: #6b7280;
    --danger-color: #dc2626;
    --success-color: #16a34a;
    --bg-color: #f3f4f6;
    --panel-bg: #ffffff;
    --border-color: #e5e7eb;
    --text-color: #1f2937;
    --text-muted: #6b7280;
    --header-height: 60px;
}

/* Reset */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* Header */
.app-header {
    height: var(--header-height);
    background: var(--panel-bg);
    border-bottom: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 1.5rem;
}

.app-header h1 {
    font-size: 1.25rem;
    font-weight: 600;
}

.header-actions {
    display: flex;
    gap: 0.5rem;
}

/* Buttons */
.btn {
    padding: 0.5rem 1rem;
    border: none;
    border-radius: 0.375rem;
    font-size: 0.875rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.15s ease;
}

.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

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

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

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

.btn-secondary:hover:not(:disabled) {
    background: #4b5563;
}

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

.btn-danger:hover:not(:disabled) {
    background: #b91c1c;
}

.btn-small {
    padding: 0.375rem 0.75rem;
    font-size: 0.75rem;
}

.btn-link {
    background: transparent;
    color: var(--text-muted);
    text-decoration: none;
    display: inline-flex;
    align-items: center;
}

.btn-link:hover {
    color: var(--primary-color);
}

.btn-tool {
    width: 100%;
    padding: 0.75rem;
    background: var(--bg-color);
    color: var(--text-color);
    border: 1px solid var(--border-color);
    margin-bottom: 0.5rem;
}

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

.btn-full {
    width: 100%;
}

/* Main Layout */
.app-main {
    flex: 1;
    display: flex;
    flex-direction: column;
}

/* Screens */
.screen {
    display: none;
    flex: 1;
}

.screen.active {
    display: flex;
}

/* Upload Screen */
#upload-screen {
    align-items: center;
    justify-content: center;
    padding: 2rem;
}

.upload-zone {
    width: 100%;
    max-width: 500px;
    padding: 3rem 2rem;
    background: var(--panel-bg);
    border: 2px dashed var(--border-color);
    border-radius: 0.5rem;
    text-align: center;
    transition: all 0.2s ease;
}

.upload-zone.dragover {
    border-color: var(--primary-color);
    background: #eff6ff;
}

.upload-icon {
    font-size: 4rem;
    margin-bottom: 1rem;
}

.upload-zone p {
    margin: 0.5rem 0;
    color: var(--text-muted);
}

/* Editor Layout */
.editor-layout {
    display: grid;
    grid-template-columns: 1fr 1fr 300px;
    gap: 1rem;
    padding: 1rem;
    height: calc(100vh - var(--header-height));
    overflow: hidden;
}

/* PDF Panels */
.pdf-panel {
    background: var(--panel-bg);
    border-radius: 0.5rem;
    border: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    overflow: hidden;
}

.panel-header {
    padding: 0.75rem 1rem;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
    background: var(--bg-color);
}

.panel-title {
    font-weight: 600;
    font-size: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.page-info {
    font-size: 0.75rem;
    color: var(--text-muted);
}

.pdf-container {
    flex: 1;
    overflow-y: auto;
    padding: 1rem;
    background: #e5e7eb;
}

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

.pdf-page {
    background: white;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
    max-width: 100%;
}

.pdf-page img {
    display: block;
    max-width: 100%;
    height: auto;
}

.pdf-page.modified {
    box-shadow: 0 0 0 3px var(--primary-color), 0 2px 8px rgba(0, 0, 0, 0.1);
}

/* Tools Panel */
.tools-panel {
    background: var(--panel-bg);
    border-radius: 0.5rem;
    border: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    overflow: hidden;
}

.tools-content {
    flex: 1;
    overflow-y: auto;
    padding: 1rem;
}

.tool-section {
    margin-bottom: 1rem;
}

.section-label {
    display: block;
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: 0.5rem;
    color: var(--text-muted);
}

.divider {
    border: none;
    border-top: 1px solid var(--border-color);
    margin: 1rem 0;
}

/* Command Input */
.command-input-wrapper {
    display: flex;
    align-items: center;
    background: var(--bg-color);
    border: 1px solid var(--border-color);
    border-radius: 0.375rem;
    padding: 0.5rem;
    margin-bottom: 0.5rem;
}

.command-prompt {
    color: var(--text-muted);
    margin-right: 0.5rem;
    font-family: monospace;
}

.command-input {
    flex: 1;
    border: none;
    background: transparent;
    font-family: monospace;
    font-size: 0.875rem;
    outline: none;
}

.command-help {
    margin-top: 0.5rem;
}

.command-help summary {
    font-size: 0.75rem;
    color: var(--text-muted);
    cursor: pointer;
}

.command-help pre {
    font-size: 0.7rem;
    background: var(--bg-color);
    padding: 0.5rem;
    border-radius: 0.25rem;
    margin-top: 0.5rem;
    overflow-x: auto;
}

/* History List */
.history-list {
    max-height: 200px;
    overflow-y: auto;
}

.history-empty {
    font-size: 0.875rem;
    color: var(--text-muted);
    font-style: italic;
}

.history-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0.5rem;
    background: var(--bg-color);
    border-radius: 0.25rem;
    margin-bottom: 0.5rem;
    font-size: 0.75rem;
}

.history-item-text {
    flex: 1;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

.history-item .btn-small {
    margin-left: 0.5rem;
    flex-shrink: 0;
}

/* Loading Overlay */
.loading-overlay {
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.5);
    display: none;
    align-items: center;
    justify-content: center;
    flex-direction: column;
    z-index: 1000;
}

.loading-overlay.active {
    display: flex;
}

.spinner {
    width: 48px;
    height: 48px;
    border: 4px solid #fff;
    border-top-color: var(--primary-color);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

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

.loading-overlay p {
    color: white;
    margin-top: 1rem;
}

/* Toast Messages */
.toast-container {
    position: fixed;
    bottom: 1rem;
    right: 1rem;
    z-index: 1001;
}

.toast {
    background: var(--text-color);
    color: white;
    padding: 0.75rem 1rem;
    border-radius: 0.375rem;
    margin-top: 0.5rem;
    animation: slideIn 0.3s ease;
    max-width: 300px;
}

.toast.success {
    background: var(--success-color);
}

.toast.error {
    background: var(--danger-color);
}

@keyframes slideIn {
    from {
        transform: translateX(100%);
        opacity: 0;
    }
    to {
        transform: translateX(0);
        opacity: 1;
    }
}

/* Responsive */
@media (max-width: 1024px) {
    .editor-layout {
        grid-template-columns: 1fr 1fr;
        grid-template-rows: 1fr auto;
    }

    .tools-panel {
        grid-column: 1 / -1;
        max-height: 300px;
    }
}

@media (max-width: 768px) {
    .editor-layout {
        grid-template-columns: 1fr;
    }

    .pdf-panel:first-child {
        display: none;
    }
}