/* ===== CSS Variables ===== */
:root {
    --bg-primary: #0f1117;
    --bg-secondary: #1a1b26;
    --bg-tertiary: #24253a;
    --bg-hover: #2a2b3d;
    --text-primary: #e1e2e8;
    --text-secondary: #8b8fa3;
    --text-muted: #565a6e;
    --border: #2e2f45;
    --accent: #6366f1;
    --accent-light: #818cf8;
    --accent-bg: rgba(99, 102, 241, 0.1);
    --success: #22c55e;
    --warning: #f59e0b;
    --error: #ef4444;
    --info: #3b82f6;
    --shadow: 0 4px 24px rgba(0, 0, 0, 0.3);
    --radius: 8px;
    --radius-sm: 4px;
    --transition: 150ms ease;
    --font-mono: 'JetBrains Mono', 'Fira Code', 'Cascadia Code', 'Consolas', monospace;
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;

    /* Diagram colors */
    --diagram-block-bg: #1e1f35;
    --diagram-block-border: #6366f1;
    --diagram-block-header: #6366f1;
    --diagram-req-bg: #1e2a1f;
    --diagram-req-border: #22c55e;
    --diagram-req-header: #22c55e;
    --diagram-ibd-bg: #1e2535;
    --diagram-ibd-border: #3b82f6;
    --diagram-ibd-header: #3b82f6;
    --diagram-port-bg: #2a2b3d;
    --diagram-port-border: #f59e0b;
    --diagram-param-bg: #2a1e2e;
    --diagram-param-border: #a855f7;
    --diagram-param-header: #a855f7;
    --diagram-state-bg: #1e2535;
    --diagram-state-border: #3b82f6;
    --diagram-state-header: #3b82f6;
    --diagram-actor-color: #6366f1;
    --diagram-usecase-bg: #1e1f35;
    --diagram-usecase-border: #6366f1;
    --diagram-activity-bg: #1e2a1f;
    --diagram-activity-border: #22c55e;
    --diagram-line-color: #8b8fa3;
    --diagram-text-color: #e1e2e8;
    --diagram-text-secondary: #8b8fa3;
    --diagram-bg: #0f1117;
    --diagram-package-bg: rgba(99, 102, 241, 0.05);
    --diagram-package-border: #4f46e5;
    --diagram-lifeline-color: #565a6e;
    --diagram-message-color: #e1e2e8;
    --diagram-activation-bg: rgba(99, 102, 241, 0.2);
}

[data-theme="light"] {
    --bg-primary: #ffffff;
    --bg-secondary: #f8f9fc;
    --bg-tertiary: #eef0f4;
    --bg-hover: #e5e7ec;
    --text-primary: #1a1b26;
    --text-secondary: #565a6e;
    --text-muted: #8b8fa3;
    --border: #d4d6e0;
    --accent: #4f46e5;
    --accent-light: #6366f1;
    --accent-bg: rgba(79, 70, 229, 0.08);
    --shadow: 0 4px 24px rgba(0, 0, 0, 0.08);

    --diagram-block-bg: #f0f0ff;
    --diagram-block-border: #4f46e5;
    --diagram-block-header: #4f46e5;
    --diagram-req-bg: #f0fdf4;
    --diagram-req-border: #16a34a;
    --diagram-req-header: #16a34a;
    --diagram-ibd-bg: #eff6ff;
    --diagram-ibd-border: #2563eb;
    --diagram-ibd-header: #2563eb;
    --diagram-port-bg: #fefce8;
    --diagram-port-border: #d97706;
    --diagram-param-bg: #faf5ff;
    --diagram-param-border: #9333ea;
    --diagram-param-header: #9333ea;
    --diagram-state-bg: #eff6ff;
    --diagram-state-border: #2563eb;
    --diagram-state-header: #2563eb;
    --diagram-actor-color: #4f46e5;
    --diagram-usecase-bg: #f0f0ff;
    --diagram-usecase-border: #4f46e5;
    --diagram-activity-bg: #f0fdf4;
    --diagram-activity-border: #16a34a;
    --diagram-line-color: #565a6e;
    --diagram-text-color: #1a1b26;
    --diagram-text-secondary: #565a6e;
    --diagram-bg: #ffffff;
    --diagram-package-bg: rgba(79, 70, 229, 0.05);
    --diagram-package-border: #4f46e5;
    --diagram-lifeline-color: #8b8fa3;
    --diagram-message-color: #1a1b26;
    --diagram-activation-bg: rgba(79, 70, 229, 0.15);
}

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

html, body {
    height: 100%;
    overflow: hidden;
}

body {
    font-family: var(--font-sans);
    background: var(--bg-primary);
    color: var(--text-primary);
    display: flex;
    flex-direction: column;
}

/* ===== Header ===== */
header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 8px 16px;
    background: var(--bg-secondary);
    border-bottom: 1px solid var(--border);
    z-index: 100;
    flex-shrink: 0;
}

.logo {
    display: flex;
    align-items: center;
    gap: 10px;
}

.logo h1 {
    font-size: 16px;
    font-weight: 700;
    letter-spacing: -0.02em;
}

.badge {
    font-size: 10px;
    font-weight: 700;
    padding: 2px 6px;
    border-radius: 4px;
    background: var(--accent);
    color: white;
    letter-spacing: 0.05em;
}

.toolbar {
    display: flex;
    align-items: center;
    gap: 8px;
}

/* ===== Buttons ===== */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 6px 12px;
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    background: var(--bg-tertiary);
    color: var(--text-primary);
    font-size: 12px;
    font-weight: 500;
    cursor: pointer;
    transition: all var(--transition);
    white-space: nowrap;
    font-family: var(--font-sans);
}

.btn:hover {
    background: var(--bg-hover);
    border-color: var(--accent);
}

.btn-icon {
    padding: 6px;
    border: none;
    background: transparent;
}

.btn-icon:hover {
    background: var(--bg-hover);
}

.btn-small {
    padding: 4px;
    font-size: 11px;
}

/* ===== Dropdown ===== */
.dropdown {
    position: relative;
}

.dropdown-menu {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    margin-top: 4px;
    min-width: 260px;
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    z-index: 200;
    padding: 4px;
}

.dropdown-menu.show {
    display: block;
}

.dropdown-menu button {
    display: block;
    width: 100%;
    text-align: left;
    padding: 8px 12px;
    border: none;
    background: none;
    color: var(--text-primary);
    font-size: 12px;
    cursor: pointer;
    border-radius: var(--radius-sm);
    font-family: var(--font-sans);
}

.dropdown-menu button:hover {
    background: var(--accent-bg);
    color: var(--accent-light);
}

/* ===== Main Layout ===== */
main {
    display: flex;
    flex: 1;
    overflow: hidden;
}

/* ===== Editor Panel ===== */
.editor-panel {
    width: 45%;
    min-width: 300px;
    display: flex;
    flex-direction: column;
    background: var(--bg-primary);
    border-right: 1px solid var(--border);
}

.panel-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 8px 12px;
    background: var(--bg-secondary);
    border-bottom: 1px solid var(--border);
    font-size: 11px;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--text-secondary);
    flex-shrink: 0;
}

.editor-wrapper {
    flex: 1;
    display: flex;
    overflow: hidden;
    position: relative;
}

.line-numbers {
    width: 44px;
    padding: 12px 8px 12px 4px;
    text-align: right;
    font-family: var(--font-mono);
    font-size: 12px;
    line-height: 1.6;
    color: var(--text-muted);
    background: var(--bg-secondary);
    border-right: 1px solid var(--border);
    overflow: hidden;
    user-select: none;
    flex-shrink: 0;
}

#codeEditor {
    flex: 1;
    padding: 12px;
    border: none;
    outline: none;
    background: var(--bg-primary);
    color: var(--text-primary);
    font-family: var(--font-mono);
    font-size: 12px;
    line-height: 1.6;
    resize: none;
    tab-size: 4;
    white-space: pre;
    overflow: auto;
}

#codeEditor::placeholder {
    color: var(--text-muted);
}

.status-bar {
    display: flex;
    justify-content: space-between;
    padding: 4px 12px;
    background: var(--bg-secondary);
    border-top: 1px solid var(--border);
    font-size: 11px;
    color: var(--text-muted);
    flex-shrink: 0;
}

/* ===== Resizer ===== */
.resizer {
    width: 4px;
    cursor: col-resize;
    background: var(--border);
    transition: background var(--transition);
    flex-shrink: 0;
}

.resizer:hover, .resizer.active {
    background: var(--accent);
}

/* ===== Preview Panel ===== */
.preview-panel {
    flex: 1;
    display: flex;
    flex-direction: column;
    background: var(--bg-primary);
    min-width: 300px;
}

.zoom-controls {
    display: flex;
    align-items: center;
    gap: 4px;
    font-size: 11px;
    color: var(--text-muted);
}

#zoomLevel {
    min-width: 36px;
    text-align: center;
}

.preview-wrapper {
    flex: 1;
    overflow: auto;
    display: flex;
    align-items: flex-start;
    justify-content: center;
    padding: 24px;
    background: var(--diagram-bg);
    background-image:
        radial-gradient(circle, var(--border) 1px, transparent 1px);
    background-size: 20px 20px;
}

.preview-content {
    transform-origin: center top;
    transition: transform 100ms ease;
}

.preview-content svg {
    max-width: none;
}

/* ===== Error display ===== */
.error-message {
    padding: 16px;
    color: var(--error);
    font-family: var(--font-mono);
    font-size: 12px;
    white-space: pre-wrap;
}

/* ===== Empty state ===== */
.empty-state {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 48px;
    color: var(--text-muted);
    text-align: center;
    gap: 12px;
}

.empty-state svg {
    opacity: 0.3;
}

.empty-state p {
    font-size: 13px;
    max-width: 300px;
    line-height: 1.5;
}

/* ===== Scrollbar ===== */
::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}

::-webkit-scrollbar-track {
    background: transparent;
}

::-webkit-scrollbar-thumb {
    background: var(--border);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--text-muted);
}

/* ===== Responsive ===== */
@media (max-width: 768px) {
    main {
        flex-direction: column;
    }

    .editor-panel {
        width: 100%;
        height: 40%;
        min-width: unset;
        border-right: none;
        border-bottom: 1px solid var(--border);
    }

    .resizer {
        width: 100%;
        height: 4px;
        cursor: row-resize;
    }

    .preview-panel {
        min-width: unset;
    }
}