:root {
    --font-ui: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    --font-mono: "JetBrains Mono", "Fira Code", "SF Mono", Monaco, "Cascadia Code", Consolas, monospace;

    --color-bg: #f5f7fa;
    --color-panel: #ffffff;
    --color-text: #1f2937;
    --color-text-muted: #6b7280;
    --color-border: #d1d5db;
    --color-primary: #2563eb;
    --color-primary-hover: #1d4ed8;
    --color-primary-active: #1e40af;
    --color-secondary-bg: #ffffff;
    --color-secondary-hover: #f3f4f6;
    --color-secondary-active: #e5e7eb;
    --color-error-bg: #fef2f2;
    --color-error-text: #991b1b;
    --color-error-border: #fecaca;
    --color-warning-bg: #fffbeb;
    --color-warning-text: #92400e;
    --color-warning-border: #fde68a;
    --color-success-bg: #f0fdf4;
    --color-success-text: #166534;
    --color-success-border: #bbf7d0;
    --color-output-bg: #fafafa;

    --color-sql-keyword: #2563eb;
    --color-sql-string: #16a34a;
    --color-sql-number: #ea580c;
    --color-sql-comment: #6b7280;

    --radius: 8px;
    --shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
    --spacing-1: 8px;
    --spacing-2: 16px;
    --spacing-3: 24px;
    --spacing-4: 32px;
}

* {
    box-sizing: border-box;
}

html,
body {
    height: 100%;
    margin: 0;
}

body {
    display: flex;
    flex-direction: column;
    font-family: var(--font-ui);
    background-color: var(--color-bg);
    color: var(--color-text);
    line-height: 1.5;
}

.app-header {
    padding: var(--spacing-2) var(--spacing-4);
    text-align: center;
    flex-shrink: 0;
}

.app-header h1 {
    margin: 0;
    font-size: 24px;
    font-weight: 700;
    line-height: 1.2;
}

.subtitle {
    margin: 4px 0 0;
    color: var(--color-text-muted);
    font-size: 13px;
}

.container {
    flex: 1;
    display: flex;
    flex-direction: row;
    gap: 0;
    padding: var(--spacing-2) var(--spacing-4);
    max-width: 1600px;
    margin: 0 auto;
    width: 100%;
    min-height: 0;
    overflow: hidden;
}

.panel {
    display: flex;
    flex-direction: column;
    flex: 1 1 50%;
    background-color: var(--color-panel);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    overflow: hidden;
    min-height: 0;
    height: 100%;
}

.input-panel {
    border-top-right-radius: 0;
    border-bottom-right-radius: 0;
}

.output-panel {
    border-top-left-radius: 0;
    border-bottom-left-radius: 0;
}

.resizer {
    flex: 0 0 8px;
    cursor: col-resize;
    background-color: transparent;
    transition: background-color 0.15s ease;
    position: relative;
    z-index: 1;
}

.resizer:hover,
.resizer.dragging {
    background-color: var(--color-border);
}

.resizer::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 2px;
    height: 24px;
    border-radius: 1px;
    background-color: var(--color-text-muted);
    opacity: 0.4;
}

.panel-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--spacing-2);
    border-bottom: 1px solid var(--color-border);
    background-color: #f9fafb;
}

.panel-header h2 {
    margin: 0;
    font-size: 16px;
    font-weight: 600;
}

.panel-actions {
    display: flex;
    gap: var(--spacing-1);
}

.panel-footer {
    padding: var(--spacing-2);
    border-top: 1px solid var(--color-border);
}

button {
    padding: 8px 12px;
    font-family: var(--font-ui);
    font-size: 14px;
    font-weight: 500;
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    cursor: pointer;
    transition: background-color 0.15s ease, border-color 0.15s ease, color 0.15s ease;
}

button:focus-visible {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
}

button:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.btn-primary {
    color: #ffffff;
    background-color: var(--color-primary);
    border-color: var(--color-primary);
}

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

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

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

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

.btn-secondary:active:not(:disabled) {
    background-color: var(--color-secondary-active);
}

#sql-input {
    flex: 1;
    width: 100%;
    min-height: 0;
    padding: var(--spacing-2);
    font-family: var(--font-mono);
    font-size: 14px;
    line-height: 1.6;
    border: none;
    outline: none;
    resize: none;
    background-color: var(--color-panel);
    color: var(--color-text);
}

.output-wrapper {
    flex: 1;
    min-height: 0;
    padding: var(--spacing-2);
    overflow: auto;
    background-color: var(--color-output-bg);
}

#sql-output {
    margin: 0;
    font-family: var(--font-mono);
    font-size: 14px;
    line-height: 1.6;
    white-space: pre-wrap;
    word-break: break-word;
    color: var(--color-text);
}

#sql-output code {
    font-family: inherit;
}

.sql-keyword {
    color: var(--color-sql-keyword);
    font-weight: 600;
}

.sql-string {
    color: var(--color-sql-string);
}

.sql-number {
    color: var(--color-sql-number);
}

.sql-comment {
    color: var(--color-sql-comment);
    font-style: italic;
}

.message {
    margin: 0 var(--spacing-2) var(--spacing-2);
    padding: 12px var(--spacing-2);
    border-radius: var(--radius);
    border: 1px solid transparent;
    font-size: 14px;
}

.message.hidden {
    display: none;
}

.message.error {
    background-color: var(--color-error-bg);
    color: var(--color-error-text);
    border-color: var(--color-error-border);
}

.message.warning {
    background-color: var(--color-warning-bg);
    color: var(--color-warning-text);
    border-color: var(--color-warning-border);
}

.message.success {
    background-color: var(--color-success-bg);
    color: var(--color-success-text);
    border-color: var(--color-success-border);
}

@media (max-width: 1024px) {
    .container {
        flex-direction: column;
        padding: var(--spacing-2);
        gap: var(--spacing-2);
    }

    .panel {
        flex: 1 1 50%;
        width: auto !important;
        height: 100%;
        min-height: 0;
        border-radius: var(--radius);
    }

    .resizer {
        display: none;
    }

    #sql-input,
    .output-wrapper {
        min-height: 0;
    }
}