:root {
    color-scheme: light;
    --bg: #f4f6fb;
    --card: #ffffff;
    --line: #d9e0ef;
    --text: #213047;
    --muted: #5b6b86;
    --primary: #2f70ff;
    --primary-dark: #1858e6;
}

* {
    box-sizing: border-box;
}

body {
    margin: 0;
    font-family: Arial, sans-serif;
    color: var(--text);
    background: var(--bg);
}

.app {
    max-width: 1280px;
    margin: 0 auto;
    padding: 20px;
}

.app-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 16px;
    margin-bottom: 16px;
}

.app-header h1 {
    margin: 0 0 6px;
    font-size: 30px;
}

.app-header p {
    margin: 0;
    color: var(--muted);
}

.toolbar {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(170px, 1fr));
    gap: 12px;
    background: var(--card);
    border: 1px solid var(--line);
    border-radius: 14px;
    padding: 12px;
    margin-bottom: 12px;
}

.tool-group {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.tools-inline {
    display: flex;
    flex-wrap: wrap;
    gap: 6px;
}

.label {
    font-size: 12px;
    font-weight: 700;
    color: var(--muted);
    letter-spacing: 0.2px;
}

.value {
    font-size: 12px;
    color: var(--muted);
}

.actions {
    justify-content: end;
}

.btn {
    border: 1px solid var(--line);
    background: #fff;
    color: var(--text);
    border-radius: 8px;
    padding: 8px 10px;
    cursor: pointer;
    font-size: 13px;
    text-decoration: none;
    text-align: center;
}

.btn:hover {
    border-color: #b8c4df;
}

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

.btn-primary:hover {
    background: var(--primary-dark);
}

.btn-secondary {
    background: #f7f9ff;
}

.tool-btn.active {
    border-color: var(--primary);
    background: #eaf1ff;
    color: var(--primary-dark);
    font-weight: 700;
}

.canvas-panel {
    background: var(--card);
    border: 1px solid var(--line);
    border-radius: 14px;
    padding: 12px;
}

.canvas-wrap {
    position: relative;
    border: 1px dashed #b8c4df;
    border-radius: 12px;
    overflow: auto;
    background-image:
        linear-gradient(45deg, #edf2fb 25%, transparent 25%),
        linear-gradient(-45deg, #edf2fb 25%, transparent 25%),
        linear-gradient(45deg, transparent 75%, #edf2fb 75%),
        linear-gradient(-45deg, transparent 75%, #edf2fb 75%);
    background-size: 20px 20px;
    background-position: 0 0, 0 10px, 10px -10px, -10px 0;
    min-height: 450px;
}

canvas {
    position: absolute;
    top: 0;
    left: 0;
    image-rendering: auto;
}

.tips {
    margin-top: 10px;
    font-size: 14px;
    color: var(--muted);
}

@media (max-width: 768px) {
    .app {
        padding: 12px;
    }

    .app-header {
        flex-direction: column;
        align-items: flex-start;
    }
}