* { margin: 0; padding: 0; box-sizing: border-box; }

body {
    font-family: 'Microsoft YaHei', 'Segoe UI', sans-serif;
    background: linear-gradient(135deg, #f5f7fa, #c3cfe2);
    min-height: 100vh;
    padding: 20px;
}

.container {
    max-width: 1400px;
    margin: 0 auto;
    background: white;
    border-radius: 15px;
    box-shadow: 0 10px 40px rgba(0,0,0,0.1);
    overflow: hidden;
}

.header {
    background: linear-gradient(135deg, #1a3c6e, #2c5282);
    color: white;
    padding: 25px 40px;
    text-align: center;
    border-bottom: 4px solid #d4a853;
}

.header h1 { font-size: 26px; letter-spacing: 4px; }
.header .subtitle { font-size: 13px; margin-top: 4px; opacity: 0.9; }

/* 概念说明 */
.concept-box {
    background: #fff3cd;
    border-left: 4px solid #ffc107;
    padding: 12px 16px;
    border-radius: 0 8px 8px 0;
    font-size: 13px;
    color: #856404;
    margin: 15px 20px 0;
    line-height: 1.8;
}
.concept-box strong { color: #664d03; }

/* 控制区 */
.control-panel {
    display: flex;
    flex-wrap: wrap;
    gap: 15px;
    padding: 15px 25px;
    background: #f8f9fa;
    border-bottom: 1px solid #e0e0e0;
    align-items: center;
}

.control-item { display: flex; align-items: center; gap: 6px; }
.control-item label { font-weight: 600; color: #333; font-size: 13px; white-space: nowrap; }

.control-item select {
    padding: 6px 10px;
    font-size: 13px;
    border: 2px solid #ccc;
    border-radius: 5px;
    background: white;
    cursor: pointer;
}

.control-item select:focus { outline: none; border-color: #1a3c6e; }

.control-item input[type="range"] {
    width: 120px;
    height: 5px;
    border-radius: 3px;
    background: #ddd;
    outline: none;
    -webkit-appearance: none;
}

.control-item input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    width: 14px;
    height: 14px;
    border-radius: 50%;
    background: #d4a853;
    cursor: pointer;
}

.radio-label {
    cursor: pointer;
    font-size: 13px;
    display: flex;
    align-items: center;
    gap: 4px;
    margin-right: 10px;
}

.radio-label input { width: 14px; height: 14px; }

.tf-display { flex: 1; min-width: 200px; }
.tf-display div {
    background: white;
    padding: 6px 12px;
    border-radius: 5px;
    border: 1px solid #ddd;
    font-size: 13px;
}

/* 步骤导航 */
.step-nav {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 12px;
    padding: 12px 25px;
    background: #f0f4ff;
    border-bottom: 2px solid #dbeafe;
}

.step-indicator {
    font-size: 14px;
    font-weight: 600;
    color: #1a3c6e;
    min-width: 100px;
    text-align: center;
}

.btn {
    padding: 8px 18px;
    border: none;
    border-radius: 6px;
    font-size: 13px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
}

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

.btn-primary { background: #1a3c6e; color: white; }
.btn-primary:hover:not(:disabled) { background: #143049; }

.btn-secondary { background: #d4a853; color: #1a3c6e; }
.btn-secondary:hover:not(:disabled) { background: #c19742; }

.btn-accent { background: #16a34a; color: white; }
.btn-accent:hover:not(:disabled) { background: #15803d; }

/* 步骤内容 */
.step-content {
    margin: 0 25px 10px;
    padding: 15px 18px;
    background: #f8fafc;
    border-radius: 8px;
    border: 1px solid #e2e8f0;
    min-height: 60px;
}

.step-content .step-title {
    font-size: 15px;
    font-weight: 700;
    color: #1a3c6e;
    margin-bottom: 10px;
    padding-bottom: 6px;
    border-bottom: 2px solid #d4a853;
}

.step-content .step-body {
    font-size: 14px;
    line-height: 1.8;
    color: #333;
}

.step-content .formula-box {
    background: white;
    padding: 10px 15px;
    border-radius: 6px;
    border: 1px solid #e2e8f0;
    margin: 10px 0;
    font-size: 15px;
}

.step-content .note {
    background: #e0f2fe;
    border-left: 3px solid #0284c7;
    padding: 8px 12px;
    border-radius: 0 5px 5px 0;
    font-size: 13px;
    color: #075985;
    margin-top: 10px;
}

/* 图表区 */
.plots-row {
    display: flex;
    gap: 15px;
    padding: 15px 25px;
}

.plot-box {
    background: #f8f9fa;
    border-radius: 8px;
    padding: 12px;
    border-left: 4px solid #1a3c6e;
}

.plot-box h3 {
    color: #333;
    margin-bottom: 8px;
    font-size: 14px;
}

.main-plot { flex: 0 0 550px; }
.side-panel { flex: 1; overflow: hidden; }

.plot-box canvas {
    width: 100%;
    height: auto;
    background: white;
    border-radius: 5px;
    box-shadow: 0 2px 6px rgba(0,0,0,0.06);
}

/* 奈奎斯特图控件 */
.nyquist-controls {
    display: flex;
    align-items: center;
    gap: 10px;
    margin-bottom: 8px;
    flex-wrap: wrap;
}

.checkbox-label {
    cursor: pointer;
    font-size: 12px;
    display: flex;
    align-items: center;
    gap: 4px;
}

.checkbox-label input { width: 14px; height: 14px; }

.range-group {
    display: flex;
    align-items: center;
    gap: 4px;
    font-size: 12px;
    color: #555;
}

.range-group label { font-weight: 500; margin-left: 6px; }

.range-group input[type="number"] {
    width: 55px;
    padding: 4px 6px;
    font-size: 12px;
    border: 1px solid #ccc;
    border-radius: 4px;
    text-align: center;
}

.range-group input[type="number"]:focus {
    outline: none;
    border-color: #1a3c6e;
}

.range-group span { color: #999; }

/* 频率计算表 */
.table-scroll {
    max-height: 520px;
    overflow-y: auto;
    font-size: 12px;
}

.freq-table {
    width: 100%;
    border-collapse: collapse;
}

.freq-table th {
    position: sticky;
    top: 0;
    background: #1a3c6e;
    color: white;
    padding: 6px 4px;
    font-weight: 600;
    font-size: 11px;
    text-align: center;
    white-space: nowrap;
}

.freq-table td {
    padding: 4px;
    text-align: center;
    border-bottom: 1px solid #e8e8e8;
    white-space: nowrap;
}

.freq-table tr:hover { background: #f0f4ff; }
.freq-table tr.highlight { background: #fef3c7; font-weight: 600; }

.freq-table .w-col { color: #1a3c6e; font-weight: 600; }
.freq-table .mag-col { color: #16a34a; font-weight: 700; background: #f0fdf4; }
.freq-table .phase-col { color: #d97706; font-weight: 700; background: #fffbeb; }
.freq-table .re-col { color: #2563eb; font-size: 11px; }
.freq-table .im-col { color: #dc2626; font-size: 11px; }

/* ω 探索条 */
.omega-bar {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 12px 25px;
    background: #f8f9fa;
    border-top: 1px solid #e0e0e0;
}

.omega-bar label {
    font-weight: 600;
    font-size: 13px;
    color: #333;
    white-space: nowrap;
}

.omega-bar input[type="range"] {
    flex: 1;
    height: 6px;
    border-radius: 3px;
    background: #ddd;
    outline: none;
    -webkit-appearance: none;
}

.omega-bar input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    width: 16px;
    height: 16px;
    border-radius: 50%;
    background: #1a3c6e;
    cursor: pointer;
}

.omega-hint {
    font-size: 12px;
    color: #666;
    white-space: nowrap;
}

/* 页脚 */
.footer { padding: 18px 40px 22px; text-align: center; }

.footer-divider {
    height: 3px;
    background: linear-gradient(90deg, transparent, #1a3c6e 20%, #d4a853 50%, #1a3c6e 80%, transparent);
    margin-bottom: 12px;
}

.footer-text {
    color: #1a3c6e;
    font-size: 14px;
    font-weight: 500;
    letter-spacing: 4px;
}

mjx-container { display: inline-block !important; }

@media (max-width: 1100px) {
    .plots-row { flex-direction: column; }
    .main-plot { flex: 1; }
    .control-panel { flex-direction: column; }
}

@media (max-width: 600px) {
    body { padding: 5px; }
    .header { padding: 15px 20px; }
    .header h1 { font-size: 20px; letter-spacing: 2px; }
}