/* 周期函数叠加演示系统样式 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Microsoft YaHei', 'Segoe UI', sans-serif;
    background: #f5f7fb;
    min-height: 100vh;
    padding: 10px;
}

.container {
    max-width: 1400px;
    margin: 0 auto;
    background: #fff;
    border-radius: 10px;
    box-shadow: 0 5px 20px rgba(0,0,0,0.1);
    overflow: hidden;
}

.header {
    background: linear-gradient(135deg, #1a3c6e, #2c5282);
    color: #fff;
    padding: 15px 30px;
    text-align: center;
    border-bottom: 3px solid #d4a853;
}

.header h1 {
    font-size: 24px;
    font-weight: 700;
    letter-spacing: 3px;
}

/* 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}

.header .subtitle {
    font-size: 13px;
    margin-top: 3px;
    opacity: 0.9;
}

/* 预设示例区域 */
.preset-area {
    background: #f8f9fa;
    padding: 12px 20px;
    border-bottom: 2px solid #d4a853;
}

.preset-area h4 {
    color: #1a3c6e;
    font-size: 14px;
    margin-bottom: 8px;
}

.preset-buttons {
    display: flex;
    gap: 10px;
    flex-wrap: wrap;
}

.main-row {
    display: flex;
    gap: 15px;
    padding: 15px 20px;
}

.plot-area {
    flex: 3;
    min-width: 600px;
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.plot-section {
    background: #f8f9fa;
    border-radius: 8px;
    padding: 10px 12px;
    border: 1px solid #e8e8e8;
}

.plot-section h4 {
    color: #1a3c6e;
    font-size: 14px;
    margin-bottom: 6px;
    padding-bottom: 4px;
    border-bottom: 2px solid #d4a853;
}

.plot-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 8px;
}

.plot-card {
    background: #fff;
    border-radius: 6px;
    padding: 8px;
    border: 1px solid #e2e8f0;
    margin-bottom: 8px;
}

.plot-card h5 {
    color: #1a3c6e;
    font-size: 12px;
    margin-bottom: 4px;
}

.canvas-wrap {
    position: relative;
    width: 100%;
    height: 120px;
}

/* 范围设置样式 */
.range-settings {
    margin-top: 8px;
    padding-top: 8px;
    border-top: 1px solid #e2e8f0;
}

.range-header {
    display: flex;
    align-items: center;
    gap: 6px;
    margin-bottom: 6px;
}

.range-header input[type="checkbox"] {
    width: 14px;
    height: 14px;
    cursor: pointer;
}

.range-header label {
    font-size: 11px;
    color: #1a3c6e;
    font-weight: 600;
    cursor: pointer;
}

.range-inputs .range-row {
    display: flex;
    gap: 8px;
}

.range-inputs .input-group {
    flex: 1;
    margin-bottom: 0;
}

.range-inputs .input-group label {
    font-size: 10px;
}

.range-inputs .input-group input {
    padding: 4px 8px;
    font-size: 11px;
}

/* 频率单位选择器 */
.freq-unit-selector {
    display: flex;
    align-items: center;
    gap: 10px;
    margin-top: 8px;
    padding-top: 8px;
    border-top: 1px solid #e2e8f0;
}

.freq-unit-selector label:first-child {
    font-size: 11px;
    color: #1a3c6e;
    font-weight: 600;
}

.radio-label {
    display: flex;
    align-items: center;
    gap: 4px;
    font-size: 11px;
    color: #333;
    cursor: pointer;
}

.radio-label input[type="radio"] {
    width: 12px;
    height: 12px;
    cursor: pointer;
}

canvas {
    display: block;
    width: 100%;
    height: 100%;
    background: #fff;
    border-radius: 6px;
}

.ctrl-area {
    flex: 1;
    min-width: 280px;
    background: #f2f6fd;
    border-radius: 8px;
    padding: 15px;
    border: 1px solid #dde5ed;
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.ctrl-area h3 {
    color: #1a3c6e;
    font-size: 16px;
    border-bottom: 2px solid #d4a853;
    padding-bottom: 4px;
    margin-bottom: 2px;
}

.func-box {
    background: #fff;
    border-radius: 6px;
    padding: 10px;
    border: 1px solid #e2e8f0;
}

.func-box h4 {
    color: #1a3c6e;
    font-size: 13px;
    margin-bottom: 8px;
}

.input-group {
    margin-bottom: 6px;
}

.input-group label {
    display: block;
    font-size: 12px;
    font-weight: 600;
    color: #333;
    margin-bottom: 2px;
}

.input-group input,
.input-group select {
    width: 100%;
    padding: 6px 10px;
    border: 1px solid #ccc;
    border-radius: 4px;
    font-size: 13px;
    background: #f8f9fa;
    transition: border-color 0.2s;
}

.input-group input:focus,
.input-group select:focus {
    outline: none;
    border-color: #1a3c6e;
    background: #fff;
}

.input-group .hint {
    font-size: 10px;
    color: #888;
    margin-top: 1px;
}

.range-row {
    display: flex;
    gap: 8px;
}

.range-row .input-group {
    flex: 1;
}

.btn-row {
    margin-top: 4px;
    display: flex;
    gap: 8px;
}

.btn {
    padding: 8px 12px;
    border: none;
    border-radius: 6px;
    font-size: 13px;
    font-weight: 600;
    cursor: pointer;
    transition: background 0.2s;
}

.btn-primary {
    background: #1a3c6e;
    color: #fff;
}

.btn-primary:hover {
    background: #143049;
}

.btn-secondary {
    background: #e2e8f0;
    color: #333;
}

.btn-secondary:hover {
    background: #cbd5e0;
}

.btn-danger {
    background: #c53030;
    color: #fff;
}

.btn-danger:hover {
    background: #9b2c2c;
}

.signal-controls {
    display: flex;
    gap: 8px;
    margin-bottom: 8px;
}

.signal-controls .btn {
    flex: 1;
}

.formula-box {
    background: #f8f9fa;
    border-radius: 6px;
    padding: 12px 14px;
    border: 1px solid #e2e8f0;
    font-family: 'Cambria Math', 'Times New Roman', 'Courier New', serif;
    font-size: 18px;
    line-height: 1.8;
    min-height: 56px;
    color: #1a3c6e;
}

/* 排版公式：根式 */
.m-sqrt {
    display: inline-flex;
    align-items: flex-start;
    margin: 0 1px;
}
.m-sqrt-sym {
    font-size: 1.05em;
    line-height: 1;
}
.m-sqrt-body {
    border-top: 1.5px solid currentColor;
    padding: 0 3px;
    margin-top: 0.14em;
}

/* 排版公式：分数 */
.m-frac {
    display: inline-flex;
    flex-direction: column;
    text-align: center;
    vertical-align: middle;
    margin: 0 2px;
}
.m-frac-num {
    padding: 0 4px;
}
.m-frac-den {
    border-top: 1.5px solid currentColor;
    padding: 0 4px;
}

/* 排版公式：上标（幂次） */
.formula-box sup {
    font-size: 0.68em;
}

.footer {
    padding: 10px 30px 15px;
    text-align: center;
}

.footer-divider {
    height: 2px;
    background: linear-gradient(90deg, transparent, #1a3c6e 20%, #d4a853 50%, #1a3c6e 80%, transparent);
    margin-bottom: 8px;
}

.footer-text {
    color: #1a3c6e;
    font-size: 13px;
    font-weight: 500;
    letter-spacing: 3px;
}

@media (max-width: 900px) {
    .main-row {
        flex-direction: column;
    }
    
    .plot-area {
        min-width: auto;
    }
}