* { 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 { padding: 8px 25px 0; }
.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; }
.plot-box canvas {
    width: 100%; height: auto; background: white;
    border-radius: 5px; box-shadow: 0 2px 6px rgba(0,0,0,0.06);
}

/* ω 探索条 */
.omega-bar {
    display: flex; align-items: center; gap: 12px; padding: 12px 25px;
    background: #f8f9fa; border-top: 1px solid #e0e0e0; margin-top: 8px;
}
.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: 900px) {
    .control-panel { flex-direction: column; }
}
@media (max-width: 600px) {
    body { padding: 5px; }
    .header { padding: 15px 20px; }
    .header h1 { font-size: 20px; letter-spacing: 2px; }
}