/* 全局样式 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
/* 添加超小屏幕优化 */
@media (max-width: 360px) {
    body {
        padding: 5px;
    }
    
    .card {
        padding: 12px 10px;
    }
    
    .header {
        margin-bottom: 15px;
    }
    
    .header h1 {
        font-size: 1.4rem;
        margin-bottom: 2px;
    }
    
    .subtitle {
        font-size: 0.75rem;
    }
    
    .form-section {
        margin-bottom: 12px;
    }
    
    .input-group {
        margin-bottom: 12px;
    }
    
    .input-group label {
        font-size: 0.8rem;
        margin-bottom: 5px;
    }
    
    .input-wrapper input {
        padding: 10px 14px;
        padding-right: 35px;
        font-size: 0.9rem;
    }
    
    .unit {
        right: 14px;
        font-size: 0.75rem;
    }
    
    .button-group {
        margin-top: 12px;
    }
    
    .btn {
        padding: 10px 16px;
        font-size: 0.85rem;
        margin-bottom: 5px;
    }
    
    .result-section {
        margin-top: 15px;
    }
    
    .result-card {
        padding: 12px 10px;
    }
    
    .bmi-value {
        margin-bottom: 12px;
    }
    
    .bmi-value .label {
        font-size: 0.75rem;
        margin-bottom: 4px;
    }
    
    .bmi-value .value {
        font-size: 1.8rem;
    }
    
    .status-indicator {
        margin-bottom: 12px;
    }
    
    .status-badge {
        padding: 5px 10px;
        font-size: 0.75rem;
    }
    
    .advice-section {
        margin-bottom: 10px;
    }
    
    .advice-section h3 {
        font-size: 0.85rem;
        margin-bottom: 5px;
    }
    
    .advice-section p {
        font-size: 0.75rem;
        line-height: 1.25;
    }
    
    .bmi-ranges {
        margin-top: 12px;
        padding-top: 10px;
    }
    
    .bmi-ranges h3 {
        font-size: 0.8rem;
        margin-bottom: 8px;
    }
    
    .range-list {
        gap: 4px;
    }
    
    .range-item {
        padding: 5px 8px;
        font-size: 0.7rem;
    }
    
    .footer {
        margin-top: 15px;
    }
    
    .footer p {
        font-size: 0.7rem;
        margin-bottom: 2px;
    }
    
    .footer .copyright {
        font-size: 0.65rem;
    }
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 20px;
    color: #333;
}

.container {
    width: 100%;
    max-width: 480px;
    margin: 0 auto;
}

/* 主卡片样式 */
.card {
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(20px);
    border-radius: 20px;
    padding: 40px 30px;
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.1);
    border: 1px solid rgba(255, 255, 255, 0.2);
    transition: all 0.3s ease;
}

.card:hover {
    transform: translateY(-5px);
    box-shadow: 0 25px 50px rgba(0, 0, 0, 0.15);
}

/* 头部样式 */
.header {
    text-align: center;
    margin-bottom: 40px;
}

.header h1 {
    font-size: 2.5rem;
    font-weight: 300;
    color: #2c3e50;
    margin-bottom: 10px;
    letter-spacing: -0.5px;
}

.subtitle {
    color: #7f8c8d;
    font-size: 1rem;
    font-weight: 400;
}

/* 表单样式 */
.form-section {
    margin-bottom: 30px;
}

.input-group {
    margin-bottom: 25px;
}

.input-group label {
    display: block;
    margin-bottom: 8px;
    font-weight: 500;
    color: #2c3e50;
    font-size: 0.95rem;
}

.input-wrapper {
    position: relative;
    display: flex;
    align-items: center;
}

.input-wrapper input {
    width: 100%;
    padding: 16px 20px;
    padding-right: 50px;
    border: 2px solid #e9ecef;
    border-radius: 12px;
    font-size: 1.1rem;
    background: #fff;
    transition: all 0.3s ease;
    outline: none;
}

.input-wrapper input:focus {
    border-color: #667eea;
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
}

.input-wrapper input::placeholder {
    color: #adb5bd;
}

.unit {
    position: absolute;
    right: 20px;
    color: #6c757d;
    font-weight: 500;
    font-size: 0.9rem;
}

/* 按钮样式 */
.button-group {
    display: flex;
    gap: 15px;
    margin-top: 30px;
}

.btn {
    flex: 1;
    padding: 16px 24px;
    border: none;
    border-radius: 12px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    outline: none;
}

.btn-primary {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 25px rgba(102, 126, 234, 0.3);
}

.btn-primary:active {
    transform: translateY(0);
}

.btn-secondary {
    background: #f8f9fa;
    color: #6c757d;
    border: 2px solid #e9ecef;
}

.btn-secondary:hover {
    background: #e9ecef;
    color: #495057;
}

/* 结果区域样式 */
.result-section {
    margin-top: 30px;
    animation: fadeInUp 0.5s ease;
}

.result-card {
    background: #f8f9fa;
    border-radius: 16px;
    padding: 30px;
    text-align: center;
}

.bmi-value {
    display: flex;
    flex-direction: column;
    align-items: center;
    margin-bottom: 25px;
}

.bmi-value .label {
    font-size: 0.9rem;
    color: #6c757d;
    margin-bottom: 8px;
}

.bmi-value .value {
    font-size: 3rem;
    font-weight: 300;
    color: #2c3e50;
    line-height: 1;
}

.status-indicator {
    margin-bottom: 25px;
}

.status-badge {
    display: inline-block;
    padding: 10px 20px;
    border-radius: 25px;
    font-weight: 600;
    font-size: 0.9rem;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

/* BMI状态颜色 */
.status-underweight {
    background: rgba(52, 152, 219, 0.1);
    color: #3498db;
    border: 2px solid rgba(52, 152, 219, 0.3);
}

.status-normal {
    background: rgba(46, 204, 113, 0.1);
    color: #2ecc71;
    border: 2px solid rgba(46, 204, 113, 0.3);
}

.status-overweight {
    background: rgba(243, 156, 18, 0.1);
    color: #f39c12;
    border: 2px solid rgba(243, 156, 18, 0.3);
}

.status-obese {
    background: rgba(231, 76, 60, 0.1);
    color: #e74c3c;
    border: 2px solid rgba(231, 76, 60, 0.3);
}

.advice-section h3 {
    font-size: 1.1rem;
    color: #2c3e50;
    margin-bottom: 12px;
    font-weight: 600;
}

.advice-section p {
    color: #5a6c7d;
    line-height: 1.6;
    font-size: 0.95rem;
}

/* BMI范围说明样式 */
.bmi-ranges {
    margin-top: 25px;
    padding-top: 20px;
    border-top: 1px solid #e9ecef;
}

.bmi-ranges h3 {
    font-size: 1rem;
    color: #2c3e50;
    margin-bottom: 15px;
    font-weight: 600;
    text-align: center;
}

.range-list {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 8px;
}

@media (max-width: 768px) {
    .range-list {
        grid-template-columns: 1fr 1fr;
        gap: 6px;
    }
}

.range-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 8px 12px;
    border-radius: 8px;
    font-size: 0.85rem;
    font-weight: 500;
}

.range-item.underweight {
    background: rgba(52, 152, 219, 0.1);
    color: #3498db;
}

.range-item.normal {
    background: rgba(46, 204, 113, 0.1);
    color: #2ecc71;
}

.range-item.overweight {
    background: rgba(243, 156, 18, 0.1);
    color: #f39c12;
}

.range-item.obese {
    background: rgba(231, 76, 60, 0.1);
    color: #e74c3c;
}

.range-label {
    font-weight: 600;
}

.range-value {
    font-weight: 500;
    opacity: 0.8;
}

/* 页脚样式 */
.footer {
    text-align: center;
    margin-top: 30px;
}

.footer p {
    color: rgba(255, 255, 255, 0.8);
    font-size: 0.85rem;
    font-weight: 300;
    margin-bottom: 5px;
}

.footer .copyright {
    font-size: 0.75rem;
    opacity: 0.7;
}

/* 动画效果 */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* 响应式设计 */
@media (max-width: 768px) {
    body {
        padding: 10px;
    }
    
    .card {
        padding: 20px 15px;
    }
    
    .header {
        margin-bottom: 25px;
    }
    
    .header h1 {
        font-size: 1.8rem;
        margin-bottom: 5px;
    }
    
    .subtitle {
        font-size: 0.9rem;
    }
    
    .form-section {
        margin-bottom: 20px;
    }
    
    .input-group {
        margin-bottom: 18px;
    }
    
    .button-group {
        flex-direction: column;
        margin-top: 20px;
    }
    
    .btn {
        margin-bottom: 8px;
        padding: 12px 20px;
    }
    
    .bmi-value .value {
        font-size: 2.2rem;
    }
    
    .result-card {
        padding: 20px 15px;
    }
    
    .advice-section {
        margin-bottom: 15px;
    }
    
    .advice-section h3 {
        font-size: 1rem;
        margin-bottom: 8px;
    }
    
    .advice-section p {
        font-size: 0.85rem;
        line-height: 1.4;
    }
}

@media (max-width: 480px) {
    body {
        padding: 8px;
    }
    
    .card {
        padding: 15px 12px;
    }
    
    .header {
        margin-bottom: 20px;
    }
    
    .header h1 {
        font-size: 1.6rem;
        margin-bottom: 3px;
    }
    
    .subtitle {
        font-size: 0.8rem;
    }
    
    .form-section {
        margin-bottom: 15px;
    }
    
    .input-group {
        margin-bottom: 15px;
    }
    
    .input-group label {
        font-size: 0.85rem;
        margin-bottom: 6px;
    }
    
    .input-wrapper input {
        padding: 12px 16px;
        padding-right: 40px;
        font-size: 0.95rem;
    }
    
    .unit {
        right: 16px;
        font-size: 0.8rem;
    }
    
    .button-group {
        margin-top: 15px;
    }
    
    .btn {
        padding: 12px 18px;
        font-size: 0.9rem;
        margin-bottom: 6px;
    }
    
    .result-section {
        margin-top: 20px;
    }
    
    .result-card {
        padding: 15px 12px;
    }
    
    .bmi-value {
        margin-bottom: 15px;
    }
    
    .bmi-value .label {
        font-size: 0.8rem;
        margin-bottom: 5px;
    }
    
    .bmi-value .value {
        font-size: 2rem;
    }
    
    .status-indicator {
        margin-bottom: 15px;
    }
    
    .status-badge {
        padding: 6px 12px;
        font-size: 0.8rem;
    }
    
    .advice-section {
        margin-bottom: 12px;
    }
    
    .advice-section h3 {
        font-size: 0.9rem;
        margin-bottom: 6px;
    }
    
    .advice-section p {
        font-size: 0.8rem;
        line-height: 1.3;
    }
    
    .bmi-ranges {
        margin-top: 15px;
        padding-top: 12px;
    }
    
    .bmi-ranges h3 {
        font-size: 0.85rem;
        margin-bottom: 10px;
    }
    
    .range-list {
        grid-template-columns: 1fr;
        gap: 6px;
    }
    
    .range-item {
        padding: 6px 10px;
        font-size: 0.75rem;
    }
    
    .footer {
        margin-top: 20px;
    }
    
    .footer p {
        font-size: 0.75rem;
        margin-bottom: 3px;
    }
    
    .footer .copyright {
        font-size: 0.7rem;
    }
}

/* 输入验证样式 */
.input-error {
    border-color: #e74c3c !important;
    box-shadow: 0 0 0 3px rgba(231, 76, 60, 0.1) !important;
}

.error-message {
    color: #e74c3c;
    font-size: 0.8rem;
    margin-top: 5px;
    display: none;
}

.error-message.show {
    display: block;
}