* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: system-ui, -apple-system, 'Segoe UI', 'Roboto', 'Noto Sans', sans-serif;
}

/* 引入 Font Awesome 图标库 */
@import url('https://cdnjs.cloudflare.com/ajax/libs/font-awesome/6.0.0-beta3/css/all.min.css');

body {
    min-height: 100vh;
    background: linear-gradient(145deg, #e0f0ff 0%, #c8e2fc 100%);
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 1.5rem;
}

/* 主卡片容器 */
.card {
    max-width: 620px;
    width: 100%;
    background: rgba(255, 255, 255, 0.96);
    backdrop-filter: blur(2px);
    border-radius: 2.5rem;
    box-shadow: 0 25px 45px -12px rgba(0, 0, 0, 0.3), 0 4px 12px rgba(0, 0, 0, 0.05);
    overflow: hidden;
    transition: transform 0.2s ease;
    position: relative;
}

.card:hover {
    transform: translateY(-3px);
}

/* 返回首页按钮 */
.back-home-btn {
    position: absolute;
    top: 1rem;
    left: 1rem;
    display: flex;
    align-items: center;
    gap: 6px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    text-decoration: none;
    padding: 8px 16px;
    border-radius: 20px;
    font-size: 0.9rem;
    font-weight: 500;
    transition: all 0.3s ease;
    box-shadow: 0 2px 8px rgba(102, 126, 234, 0.3);
    z-index: 100;
}

.back-home-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(102, 126, 234, 0.5);
}

.back-home-btn i {
    font-size: 1rem;
}

/* 头部渐变区域 */
.hero {
    background: linear-gradient(135deg, #1d4e89 0%, #2b6a9f 100%);
    padding: 2rem 1.8rem 1.8rem;
    color: white;
    text-align: center;
}

.hero h1 {
    font-size: 1.9rem;
    font-weight: 700;
    letter-spacing: -0.3px;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.6rem;
    flex-wrap: wrap;
}

.hero h1 span {
    background: rgba(255, 255, 255, 0.2);
    padding: 0.2rem 0.7rem;
    border-radius: 60px;
    font-size: 0.9rem;
    font-weight: 500;
}

.hero p {
    margin-top: 0.7rem;
    opacity: 0.9;
    font-size: 0.95rem;
}

/* 主体内容 */
.content {
    padding: 2rem 1.8rem 2rem;
}

/* 输入组 */
.input-group {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    margin-bottom: 1.5rem;
}

.input-group label {
    font-weight: 600;
    color: #1e2f3e;
    font-size: 0.95rem;
    display: flex;
    align-items: center;
    gap: 0.4rem;
}

.input-group label i {
    font-style: normal;
    font-weight: 400;
    background: #eef3fc;
    padding: 0.1rem 0.4rem;
    border-radius: 30px;
    font-size: 0.75rem;
    color: #1d4e89;
}

.input-field {
    display: flex;
    align-items: center;
    background: #f8fafd;
    border: 1.5px solid #e2edf7;
    border-radius: 1.5rem;
    padding: 0.2rem 1rem;
    transition: all 0.2s;
}

.input-field:focus-within {
    border-color: #2b6a9f;
    box-shadow: 0 0 0 3px rgba(43, 106, 159, 0.2);
    background: white;
}

.input-field input {
    width: 100%;
    padding: 0.9rem 0;
    border: none;
    background: transparent;
    font-size: 1.1rem;
    font-weight: 500;
    color: #0a2a3b;
    outline: none;
}

.input-field input::placeholder {
    color: #b9cfec;
    font-weight: 400;
    font-size: 0.95rem;
}

.input-unit {
    font-weight: 600;
    color: #5c7f9c;
    background: #eef3fc;
    padding: 0.2rem 0.7rem;
    border-radius: 2rem;
    font-size: 0.85rem;
    margin-left: 0.5rem;
}

/* 按钮 */
.calc-btn {
    width: 100%;
    background: linear-gradient(100deg, #1d4e89, #2f7fb5);
    border: none;
    border-radius: 3rem;
    padding: 1rem;
    color: white;
    font-size: 1.2rem;
    font-weight: 700;
    margin-top: 0.8rem;
    margin-bottom: 1.8rem;
    cursor: pointer;
    transition: all 0.2s;
    box-shadow: 0 8px 18px rgba(29, 78, 137, 0.3);
    letter-spacing: 0.5px;
}

.calc-btn:hover {
    background: linear-gradient(100deg, #103e68, #23658f);
    transform: scale(0.98);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.2);
}

.calc-btn:active {
    transform: scale(0.96);
}

/* 结果卡片区域 */
.result-area {
    background: #f0f6fe;
    border-radius: 1.8rem;
    padding: 1.2rem 1.4rem;
    margin-bottom: 1.8rem;
    border: 1px solid rgba(43, 106, 159, 0.15);
}

.bmi-number {
    display: flex;
    align-items: baseline;
    justify-content: space-between;
    flex-wrap: wrap;
    margin-bottom: 0.8rem;
}

.bmi-number .label {
    font-weight: 600;
    color: #1f4e6e;
    font-size: 1rem;
}

.bmi-number .value {
    font-size: 2.6rem;
    font-weight: 800;
    color: #134b73;
    line-height: 1;
    transition: color 0.3s ease;
}

/* BMI状态颜色 - 偏瘦（蓝色警示） */
.bmi-number .value.underweight {
    color: #3b82f6;
}

.status-badge.underweight {
    background: linear-gradient(135deg, #dbeafe 0%, #bfdbfe 100%);
    color: #1e40af;
    box-shadow: 0 2px 8px rgba(59, 130, 246, 0.2);
}

.result-area.underweight {
    background: linear-gradient(135deg, #eff6ff 0%, #dbeafe 100%);
    border-color: rgba(59, 130, 246, 0.3);
}

/* BMI状态颜色 - 正常（绿色健康） */
.bmi-number .value.normal {
    color: #10b981;
}

.status-badge.normal {
    background: linear-gradient(135deg, #d1fae5 0%, #a7f3d0 100%);
    color: #065f46;
    box-shadow: 0 2px 8px rgba(16, 185, 129, 0.2);
}

.result-area.normal {
    background: linear-gradient(135deg, #ecfdf5 0%, #d1fae5 100%);
    border-color: rgba(16, 185, 129, 0.3);
}

/* BMI状态颜色 - 超重（橙色警告） */
.bmi-number .value.overweight {
    color: #f59e0b;
}

.status-badge.overweight {
    background: linear-gradient(135deg, #fef3c7 0%, #fde68a 100%);
    color: #92400e;
    box-shadow: 0 2px 8px rgba(245, 158, 11, 0.3);
}

.result-area.overweight {
    background: linear-gradient(135deg, #fffbeb 0%, #fef3c7 100%);
    border-color: rgba(245, 158, 11, 0.3);
}

/* BMI状态颜色 - 肥胖（红色危险） */
.bmi-number .value.obese {
    color: #ef4444;
    animation: pulse-warning 2s ease-in-out infinite;
}

.status-badge.obese {
    background: linear-gradient(135deg, #fee2e2 0%, #fecaca 100%);
    color: #991b1b;
    box-shadow: 0 2px 12px rgba(239, 68, 68, 0.4);
    animation: pulse-badge 2s ease-in-out infinite;
}

.result-area.obese {
    background: linear-gradient(135deg, #fef2f2 0%, #fee2e2 100%);
    border-color: rgba(239, 68, 68, 0.4);
    box-shadow: 0 4px 16px rgba(239, 68, 68, 0.15);
}

@keyframes pulse-warning {
    0%, 100% {
        opacity: 1;
    }
    50% {
        opacity: 0.85;
    }
}

@keyframes pulse-badge {
    0%, 100% {
        transform: scale(1);
        box-shadow: 0 2px 12px rgba(239, 68, 68, 0.4);
    }
    50% {
        transform: scale(1.02);
        box-shadow: 0 4px 16px rgba(239, 68, 68, 0.6);
    }
}

.bmi-number .unit {
    font-size: 1rem;
    font-weight: 500;
    color: #5a7e9c;
}

.assessment {
    background: white;
    border-radius: 2rem;
    padding: 0.8rem 1.2rem;
    margin-top: 0.6rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    flex-wrap: wrap;
    gap: 0.6rem;
    box-shadow: 0 1px 3px rgba(0,0,0,0.05);
}

.status-badge {
    font-weight: 700;
    font-size: 1.15rem;
    padding: 0.3rem 1rem;
    border-radius: 40px;
    background: #eef2fa;
    color: #1e4663;
}

.status-desc {
    font-size: 0.85rem;
    color: #2c5a7a;
}

/* 健康方案专区 */
.plan-section {
    background: #ffffff;
    border-radius: 1.8rem;
    padding: 1.2rem 1.4rem;
    border: 1px solid #dde9f5;
    box-shadow: 0 6px 12px -8px rgba(0, 0, 0, 0.05);
}

.plan-title {
    font-size: 1.3rem;
    font-weight: 700;
    color: #1f5a3e;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    margin-bottom: 1rem;
    border-left: 5px solid #2f9e68;
    padding-left: 0.9rem;
}

.plan-title::before {
    content: "🌿";
    font-size: 1.3rem;
}

.ideal-weight {
    background: #eef7e9;
    padding: 0.7rem 1rem;
    border-radius: 1.2rem;
    margin-bottom: 1.2rem;
    font-size: 0.9rem;
    color: #1c5a2d;
    font-weight: 500;
}

.advice-block {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.advice-item {
    display: flex;
    gap: 0.7rem;
    align-items: flex-start;
}

.advice-icon {
    font-size: 1.3rem;
    min-width: 32px;
    text-align: center;
}

.advice-text {
    color: #2c3e45;
    line-height: 1.4;
    font-size: 0.92rem;
}

.advice-text strong {
    color: #1f5e3a;
    font-weight: 700;
}

.error-message {
    color: #c23d2e;
    background: #ffe9e5;
    padding: 0.9rem;
    border-radius: 1.2rem;
    text-align: center;
    font-weight: 500;
}

hr {
    margin: 1rem 0;
    border: none;
    height: 1px;
    background: #d9e5f0;
}

footer {
    font-size: 0.7rem;
    text-align: center;
    color: #6f8eaa;
    padding: 1rem 1rem 1.2rem;
    border-top: 1px solid #e2edf7;
}

@media (max-width: 480px) {
    .content {
        padding: 1.5rem;
    }
    .hero h1 {
        font-size: 1.5rem;
    }
    .bmi-number .value {
        font-size: 2rem;
    }
    .plan-title {
        font-size: 1.15rem;
    }
}