:root {
    --green: #006633;
    --light-green: #009944;
    --yellow: #f9e11a;
    --white: #fff;
    --gray: #f6f7f9;
    --shadow: 0 8px 32px rgba(0,0,0,0.10);
}
body {
    font-family: 'Noto Sans SC', 'Microsoft YaHei', 'Segoe UI', Arial, sans-serif;
    margin: 0;
    background: var(--gray);
    color: #222;
}
header {
    background: linear-gradient(90deg, var(--green) 0%, var(--light-green) 100%);
    color: var(--white);
    padding: 36px 0 18px 0;
    text-align: center;
    letter-spacing: 2px;
    box-shadow: var(--shadow);
    position: relative;
}
header::after {
    content: "";
    display: block;
    width: 120px;
    height: 4px;
    background: linear-gradient(90deg, var(--yellow) 0%, var(--light-green) 100%);
    margin: 18px auto 0 auto;
    border-radius: 2px;
}
nav {
    background: var(--light-green);
    display: flex;
    justify-content: center;
    box-shadow: 0 2px 12px #e0e0e0;
    position: sticky;
    top: 0;
    z-index: 10;
}
nav .tab {
    color: var(--white);
    padding: 18px 40px;
    cursor: pointer;
    font-size: 20px;
    border: none;
    background: none;
    outline: none;
    transition: background 0.2s, color 0.2s, box-shadow 0.2s;
    font-family: inherit;
    position: relative;
    text-decoration: none;
    display: inline-block;
    text-align: center;
}
nav .tab.active, nav .tab:hover {
    background: var(--yellow);
    color: var(--green);
    font-weight: bold;
    box-shadow: 0 4px 16px #e0e0e0;
}
nav .tab.active::after {
    content: "";
    display: block;
    margin: 6px auto 0 auto;
    width: 32px;
    height: 4px;
    background: var(--green);
    border-radius: 2px;
    animation: tab-underline 0.4s;
}
@keyframes tab-underline {
    from { width: 0; opacity: 0; }
    to { width: 32px; opacity: 1; }
}
main {
    max-width: 1000px;
    margin: 40px auto;
    background: var(--white);
    border-radius: 18px;
    box-shadow: var(--shadow);
    padding: 48px 56px;
    min-height: 520px;
    animation: fadein 0.7s;
}
@keyframes fadein {
    from { opacity: 0; transform: translateY(40px);}
    to { opacity: 1; transform: none;}
}
section { display: none; }
section.active { display: block; }
h2 {
    color: var(--green);
    font-size: 2.1em;
    margin-top: 0;
    letter-spacing: 1px;
}
.highlight {
    color: var(--yellow);
    background: var(--green);
    padding: 2px 8px;
    border-radius: 6px;
    font-weight: bold;
}
.card-list {
    display: flex;
    flex-wrap: wrap;
    gap: 32px;
    margin: 32px 0;
}
.card {
    background: linear-gradient(120deg, #f9fbe7 0%, #e0f2f1 100%);
    border-radius: 12px;
    box-shadow: 0 2px 12px #e0e0e0;
    padding: 28px 24px;
    flex: 1 1 260px;
    min-width: 220px;
    max-width: 320px;
    transition: transform 0.2s;
}
.card:hover {
    transform: translateY(-8px) scale(1.03);
    box-shadow: 0 8px 32px #b2dfdb;
}
.card-title {
    color: var(--green);
    font-size: 1.2em;
    margin-bottom: 8px;
}
.card-desc {
    color: #444;
    font-size: 1em;
}
/* 邮资计算器样式 */
.calc-form {
    background: #f1f8e9;
    border-radius: 12px;
    padding: 32px 24px;
    box-shadow: 0 2px 12px #e0e0e0;
    max-width: 480px;
    margin: 0 auto 32px auto;
}
.calc-form label {
    font-weight: bold;
    color: var(--green);
    margin-top: 12px;
    display: block;
}
.calc-form input, .calc-form select {
    padding: 10px;
    font-size: 17px;
    margin: 8px 0 18px 0;
    border-radius: 6px;
    border: 1px solid #b2dfdb;
    width: 100%;
    box-sizing: border-box;
}
.calc-form button {
    display: block;
    margin: 18px auto 0 auto; /* 上间距18px，左右自动居中 */
    background: var(--green);
    color: var(--yellow);
    border: none;
    padding: 12px 32px;
    border-radius: 6px;
    font-size: 18px;
    cursor: pointer;
    margin-top: 8px;
    font-weight: bold;
    transition: background 0.2s, color 0.2s;
}
.calc-form button:hover {
    background: var(--yellow);
    color: var(--green);
}
#result {
    margin-top: 18px;
    font-size: 20px;
    font-weight: bold;
    color: var(--green);
    text-align: center;
}
.fee-table {
    width: 100%;
    border-collapse: collapse;
    margin-top: 24px;
    background: #f9fbe7;
    border-radius: 8px;
    overflow: hidden;
    font-size: 12px;
}
.fee-table th, .fee-table td {
    border: 1px solid #b2dfdb;
    padding: 6px 8px;
    text-align: center;
}
.fee-table th {
    background: #e0f2f1;
    color: var(--green);
}
/* 响应式 */
@media (max-width: 900px) {
    main { padding: 18px 2vw; }
    .card-list { flex-direction: column; gap: 18px;}
}
@media (max-width: 600px) {
    nav .tab { padding: 10px 8px; font-size: 15px; }
    main { padding: 8px 2vw; }
    .calc-form { padding: 18px 6px; }
}
footer {
    text-align: center;
    color: #888;
    padding: 32px 0 18px 0;
    background: var(--gray);
    font-size: 16px;
    margin-top: 40px;
    letter-spacing: 1px;
}
a {
    color: var(--green);
    text-decoration: underline;
    transition: color 0.2s;
}
a:hover {
    color: var(--yellow);
}

.download-list {
    font-size: 1.1em;
    list-style-type: disc;
    padding-left: 24px;
    margin-top: 16px;
}

/* 下载列表样式 */
.download-list li {
    margin-bottom: 12px;      /* 每行之间的间隔 */
    line-height: 1.7em;       /* 控制文字行距 */
}

.download-list a {
    color: #00754b;           /* 邮政绿色风格 */
    text-decoration: none;
    transition: color 0.2s ease, padding-left 0.2s ease;
}

.download-list a:hover {
    color: #009f60;            /* 悬停时更亮的绿色 */
    padding-left: 6px;         /* 悬停时轻微右移 */
}

.download-note {
    margin-top: 28px;
    color: #777;
    font-size: 0.95em;
    font-style: italic;
}