:root {
    --ut-dark-gray: #434a54;  /* UT 深灰 */
    --ut-dark-gray-rgb: 67, 74, 84;
    --ut-light-gray: #a2a9b5;  /* UI 浅灰 */

    --soft-white: #f8f9fa;
    --soft-black: #212529;
    --soft-gray: #868e96;
}

/* ======================================== 通用 ======================================== */

body {
    font-family: system-ui, sans-serif;
    font-size: 18px;
    background-color: var(--soft-white);
    color: var(--soft-black);

    min-height: 100vh;
    margin: 0;
    display: flex;
    flex-direction: column;
}

nav, section, footer {
    padding-block: 1rem;
}

article {
    max-width: 768px;  /* 与 container 窄屏下一致 */
    margin: 0 auto;
    padding-inline: 2rem;  /* 横向最小边距，与 container 一致 */
    padding-block: 1rem;
}

a {
    color: inherit;
}
.no-link-underline a {
    text-decoration: none;
}

p {
    line-height: 1.6;
}
article p {
    line-height: unset;
}

/* ------------------------------ Container ------------------------------ */

.container {
    max-width: 1200px;
    margin: 0 auto;  /* 居中 */
    padding-inline: 2rem;  /* 横向最小边距 */
    padding-block: 1rem;

    display: flex;
    justify-content: space-between;
    flex-wrap: wrap;
    align-items: center;
    gap: 2rem;
    /* border: 1px dashed; */

    @media (max-width: 1200px) {
        max-width: 768px;
        flex-direction: column;
    }
}

.container.reverse {
    flex-direction: row-reverse;

    @media (max-width: 1200px) {
        flex-direction: column;
    }
}

/* ------------------------------ Block ------------------------------ */

.block {
    min-width: 350px;
    display: flex;
    flex-direction: column;
    flex: 1 1;
    /* border: 1px dashed; */

    @media (max-width: 1200px) {
        min-width: unset;
        max-width: unset;
        width: 100%;
        margin: 0 auto;
        flex: 1;
    }
}

.block>*:first-child {
    margin-top: 0;
}

.block>*:last-child {
    margin-bottom: 0;
}

/* ------------------------------ Bullet ------------------------------ */

span.bullet {
    display: inline-block;
    height: 1em;
    width: 1em;
    margin-right: 0.4em;
    vertical-align: -0.17em;
}

span.bullet img {
    width: 100%;
    height: 100%;
    object-fit: contain;
    filter: drop-shadow(0 0 0.1em rgba(0, 0, 0, 0.3));
}

/* ======================================== nav 区 ======================================== */

nav {
    background-color: var(--ut-dark-gray);
    color: var(--soft-white);
}

nav .container {
    justify-content: space-between;
    font-size: 1.5rem;

    @media (max-width: 1200px) {
        max-width: 768px;
        flex-direction: row;
    }
}

nav a {
    text-decoration: none;
}

/* ======================================== hero 区 ======================================== */

section.hero {
    background-color: var(--ut-dark-gray);
    color: var(--soft-white);
    padding-block: 2rem;
    overflow: hidden;  /* 服务 hero 图 */

    @media (max-width: 1200px) {
        padding-block: 1rem;
    }
}

section.hero .container {
    flex-wrap: nowrap;  /* 希望 hero 图挤压左侧文本而不是换行 */
}

/* ------------------------------ App 信息 ------------------------------ */

section.hero .block.app-info {
    gap: 2rem;
}
section.hero .block.app-info *{
    margin-block: 0;
}

section.hero .block.app-info .app-title {
    display: flex;
    gap: 1.5rem;
    align-items: center
}

section.hero .block.app-info .app-title img {
    height: 80px;
}

section.hero .block.app-info h1 {
    font-size: 2.5rem;

    @media (max-width: 500px) {
        font-size: 2rem;
    }
}

section.hero .block.app-info .app-download {
    display: flex;
    gap: 1rem;
    align-items: center;
}
section.hero .block.app-info .app-download img {
    height: 60px;
    vertical-align: -0.3rem;
}
section.hero .block.app-info figcaption {
    font-size: 0.75em;
    font-style: italic;
    color: #bbb;
    line-height: 1.7em;
}

/* ------------------------------ Hero 图 ------------------------------ */

section.hero .block.hero-image {
    flex: 0 0 700px;

    @media (max-width: 1200px) {
        flex: 0 1 auto !important;
    }
}

section.hero .block.hero-image img {
    display: block;
    margin: 0 auto;
    object-fit: contain;
    width: 100%;
}

/* ======================================== 主区域 ======================================== */

/* ------------------------------ product-cards ------------------------------ */

.container.product-cards {
    align-items: flex-start;
}
.container.product-cards .block {
    flex-direction: row;
    gap: 1rem;
}

.container.product-cards .product-icon {
    width: 80px;
    flex-shrink: 0;
}
.container.product-cards .product-icon img {
    display: block;
    margin: 0 auto;
    object-fit: contain;
    width: 100%;
}

.container.product-cards .product-info {
    display: flex;
    flex-direction: column;    
    gap: 0.8rem;
}
.container.product-cards .product-info * {
    margin-block: 0;
}
.container.product-cards .product-info h3 a {
    text-decoration: none;
}

/* ------------------------------ feature-cards ------------------------------ */

.container.feature-cards {
    align-items: flex-start;
}
.container.feature-cards .block {
    gap: 1rem;
}

.container.feature-cards .block * {
    margin-block: 0;
}

/* ------------------------------ feature ------------------------------ */

.container.feature {
    flex-wrap: nowrap;
    padding-block: 2rem;  /* 因为图片可能有内部空白，所以需要额外垂直间距来区分不同 feature 行 */
}
.container.feature .block {
    gap: 1.5rem;
}

.container.feature .block * {
    margin-block: 0;
}
.container.feature .block.showcase {
    flex: 0 0 700px;

    @media (max-width: 1200px) {
        flex: 0 1 auto;
    }
}
.container.feature .block.showcase img {
    display: block;
    margin: 0 auto;
    object-fit: contain;
    width: 100%;
}
.container.feature > .block > ul,
.container.feature > .block > div {
    display: flex;
    flex-direction: column;
    gap: 0.7em;
    line-height: 1.5;
}
.container.feature ul {
    padding-inline-start: 1.1em;
}

.container.feature.no-showcase {
    max-width: 800px;
}
.container.feature.no-showcase h3 {
    text-align: center;

    @media (max-width: 1200px) {
        text-align:start;
    }
}

/* ------------------------------ support ------------------------------ */

.container.support {
    align-items: flex-start;
}
.container.support .block * {
    margin-block: 0;
}
.container.support .block h2 {
    margin-bottom: 1.5rem;
}
.container.support .block.faqs h3 {
    margin-bottom: 0.9rem;
    line-height: 1.5;
    font-size: 20px;
}
.container.support .block.faqs h3:not(:first-of-type) {
    margin-top: 1.5rem;
}

/* ======================================== footer 区 ======================================== */

footer {
    background-color: var(--ut-light-gray);
    margin-top: auto;
    font-size: 16px;
}

footer a {
    text-decoration: none;
}

footer .block {
    margin: 0 auto;
    flex: 0 0 auto;
    min-width: unset;
}

/* ------------------------------ Links ------------------------------ */

footer .container.links {
    align-items: flex-start;
    justify-content: space-between;
    gap: 1rem;
}

footer .container.links .block {
    gap: 0.7rem;
}

/* ------------------------------ Copyright ------------------------------ */

footer .container.copyright {
    flex-direction: column;
    text-decoration: none;
    font-size: 14px;
    opacity: 0.6;
}