:root {
    --container-max: 1320px;
    --container-wide: 1480px;
    --container-reading: 840px;
    --section-gap: 160px;
    --hero-gap: 220px;
    --grid-gap: 32px;
    --content-gap: 56px;
}

/* Container */
.ls-container {
    width: min(1320px, 92vw);
    margin: auto;
    position: relative;
}
.ls-container-wide {
    width: min(1480px, 94vw);
    margin: auto;
}
.ls-reading {
    width: min(840px, 92vw);
    margin: auto;
}

/* Section */
.ls-section {
    padding: 160px 0;
    position: relative;
}

/* Section Header */
.section-header {
    display: flex;
    flex-direction: column;
    align-items: center;
    text-align: center;
    margin-bottom: 72px;
}
.section-title {
    font-size: clamp(38px, 4vw, 64px);
    font-family: var(--font-primary);
    margin-bottom: 18px;
}
.section-subtitle {
    max-width: 760px;
    line-height: 1.8;
    opacity: 0.82;
}

/* Grid utilities */
.grid-2 {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 32px;
}
.grid-3 {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 32px;
}
.grid-4 {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 28px;
}

/* Hero */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
    overflow: hidden;
}

/* Footer */
.footer {
    padding: 120px 0 80px;
    border-top: 1px solid rgba(255, 255, 255, 0.06);
}

/* ===== 排版等级 (Typography Scale) ===== */
.card-title {
    font-size: 22px;
    font-weight: 600;
    line-height: 1.3;
}
.body-title {
    font-size: 18px;
    font-weight: 500;
    line-height: 1.5;
}
.caption {
    font-size: 14px;
    font-weight: 400;
    opacity: 0.75;
    line-height: 1.6;
}

/* ===== 媒体框架 (Image/Media Frame) ===== */
.media-frame {
    overflow: hidden;
    border-radius: 24px;
    position: relative;
}
.media-frame img,
.media-frame video {
    width: 100%;
    height: 100%;
    object-fit: cover;
    display: block;
}

/* ===== Section 变体 ===== */
.section-small {
    padding: 56px 0;
}
.section-large {
    padding: 140px 0;
}

/* ===== Grid 自适应 ===== */
.grid-auto {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--grid-gap, 32px);
}

/* ===== 响应式 Grid 坍塌（移动端单列） ===== */
@media (max-width: 768px) {
    .grid-2,
    .grid-3,
    .grid-4 {
        grid-template-columns: 1fr;
    }
}