/* ===========================================================
   页面骨架：顶栏、移动端抽屉、Hero、内容区、功能卡、贡献者、页脚
   =========================================================== */

/* ---------- Top App Bar ---------- */
#top-app-bar {
    background-color: var(--md-sys-color-surface-container);
    position: sticky;
    top: 0;
    z-index: 100;
    transition: background-color var(--transition-duration) var(--transition-timing);
}
#top-app-bar.is-scrolled {
    background-color: var(--md-sys-color-surface-container-high);
    box-shadow: 0 2px 6px -1px rgba(0,0,0,0.1);
}
.nav-container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 4rem;
}
.nav-logo {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}
.nav-logo-img {
    width: 2rem;
    height: 2rem;
    border-radius: 50%;
}
.nav-links-desktop {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}
@media (max-width: 767px) {
    .nav-links-desktop { display: none; }
}
.nav-mobile-toggle {
    display: none;
}
@media (max-width: 767px) {
    .nav-mobile-toggle { display: flex; }
}

/* ---------- Mobile Navigation ---------- */
#mobile-nav-scrim {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0,0,0,0.4);
    z-index: 198;
    opacity: 0;
    pointer-events: none;
    transition: opacity var(--transition-duration) var(--transition-timing);
    will-change: opacity;
}
#mobile-nav-scrim.is-open {
    opacity: 1;
    pointer-events: auto;
}

#mobile-nav-drawer {
    position: fixed;
    top: 0;
    left: 0;
    width: 80%;
    max-width: 320px;
    height: 100%;
    background-color: var(--md-sys-color-surface-container-high);
    z-index: 199;
    padding: 1rem;
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    transform: translateX(-100%);
    opacity: 0;
    transition: transform var(--transition-duration) var(--transition-timing),
                opacity var(--transition-duration) var(--transition-timing),
                background-color var(--transition-duration) var(--transition-timing);
    will-change: transform, opacity;
}
#mobile-nav-drawer.is-open {
    transform: translateX(0);
    opacity: 1;
}

.mobile-nav-header {
    padding: 1rem 0.5rem;
}
.mobile-nav-link {
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 0.75rem 1rem;
    border-radius: 1.5rem;
    font-size: var(--md-sys-typescale-body-large-size);
    color: var(--md-sys-color-on-surface-variant);
    transition: background-color var(--transition-duration) var(--transition-timing);
    cursor: pointer;
    background: none;
    border: none;
    width: 100%;
    text-align: left;
}
.mobile-nav-link:hover {
    background-color: color-mix(in srgb, var(--md-sys-color-on-surface), transparent 90%);
}

/* ---------- Hero ---------- */
.hero-section {
    background-color: var(--md-sys-color-surface-container-low);
    padding: 4rem 0;
    text-align: center;
    transition: background-color var(--transition-duration) var(--transition-timing);
}
.hero-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 2rem;
}
.hero-logo {
    width: 7rem;
    height: 7rem;
    margin-bottom: -1rem;
}
.hero-subtitle {
    color: var(--md-sys-color-on-surface-variant);
    max-width: 35ch;
    margin: -1rem auto 0;
}
.hero-actions {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 1rem;
    margin-top: 1rem;
}

/* ---------- Content Sections ---------- */
.content-section {
    padding: 4rem 0;
}
.section-title {
    text-align: center;
    margin-bottom: 3rem;
}

/* ---------- Features ---------- */
.feature-card {
    display: flex;
    flex-direction: column;
}
.feature-icon {
    width: 3rem;
    height: 3rem;
    margin-bottom: 1rem;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: var(--md-sys-color-primary-container);
    color: var(--md-sys-color-on-primary-container);
}
.feature-icon > .material-symbols-outlined { font-size: 1.5rem; }
.feature-card h3 {
    margin-bottom: 0.75rem;
}

/* ---------- Contributors ---------- */
.contributor-card {
    text-align: center;
}
.contributor-avatar {
    width: 6rem;
    height: 6rem;
    border-radius: 50%;
    margin: 0 auto 0.75rem;
    transition: transform var(--transition-duration) var(--transition-timing);
}
.contributor-card a:hover .contributor-avatar {
    transform: scale(1.05);
}
.contributor-name {
    color: var(--md-sys-color-on-surface-variant);
}
.contributor-card .chips-group {
    margin-top: 0.5rem;
}
#contributors table {
    width: 100%;
    border-collapse: separate;
    border-spacing: 0 0.9rem;
}
#contributors table td {
    padding: 0.25rem 0.35rem;
}
#contributors table td img {
    display: inline-block;
    border-radius: 50%;
    object-fit: cover;
}

/* ---------- Footer ---------- */
.site-footer {
    background-color: var(--md-sys-color-surface-container-high);
    color: var(--md-sys-color-on-surface-variant);
    padding: 3rem 0;
}
.footer-content {
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    align-items: center;
    gap: 2rem;
    text-align: center;
}
@media (min-width: 768px) {
    .footer-content {
        flex-direction: row;
        text-align: left;
    }
}
.footer-subtitle {
    margin-top: 0.25rem;
}
.footer-socials {
    display: flex;
    gap: 0.5rem;
}
.footer-socials .btn--icon {
    font-size: 1.25rem;
}
.site-footer .divider {
    margin-top: 2rem;
    margin-bottom: 2rem;
}
.footer-copyright {
    text-align: center;
}