/* ===== CSS Variables - 低饱和度现代配色 ===== */
:root {
    --primary: #2D5F4F;
    --primary-light: #3D7A64;
    --primary-dark: #1E4035;
    --secondary: #5B7D72;
    --accent: #C4A35A;
    --accent-light: #D4B86A;
    --bg-main: #FAFBF9;
    --bg-card: #FFFFFF;
    --bg-section: #F0F4F1;
    --text-primary: #2A332D;
    --text-secondary: #5A6660;
    --text-muted: #8A9690;
    --border-light: #E2E8E4;
    --shadow-sm: 0 2px 8px rgba(45,95,79,0.06);
    --shadow-md: 0 4px 16px rgba(45,95,79,0.08);
    --shadow-lg: 0 8px 32px rgba(45,95,79,0.10);
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 20px;
    --radius-xl: 24px;
}

/* ===== Dark Mode ===== */
@media (prefers-color-scheme: dark) {
    :root {
        --primary: #5B9E84;
        --primary-light: #6DB599;
        --primary-dark: #3A6B56;
        --secondary: #7AA894;
        --accent: #C4A35A;
        --accent-light: #D4B774;
        --bg-main: #141715;
        --bg-card: #1C201E;
        --bg-section: #1A1E1C;
        --text-primary: #E2E6E3;
        --text-secondary: #A8B0AB;
        --text-muted: #6E7872;
        --border-light: #252B27;
        --shadow-sm: 0 2px 8px rgba(0,0,0,0.24);
        --shadow-md: 0 4px 16px rgba(0,0,0,0.32);
        --shadow-lg: 0 8px 32px rgba(0,0,0,0.40);
    }

    body {
        background-color: var(--bg-main);
        color: var(--text-primary);
    }

    /* Dark mode section alt */
    .section-alt {
        background-color: var(--bg-section);
    }

    /* Dark mode cards */
    .card, .feature-card, .major-body, .contact-item, .programs-table {
        background: var(--bg-card);
        border-color: var(--border-light);
    }

    /* Dark mode stat items */
    .stat-item {
        background: var(--bg-section);
    }

    /* Dark mode requirement box */
    .requirement-box {
        background: linear-gradient(135deg, rgba(91,158,132,0.08), rgba(91,158,132,0.03));
        border-color: rgba(91,158,132,0.16);
    }

    /* Dark mode notice markers */
    .notice-list li::before {
        background: var(--primary-dark);
    }

    /* Dark mode tags */
    .tag {
        background: var(--bg-card);
    }
}

/* ===== Dark Mode — Bottom Navigation ===== */
@media (prefers-color-scheme: dark) {
    .bottom-nav {
        background: rgba(20, 23, 21, 0.95);
        border-top-color: rgba(255, 255, 255, 0.04);
    }

    .back-to-top {
        background: #2A302E;
        color: #A8B0AB;
        border-color: rgba(255,255,255,0.06);
        box-shadow: 0 2px 12px rgba(0,0,0,0.32);
    }

    .back-to-top:active {
        background: #353B39;
    }
}

/* ===== Responsive — Desktop Nav ===== */
@media (min-width: 768px) {
    .bottom-nav-inner {
        max-width: 480px;
        padding: 6px 0 max(6px, env(safe-area-inset-bottom));
    }

    .nav-icon-svg {
        width: 22px;
        height: 22px;
    }

    .nav-label {
        font-size: 11px;
    }
}

/* ===== Reset & Base ===== */
*, *::before, *::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    font-size: 16px;
    -webkit-text-size-adjust: 100%;
    scroll-behavior: smooth;
}

body {
    font-family: 'Noto Sans SC', -apple-system, BlinkMacSystemFont, 'PingFang SC', sans-serif;
    background-color: var(--bg-main);
    color: var(--text-primary);
    line-height: 1.7;
    min-height: 100vh;
    overflow-x: hidden;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    padding-bottom: 72px;
}

img {
    max-width: 100%;
    height: auto;
    display: block;
}

/* ===== Header / Hero Section ===== */
.hero {
    position: relative;
    background: linear-gradient(135deg, var(--primary-dark) 0%, var(--primary) 50%, var(--primary-light) 100%);
    padding: 60px 20px 80px;
    color: #fff;
    text-align: center;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: -50%;
    right: -30%;
    width: 80%;
    height: 200%;
    background: radial-gradient(circle, rgba(255,255,255,0.05) 0%, transparent 70%);
    pointer-events: none;
}

.hero-badge {
    display: inline-block;
    background: rgba(255,255,255,0.15);
    backdrop-filter: blur(10px);
    padding: 6px 18px;
    border-radius: 20px;
    font-size: 13px;
    letter-spacing: 2px;
    margin-bottom: 20px;
    border: 1px solid rgba(255,255,255,0.2);
}

.hero-title {
    font-family: 'Noto Serif SC', serif;
    font-size: 32px;
    font-weight: 700;
    line-height: 1.3;
    margin-bottom: 12px;
    letter-spacing: 4px;
}

.hero-subtitle {
    font-size: 15px;
    opacity: 0.88;
    font-weight: 300;
    letter-spacing: 3px;
    margin-bottom: 28px;
}

.hero-code {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    background: rgba(255,255,255,0.12);
    backdrop-filter: blur(10px);
    padding: 10px 24px;
    border-radius: var(--radius-lg);
    font-size: 14px;
}

.hero-code strong {
    font-size: 22px;
    font-weight: 700;
    color: var(--accent-light);
}

.hero-highlight {
    margin-top: 30px;
    background: rgba(196,163,90,0.18);
    border: 1px solid rgba(196,163,90,0.3);
    border-radius: var(--radius-md);
    padding: 16px 24px;
    max-width: 340px;
    margin-left: auto;
    margin-right: auto;
}

.hero-highlight-title {
    font-size: 17px;
    font-weight: 600;
    color: var(--accent-light);
    margin-bottom: 8px;
}

.hero-highlight-text {
    font-size: 13px;
    line-height: 1.7;
    opacity: 0.92;
}

.hero-image {
    margin-top: 36px;
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-lg);
    transform: translateY(0);
    transition: transform 0.3s ease;
}

/* ===== Section Base ===== */
.section {
    padding: 50px 20px;
}

.section-alt {
    background-color: var(--bg-section);
}

.container {
    max-width: 420px;
    margin: 0 auto;
}

.section-header {
    text-align: center;
    margin-bottom: 36px;
}

.section-icon {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    border-radius: 10px;
    background: rgba(45,95,79,0.06);
    margin-bottom: 12px;
}

.section-icon svg {
    width: 22px;
    height: 22px;
    stroke: #2D5F4F;
    stroke-width: 1.5;
    stroke-linecap: round;
    stroke-linejoin: round;
    fill: none;
}

.section-title {
    font-family: 'Noto Serif SC', serif;
    font-size: 24px;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 8px;
}

.section-desc {
    font-size: 14px;
    color: var(--text-muted);
}

/* ===== Card Styles ===== */
.card {
    background: var(--bg-card);
    border-radius: var(--radius-md);
    padding: 24px;
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border-light);
    margin-bottom: 16px;
}

.card-title {
    font-size: 17px;
    font-weight: 600;
    color: var(--primary);
    margin-bottom: 12px;
    display: flex;
    align-items: center;
    gap: 8px;
}

.card-title::before {
    content: '';
    display: block;
    width: 4px;
    height: 18px;
    background: linear-gradient(to bottom, var(--primary), var(--accent));
    border-radius: 2px;
}

.card-text {
    font-size: 14px;
    line-height: 1.85;
    color: var(--text-secondary);
}

/* ===== School Intro Section ===== */
.intro-content {
    position: relative;
}

.intro-image-wrapper {
    border-radius: var(--radius-md);
    overflow: hidden;
    margin-bottom: 24px;
    box-shadow: var(--shadow-md);
}

.intro-image {
    width: 100%;
    height: auto;
    display: block;
}

.intro-stats {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 12px;
    margin-top: 24px;
}

.stat-item {
    text-align: center;
    padding: 16px 10px;
    background: var(--bg-section);
    border-radius: var(--radius-md);
}

.stat-number {
    font-size: 26px;
    font-weight: 700;
    color: var(--primary);
    line-height: 1.2;
}

.stat-label {
    font-size: 12px;
    color: var(--text-muted);
    margin-top: 4px;
}

/* ===== Features / Advantages ===== */
.feature-grid {
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.feature-card {
    background: var(--bg-card);
    border-radius: var(--radius-md);
    padding: 20px;
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border-light);
    display: flex;
    align-items: flex-start;
    gap: 14px;
}

.feature-icon {
    flex-shrink: 0;
    width: 36px;
    height: 36px;
    border-radius: 8px;
    background: rgba(45,95,79,0.06);
    display: flex;
    align-items: center;
    justify-content: center;
}

.feature-icon svg {
    width: 18px;
    height: 18px;
    stroke: #2D5F4F;
    stroke-width: 1.5;
    stroke-linecap: round;
    stroke-linejoin: round;
    fill: none;
}

.feature-content h4 {
    font-size: 15px;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 4px;
}

.feature-content p {
    font-size: 13px;
    color: var(--text-muted);
    line-height: 1.65;
}

/* ===== Registration Notice ===== */
.notice-list {
    list-style: none;
}

.notice-list li {
    position: relative;
    padding-left: 28px;
    margin-bottom: 16px;
    font-size: 14px;
    line-height: 1.75;
    color: var(--text-secondary);
}

.notice-list li::before {
    content: attr(data-num);
    position: absolute;
    left: 0;
    top: 0;
    width: 22px;
    height: 22px;
    background: var(--primary);
    color: #fff;
    border-radius: 6px;
    font-size: 12px;
    font-weight: 600;
    display: flex;
    align-items: center;
    justify-content: center;
}

.notice-list li strong {
    color: var(--primary);
}

/* ===== Programs Table ===== */
.programs-table {
    background: var(--bg-card);
    border-radius: var(--radius-md);
    overflow: hidden;
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border-light);
}

.table-header {
    background: var(--primary);
    color: #fff;
    padding: 14px 16px;
    font-size: 14px;
    font-weight: 600;
    text-align: center;
}

.program-item {
    padding: 16px;
    border-bottom: 1px solid var(--border-light);
}

.program-item:last-child {
    border-bottom: none;
}

.program-name {
    font-size: 15px;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 6px;
}

.program-code {
    display: inline-block;
    font-size: 11px;
    color: var(--text-muted);
    background: var(--bg-section);
    padding: 2px 8px;
    border-radius: 4px;
    margin-right: 6px;
}

.program-meta {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-top: 8px;
}

.program-count {
    font-size: 20px;
    font-weight: 700;
    color: var(--accent);
}

.program-count-label {
    font-size: 11px;
    color: var(--text-muted);
}

.program-type {
    font-size: 12px;
    color: #fff;
    background: var(--secondary);
    padding: 3px 10px;
    border-radius: 12px;
}

/* ===== Major Details ===== */
.major-section {
    margin-bottom: 28px;
}

.major-header {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 14px;
}

.major-icon {
    width: 40px;
    height: 40px;
    border-radius: 10px;
    background: rgba(45,95,79,0.06);
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
}

.major-icon svg {
    width: 20px;
    height: 20px;
    stroke: #2D5F4F;
    stroke-width: 1.5;
    stroke-linecap: round;
    stroke-linejoin: round;
    fill: none;
}

.major-name {
    font-size: 17px;
    font-weight: 700;
    color: var(--text-primary);
}

.major-body {
    background: var(--bg-card);
    border-radius: var(--radius-md);
    padding: 20px;
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border-light);
}

.major-row {
    margin-bottom: 14px;
}

.major-row:last-child {
    margin-bottom: 0;
}

.major-label {
    font-size: 12px;
    font-weight: 600;
    color: var(--primary);
    text-transform: uppercase;
    letter-spacing: 1px;
    margin-bottom: 6px;
}

.major-value {
    font-size: 13px;
    line-height: 1.8;
    color: var(--text-secondary);
}

.major-image {
    margin-top: 14px;
    border-radius: var(--radius-sm);
    overflow: hidden;
}

.major-image img {
    width: 100%;
    height: auto;
}

/* ===== Campus Culture Gallery ===== */
.gallery-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 12px;
}

.gallery-item {
    border-radius: var(--radius-md);
    overflow: hidden;
    aspect-ratio: 1;
    position: relative;
    box-shadow: var(--shadow-sm);
}

.gallery-item img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.gallery-item.wide {
    grid-column: span 2;
    aspect-ratio: 2/1;
}

/* ===== Contact Section ===== */
.contact-info {
    text-align: center;
}

.contact-item {
    background: var(--bg-card);
    border-radius: var(--radius-md);
    padding: 18px 20px;
    margin-bottom: 12px;
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border-light);
    text-align: left;
}

.contact-label {
    font-size: 12px;
    font-weight: 600;
    color: var(--text-muted);
    margin-bottom: 4px;
    text-transform: uppercase;
    letter-spacing: 1px;
}

.contact-value {
    font-size: 15px;
    color: var(--text-primary);
    word-break: break-all;
}

.contact-value a {
    color: var(--primary);
    text-decoration: none;
}

.contact-phone {
    display: flex;
    flex-direction: column;
    gap: 6px;
}

.contact-phone-num {
    font-size: 18px;
    font-weight: 600;
    color: var(--primary);
}

.contact-phone-meta {
    font-size: 13px;
    color: var(--text-muted);
}

.map-container {
    border-radius: var(--radius-md);
    overflow: hidden;
    margin-top: 20px;
    box-shadow: var(--shadow-md);
}

.map-container img {
    width: 100%;
    height: auto;
}

/* ===== CTA Button ===== */
.cta-button {
    display: block;
    width: 100%;
    padding: 16px 32px;
    background: linear-gradient(135deg, var(--primary), var(--primary-light));
    color: #fff;
    font-size: 17px;
    font-weight: 600;
    text-align: center;
    text-decoration: none;
    border-radius: var(--radius-lg);
    box-shadow: 0 4px 20px rgba(45,95,79,0.25);
    transition: all 0.3s ease;
    border: none;
    cursor: pointer;
    letter-spacing: 2px;
}

.cta-button:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 28px rgba(45,95,79,0.35);
}

.cta-button:active {
    transform: translateY(0);
}

.cta-button-mt {
    margin-top: 28px;
}

/* ===== Footer ===== */
.footer {
    background: var(--primary-dark);
    color: rgba(255,255,255,0.7);
    text-align: center;
    padding: 36px 20px;
    font-size: 13px;
}

.footer-brand {
    font-family: 'Noto Serif SC', serif;
    font-size: 18px;
    color: #fff;
    margin-bottom: 8px;
    letter-spacing: 2px;
}

.footer-tags {
    display: flex;
    justify-content: center;
    gap: 10px;
    margin-top: 16px;
    flex-wrap: wrap;
}

.footer-tag {
    background: rgba(255,255,255,0.1);
    padding: 4px 12px;
    border-radius: 12px;
    font-size: 11px;
    color: rgba(255,255,255,0.8);
}

.footer-org {
    margin-top: 12px;
    font-size: 12px;
    opacity: 0.6;
}

.footer-copyright {
    margin-top: 20px;
    font-size: 11px;
    opacity: 0.5;
}

/* ===== Tag Bar ===== */
.tag-bar {
    display: flex;
    gap: 8px;
    padding: 0 20px;
    margin-top: -20px;
    position: relative;
    z-index: 2;
}

.tag-bar-inner {
    display: flex;
    gap: 8px;
    flex-wrap: wrap;
    justify-content: center;
    width: 100%;
    max-width: 420px;
    margin: 0 auto;
}

.tag {
    background: var(--bg-card);
    color: var(--primary);
    font-size: 12px;
    font-weight: 500;
    padding: 6px 14px;
    border-radius: 16px;
    box-shadow: var(--shadow-md);
}

/* ===== Image Cropped Sections ===== */
.image-showcase {
    border-radius: var(--radius-md);
    overflow: hidden;
    margin: 20px 0;
    box-shadow: var(--shadow-md);
}

.image-showcase img {
    width: 100%;
    height: auto;
    display: block;
}

.image-showcase-cover {
    object-fit: cover;
    max-height: 220px;
}

.culture-image {
    width: 100%;
    height: auto;
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-md);
}

.culture-image-mt {
    margin-top: 20px;
}

/* ===== Requirement Box ===== */
.requirement-box {
    background: linear-gradient(135deg, rgba(45,95,79,0.06), rgba(45,95,79,0.02));
    border: 1px solid rgba(45,95,79,0.12);
    border-radius: var(--radius-md);
    padding: 20px;
    margin-top: 20px;
}

.requirement-box h4 {
    font-size: 15px;
    font-weight: 600;
    color: var(--primary);
    margin-bottom: 12px;
}

.requirement-box p {
    font-size: 13px;
    line-height: 1.8;
    color: var(--text-secondary);
}

/* ===== Enroll Note ===== */
.enroll-note {
    margin-top: 24px;
    text-align: center;
}

.enroll-note-text {
    font-size: 14px;
    color: var(--text-secondary);
    line-height: 1.8;
}

/* ===== QR Code Section ===== */
.qrcode-section {
    margin-top: 24px;
    text-align: center;
}

.qrcode-title {
    font-size: 14px;
    font-weight: 600;
    color: var(--primary);
    margin-bottom: 12px;
}

.qrcode-card {
    background: var(--bg-card);
    border-radius: var(--radius-md);
    padding: 20px;
    display: inline-block;
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border-light);
}

.qrcode-img {
    width: 160px;
    height: 160px;
    border-radius: 8px;
}

.qrcode-caption {
    font-size: 12px;
    color: var(--text-muted);
    margin-top: 10px;
}

/* ===== Register Section ===== */
.register-wrapper {
    text-align: center;
    background: var(--bg-card);
    border-radius: var(--radius-lg);
    padding: 32px 20px;
    box-shadow: var(--shadow-md);
    border: 1px solid var(--border-light);
}

.register-img {
    width: 200px;
    height: 200px;
    margin: 0 auto;
    border-radius: var(--radius-md);
}

.register-heading {
    font-size: 16px;
    font-weight: 600;
    color: var(--primary);
    margin-top: 18px;
}

.register-subtitle {
    font-size: 13px;
    color: var(--text-muted);
    margin-top: 8px;
}

/* ===== Feature Spacer ===== */
.feature-spacer {
    margin-top: 20px;
}

/* ===== Responsive ===== */
@media (max-width: 380px) {
    .hero-title { font-size: 26px; }
    .section-title { font-size: 21px; }
    .intro-stats { gap: 8px; }
    .stat-number { font-size: 22px; }
    .stat-item { padding: 12px 8px; }
    .nav-icon-svg { width: 20px; height: 20px; }
    .nav-label { font-size: 9px; }
    .nav-item { gap: 1px; }
}

@media (max-width: 320px) {
    .hero-title { font-size: 22px; }
    .hero-subtitle { font-size: 13px; }
    .section-title { font-size: 19px; }
    .nav-icon-svg { width: 18px; height: 18px; }
    .nav-label { font-size: 8px; }
}

/* ===== Animations ===== */
.fade-in {
    opacity: 0;
    transform: translateY(20px);
    animation: fadeInUp 0.6s ease forwards;
}

@keyframes fadeInUp {
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.delay-1 { animation-delay: 0.1s; }
.delay-2 { animation-delay: 0.2s; }
.delay-3 { animation-delay: 0.3s; }
.delay-4 { animation-delay: 0.4s; }

/* ===== Bottom Navigation ===== */
.bottom-nav {
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: saturate(180%) blur(20px);
    -webkit-backdrop-filter: saturate(180%) blur(20px);
    border-top: 0.5px solid rgba(0, 0, 0, 0.06);
    padding: 0;
    transition: transform 0.4s cubic-bezier(0.16, 1, 0.3, 1);
}

.bottom-nav.hidden {
    transform: translateY(100%);
}

/* Centralize and constrain for desktop */
.bottom-nav-inner {
    max-width: 560px;
    margin: 0 auto;
    display: flex;
    justify-content: space-around;
    align-items: stretch;
    padding: 8px 0 max(8px, env(safe-area-inset-bottom));
}

/* ===== Nav Item ===== */
.nav-item {
    flex: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 2px;
    padding: 4px 0;
    text-decoration: none;
    color: var(--text-muted);
    font-size: 10px;
    font-weight: 400;
    letter-spacing: 0.02em;
    transition: color 0.2s cubic-bezier(0.16, 1, 0.3, 1);
    -webkit-tap-highlight-color: transparent;
    position: relative;
    cursor: pointer;
    background: none;
    border: none;
    font-family: inherit;
    -webkit-user-select: none;
    user-select: none;
}

/* Active indicator dot */
.nav-item::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 50%;
    transform: translateX(-50%) scale(0);
    width: 3px;
    height: 3px;
    border-radius: 50%;
    background: var(--primary);
    transition: transform 0.25s cubic-bezier(0.16, 1, 0.3, 1);
}

.nav-item.active::after {
    transform: translateX(-50%) scale(1);
}

.nav-item.active {
    color: var(--primary);
    font-weight: 500;
}

/* Tap feedback */
.nav-item:active {
    opacity: 0.7;
    transition: opacity 0.05s ease;
}

/* ===== Nav Icon ===== */
.nav-icon-svg {
    width: 24px;
    height: 24px;
    display: block;
    stroke-linecap: round;
    stroke-linejoin: round;
    fill: none;
    transition: transform 0.2s cubic-bezier(0.16, 1, 0.3, 1);
}

/* Icon outline paths — muted gray-green */
.nav-icon-svg .icon-outline {
    stroke: var(--text-muted);
    stroke-width: 1.5;
    transition: stroke 0.2s cubic-bezier(0.16, 1, 0.3, 1);
}

/* Icon accent paths — hidden by default, reveal on active */
.nav-icon-svg .icon-accent {
    stroke: var(--primary);
    stroke-width: 1.5;
    opacity: 0;
    transition: opacity 0.2s cubic-bezier(0.16, 1, 0.3, 1);
}

/* Active icon states */
.nav-item.active .nav-icon-svg {
    transform: scale(1.05);
}

.nav-item.active .nav-icon-svg .icon-outline {
    stroke: var(--primary);
}

.nav-item.active .nav-icon-svg .icon-accent {
    opacity: 1;
}

/* ===== Nav Label ===== */
.nav-label {
    line-height: 1;
    font-size: 10px;
}

/* ===== Disabled State ===== */
.nav-item[aria-disabled="true"],
.nav-item.disabled {
    opacity: 0.35;
    pointer-events: none;
    cursor: not-allowed;
}

/* ===== Back to Top Button ===== */
.back-to-top {
    position: fixed;
    bottom: 80px;
    right: 16px;
    width: 38px;
    height: 38px;
    border-radius: 50%;
    background: #fff;
    color: #666;
    border: 0.5px solid rgba(0,0,0,0.12);
    box-shadow: 0 2px 8px rgba(0,0,0,0.06);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 15px;
    cursor: pointer;
    z-index: 999;
    opacity: 0;
    transform: translateY(8px);
    transition: opacity 0.3s cubic-bezier(0.33, 1, 0.68, 1),
                transform 0.3s cubic-bezier(0.33, 1, 0.68, 1);
    -webkit-tap-highlight-color: transparent;
}

.back-to-top.visible {
    opacity: 1;
    transform: translateY(0);
}

.back-to-top:active {
    background: #f5f5f5;
}