:root {
    --color-white: #FFFFFF;
    --color-black: #000000;
    --color-gray-50: #FAFAFA;
    --color-gray-100: #F5F5F5;
    --color-gray-200: #E5E5E5;
    --color-gray-300: #D4D4D4;
    --color-gray-400: #A3A3A4;
    --color-gray-500: #737373;
    --color-gray-600: #525252;
    --color-gray-700: #404040;
    --radius-sm: 2px;
    --radius-md: 4px;
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.04);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.08);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    font-size: 16px;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
    background-color: var(--color-white);
    color: var(--color-black);
    line-height: 1.5;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

.app {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    padding-bottom: 72px;
}

/* Header */
.header {
    position: sticky;
    top: 0;
    z-index: 100;
    background-color: rgba(255, 255, 255, 0.96);
    backdrop-filter: blur(8px);
    border-bottom: 1px solid var(--color-gray-200);
}

.header-inner {
    max-width: 1200px;
    margin: 0 auto;
    padding: 16px 20px;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.brand {
    display: flex;
    align-items: center;
    gap: 10px;
}

.brand-icon {
    width: 36px;
    height: 36px;
    background-color: var(--color-black);
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
}

.brand-icon svg {
    width: 20px;
    height: 20px;
    color: var(--color-white);
}

.brand-title {
    font-size: 20px;
    font-weight: 700;
    letter-spacing: -0.02em;
}

.header-actions {
    display: flex;
    gap: 12px;
}

.btn-icon {
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: transparent;
    border: 1px solid var(--color-gray-200);
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all 0.2s ease;
}

.btn-icon:hover {
    background-color: var(--color-gray-100);
    border-color: var(--color-gray-300);
}

.btn-icon svg {
    width: 20px;
    height: 20px;
    color: var(--color-gray-700);
}

.header-link {
    display: inline-flex;
    align-items: center;
    padding: 0 14px;
    height: 40px;
    font-size: 14px;
    font-weight: 600;
    color: var(--color-black);
    text-decoration: none;
    border-radius: var(--radius-md);
    transition: all 0.2s ease;
}

.header-link:hover {
    background-color: var(--color-gray-100);
}

.header-link-primary {
    background-color: var(--color-black);
    color: var(--color-white);
}

.header-link-primary:hover {
    opacity: 0.88;
    background-color: var(--color-black);
}

/* Main Content */
.main {
    flex: 1;
    max-width: 1200px;
    width: 100%;
    margin: 0 auto;
    padding: 32px 20px 40px;
}

.page-header {
    margin-bottom: 32px;
}

.page-title {
    font-size: 28px;
    font-weight: 800;
    letter-spacing: -0.02em;
    line-height: 1.2;
}

.page-subtitle {
    font-size: 15px;
    color: var(--color-gray-500);
    margin-top: 8px;
}

.section-title {
    font-size: 14px;
    font-weight: 600;
    color: var(--color-gray-500);
    text-transform: uppercase;
    letter-spacing: 0.04em;
    margin-bottom: 16px;
}

/* Hero Slider */
.hero-slider {
    position: relative;
    width: 100%;
    height: auto;
    aspect-ratio: 3 / 1;
    min-height: 180px;
    max-height: 360px;
    border-radius: var(--radius-md);
    overflow: hidden;
    margin-bottom: 40px;
    background-color: #171717;
}

.hero-slides {
    position: relative;
    width: 100%;
    height: 100%;
}

.hero-slide {
    position: absolute;
    inset: 0;
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.5s ease, visibility 0.5s ease;
}

.hero-slide.active {
    opacity: 1;
    visibility: visible;
}

.hero-slide img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    display: block;
}

.hero-overlay {
    position: absolute;
    inset: 0;
    display: flex;
    flex-direction: column;
    justify-content: center;
    padding: 28px;
    background: linear-gradient(to right, rgba(0,0,0,0.72) 0%, rgba(0,0,0,0.2) 100%);
}

.hero-overlay-hidden {
    display: none;
}

.hero-overlay h2 {
    color: var(--color-white);
    font-size: 28px;
    font-weight: 800;
    letter-spacing: -0.02em;
    line-height: 1.2;
    margin-bottom: 10px;
}

.hero-overlay p {
    color: rgba(255,255,255,0.85);
    font-size: 15px;
    max-width: 420px;
    line-height: 1.5;
}

.hero-link {
    display: inline-block;
    margin-top: 12px;
    padding: 8px 18px;
    background: var(--color-white);
    color: var(--color-black);
    border-radius: var(--radius-md);
    font-size: 13px;
    font-weight: 600;
    text-decoration: none;
    width: fit-content;
}

.hero-arrow {
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
    width: 36px;
    height: 36px;
    background: rgba(255,255,255,0.15);
    color: var(--color-white);
    border: none;
    border-radius: 50%;
    font-size: 14px;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: background 0.2s ease;
    z-index: 2;
}

.hero-arrow:hover { background: rgba(255,255,255,0.3); }
.hero-prev { left: 12px; }
.hero-next { right: 12px; }

.hero-dots {
    position: absolute;
    bottom: 14px;
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    gap: 8px;
    z-index: 2;
}

.hero-dot {
    width: 8px;
    height: 8px;
    border-radius: 50%;
    border: none;
    background: rgba(255,255,255,0.4);
    cursor: pointer;
    transition: background 0.2s ease;
}

.hero-dot.active { background: var(--color-white); }

/* Tool Cards Grid */
.tools-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 16px;
    margin-bottom: 40px;
}

.tool-card {
    position: relative;
    display: flex;
    align-items: center;
    gap: 18px;
    padding: 20px 22px;
    background-color: var(--color-white);
    border: 1px solid var(--color-gray-200);
    border-radius: var(--radius-md);
    text-decoration: none;
    color: inherit;
    transition: all 0.25s ease;
}

.tool-card:hover {
    border-color: var(--color-gray-400);
    box-shadow: var(--shadow-lg);
    transform: translateY(-3px);
}

.tool-icon {
    width: 52px;
    height: 52px;
    background-color: var(--color-gray-100);
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
}

.tool-icon svg {
    width: 26px;
    height: 26px;
    color: var(--color-black);
}

.tool-body {
    flex: 1;
    min-width: 0;
}

.tool-name {
    font-size: 16px;
    font-weight: 700;
    margin-bottom: 4px;
}

.tool-desc {
    font-size: 13px;
    color: var(--color-gray-500);
    line-height: 1.5;
}

.tool-arrow {
    width: 20px;
    height: 20px;
    color: var(--color-gray-300);
    flex-shrink: 0;
    transition: color 0.2s ease, transform 0.2s ease;
}

.tool-card:hover .tool-arrow {
    color: var(--color-black);
    transform: translateX(3px);
}

/* Feature List */
.features {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: 12px;
    padding: 24px;
    background-color: var(--color-gray-50);
    border: 1px solid var(--color-gray-200);
    border-radius: var(--radius-md);
}

.feature-item {
    display: flex;
    align-items: center;
    gap: 12px;
    font-size: 14px;
    color: var(--color-gray-600);
}

.feature-dot {
    width: 6px;
    height: 6px;
    background-color: var(--color-black);
    border-radius: 50%;
    flex-shrink: 0;
}

/* Bottom Tab Bar */
.tab-bar {
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    z-index: 200;
    background-color: rgba(255, 255, 255, 0.98);
    backdrop-filter: blur(12px);
    border-top: 1px solid var(--color-gray-200);
    box-shadow: 0 -2px 12px rgba(0, 0, 0, 0.04);
}

.tab-bar-inner {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    justify-content: space-around;
    align-items: center;
    height: 64px;
}

.tab-item {
    flex: 1;
    height: 100%;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 4px;
    text-decoration: none;
    color: var(--color-gray-500);
    transition: color 0.2s ease;
    min-width: 64px;
}

.tab-item.active,
.tab-item:hover {
    color: var(--color-black);
}

.tab-item svg {
    width: 24px;
    height: 24px;
}

.tab-label {
    font-size: 11px;
    font-weight: 500;
}

/* Mobile Optimizations */
@media (max-width: 640px) {
    .header-inner {
        padding: 14px 16px;
    }

    .main {
        padding: 24px 16px 32px;
    }

    .page-title {
        font-size: 24px;
    }

    .hero-slider {
        min-height: 160px;
        margin-bottom: 32px;
    }

    .hero-overlay {
        padding: 20px;
    }

    .hero-overlay h2 {
        font-size: 22px;
    }

    .hero-overlay p {
        font-size: 14px;
    }

    .tools-grid {
        grid-template-columns: 1fr;
        gap: 12px;
    }

    .tool-card {
        padding: 16px 18px;
        gap: 14px;
    }

    .tool-icon {
        width: 44px;
        height: 44px;
    }

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

    .tool-desc {
        display: none;
    }

    .features {
        grid-template-columns: 1fr;
        padding: 20px;
    }
}

@media (min-width: 1024px) {
    .main {
        padding-top: 48px;
    }

    .hero-slider {
        max-height: 420px;
    }

    .hero-overlay h2 {
        font-size: 32px;
    }

    .tools-grid {
        grid-template-columns: repeat(3, 1fr);
    }
}

/* Processing Modal */
.processing-overlay {
    position: fixed;
    inset: 0;
    background-color: rgba(255, 255, 255, 0.85);
    backdrop-filter: blur(4px);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.2s ease, visibility 0.2s ease;
}

.processing-overlay.show {
    opacity: 1;
    visibility: visible;
}

.processing-box {
    width: 90%;
    max-width: 320px;
    padding: 28px;
    background-color: var(--color-white);
    border: 1px solid var(--color-gray-200);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-lg);
    text-align: center;
}

.processing-spinner {
    width: 40px;
    height: 40px;
    margin: 0 auto 16px;
    border: 3px solid var(--color-gray-200);
    border-top-color: var(--color-black);
    border-radius: 50%;
    animation: processing-spin 0.8s linear infinite;
}

@keyframes processing-spin {
    to { transform: rotate(360deg); }
}

.processing-title {
    font-size: 16px;
    font-weight: 700;
    margin-bottom: 6px;
}

.processing-text {
    font-size: 13px;
    color: var(--color-gray-500);
}

.toast {
    position: fixed;
    top: 20px;
    left: 50%;
    transform: translateX(-50%) translateY(-20px);
    padding: 12px 22px;
    background-color: var(--color-black);
    color: var(--color-white);
    border-radius: var(--radius-md);
    font-size: 14px;
    font-weight: 600;
    box-shadow: var(--shadow-lg);
    z-index: 1001;
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.25s ease, transform 0.25s ease, visibility 0.25s ease;
}

.toast.show {
    opacity: 1;
    visibility: visible;
    transform: translateX(-50%) translateY(0);
}