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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC',
                 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
    background:
        radial-gradient(1200px 600px at 85% -10%, rgba(255, 138, 101, 0.18), transparent 60%),
        radial-gradient(900px 500px at 5% 10%, rgba(138, 200, 255, 0.20), transparent 60%),
        radial-gradient(900px 500px at 50% 110%, rgba(186, 153, 255, 0.14), transparent 60%),
        #f7f5fb;
    color: #1a2233;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    padding-bottom: 60px;
    overflow-x: hidden;
}

/* ===== 顶部 Header ===== */
header {
    width: 100%;
    max-width: 1200px;
    margin-top: 60px;
    padding: 0 24px;
    text-align: center;
}

.site-title {
    font-size: 2.6rem;
    font-weight: 800;
    letter-spacing: -1px;
    background: linear-gradient(135deg, #1a7a9e 0%, #6f4ad8 50%, #ff6b9d 100%);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
    color: transparent;
    margin-bottom: 10px;
    animation: titleFloat 4s ease-in-out infinite;
}

@keyframes titleFloat {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-4px); }
}

.site-subtitle {
    color: #6b7785;
    font-size: 1rem;
    margin-bottom: 36px;
}

/* ===== OpenFlow 主推卡片 ===== */
.feature {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 32px;
    max-width: 1200px;
    width: calc(100% - 48px);
    margin: 0 auto 56px;
    padding: 36px 44px;
    border-radius: 24px;
    background:
        radial-gradient(circle at 90% 10%, rgba(255, 255, 255, 0.20), transparent 40%),
        radial-gradient(circle at 10% 90%, rgba(255, 255, 255, 0.10), transparent 50%),
        linear-gradient(135deg, #ff6b9d 0%, #c44ad8 50%, #6f4ad8 100%);
    color: #fff;
    text-decoration: none;
    box-shadow: 0 20px 50px -10px rgba(196, 74, 216, 0.5),
                0 4px 12px rgba(0, 0, 0, 0.06);
    position: relative;
    overflow: hidden;
    transition: transform .4s cubic-bezier(.25, 1.4, .5, 1), box-shadow .35s ease;
}

.feature::after {
    content: "";
    position: absolute;
    width: 200px; height: 200px;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.14);
    top: -60px; right: -40px;
    pointer-events: none;
    animation: pulse 5s ease-in-out infinite;
}

@keyframes pulse {
    0%, 100% { transform: scale(1); opacity: 0.6; }
    50% { transform: scale(1.2); opacity: 0.4; }
}

.feature:hover {
    transform: translateY(-6px) scale(1.01);
    box-shadow: 0 30px 60px -10px rgba(196, 74, 216, 0.65),
                0 6px 16px rgba(0, 0, 0, 0.08);
}

.feature-text {
    text-align: left;
    position: relative;
    z-index: 1;
}

.feature-tag {
    display: inline-block;
    font-size: 0.75rem;
    font-weight: 700;
    letter-spacing: 1.2px;
    text-transform: uppercase;
    background: rgba(255, 255, 255, 0.22);
    border: 1px solid rgba(255, 255, 255, 0.4);
    padding: 5px 12px;
    border-radius: 999px;
    margin-bottom: 14px;
    backdrop-filter: blur(6px);
}

.feature h2 {
    font-size: 2.2rem;
    font-weight: 800;
    margin-bottom: 8px;
    letter-spacing: -0.5px;
}

.feature .feature-sub {
    font-size: 1.05rem;
    color: rgba(255, 255, 255, 0.92);
    font-weight: 400;
}

.feature-arrow {
    font-size: 3rem;
    color: rgba(255, 255, 255, 0.95);
    position: relative;
    z-index: 1;
    transition: transform .35s cubic-bezier(.25, 1.4, .5, 1);
    flex-shrink: 0;
    animation: arrowBounce 1.6s ease-in-out infinite;
}

@keyframes arrowBounce {
    0%, 100% { transform: translateX(0); }
    50% { transform: translateX(8px); }
}

.feature:hover .feature-arrow {
    transform: translateX(14px);
    animation: none;
}

/* ===== 项目区段 ===== */
main {
    width: 100%;
    max-width: 1200px;
    padding: 0 24px;
}

.section-title {
    font-size: 0.85rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 1.5px;
    color: #6b7785;
    margin-bottom: 20px;
    display: flex;
    align-items: center;
    gap: 12px;
}
.section-title::after {
    content: "";
    flex: 1;
    height: 1px;
    background: linear-gradient(to right, #d8e0e8, transparent);
}

/* ===== 项目网格 ===== */
.grid-container {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 18px;
}

/* ===== 项目卡片按钮 ===== */
.btn {
    --c1: #1a7a9e;
    --c2: #6f4ad8;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    text-decoration: none;
    background: #ffffff;
    color: var(--c1);
    border: 1.5px solid #e3eaf0;
    padding: 22px 18px;
    border-radius: 16px;
    font-weight: 700;
    font-size: 0.98rem;
    line-height: 1.4;
    min-height: 84px;
    transition: transform .35s cubic-bezier(.25, 1.4, .5, 1),
                box-shadow .25s ease, border-color .25s ease;
    box-shadow: 0 3px 6px rgba(0, 0, 0, 0.05);
    position: relative;
    overflow: hidden;
    z-index: 0;
    animation: cardBob 3.6s ease-in-out infinite;
}

/* 持续微浮动（每张卡 duration/delay 由 JS 设置） */
@keyframes cardBob {
    0%, 100% { transform: translateY(0); }
    50%      { transform: translateY(-5px); }
}

/* 悬停时的彩虹渐变层（z-index 高于文字盖不住，用 -1 放文字下） */
.btn::before {
    content: "";
    position: absolute;
    inset: 0;
    border-radius: inherit;
    background: linear-gradient(
        110deg,
        #ff6b6b, #ff9f43, #ffd93d, #6bcf7f,
        #4ecdc4, #4a90e2, #9b59b6, #ff6b9d,
        #ff6b6b
    );
    background-size: var(--band-width, 600%) 100%;
    background-position: var(--band-start, 0%) 50%;
    opacity: 0;
    transition: opacity .3s ease;
    pointer-events: none;
    z-index: -1;
    animation: rainbowSlide var(--band-duration, 10s) linear infinite;
    animation-play-state: paused;
}

@keyframes rainbowSlide {
    0%   { background-position: var(--band-start, 0%) 50%; }
    100% { background-position: calc(var(--band-start, 0%) + var(--band-width, 300%)) 50%; }
}

/* ===== 可调节参数（顶部）=====
 * --band-width     色带宽度：300% = 较密的彩虹，500% = 更细的色带
 * --band-duration  流动速度：4s = 中速，越小越快
 * --band-start     起始位置：0-300% 之间，JS 每次悬停随机设
 */

.btn:hover {
    /* 悬停时压住浮动动画 */
    animation: none;
    transform: translateY(-8px) rotate(-2deg) scale(1.04);
    border-color: transparent;
    color: #fff;
    box-shadow: 0 18px 36px -6px rgba(0, 0, 0, 0.28),
                0 6px 12px rgba(0, 0, 0, 0.08);
}

.btn:hover::before {
    opacity: 1;
    animation-play-state: running;
}

.btn:active {
    transform: translateY(-3px) rotate(0) scale(1);
    transition: transform .12s ease;
}

/* emoji 文字稍大 */
.btn {
    font-variant-emoji: text;
}

/* ===== 底部 ===== */
footer {
    margin-top: auto;
    width: 100%;
    padding: 24px;
    text-align: center;
    color: #8a96a3;
    font-size: 0.85rem;
}

/* ===== 响应式 ===== */
@media (max-width: 960px) {
    .grid-container { grid-template-columns: repeat(3, 1fr); }
    .feature h2 { font-size: 1.8rem; }
    .site-title { font-size: 2.2rem; }
}

@media (max-width: 720px) {
    .grid-container { grid-template-columns: repeat(2, 1fr); }
    .feature {
        flex-direction: column;
        align-items: flex-start;
        padding: 28px;
    }
    .feature-arrow { display: none; }
    .feature h2 { font-size: 1.6rem; }
    .site-title { font-size: 1.9rem; }
    /* 移动端关闭浮动动画，避免干扰 */
    .btn { animation: none; }
}

@media (max-width: 480px) {
    .grid-container { grid-template-columns: 1fr; }
    .btn:hover { transform: translateY(-4px) rotate(-1deg); }
}

/* 减少动画偏好 */
@media (prefers-reduced-motion: reduce) {
    *, *::before, *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}