/* ==========================================================================
   Stripe 主题设计系统（基于 Stripe DESIGN.md）
   浅色 canvas、indigo 紫、渐变 mesh hero、细体标题、胶囊按钮
   ========================================================================== */
:root {
    /* 品牌色 */
    --primary: #533afd;
    --primary-deep: #4434d4;
    --primary-press: #2e2b8c;
    --primary-soft: #665efd;
    --primary-subdued: #b9b9f9;
    --brand-dark-900: #1c1e54;

    /* 文本 */
    --ink: #0d253d;
    --ink-secondary: #273951;
    --ink-mute: #64748d;
    --on-primary: #ffffff;

    /* 表面 */
    --canvas: #ffffff;
    --canvas-soft: #f6f9fc;
    --canvas-cream: #f5e9d4;
    --hairline: #e3e8ee;
    --hairline-input: #a8c3de;

    /* 渐变辅助色 */
    --ruby: #ea2261;
    --magenta: #f96bee;
    --lemon: #9b6829;

    /* 圆角 */
    --r-xs: 4px;
    --r-sm: 6px;
    --r-md: 8px;
    --r-lg: 12px;
    --r-xl: 16px;
    --r-pill: 9999px;

    /* 间距 */
    --sp-xs: 4px;
    --sp-sm: 8px;
    --sp-md: 12px;
    --sp-lg: 16px;
    --sp-xl: 24px;
    --sp-xxl: 32px;
    --sp-huge: 64px;

    /* 字体 */
    --font-display: "Inter", "SF Pro Display", -apple-system, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
    --font-body: "Inter", -apple-system, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
}

/* ===== Stripe 标志性渐变 mesh（hero 背景） ===== */
.stripe-mesh {
    background:
        radial-gradient(60% 120% at 0% 0%, rgba(245, 233, 212, .9) 0%, transparent 55%),
        radial-gradient(50% 110% at 30% 0%, rgba(249, 107, 238, .35) 0%, transparent 55%),
        radial-gradient(55% 120% at 65% 0%, rgba(83, 58, 253, .30) 0%, transparent 60%),
        radial-gradient(45% 110% at 100% 0%, rgba(234, 34, 97, .30) 0%, transparent 55%),
        linear-gradient(180deg, #ffffff 0%, #ffffff 100%);
}

/* ===== 胶囊按钮 ===== */
.st-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 8px 16px;
    border-radius: var(--r-pill);
    font-family: var(--font-body);
    font-size: 16px;
    font-weight: 400;
    line-height: 1.0;
    border: 1px solid transparent;
    cursor: pointer;
    transition: background .15s, color .15s, border-color .15s;
    white-space: nowrap;
}
.st-btn-primary { background: var(--primary); color: var(--on-primary); }
.st-btn-primary:hover { background: var(--primary-soft); color: var(--on-primary); }
.st-btn-primary:active { background: var(--primary-press); }
.st-btn-secondary { background: var(--canvas); color: var(--primary); border-color: var(--primary); }
.st-btn-secondary:hover { background: var(--primary); color: var(--on-primary); }
.st-btn-on-dark { background: var(--brand-dark-900); color: var(--on-primary); }
.st-btn-on-dark:hover { background: #2a2d6e; color: var(--on-primary); }

/* ===== 卡片 ===== */
.st-card {
    background: var(--canvas);
    border: 1px solid var(--hairline);
    border-radius: var(--r-lg);
    padding: 32px;
}
.st-card-soft { background: var(--canvas-soft); }
.st-card-cream { background: var(--canvas-cream); }
.st-card-dark { background: var(--brand-dark-900); color: var(--on-primary); }

/* ===== 输入框 ===== */
.st-input {
    width: 100%;
    padding: 8px 12px;
    background: var(--canvas);
    border: 1px solid var(--hairline-input);
    border-radius: var(--r-sm);
    color: var(--ink);
    font-family: var(--font-body);
    font-size: 15px;
    line-height: 1.4;
    transition: border-color .15s;
}
.st-input::placeholder { color: var(--ink-mute); }
.st-input:focus { outline: none; border-color: var(--primary); }

/* ===== 文本工具 ===== */
.st-display { font-family: var(--font-display); font-weight: 300; letter-spacing: -0.64px; color: var(--ink); }
.st-eyebrow { font-size: 13px; font-weight: 500; letter-spacing: .1px; color: var(--primary-deep); }

/* ===== 标签 ===== */
.st-tag {
    display: inline-flex;
    align-items: center;
    padding: 4px 8px;
    border-radius: var(--r-pill);
    background: var(--primary-subdued);
    color: var(--primary-deep);
    font-size: 11px;
    font-weight: 500;
}