/* ==========================================================================
   十年之约 · 基础层
   设计语言：暖白纸张 + 墨黑 + 朱红印章，中文书籍排版
   ========================================================================== */

/* ---------- 字体 ---------- */
@font-face {
    font-family: "Numeral";
    src: url("../fonts/geist-mono-latin.woff2") format("woff2");
    font-weight: 100 900;
    font-display: swap;
}

/* ---------- 令牌 ---------- */
:root {
    /* 纸张与墨 */
    --paper:      #f4f0e6;
    --paper-2:    #ece6d8;
    --paper-3:    #e2dac7;
    --ink:        #1b1a17;
    --ink-2:      #3d3a33;
    --ink-3:      #6b665c;
    --ink-4:      #9c968a;
    --rule:       #d3cab4;
    --rule-2:     #bfb49a;

    /* 朱红 */
    --seal:       #b23a2e;
    --seal-deep:  #8e2b21;

    /* 辅助 */
    --moss:       #4a5c46;

    /* 排版尺度 */
    --fs-xs:   12px;
    --fs-sm:   13px;
    --fs-base: 15px;
    --fs-md:   17px;
    --fs-lg:   21px;
    --fs-xl:   30px;
    --fs-2xl:  44px;
    --fs-3xl:  62px;

    --sp-1: 4px;
    --sp-2: 8px;
    --sp-3: 12px;
    --sp-4: 16px;
    --sp-5: 24px;
    --sp-6: 32px;
    --sp-7: 48px;
    --sp-8: 72px;
    --sp-9: 104px;

    --wide: 1180px;
    --narrow: 760px;

    --serif: "Songti SC", "SimSun", "Noto Serif SC", Georgia, serif;
    --sans:  "PingFang SC", "Microsoft YaHei", "Hiragino Sans GB", system-ui, sans-serif;
    --mono:  "Numeral", ui-monospace, "Cascadia Mono", Consolas, monospace;
}

/* ---------- 重置 ---------- */
*, *::before, *::after { box-sizing: border-box; }

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

body {
    margin: 0;
    font-family: var(--sans);
    font-size: var(--fs-base);
    line-height: 1.75;
    color: var(--ink);
    background-color: var(--paper);
    background-image:
        radial-gradient(circle at 12% 8%,  rgba(255, 255, 255, 0.55), transparent 42%),
        radial-gradient(circle at 88% 92%, rgba(191, 180, 154, 0.18), transparent 46%),
        url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='120' height='120'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.85' numOctaves='3'/%3E%3C/filter%3E%3Crect width='120' height='120' filter='url(%23n)' opacity='0.035'/%3E%3C/svg%3E");
    background-attachment: fixed;
    -webkit-font-smoothing: antialiased;
        text-rendering: optimizeLegibility;
}

h1, h2, h3, h4 {
    margin: 0;
    font-family: var(--serif);
    font-weight: 600;
    line-height: 1.28;
    letter-spacing: 0.01em;
    color: var(--ink);
}

p { margin: 0; }

a { color: inherit; text-decoration: none; }

ul, ol { margin: 0; padding: 0; list-style: none; }

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

button, input, select, textarea {
    font: inherit;
    color: inherit;
    margin: 0;
}

button { cursor: pointer; background: none; border: 0; padding: 0; }

:focus-visible { outline: 2px solid var(--seal); outline-offset: 3px; }

::selection { background: var(--seal); color: var(--paper); }

/* ---------- 布局容器 ---------- */
.l-wide {
    width: 100%;
    max-width: var(--wide);
    margin-inline: auto;
    padding-inline: var(--sp-6);
}

.l-narrow {
    width: 100%;
    max-width: var(--narrow);
    margin-inline: auto;
    padding-inline: var(--sp-6);
}

/* ---------- 汉字编号 ---------- */
.numeral {
    font-family: var(--serif);
    font-size: var(--fs-3xl);
    line-height: 1;
    color: var(--rule-2);
    font-weight: 400;
    user-select: none;
}

/* ---------- 印章 ---------- */
.seal {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 66px;
    height: 66px;
    flex: 0 0 auto;
    border: 2px solid var(--seal);
    border-radius: 6px;
    color: var(--seal);
    font-family: var(--serif);
    font-size: 19px;
    line-height: 1.05;
    font-weight: 600;
    letter-spacing: 0.06em;
    text-align: center;
    padding: 4px;
    box-shadow: inset 0 0 0 1px rgba(178, 58, 46, 0.35);
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='60' height='60'%3E%3Cfilter id='s'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.6' numOctaves='2'/%3E%3C/filter%3E%3Crect width='60' height='60' filter='url(%23s)' opacity='0.10'/%3E%3C/svg%3E");
}

.seal--sm {
    width: 46px;
    height: 46px;
    font-size: 13px;
    border-width: 1.5px;
    border-radius: 4px;
}

/* ---------- 按钮 ---------- */
.btn {
    display: inline-flex;
    align-items: center;
    gap: var(--sp-2);
    padding: 11px 22px;
    font-size: var(--fs-sm);
    letter-spacing: 0.03em;
    border: 1px solid var(--ink);
    border-radius: 2px;
    background: var(--ink);
    color: var(--paper);
    transition: background-color .18s, color .18s, border-color .18s, transform .18s;
}

.btn:hover {
    background: var(--seal);
    border-color: var(--seal);
    color: #fff;
    transform: translateY(-1px);
}

.btn--ghost {
    background: transparent;
    color: var(--ink);
    border-color: var(--rule-2);
}

.btn--ghost:hover {
    background: transparent;
    color: var(--seal);
    border-color: var(--seal);
}

.btn--sm { padding: 7px 15px; font-size: var(--fs-xs); }

.btn--seal {
    background: var(--seal);
    border-color: var(--seal);
    color: #fff;
}

.btn--seal:hover {
    background: var(--seal-deep);
    border-color: var(--seal-deep);
}

/* ---------- 文字链接 ---------- */
.link {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    font-size: var(--fs-sm);
    color: var(--ink-2);
    border-bottom: 1px solid var(--rule-2);
    padding-bottom: 2px;
    transition: color .18s, border-color .18s;
}

.link:hover { color: var(--seal); border-color: var(--seal); }

/* ---------- 小标签 ---------- */
.tag {
    display: inline-block;
    padding: 3px 10px;
    font-size: var(--fs-xs);
    letter-spacing: 0.06em;
    border: 1px solid var(--rule-2);
    border-radius: 999px;
    color: var(--ink-3);
    background: rgba(255, 255, 255, 0.45);
}

/* ---------- 区块标题 ---------- */
.sec-head {
    display: flex;
    align-items: flex-end;
    justify-content: space-between;
    gap: var(--sp-5);
    padding-bottom: var(--sp-4);
    border-bottom: 1px solid var(--rule);
    margin-bottom: var(--sp-7);
}

.sec-head__left {
    display: flex;
    align-items: baseline;
    gap: var(--sp-4);
}

.sec-head__title {
    font-size: var(--fs-xl);
    letter-spacing: 0.06em;
}

.sec-head__desc {
    margin-top: 6px;
    font-size: var(--fs-sm);
    color: var(--ink-3);
}

.sec-head__acts {
    display: flex;
    align-items: center;
    gap: var(--sp-4);
    flex: 0 0 auto;
}

.sec-head__count {
    font-family: var(--mono);
    font-size: var(--fs-xs);
    color: var(--ink-4);
    letter-spacing: 0.08em;
}

/* ---------- 入场动效 ---------- */
[data-reveal] {
    opacity: 0;
    transform: translateY(18px);
    transition: opacity .6s cubic-bezier(.2,.7,.3,1), transform .6s cubic-bezier(.2,.7,.3,1);
}

[data-reveal].is-in { opacity: 1; transform: none; }

@media (prefers-reduced-motion: reduce) {
    html { scroll-behavior: auto; }
    [data-reveal] { opacity: 1; transform: none; transition: none; }
    .btn:hover { transform: none; }
}

/* ---------- 无障碍 ---------- */
.skip-link {
    position: absolute;
    left: -9999px;
    top: 0;
    z-index: 200;
    padding: 10px 18px;
    background: var(--ink);
    color: var(--paper);
    font-size: var(--fs-sm);
}

.skip-link:focus { left: var(--sp-4); top: var(--sp-4); }

/* ---------- 响应式尺度 ---------- */
@media (max-width: 1024px) {
    :root {
        --fs-3xl: 48px;
        --fs-2xl: 36px;
        --fs-xl: 26px;
        --sp-9: 80px;
    }

    .sec-head { flex-wrap: wrap; }
}

@media (max-width: 760px) {
    :root {
        --fs-3xl: 36px;
        --fs-2xl: 28px;
        --fs-xl: 22px;
        --fs-lg: 18px;
        --sp-8: 52px;
        --sp-9: 60px;
        --sp-6: 24px;
    }

    body { font-size: 14px; }

    .sec-head {
        flex-direction: column;
        align-items: flex-start;
        gap: var(--sp-3);
        margin-bottom: var(--sp-6);
    }
}