/* 邓老师的科学小课堂 —— 公共样式 */
:root {
    --bg: #f8f4e8;
    --bg-deep: #efe8d4;
    --surface: #ffffff;
    --surface-2: #fbf9f2;
    --ink: #22312a;
    --ink-2: #4a5a51;
    --muted: #7c8a80;
    --line: #e6dfca;
    --primary: #2f7d4f;
    --primary-deep: #1f5c38;
    --primary-soft: #e3f1e7;
    --accent: #f08c1f;
    --accent-soft: #fff1dc;
    --danger: #d9473b;
    --danger-soft: #fde8e5;
    --ok: #2e9d3a;
    --ok-soft: #e4f5e5;
    --head: #ff8f00;
    --thorax: #2e9d3a;
    --abdomen: #9c27b0;
    --radius: 18px;
    --radius-sm: 12px;
    --shadow: 0 1px 2px rgba(60, 50, 20, .06), 0 8px 24px rgba(60, 50, 20, .08);
    --shadow-lg: 0 2px 4px rgba(60, 50, 20, .06), 0 18px 48px rgba(60, 50, 20, .14);
    --font: "PingFang SC", "Microsoft YaHei", "Noto Sans CJK SC", "Source Han Sans SC", "Hiragino Sans GB", sans-serif;
}

* { box-sizing: border-box; }
[hidden] { display: none !important; }
html, body { margin: 0; padding: 0; }
body {
    background: var(--bg);
    color: var(--ink);
    font-family: var(--font);
    -webkit-font-smoothing: antialiased;
    line-height: 1.6;
}
img { max-width: 100%; display: block; }
button { font-family: inherit; }
h1, h2, h3, h4 { line-height: 1.25; margin: 0; }

.btn {
    display: inline-flex; align-items: center; justify-content: center; gap: 8px;
    min-height: 44px; padding: 0 20px;
    border: 2px solid transparent; border-radius: 999px;
    font-size: 17px; font-weight: 700; cursor: pointer; text-decoration: none;
    transition: transform .12s ease, background-color .15s ease, box-shadow .15s ease, color .15s ease;
    user-select: none; -webkit-tap-highlight-color: transparent;
}
.btn:active { transform: scale(.97); }
.btn:focus-visible { outline: 3px solid var(--accent); outline-offset: 2px; }
.btn[disabled] { opacity: .45; cursor: not-allowed; }
.btn-primary { background: var(--primary); color: #fff; box-shadow: 0 4px 12px rgba(47, 125, 79, .28); }
.btn-primary:hover { background: var(--primary-deep); }
.btn-accent { background: var(--accent); color: #fff; box-shadow: 0 4px 12px rgba(240, 140, 31, .3); }
.btn-accent:hover { background: #d97810; }
.btn-ghost { background: var(--surface); color: var(--ink-2); border-color: var(--line); }
.btn-ghost:hover { border-color: var(--primary); color: var(--primary); }
.btn-lg { min-height: 54px; padding: 0 28px; font-size: 19px; }
.btn-sm { min-height: 36px; padding: 0 14px; font-size: 15px; }

.card {
    background: var(--surface);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
}

.icon { width: 1.15em; height: 1.15em; flex: none; }

.chip {
    display: inline-flex; align-items: center; gap: 6px;
    padding: 3px 12px; border-radius: 999px;
    font-size: 14px; font-weight: 700;
    background: var(--primary-soft); color: var(--primary-deep);
}
.chip-accent { background: var(--accent-soft); color: #a65a00; }