.copybox {
    display: flex; align-items: center; flex-wrap: wrap; gap: 0.6rem;
    background: #f6f8fb; border: 1px solid #dde4ee; border-radius: 4px;
    padding: 0.6rem 0.9rem; margin-bottom: 1.2rem;
}
.copybox-label { font-size: 0.75rem; text-transform: uppercase; letter-spacing: 0.05em; color: #2a6fdb; font-weight: 600; }
.copybox code { font-size: 1.05rem; background: white; border: 1px solid #ddd; padding: 0.15rem 0.5rem; user-select: all; }
.copy-btn { min-width: 4.5rem; text-align: center; padding: 0.25rem 0.7rem; border: 1px solid #ccc; background: white; border-radius: 4px; cursor: pointer; font-size: 0.8rem; }
.copy-btn:hover { background: #f3f3f3; }
.copybox-note { flex-basis: 100%; font-size: 0.8rem; color: #777; }
.after { margin: 0 0 1rem; padding: 0.6rem 0.9rem; background: #eef6ff; border-left: 3px solid #2a6fdb; border-radius: 0 4px 4px 0; font-size: 0.9rem; }

.steps { display: flex; flex-wrap: wrap; gap: 0.5rem; margin-bottom: 1.5rem; }
.step {
    width: 2.2rem; height: 2.2rem; border-radius: 50%;
    border: 1px solid #ccc; background: white; color: #555;
    font-size: 0.95rem; cursor: pointer;
}
.step.active { border-color: #2a6fdb; color: #2a6fdb; font-weight: 600; }
.step.done { background: #e6f4ea; border-color: #4caf50; color: #2e7d32; }

.lesson h2 { font-size: 1.3rem; font-weight: 500; margin-bottom: 0.75rem; }
.explain { margin-bottom: 1rem; }
.explain p { margin-bottom: 0.5rem; }
code {
    font-family: Menlo, Consolas, monospace; background: #f3f3f3;
    padding: 0.05rem 0.3rem; border-radius: 3px; font-size: 0.9em;
}
.task {
    background: #f6f8fb; border-left: 3px solid #2a6fdb;
    padding: 0.6rem 0.9rem; margin-bottom: 1.2rem;
}
.task-label {
    font-size: 0.75rem; text-transform: uppercase; letter-spacing: 0.05em;
    color: #2a6fdb; margin-right: 0.4rem; font-weight: 600;
}

.regex-label { display: block; font-size: 0.8rem; color: #666; margin-bottom: 0.25rem; }
.regex-row {
    display: flex; align-items: center; gap: 0.4rem;
    border: 1px solid #bbb; border-radius: 4px; padding: 0.3rem 0.6rem;
}
.regex-row:focus-within { border-color: #2a6fdb; box-shadow: 0 0 0 2px rgba(42,111,219,0.15); }
.slash { font-family: Menlo, Consolas, monospace; color: #999; font-size: 1.1rem; }
#regexInput {
    flex: 1; border: none; outline: none; font-size: 1.1rem;
    font-family: Menlo, Consolas, "PingFang TC", "Noto Sans CJK TC", monospace;
    padding: 0.3rem 0;
}

.status { margin: 0.6rem 0 1rem; font-size: 0.85rem; color: #666; min-height: 1.3rem; }
.status.error { color: #c62828; }
.status.success { color: #2e7d32; font-weight: 600; }

.samples { display: flex; flex-direction: column; gap: 0.4rem; margin-bottom: 1.2rem; }
.sample {
    display: flex; align-items: center; gap: 0.7rem;
    border: 1px solid #e0e0e0; border-radius: 4px; padding: 0.5rem 0.8rem;
    font-size: 1.25rem; white-space: pre-wrap;
}
.sample.ok { border-color: #a5d6a7; background: #fafffa; }
.sample .text { flex: 1; line-height: 1.8; }
.sample .badge { font-size: 0.9rem; color: #c62828; width: 1.2rem; }
.sample.ok .badge { color: #2e7d32; }
.sample .count { font-size: 0.75rem; color: #999; }
mark { background: #ffe066; color: inherit; border-radius: 2px; box-shadow: 0 0 0 1px #e6b800; }

.actions { display: flex; gap: 0.5rem; flex-wrap: wrap; }
.actions button {
    padding: 0.45rem 0.9rem; border: 1px solid #ccc; background: white;
    border-radius: 4px; cursor: pointer; font-size: 0.9rem;
}
.actions button:hover:not(:disabled) { background: #f3f3f3; }
.actions button:disabled { opacity: 0.4; cursor: default; }
.actions .primary { background: #2a6fdb; border-color: #2a6fdb; color: white; margin-left: auto; }
.actions .primary:hover:not(:disabled) { background: #1f5ab5; }
.hint { margin-top: 0.8rem; padding: 0.5rem 0.8rem; background: #fff8e1; border-radius: 4px; }

.reference { margin-top: 2.5rem; border-top: 1px solid #e0e0e0; padding-top: 1rem; }
.reference summary { cursor: pointer; color: #666; margin-bottom: 0.5rem; }
.reference table { border-collapse: collapse; width: 100%; }
.reference td { padding: 0.35rem 0.5rem; border-bottom: 1px solid #eee; vertical-align: top; }
.reference td:first-child { white-space: nowrap; }

.inv { font-family: Menlo, Consolas, monospace; font-size: 0.6rem; background: #c62828; color: white; border-radius: 3px; padding: 0 0.25rem; margin: 0 1px; vertical-align: middle; }
.step.extra { border-style: dashed; }
.extras-label { align-self: center; font-size: 0.75rem; color: #999; margin: 0 0.2rem 0 0.6rem; text-transform: uppercase; letter-spacing: 0.05em; }
.sample.idle .badge { color: #bbb; }