/* 知识共建共享平台：暖黑底、米色卡片，刻意与习惯页的纸页区分开。 */
:root {
  --plane: #14120f;
  --bar: #1c1916;
  --line-dark: #2c2823;
  --ink: #f3efe6;
  --ink-muted: #a39888;
  --card: #f7f3ea;
  --card-ink: #1c1916;
  --prereq: #b08968;
  --instance: #8aa0a2;
  --aside: #1c1916;
}

* {
  box-sizing: border-box;
}

.save-status {
  padding: 8px 20px;
  background: var(--bar);
  color: var(--ink-muted);
  border-bottom: 1px solid var(--line-dark);
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  font-size: 13px;
}
.save-status.save-problem { color: #a84444; }
.save-status button { font-size: inherit; padding: 4px 10px; }
.save-status [hidden] { display: none; }

html,
body {
  margin: 0;
  padding: 0;
}

body {
  min-height: 100vh;
  background-color: var(--plane);
  color: var(--ink);
  font-family: "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  line-height: 1.6;
}

.hidden {
  display: none !important;
}

/* 账号门：同一块暖黑底，不做习惯页的纸面卡片 */
.account-gate {
  min-height: 100vh;
  display: grid;
  place-items: center;
  padding: 24px;
}

.account-card {
  width: min(420px, 100%);
  background: var(--aside);
  border: 1px solid var(--line-dark);
  border-radius: 16px;
  padding: 28px;
}

.eyebrow {
  margin: 0 0 6px;
  font-size: 12px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--ink-muted);
}

.account-card h1 {
  margin: 0 0 8px;
  font-size: 24px;
}

.account-lead {
  margin: 0 0 20px;
  color: var(--ink-muted);
}

.form {
  display: grid;
  gap: 14px;
}

.field {
  display: grid;
  gap: 6px;
  font-size: 13px;
  color: var(--ink-muted);
}

input[type="text"],
input[type="password"],
input[type="number"],
select,
textarea,
input[type="file"] {
  width: 100%;
  padding: 10px 12px;
  border: 1px solid var(--line-dark);
  border-radius: 10px;
  background: #1b1815;
  color: var(--ink);
  font: inherit;
}

input:focus,
select:focus,
textarea:focus {
  outline: 1px solid var(--prereq);
  border-color: var(--prereq);
}

.primary {
  border: 1px solid transparent;
  border-radius: 10px;
  background: #f3eadc;
  color: #1c1916;
  padding: 10px 16px;
  font: inherit;
  font-weight: 700;
  cursor: pointer;
}

.primary:hover {
  background: #e8dcc7;
}

.account-modes {
  display: flex;
  gap: 10px;
  margin-top: 16px;
}

.account-mode-button,
.link-button,
.ghost-button {
  border: 1px solid var(--line-dark);
  border-radius: 10px;
  background: transparent;
  color: var(--ink-muted);
  padding: 8px 14px;
  font: inherit;
  cursor: pointer;
}

.account-mode-button.active {
  border-color: var(--prereq);
  color: var(--prereq);
}

.link-button:hover,
.ghost-button:hover {
  color: var(--ink);
  border-color: var(--instance);
}

.ghost-button.danger:hover {
  color: #e08686;
  border-color: #8a4444;
}

.report {
  margin-top: 14px;
  padding: 10px 12px;
  border: 1px solid #8a4444;
  border-radius: 10px;
  color: #e0a0a0;
  background: rgba(138, 68, 68, 0.12);
}

/* 顶栏：只有标题、新建节点、回习惯页的链接、退出 */
.platform-root {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.platform-bar {
  position: sticky;
  top: 0;
  z-index: 2;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 16px;
  padding: 14px 22px;
  background: var(--bar);
  border-bottom: 1px solid var(--line-dark);
}

.platform-title {
  margin: 0;
  font-family: "Palatino Linotype", "Songti SC", "STSong", serif;
  font-size: 18px;
  font-weight: 500;
  letter-spacing: 0.04em;
}

.platform-bar-actions {
  display: flex;
  align-items: center;
  gap: 16px;
}

.platform-link {
  color: var(--ink-muted);
  text-decoration: none;
  border-bottom: 1px solid transparent;
}

.platform-link:hover {
  border-bottom-color: var(--ink-muted);
}

.platform-stage {
  flex: 1;
  display: flex;
  align-items: stretch;
  min-height: 0;
}

.platform-feed {
  flex: 1;
  min-width: 0;
  overflow: auto;
  padding: 24px;
}

/* 平面与节点：米色卡片绝对定位铺在暖黑底上 */
.tree-plane {
  position: relative;
}

.tree-legend {
  position: absolute;
  top: 12px;
  left: 20px;
  display: flex;
  gap: 20px;
  font-size: 12px;
  color: var(--ink-muted);
}

.tree-legend-item {
  display: inline-flex;
  align-items: center;
  gap: 6px;
}

.tree-legend-swatch {
  width: 24px;
  border-top: 2px solid var(--prereq);
}

.tree-legend-swatch.instance {
  border-top-style: dashed;
  border-top-color: var(--instance);
}

.tree-svg {
  position: absolute;
  top: 0;
  left: 0;
  pointer-events: none;
}

.tree-edge {
  fill: none;
  stroke-width: 1.25;
}

.tree-edge-prereq {
  stroke: var(--prereq);
}

.tree-edge-instance {
  stroke: var(--instance);
  stroke-dasharray: 6 5;
}

.tree-node {
  position: absolute;
  display: flex;
  flex-direction: column;
  justify-content: center;
  gap: 4px;
  width: 168px;
  height: 72px;
  padding: 10px 14px;
  border: 0;
  border-radius: 14px;
  background: var(--card);
  color: var(--card-ink);
  text-align: left;
  cursor: pointer;
  box-shadow: 0 12px 28px rgba(0, 0, 0, 0.28);
}

.tree-node:hover {
  background: #fffaf0;
}

.tree-node:focus-visible {
  outline: 2px solid var(--prereq);
  outline-offset: 2px;
}

.node-title {
  font-weight: 700;
}

.node-count {
  font-size: 12px;
  color: #7a6f5f;
}

/* 右侧阅读栏 */
.platform-detail {
  flex: 0 0 380px;
  width: 380px;
  background: var(--aside);
  border-left: 1px solid var(--line-dark);
  padding: 20px;
  overflow: auto;
}

.platform-detail > .link-button {
  margin-bottom: 16px;
}

.detail-body h2 {
  margin: 0 0 4px;
  font-size: 20px;
}

.detail-meta {
  color: var(--ink-muted);
  font-size: 13px;
}

.detail-block {
  margin-top: 22px;
  display: grid;
  gap: 12px;
}

.detail-label {
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--ink-muted);
}

.record-list {
  display: grid;
  gap: 10px;
}

.record-item {
  border: 0;
  border-radius: 12px;
  background: #26231e;
  padding: 12px 14px;
}

.record-meta {
  color: var(--ink-muted);
  font-size: 12px;
}

.record-text {
  margin-top: 8px;
  white-space: pre-wrap;
}

.record-actions {
  display: flex;
  gap: 10px;
  margin-top: 12px;
}

.practice-image {
  display: block;
  margin-top: 10px;
  max-width: 100%;
  border-radius: 10px;
}

.meta-note {
  color: var(--ink-muted);
  font-size: 13px;
}

.tutorial-head {
  display: flex;
  align-items: center;
  gap: 12px;
}

.tutorial-head h4 {
  margin: 0;
  font-size: 15px;
}

.tutorial-toggle {
  margin-left: auto;
}

/* 新建节点表单直接在阅读栏里排布，字段之间留出间距 */
.detail-body > .field {
  margin-bottom: 12px;
}

.node-edit-form {
  display: grid;
  gap: 12px;
  margin-top: 14px;
}

@media (max-width: 800px) {
  .platform-stage {
    flex-direction: column;
  }

  .platform-detail {
    flex: 1 1 auto;
    width: 100%;
    border-left: 0;
  }
}