:root {
  --lesson-bg: #f4f2ec;
  --lesson-surface: #fbfaf7;
  --lesson-surface-strong: #ffffff;
  --lesson-border: #d8d2c6;
  --lesson-border-strong: #bdb4a4;
  --lesson-text: #22211d;
  --lesson-muted: #676153;
  --lesson-heading: #1e1d19;
  --lesson-accent: #6a7a6a;
  --lesson-code-bg: #f7f5ef;
  --lesson-code-border: #cbc3b4;
  --lesson-log-bg: #fcfbf8;
  --lesson-log-text: #1c3459;
  --lesson-button-bg: #f6f2e9;
  --lesson-button-border: #c6bca8;
  --lesson-button-text: #2e2b24;
  --lesson-button-hover-bg: #ece5d7;
  --lesson-shadow: 0 10px 28px rgba(42, 37, 29, 0.08);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  padding: 0;
  background: linear-gradient(180deg, #f7f5f0 0%, #f1eee7 100%);
  color: var(--lesson-text);
  font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
  line-height: 1.72;
}

.lesson-container {
  max-width: 980px;
  margin: 0 auto;
  padding: 18px 22px 56px;
}

h1,
h2,
h3 {
  color: var(--lesson-heading);
  line-height: 1.3;
}

h1 {
  margin: 1.75rem 0 0.65rem;
  padding-bottom: 0.45rem;
  font-size: 1.55rem;
  font-weight: 700;
  border-bottom: 1px solid var(--lesson-border);
}

h2 {
  margin: 1.35rem 0 0.45rem;
  font-size: 1.16rem;
  font-weight: 650;
}

h3 {
  margin: 1rem 0 0.35rem;
  font-size: 1rem;
  font-style: normal;
  font-weight: 600;
  color: var(--lesson-muted);
}

p {
  margin: 0.9rem 0 1rem;
  padding: 0.8rem 1rem;
  border-left: 4px solid var(--lesson-border-strong);
  background: rgba(255, 255, 255, 0.55);
  color: var(--lesson-text);
  font-family: inherit;
  font-size: 1rem;
  font-weight: 600;
}

ul,
ol {
  margin: 0.4rem 0 1rem;
  padding-left: 1.45rem;
}

li {
  margin-bottom: 0.38rem;
}

table {
  width: 100%;
  margin: 0.85rem 0 1.35rem;
  border-collapse: collapse;
  background: var(--lesson-surface-strong);
  border: 1px solid var(--lesson-border);
  box-shadow: var(--lesson-shadow);
}

th,
td {
  padding: 0.8rem 0.9rem;
  border: 1px solid var(--lesson-border);
  text-align: left;
  vertical-align: top;
  font-size: 0.95rem;
}

th {
  background: #ece7dc;
  color: var(--lesson-heading);
  font-weight: 700;
}

tr:nth-child(even) {
  background: #faf8f3;
}

textarea {
  width: 100%;
  margin: 0.75rem 0 0.55rem;
  padding: 0.95rem 1rem;
  border: 1px solid var(--lesson-code-border);
  border-radius: 12px;
  background: var(--lesson-surface-strong);
  color: var(--lesson-text);
  font-family: Consolas, "Courier New", monospace;
  font-size: 0.94rem;
  font-weight: 400;
  line-height: 1.55;
  resize: vertical;
  overflow: auto;
  box-shadow: inset 0 1px 2px rgba(0, 0, 0, 0.04);
}

.codetextarea {
  background: var(--lesson-code-bg);
  border-color: var(--lesson-code-border);
  color: #1d1c18;
}

.lesson-code-wrap {
  position: relative;
  margin: 0.75rem 0 0.9rem;
}

.lesson-code-wrap .codetextarea {
  position: absolute;
  left: -9999px;
  top: auto;
  width: 1px;
  height: 1px;
  margin: 0;
  padding: 0;
  opacity: 0;
  pointer-events: none;
  overflow: hidden;
}

.lesson-code-display {
  width: 100%;
  margin: 0;
  padding: 3.1rem 1rem 1rem;
  border: 1px solid var(--lesson-code-border);
  border-radius: 12px;
  background: var(--lesson-code-bg);
  color: #1d1c18;
  font-family: Consolas, "Courier New", monospace;
  font-size: 0.94rem;
  font-weight: 400;
  line-height: 1.55;
  white-space: pre;
  overflow: auto;
  box-shadow: inset 0 1px 2px rgba(0, 0, 0, 0.04);
}

.lesson-code-syntax {
  display: block;
  color: inherit;
}

.sas-keyword,
.sas-statement {
  color: #0b57c5;
  font-weight: 700;
}

.sas-macro,
.sas-macro-var {
  color: #8a2db8;
}

.sas-string {
  color: #0b7f4f;
}

.sas-comment {
  color: #8b6f3d;
  font-style: italic;
}

.sas-option {
  color: #b05900;
}

.logtextarea {
  background: var(--lesson-log-bg);
  color: var(--lesson-log-text);
  font-size: 0.88rem;
}

.lesson-action,
.btn-view,
.btn-copy {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.35rem;
  min-height: 38px;
  margin: 0 0.5rem 0.9rem 0;
  padding: 0.45rem 0.9rem;
  border: 1px solid var(--lesson-button-border);
  border-radius: 999px;
  background: var(--lesson-button-bg);
  color: var(--lesson-button-text);
  font-family: inherit;
  font-size: 0.92rem;
  font-weight: 600;
  text-decoration: none;
  cursor: pointer;
  transition: background-color 0.18s ease, border-color 0.18s ease, color 0.18s ease, transform 0.18s ease;
}

.btn-view {
  min-height: 42px;
  padding: 0.52rem 1rem;
  border-color: #b89f6f;
  background: #f6efe0;
  color: #433116;
  font-weight: 700;
  box-shadow: 0 3px 10px rgba(120, 93, 47, 0.12);
}

.btn-view::before {
  content: "";
  width: 0.55rem;
  height: 0.55rem;
  border-radius: 999px;
  background: #b27b1d;
  box-shadow: 0 0 0 3px rgba(178, 123, 29, 0.16);
  flex: 0 0 auto;
}

.lesson-action:hover,
.btn-view:hover,
.btn-copy:hover {
  background: var(--lesson-button-hover-bg);
  border-color: var(--lesson-border-strong);
  color: var(--lesson-heading);
  transform: translateY(-1px);
}

.btn-view:hover {
  background: #f2e6cf;
  border-color: #9d8454;
  color: #2f2412;
}

.btn-copy.is-copied {
  background: #e6efe7;
  border-color: #a9bea9;
}

.lesson-code-copy {
  position: absolute;
  top: 0.8rem;
  right: 0.8rem;
  z-index: 2;
  margin: 0;
  min-height: 34px;
  padding: 0.35rem 0.8rem;
  font-size: 0.84rem;
}

.modal-content {
  border: 1px solid var(--lesson-border);
  border-radius: 18px;
  overflow: hidden;
  box-shadow: 0 24px 60px rgba(24, 22, 18, 0.22);
}

.modal-header {
  background: #f2eee5;
  border-bottom: 1px solid var(--lesson-border);
}

.modal-title {
  color: var(--lesson-heading);
  font-weight: 700;
}

.modal-body {
  background: var(--lesson-surface);
}

.lesson-data-frame {
  display: block;
  width: 100%;
  height: min(72vh, 640px);
  border: 0;
  background: #fff;
}

.lesson-modal-image {
  max-width: 100%;
  border-radius: 10px;
}

.column {
  float: left;
  padding: 10px;
  box-sizing: border-box;
}

.left,
.right {
  width: 100%;
}

ul#menu {
  list-style-type: none;
  margin: 0;
  padding: 0.35rem 0.5rem;
  background: rgba(42, 39, 33, 0.92);
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  position: sticky;
  top: 0;
  z-index: 1000;
  backdrop-filter: blur(8px);
}

ul#menu li {
  font-size: 1rem;
}

li#menu a {
  display: block;
  margin: 0.18rem;
  padding: 0.5rem 0.9rem;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.08);
  color: #f5f1e8;
  text-decoration: none;
}

li#menu a:hover {
  background: rgba(255, 255, 255, 0.16);
}

@media (min-width: 768px) {
  .left {
    width: 25%;
  }

  .right {
    width: 75%;
  }
}

@media (max-width: 767.98px) {
  body {
    font-size: 15px;
  }

  .lesson-container {
    padding: 14px 14px 42px;
  }

  h1 {
    font-size: 1.34rem;
    margin-top: 1.35rem;
  }

  h2 {
    font-size: 1.08rem;
  }

  textarea {
    font-size: 0.86rem;
    padding: 0.8rem 0.82rem;
    border-radius: 10px;
  }

  .lesson-code-display {
    font-size: 0.86rem;
    padding: 2.8rem 0.82rem 0.82rem;
    border-radius: 10px;
  }

  .lesson-action,
  .btn-view,
  .btn-copy {
    width: 100%;
    margin-right: 0;
    margin-bottom: 0.65rem;
  }

  .lesson-code-copy {
    top: 0.65rem;
    right: 0.65rem;
    width: auto;
    max-width: calc(100% - 1.3rem);
  }

  .lesson-data-frame {
    height: 74vh;
  }

  table,
  th,
  td {
    font-size: 0.88rem;
  }
}