:root {
  --bg-main: #06111f;
  --bg-secondary: rgba(10, 25, 45, 0.7);
  --panel-border: rgba(120, 220, 255, 0.25);
  --panel-shadow: 0 0 25px rgba(0, 180, 255, 0.12);
  --text-main: #eafcff;
  --text-soft: rgba(234, 252, 255, 0.72);
  --text-faint: rgba(234, 252, 255, 0.48);
  --neon-blue: #59d7ff;
  --neon-blue-strong: #00cfff;
  --neon-green: #2dff9e;
  --editor-bg: rgba(3, 10, 22, 0.72);
  --preview-bg: rgba(5, 15, 30, 0.6);
  --line-number-bg: rgba(255, 255, 255, 0.03);
  --line-number-text: rgba(130, 220, 255, 0.6);
  --code-bg: rgba(0, 0, 0, 0.28);
  --selection: rgba(0, 207, 255, 0.22);
}

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  min-height: 100%;
  font-family: Inter, "Segoe UI", Roboto, Arial, sans-serif;
  background:
    radial-gradient(circle at top left, rgba(0, 160, 255, 0.12), transparent 30%),
    radial-gradient(circle at bottom right, rgba(0, 220, 255, 0.10), transparent 25%),
    linear-gradient(135deg, #020812, #071120 40%, #08162a 100%);
  color: var(--text-main);
}

body {
  position: relative;
  overflow-x: hidden;
}

::selection {
  background: var(--selection);
}

.background-glow {
  position: fixed;
  border-radius: 999px;
  filter: blur(70px);
  pointer-events: none;
  z-index: 0;
}

.glow-1 {
  width: 260px;
  height: 260px;
  background: rgba(0, 160, 255, 0.16);
  top: 30px;
  left: 40px;
}

.glow-2 {
  width: 320px;
  height: 320px;
  background: rgba(0, 220, 255, 0.12);
  right: 40px;
  bottom: 20px;
}

.app {
  position: relative;
  z-index: 1;
  min-height: 100vh;
  padding: 28px;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 22px;
}

.glass {
  background: linear-gradient(180deg, rgba(14, 28, 48, 0.78), rgba(8, 18, 34, 0.66));
  border: 1px solid var(--panel-border);
  border-radius: 22px;
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  box-shadow:
    inset 0 1px 0 rgba(255, 255, 255, 0.06),
    0 0 0 1px rgba(0, 207, 255, 0.04),
    var(--panel-shadow);
}

.panel {
  min-height: calc(100vh - 56px);
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

.panel-top,
.preview-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 18px 18px 14px 18px;
  border-bottom: 1px solid rgba(120, 220, 255, 0.14);
  background: linear-gradient(180deg, rgba(255, 255, 255, 0.03), transparent);
}

.preview-header h2 {
  margin: 0;
  font-size: 1.05rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  color: var(--neon-blue);
  text-shadow: 0 0 10px rgba(89, 215, 255, 0.25);
}

.top-left-actions,
.top-right-actions {
  display: flex;
  align-items: center;
  gap: 10px;
}

.btn {
  border: 1px solid transparent;
  border-radius: 12px;
  padding: 10px 16px;
  font-size: 0.95rem;
  font-weight: 700;
  cursor: pointer;
  transition:
    transform 0.16s ease,
    box-shadow 0.16s ease,
    border-color 0.16s ease,
    background 0.16s ease;
}

.btn:hover {
  transform: translateY(-1px);
}

.btn:active {
  transform: translateY(0);
}

.btn-blue {
  color: #dff8ff;
  background: linear-gradient(180deg, rgba(0, 180, 255, 0.16), rgba(0, 120, 220, 0.12));
  border-color: rgba(89, 215, 255, 0.32);
  box-shadow: 0 0 18px rgba(0, 180, 255, 0.16);
}

.btn-blue:hover {
  box-shadow: 0 0 22px rgba(0, 200, 255, 0.22);
  border-color: rgba(89, 215, 255, 0.48);
}

.btn-green {
  color: #062114;
  background: linear-gradient(180deg, rgba(45, 255, 158, 0.96), rgba(20, 218, 127, 0.92));
  border-color: rgba(118, 255, 194, 0.55);
  box-shadow: 0 0 20px rgba(45, 255, 158, 0.28);
}

.btn-green:hover {
  box-shadow: 0 0 25px rgba(45, 255, 158, 0.38);
}

.editor-wrapper {
  flex: 1;
  min-height: 0;
  display: flex;
  background: var(--editor-bg);
}

.line-numbers {
  width: 68px;
  padding: 18px 12px;
  margin: 0;
  background: var(--line-number-bg);
  border-right: 1px solid rgba(120, 220, 255, 0.12);
  color: var(--line-number-text);
  font-family: "JetBrains Mono", "Fira Code", monospace;
  font-size: 0.95rem;
  line-height: 1.6;
  text-align: right;
  user-select: none;
  overflow: hidden;
  white-space: pre;
}

#markdownInput {
  flex: 1;
  min-width: 0;
  resize: none;
  border: none;
  outline: none;
  background: transparent;
  color: var(--text-main);
  padding: 18px 20px;
  font-family: "JetBrains Mono", "Fira Code", monospace;
  font-size: 0.95rem;
  line-height: 1.6;
  caret-color: var(--neon-blue);
}

#markdownInput::placeholder {
  color: rgba(180, 235, 255, 0.34);
}

.preview-panel {
  background:
    linear-gradient(180deg, rgba(13, 28, 48, 0.78), rgba(7, 18, 34, 0.7)),
    var(--preview-bg);
}

.preview-content {
  flex: 1;
  min-height: 0;
  overflow: auto;
  padding: 22px 24px 28px;
}

.preview-placeholder {
  color: var(--text-faint);
  font-size: 1rem;
}

.preview-content h1,
.preview-content h2,
.preview-content h3,
.preview-content h4,
.preview-content h5,
.preview-content h6 {
  color: #dff9ff;
  margin-top: 1.4em;
  margin-bottom: 0.6em;
  line-height: 1.2;
}

.preview-content h1 {
  font-size: 2rem;
  color: var(--neon-blue);
  text-shadow: 0 0 16px rgba(89, 215, 255, 0.22);
  border-bottom: 1px solid rgba(89, 215, 255, 0.2);
  padding-bottom: 0.35em;
}

.preview-content h2 {
  font-size: 1.55rem;
  color: #b9f2ff;
}

.preview-content h3 {
  font-size: 1.25rem;
}

.preview-content p,
.preview-content li,
.preview-content blockquote {
  color: var(--text-soft);
  line-height: 1.75;
  font-size: 1rem;
}

.preview-content a {
  color: var(--neon-blue);
  text-decoration: none;
  border-bottom: 1px solid rgba(89, 215, 255, 0.35);
}

.preview-content a:hover {
  text-shadow: 0 0 10px rgba(89, 215, 255, 0.22);
}

.preview-content ul,
.preview-content ol {
  padding-left: 1.5rem;
}

.preview-content hr {
  border: none;
  border-top: 1px solid rgba(89, 215, 255, 0.2);
  margin: 1.6rem 0;
}

.preview-content blockquote {
  margin: 1.2rem 0;
  padding: 0.9rem 1rem;
  border-left: 4px solid rgba(89, 215, 255, 0.55);
  background: rgba(255, 255, 255, 0.03);
  border-radius: 0 14px 14px 0;
}

.preview-content code {
  font-family: "JetBrains Mono", "Fira Code", monospace;
  background: rgba(255, 255, 255, 0.06);
  color: #bff4ff;
  padding: 0.14rem 0.38rem;
  border-radius: 8px;
  font-size: 0.92em;
}

.preview-content pre {
  background: var(--code-bg);
  border: 1px solid rgba(89, 215, 255, 0.16);
  border-radius: 16px;
  padding: 16px;
  overflow: auto;
  box-shadow: inset 0 0 18px rgba(0, 180, 255, 0.04);
}

.preview-content pre code {
  background: transparent;
  padding: 0;
  border-radius: 0;
  color: #d9f7ff;
}

.preview-content table {
  width: 100%;
  border-collapse: collapse;
  margin: 1.2rem 0;
  overflow: hidden;
  border-radius: 16px;
  background: rgba(255, 255, 255, 0.03);
}

.preview-content th,
.preview-content td {
  border: 1px solid rgba(89, 215, 255, 0.14);
  padding: 12px 14px;
  text-align: left;
  color: var(--text-soft);
}

.preview-content th {
  color: #dff9ff;
  background: rgba(89, 215, 255, 0.06);
}

.preview-content img {
  max-width: 100%;
  border-radius: 16px;
  border: 1px solid rgba(89, 215, 255, 0.15);
  box-shadow: 0 0 20px rgba(0, 180, 255, 0.1);
}

.preview-content strong {
  color: #f3fdff;
}

.preview-content em {
  color: #c7f6ff;
}

@media (max-width: 980px) {
  .app {
    grid-template-columns: 1fr;
  }

  .panel {
    min-height: 420px;
  }

  .editor-panel,
  .preview-panel {
    min-height: calc(50vh - 40px);
  }
}

@media (max-width: 640px) {
  .app {
    padding: 16px;
    gap: 16px;
  }

  .panel-top,
  .preview-header {
    padding: 14px;
    flex-wrap: wrap;
  }

  .line-numbers {
    width: 56px;
    padding: 16px 8px;
    font-size: 0.88rem;
  }

  #markdownInput {
    padding: 16px 14px;
    font-size: 0.9rem;
  }

  .preview-content {
    padding: 18px 16px 24px;
  }

  .btn {
    padding: 9px 13px;
    font-size: 0.9rem;
  }
}