:root {
  --bg: #f4f7fb;
  --panel: #ffffff;
  --ink: #151922;
  --muted: #5e6978;
  --line: #d8e1ec;
  --brand: #0054a6;
  --brand-dark: #003f7d;
  --accent: #5b9bd5;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  background: var(--bg);
  color: var(--ink);
  font-family: Calibri, Arial, Helvetica, sans-serif;
}
.display-none{display: none;}
.app-shell {
  display: grid;
  grid-template-columns:  minmax(200px, 280px) minmax(360px, 520px) minmax(420px, 1fr);
  gap: 24px;
  min-height: 100vh;
  padding: 24px;
}
/* navigation Start */
nav.main-navigation{padding: 20px;}
nav.main-navigation ul {margin: 0; padding: 0; list-style: none;}
nav.main-navigation ul li{ padding: 5px 15px; border-bottom: solid 1px #00000030; transition: 0.3s;}
nav.main-navigation ul li.active{    background: #0000000f;}
nav.main-navigation ul li:hover{background: #00000030;}
nav.main-navigation ul li:last-child{border-bottom: none;}
nav.main-navigation ul li a {color: #000; text-decoration: none; line-height: 30px; font-size: 14px; width: 100%; display: block;}
nav.main-navigation ul li.active a{font-weight: 600;}
/* navigation End */
.editor-panel,
.preview-panel {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 8px;
  box-shadow: 0 18px 45px rgba(18, 43, 82, 0.08);
}

.editor-panel {
  overflow: auto;
  max-height: calc(100vh - 48px);
}

.panel-header,
.preview-header {
  padding: 24px 24px 12px;
}

.eyebrow {
  margin: 0 0 8px;
  color: var(--brand);
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0;
  text-transform: uppercase;
}

h1,
h2 {
  margin: 0;
  color: var(--ink);
  font-weight: 700;
}

h1 {
  font-size: 28px;
  line-height: 34px;
}

h2 {
  font-size: 22px;
  line-height: 28px;
}

.signature-form {
  padding: 0 24px 24px;
}

fieldset {
  display: grid;
  gap: 14px;
  margin: 18px 0 0;
  padding: 18px;
  border: 1px solid var(--line);
  border-radius: 8px;
}

legend {
  padding: 0 8px;
  color: var(--muted);
  font-size: 13px;
  font-weight: 700;
}

label {
  display: grid;
  gap: 7px;
  color: var(--muted);
  font-size: 13px;
  font-weight: 700;
}

input {
  width: 100%;
  min-height: 42px;
  border: 1px solid var(--line);
  border-radius: 6px;
  padding: 10px 12px;
  color: var(--ink);
  font: inherit;
  font-weight: 400;
  background: #fbfdff;
}

input[type="color"] {
  padding: 4px;
}

input:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(91, 155, 213, 0.18);
  outline: none;
}

.two-column {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 14px;
}

.actions {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 18px;
}

button {
  min-height: 42px;
  border: 1px solid transparent;
  border-radius: 6px;
  padding: 10px 14px;
  cursor: pointer;
  font: inherit;
  font-weight: 700;
}

.primary-button {
  background: var(--brand);
  color: #ffffff;
}

.primary-button:hover {
  background: var(--brand-dark);
}

.secondary-button {
  background: #eaf2fb;
  border-color: #c3d8ef;
  color: var(--ink);
}

.ghost-button {
  background: transparent;
  border-color: var(--line);
  color: var(--muted);
}

.status-message {
  min-height: 20px;
  margin: 12px 0 0;
  color: var(--brand);
  font-size: 13px;
  font-weight: 700;
}

.preview-panel {
  display: grid;
  grid-template-rows: auto 1fr;
  min-width: 0;
}

.preview-frame {
  margin: 0 24px 24px;
  min-height: 330px;
  overflow: auto;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #ffffff;
  padding: 32px;
}

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

  .editor-panel {
    max-height: none;
  }
}

@media (max-width: 560px) {
  .app-shell {
    padding: 12px;
  }

  .two-column {
    grid-template-columns: 1fr;
  }

  .panel-header,
  .preview-header,
  .signature-form {
    padding-left: 16px;
    padding-right: 16px;
  }

  .preview-frame {
    margin-left: 16px;
    margin-right: 16px;
    padding: 16px;
  }
}