/* ============================================
   BeamCalc Free — Design System & Base Styles
   ============================================ */

/* --- CSS Variables / Tokens --- */
:root {
  /* Colors */
  --color-primary: #1a56db;
  --color-primary-dark: #1347b3;
  --color-primary-light: #4f8bf7;
  --color-white: #ffffff;
  --color-bg: #f5f7fa;
  --color-text: #1e293b;
  --color-text-muted: #64748b;
  --color-border: #e2e8f0;
  --color-success: #16a34a;
  --color-warning: #f59e0b;
  --color-error: #dc2626;

  /* Typography */
  --font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --text-sm: 0.875rem;
  --text-base: 1rem;
  --text-lg: 1.25rem;
  --text-xl: 1.5rem;
  --text-2xl: 2rem;

  /* Spacing */
  --space-xs: 0.25rem;
  --space-sm: 0.5rem;
  --space-md: 1rem;
  --space-lg: 1.5rem;
  --space-xl: 2rem;
  --space-2xl: 3rem;

  /* Borders & Radius */
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 16px;

  /* Shadows */
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.08);
  --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.07), 0 2px 4px rgba(0, 0, 0, 0.06);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.08), 0 4px 6px -2px rgba(0, 0, 0, 0.04);

  /* Layout */
  --max-width: 1200px;
  --header-height: 72px;
}

/* --- Reset --- */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: 100%;
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-family);
  font-size: var(--text-base);
  line-height: 1.6;
  color: var(--color-text);
  background-color: var(--color-bg);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* --- Typography --- */
h1, h2, h3, h4, h5, h6 {
  line-height: 1.25;
  font-weight: 700;
  color: var(--color-text);
}

h1 { font-size: var(--text-2xl); }
h2 { font-size: var(--text-xl); }
h3 { font-size: var(--text-lg); }

a {
  color: var(--color-primary);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

/* --- Header --- */
header {
  background-color: var(--color-white);
  border-bottom: 1px solid var(--color-border);
  box-shadow: var(--shadow-sm);
  position: sticky;
  top: 0;
  z-index: 100;
}

.header-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: var(--space-sm) var(--space-md);
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  flex-wrap: wrap;
}

.logo-icon {
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

header h1 {
  font-size: var(--text-lg);
  color: var(--color-primary);
  margin: 0;
}

.tagline {
  font-size: var(--text-sm);
  color: var(--color-text-muted);
  margin-left: auto;
}

/* --- Main --- */
main {
  flex: 1;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: var(--space-lg) var(--space-md);
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-lg);
}

/* --- Sections (Cards) --- */
section {
  background-color: var(--color-white);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-sm);
  padding: var(--space-lg);
}

section h2 {
  margin-bottom: var(--space-md);
  padding-bottom: var(--space-sm);
  border-bottom: 2px solid var(--color-primary);
  color: var(--color-primary-dark);
}

/* --- Placeholders --- */
.canvas-placeholder,
.diagram-box {
  background-color: var(--color-bg);
  border: 2px dashed var(--color-border);
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 120px;
  color: var(--color-text-muted);
  font-size: var(--text-sm);
}

.diagram-group {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-md);
}

.diagram-box {
  min-height: 150px;
}

/* --- Footer --- */
footer {
  background-color: var(--color-white);
  border-top: 1px solid var(--color-border);
  padding: var(--space-lg) var(--space-md);
  text-align: center;
  font-size: var(--text-sm);
  color: var(--color-text-muted);
}

footer a {
  color: var(--color-primary);
}

footer .disclaimer {
  margin-top: var(--space-sm);
  font-style: italic;
}

footer .copyright {
  margin-top: var(--space-xs);
}

/* --- Buttons --- */
button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: var(--space-sm) var(--space-lg);
  font-family: var(--font-family);
  font-size: var(--text-base);
  font-weight: 600;
  color: var(--color-white);
  background-color: var(--color-primary);
  border: none;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: background-color 0.2s ease, box-shadow 0.2s ease;
}

button:hover:not(:disabled) {
  background-color: var(--color-primary-dark);
  box-shadow: var(--shadow-md);
}

button:disabled {
  opacity: 0.6;
  cursor: not-allowed;
}

/* --- 404 Specific --- */
body.error-page main {
  display: flex;
  align-items: center;
  justify-content: center;
}

body.error-page section {
  text-align: center;
  max-width: 500px;
}

/* --- Forms --- */
.form-group {
  margin-bottom: var(--space-md);
}

.form-group label {
  display: block;
  font-weight: 600;
  font-size: var(--text-sm);
  margin-bottom: var(--space-xs);
  color: var(--color-text);
}

.form-group input[type="number"],
.form-group select {
  width: 100%;
  padding: var(--space-sm);
  font-family: var(--font-family);
  font-size: var(--text-base);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  background-color: var(--color-white);
  color: var(--color-text);
  transition: border-color 0.2s ease;
}

.form-group input[type="number"]:focus,
.form-group select:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 2px rgba(26, 86, 219, 0.15);
}

.support-row {
  display: flex;
  align-items: center;
  gap: var(--space-xs);
}

.support-row select {
  flex: 1;
}

/* Botón secundario */
.btn-secondary {
  background-color: var(--color-bg);
  color: var(--color-primary);
  border: 1px solid var(--color-primary);
  font-size: var(--text-sm);
  padding: var(--space-xs) var(--space-md);
  margin-bottom: var(--space-md);
}

.btn-secondary:hover:not(:disabled) {
  background-color: var(--color-primary);
  color: var(--color-white);
  box-shadow: var(--shadow-sm);
}

/* Apoyos intermedios */
.support-intermediate {
  background-color: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  padding: var(--space-sm);
  margin-bottom: var(--space-sm);
}

.support-intermediate label {
  font-size: var(--text-sm);
}

.support-intermediate input[type="number"] {
  width: 100px;
  padding: var(--space-xs);
  font-size: var(--text-sm);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
}

.support-intermediate select {
  padding: var(--space-xs);
  font-size: var(--text-sm);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
}

.btn-remove-support {
  background-color: var(--color-error);
  color: var(--color-white);
  padding: var(--space-xs) var(--space-sm);
  font-size: var(--text-sm);
  border-radius: var(--radius-sm);
  min-width: 30px;
}

.btn-remove-support:hover:not(:disabled) {
  background-color: #b91c1c;
}

/* --- Editor Toolbar --- */
.editor-toolbar {
  display: flex;
  gap: var(--space-sm);
  margin-bottom: var(--space-md);
  flex-wrap: wrap;
}

.btn-tool {
  background-color: var(--color-bg);
  color: var(--color-text);
  border: 1px solid var(--color-border);
  padding: var(--space-xs) var(--space-md);
  font-size: var(--text-sm);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all 0.2s ease;
}

.btn-tool.active {
  background-color: var(--color-primary);
  color: var(--color-white);
  border-color: var(--color-primary);
}

.btn-tool:hover:not(.active) {
  border-color: var(--color-primary);
  color: var(--color-primary);
}

/* Canvas */
.canvas-wrapper {
  background-color: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  overflow: hidden;
}

.canvas-wrapper canvas {
  display: block;
  width: 100%;
  height: auto;
  cursor: pointer;
}

.canvas-hint {
  font-size: var(--text-sm);
  color: var(--color-text-muted);
  margin-top: var(--space-sm);
  text-align: center;
  font-style: italic;
}

/* --- Loads --- */
.load-form {
  margin-bottom: var(--space-lg);
}

.load-form .form-group {
  margin-bottom: var(--space-sm);
}

.loads-list {
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
}

.load-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  background-color: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  padding: var(--space-sm) var(--space-md);
  gap: var(--space-sm);
}

.load-info {
  font-size: var(--text-sm);
  color: var(--color-text);
  flex: 1;
}

.btn-remove-load {
  background-color: transparent;
  color: var(--color-error);
  border: 1px solid var(--color-error);
  padding: var(--space-xs) var(--space-sm);
  font-size: var(--text-sm);
  border-radius: var(--radius-sm);
  flex-shrink: 0;
}

.btn-remove-load:hover:not(:disabled) {
  background-color: var(--color-error);
  color: var(--color-white);
}

/* --- Results --- */
.text-muted {
  color: var(--color-text-muted);
  font-style: italic;
}

.results-inner {
  animation: fadeIn 0.3s ease;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(4px); }
  to   { opacity: 1; transform: translateY(0); }
}

.results-subtitle {
  font-size: var(--text-base);
  margin-top: var(--space-md);
  margin-bottom: var(--space-sm);
  color: var(--color-primary-dark);
  border-bottom: 1px solid var(--color-border);
  padding-bottom: var(--space-xs);
}

.results-table {
  display: flex;
  flex-direction: column;
  gap: 2px;
  font-size: var(--text-sm);
}

.results-table-header {
  display: grid;
  grid-template-columns: 1fr 1fr 1fr 1fr;
  gap: var(--space-xs);
  font-weight: 700;
  padding: var(--space-xs) var(--space-sm);
  background-color: var(--color-bg);
  border-radius: var(--radius-sm);
  color: var(--color-text-muted);
  font-size: 0.75rem;
}

.results-table-row {
  display: grid;
  grid-template-columns: 1fr 1fr 1fr 1fr;
  gap: var(--space-xs);
  padding: var(--space-xs) var(--space-sm);
  border-bottom: 1px solid var(--color-border);
}

.results-table-row .positive {
  color: var(--color-success);
  font-weight: 600;
}

.results-table-row .negative {
  color: var(--color-error);
  font-weight: 600;
}

.results-max-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-sm);
}

.max-item {
  background-color: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  padding: var(--space-sm) var(--space-md);
  display: flex;
  flex-direction: column;
  gap: var(--space-xs);
}

.max-label {
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--color-text-muted);
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.max-value {
  font-size: var(--text-lg);
  font-weight: 700;
  color: var(--color-primary);
}

.max-pos {
  font-size: var(--text-sm);
  color: var(--color-text-muted);
}

/* --- Diagram Renderer --- */
.diagram-container {
  position: relative;
  margin: 0.5rem 0;
}

.diagram-container canvas {
  display: block;
  border: 1px solid #e2e8f0;
  border-radius: 8px;
  background: #ffffff;
}

.diagram-label {
  font-weight: 600;
  font-size: 0.875rem;
  color: #475569;
  margin-bottom: 0.25rem;
}

.diagram-tooltip {
  position: absolute;
  background: #1e293b;
  color: #fff;
  padding: 6px 10px;
  border-radius: 6px;
  font-size: 12px;
  pointer-events: none;
  z-index: 100;
  white-space: nowrap;
  font-family: var(--font-family);
}

.diagram-toggle {
  display: flex;
  gap: 0.5rem;
  margin-bottom: 1rem;
  flex-wrap: wrap;
}

.diagram-toggle button {
  padding: 0.25rem 0.75rem;
  border: 1px solid #cbd5e1;
  border-radius: 4px;
  background: #fff;
  cursor: pointer;
  font-size: 0.75rem;
  font-family: var(--font-family);
  color: #475569;
  transition: all 0.15s ease;
}

.diagram-toggle button:hover {
  border-color: #1a56db;
  color: #1a56db;
}

.diagram-toggle button.active {
  background: #1a56db;
  color: #fff;
  border-color: #1a56db;
}

/* --- Responsive: Tablet --- */
@media (min-width: 768px) {
  main {
    grid-template-columns: 1fr 1fr;
  }

  #beam-editor,
  #beam-diagrams,
  #beam-pdf {
    grid-column: 1 / -1;
  }

  .diagram-group {
    grid-template-columns: repeat(3, 1fr);
  }

  .results-max-grid {
    grid-template-columns: 1fr 1fr 1fr 1fr;
  }
}

/* --- Responsive: Desktop --- */
@media (min-width: 1024px) {
  main {
    grid-template-columns: 280px 1fr 280px;
    grid-template-areas:
      "config editor loads"
      "results results results"
      "diagrams diagrams diagrams"
      "pdf pdf pdf";
  }

  #beam-config { grid-area: config; }
  #beam-editor { grid-area: editor; }
  #beam-loads { grid-area: loads; }
  #beam-results { grid-area: results; }
  #beam-diagrams { grid-area: diagrams; }
  #beam-pdf { grid-area: pdf; }
}