html {
  overflow-x: hidden;
}


/* ==========================================================================
   TOPBAR COMPONENT
   ========================================================================== */
.vec-topbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0 24px;
  height: var(--topbar-h, 60px);
  background: var(--bg-card, #ffffff);
  border-bottom: 1px solid var(--border-strong, #e2e8f0);
  position: sticky;
  top: 0;
  left: 0;
  right: 0;
  z-index: 10000;
  box-sizing: border-box;
  font-family: var(--font-academic);
  transition: background 0.3s, border-color 0.3s;
}


.vec-topbar-left, .vec-topbar-right {
  display: flex;
  align-items: center;
  gap: 16px;
  height: 100%;
}

@media (max-width: 768px) {
  .vec-topbar { padding: 0 16px; }
}

.vec-nav-link.active {
  color: var(--primary-base) !important;
  font-weight: 600;
}
.vec-nav-link.active::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  height: 2px;
  background: var(--primary-base);
  border-radius: 2px 2px 0 0;
}
/* =================== CARDS =================== */
#controls .card {
  position: relative;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--r-lg);
  padding: 12px;
  margin-bottom: 12px;
  box-shadow: var(--shadow-sm);
}

/* =================== SECTION ACCENTS =================== */
.section-create {
  --acc: var(--primary-base);
}
.section-list {
  --acc: var(--primary-hover);
}
.section-calc-new {
  --acc: #22c55e;
}
.section-calc-info {
  --acc: #f59e0b;
}

.section-create,
.section-list,
.section-calc-new,
.section-calc-info {
  padding-left: 16px;
  border-left: 4px solid var(--acc);
  background:
    linear-gradient(
      90deg,
      color-mix(in oklab, var(--acc) 10%, transparent) 0%,
      transparent 38%
    ),
    var(--card);
}

.section-create:hover,
.section-list:hover,
.section-calc-new:hover,
.section-calc-info:hover {
  box-shadow:
    0 1px 0 0 color-mix(in oklab, var(--acc) 30%, transparent) inset,
    var(--shadow-sm);
}

.section-calc-new details.calc summary:hover {
  background: color-mix(in oklab, var(--acc) 10%, transparent);
}

.section-calc-info details.calc summary:hover {
  background: color-mix(in oklab, var(--acc) 12%, transparent);
}

label {
  display: block;
  font-size: 13px;
  color: var(--muted);
  margin-bottom: 6px;
}

/* =================== FORM ELEMENTS =================== */
input,
select,
button {
  font: inherit;
  border: 1px solid var(--border);
  background: var(--card);
  color: var(--fg);
  border-radius: var(--r-sm);
  padding: 10px 12px;
  transition:
    border-color var(--t-fast),
    box-shadow var(--t-fast),
    background var(--t-fast);
}

input,
select {
  width: 100%;
}

input:focus,
select:focus,
textarea:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 4px var(--accent-soft);
  background: color-mix(in oklab, var(--card) 92%, transparent);
}

button {
  cursor: pointer;
  user-select: none;
}

button:disabled {
  opacity: 0.55;
  cursor: not-allowed;
}

/* =================== BUTTON SYSTEM =================== */
.btn {
  border-radius: var(--r-sm);
  padding: 10px 12px;
  border: 1px solid var(--border);
  background: var(--chip-bg);
  color: var(--fg);
}

.btn:hover {
  background: color-mix(in oklab, var(--chip-bg) 86%, var(--fg) 14%);
  border-color: color-mix(in oklab, var(--border) 70%, var(--fg) 30%);
}

.btn:active {
  transform: translateY(0.5px);
}

.btn.primary {
  background: var(--accent);
  color: #fff;
  border-color: color-mix(in oklab, var(--accent) 80%, #000 0%);
  box-shadow: 0 6px 18px rgba(0, 144, 255, 0.25);
}

.btn.primary:hover {
  background: var(--primary-hover);
}
.btn.primary:active {
  background: var(--primary-hover);
}

.btn.ghost {
  background: transparent;
  border-color: var(--border);
}

.btn.outline {
  background: transparent;
  color: var(--accent);
  border-color: var(--accent);
}

.btn.danger {
  background: var(--danger);
  color: #fff;
  border-color: color-mix(in oklab, var(--danger) 80%, #000 0%);
}

/* =================== MINI KEYPAD =================== */
.mini-keys {
  display: flex;
  gap: 8px;
  margin-top: 6px;
}

.mini-keys .kbtn {
  padding: 8px 12px;
  border-radius: var(--r-sm);
  border: 1px solid var(--border);
  background: var(--chip-bg);
  cursor: pointer;
  transition:
    background var(--t-fast),
    box-shadow var(--t-fast);
}

.mini-keys .kbtn:hover {
  box-shadow: var(--shadow-sm);
}
.mini-keys .kbtn:active {
  transform: translateY(0.5px);
}

/* =================== LAYOUT HELPERS =================== */
.row {
  display: flex;
  gap: 8px;
  align-items: center;
  flex-wrap: wrap;
}

.grid2 {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 8px;
}

.help {
  font-size: 12px;
  color: var(--muted);
  margin-top: 6px;
}

.small {
  font-size: 12px;
}

/* =================== PRE =================== */
pre {
  background: var(--chip-bg);
  border: 1px solid var(--border);
  border-radius: var(--r-sm);
  padding: 10px;
  margin: 6px 0 0;
  white-space: pre-wrap;
  line-height: 1.25;
  max-height: 220px;
  overflow: auto;
  box-shadow: var(--shadow-sm);
}

/* =================== VECTOR LIST =================== */
#vectorList {
  list-style: none;
  padding: 0;
  margin: 0;
  display: flex;
  flex-direction: column;
  gap: 8px;
  max-height: 350px;
  overflow-y: auto;
  padding-right: 4px;
}

.vec-item {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  border: 1px solid var(--border);
  border-radius: var(--r-lg);
  padding: 10px 12px;
  background: var(--card);
  transition:
    border-color var(--t-fast),
    background var(--t-fast),
    box-shadow var(--t-fast);
  flex-shrink: 0;
}

.vec-item:hover {
  box-shadow: var(--shadow-sm);
  background: color-mix(in oklab, var(--card) 96%, transparent);
}

.vec-item .sw {
  width: 14px;
  height: 14px;
  border-radius: 4px;
  border: 1px solid var(--border);
}

.vec-item .tag {
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  padding: 2px 8px;
  border-radius: 999px;
  background: var(--chip-bg);
  border: 1px solid var(--border);
  font-size: 12px;
  color: var(--muted);
}

.vec-item .lbl {
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  flex: 1 1 auto;
  overflow: hidden;
  white-space: nowrap;
  text-overflow: ellipsis;
}

.vec-main {
  flex: 1 1 auto;
  display: flex;
  flex-direction: column;
  gap: 6px;
  min-width: 0;
}

.vec-header {
  display: flex;
  align-items: center;
  gap: 10px;
}

.vec-header .tag {
  flex: 0 0 auto;
}
.vec-header .lbl {
  flex: 1 1 auto;
  min-width: 0;
}

.vec-actions {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  margin-top: 2px;
}

.vec-actions .btn {
  padding: 6px 10px;
}

@media (max-width: 420px) {
  .grid2 {
    grid-template-columns: 1fr;
  }
  .vec-actions .btn {
    flex: 1 0 auto;
  }
}

.vec-item.active {
  background: color-mix(in oklab, var(--accent) 8%, var(--card) 92%);
  border-color: color-mix(in oklab, var(--accent) 35%, var(--border) 65%);
  box-shadow: inset 0 0 0 1px
    color-mix(in oklab, var(--accent) 35%, transparent);
}

/* =================== CALC SECTIONS =================== */
details.calc {
  border: 1px solid var(--border);
  background: var(--card);
  border-radius: var(--r-lg);
  padding: 8px 10px 12px;
  box-shadow: var(--shadow-sm);
}

details.calc summary {
  list-style: none;
  cursor: pointer;
  padding: 8px 6px;
  border-radius: var(--r-sm);
  font-weight: 700;
  color: var(--fg);
  display: flex;
  align-items: center;
  gap: 8px;
  transition: background var(--t-fast);
}

details.calc summary:hover {
  background: color-mix(in oklab, var(--accent) 6%, transparent);
}

details.calc summary::marker,
details.calc summary::-webkit-details-marker {
  display: none;
}

details.calc summary .chev {
  margin-left: auto;
  opacity: 0.6;
  transition: transform var(--t-fast);
}

details.calc[open] summary .chev {
  transform: rotate(180deg);
}

.extra-form {
  display: none;
}
.extra-form.active {
  display: block;
}

.checklist {
  display: flex;
  flex-direction: column;
  gap: 8px;
  border: 1px solid var(--border);
  background: var(--chip-bg);
  border-radius: var(--r-sm);
  padding: 8px;
  box-shadow: var(--shadow-sm);
}

/* =================== "Lời giải" giống nút thường (như "Tính cơ sở") =================== */
.btn-solution {
  /* giống hệt button base */
  font: inherit;
  border: 1px solid var(--border);
  background: var(--card);
  color: var(--fg);
  border-radius: var(--r-sm);
  padding: 10px 12px;
  cursor: pointer;
  transition:
    border-color var(--t-fast),
    box-shadow var(--t-fast),
    background var(--t-fast);
}

.btn-solution:hover {
  /* nhẹ giống cảm giác nút thường */
  background: color-mix(in oklab, var(--card) 92%, var(--fg) 8%);
  border-color: color-mix(in oklab, var(--border) 70%, var(--fg) 30%);
}

.btn-solution:active {
  transform: translateY(0.5px);
}

/* =================== Basis animation controls =================== */
.basis-anim-controls {
  border: 1px solid var(--border, rgba(0, 0, 0, 0.1));
  background: var(--card, rgba(0, 0, 0, 0.03));
  box-shadow: 0 6px 18px rgba(0, 0, 0, 0.06);
}

.basis-anim-controls #basisSpeedVal {
  color: var(--fg, #111);
}
.basis-anim-controls #basisSpeedHelp {
  color: var(--muted, rgba(0, 0, 0, 0.7));
}

.btn.basis-anim-stop {
  border: 1px solid var(--border, rgba(0, 0, 0, 0.18));
  background: var(--card, #fff);
  color: var(--fg, #111);
  transition:
    background-color 0.12s ease,
    border-color 0.12s ease,
    transform 0.06s ease;
}

.btn.basis-anim-stop:hover {
  background: rgba(0, 0, 0, 0.04);
}
.btn.basis-anim-stop:active {
  transform: translateY(1px);
  background: rgba(0, 0, 0, 0.06);
}

.btn.basis-anim-stop:focus {
  outline: none;
}
.btn.basis-anim-stop:focus-visible {
  box-shadow: 0 0 0 3px rgba(0, 144, 255, 0.25);
}

/* DARK THEME: đúng selector của bạn */
body.dark .basis-anim-controls {
  box-shadow: 0 10px 28px rgba(0, 0, 0, 0.35);
}

body.dark .btn.basis-anim-stop {
  background: rgba(255, 255, 255, 0.06);
  color: rgba(255, 255, 255, 0.92);
  border-color: rgba(255, 255, 255, 0.14);
}

body.dark .btn.basis-anim-stop:hover {
  background: rgba(255, 255, 255, 0.1);
  border-color: rgba(255, 255, 255, 0.2);
}

body.dark .btn.basis-anim-stop:active {
  background: rgba(255, 255, 255, 0.14);
}

/* Range slider */
#basisAnimControls input[type="range"] {
  width: 100%;
  accent-color: var(--accent, var(--primary-base));
}

#basisAnimControls input[type="range"]::-webkit-slider-runnable-track {
  height: 6px;
  border-radius: 999px;
  background: rgba(0, 0, 0, 0.1);
}

#basisAnimControls input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 16px;
  height: 16px;
  border-radius: 999px;
  background: var(--accent, var(--primary-base));
  border: 2px solid rgba(255, 255, 255, 0.65);
  margin-top: -5px;
}

body.dark
  #basisAnimControls
  input[type="range"]::-webkit-slider-runnable-track {
  background: rgba(255, 255, 255, 0.14);
}

body.dark #basisAnimControls input[type="range"]::-webkit-slider-thumb {
  border-color: rgba(0, 0, 0, 0.35);
}

@media (min-width: 769px) {
  @media (hover: hover) {
    .vec-dropdown-container:hover .vec-dropdown-menu {
      display: flex;
    }
  }
  .vec-dropdown-container.open .vec-dropdown-menu {
    display: flex;
  }
}
/* Extracted Topbar Styles */

  
  
  
  
  .vec-sidebar-toggle {
    display: none; /* Shows on mobile */
    background: transparent;
    border: 1px solid transparent; /* Match vec-icon-btn */
    border-radius: 50%; /* Circular */
    width: 38px;
    height: 38px;
    color: var(--text-muted); /* Correct tone color */
    cursor: pointer;
    font-size: 18px; /* Match vec-icon-btn size */
    align-items: center;
    justify-content: center;
    transition: 0.2s;
  }
  .vec-sidebar-toggle:hover {
    background: rgba(150,150,150,0.1); /* Match vec-icon-btn hover */
    color: var(--primary-base);
  }
  .vec-brand-group {
    display: flex;
    align-items: center;
    text-decoration: none;
  }
  .vec-brand-group img {
    height: 42px;
    object-fit: contain;
    transition: filter 0.3s;
  }
  body.dark-theme .vec-brand-group img {
    filter: invert(1) hue-rotate(180deg) brightness(1.2);
  }
  
  .vec-nav-links {
    display: flex;
    gap: 20px;
    margin-left: 16px;
    height: 100%;
  }
  .vec-nav-link {
    text-decoration: none;
    color: var(--text-main, #334155);
    font-weight: 500;
    font-size: 15px;
    display: flex;
    white-space: nowrap;
    align-items: center;
    gap: 8px;
    transition: color 0.2s;
    cursor: pointer;
    position: relative;
    height: 100%;
  }
  .vec-nav-link:hover {
    color: var(--primary-base, #2563eb);
  }
  
  .vec-dropdown-container {
    position: relative;
    height: 100%;
    display: flex;
    align-items: center;
  }
  .vec-dropdown-menu {
    position: absolute;
    top: 100%;
    left: 0;
    background: var(--bg-card, #ffffff);
    border: 1px solid var(--border-strong, #e2e8f0);
    border-radius: 12px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.1);
    min-width: 240px;
    display: flex;
    flex-direction: column;
    opacity: 0;
    visibility: hidden;
    transform: translateY(10px);
    transition: all 0.2s cubic-bezier(0.175, 0.885, 0.32, 1.275);
    padding: 8px 0;
    z-index: 10001;
  }
  @media (hover: hover) {
    .vec-dropdown-container:hover .vec-dropdown-menu {
      opacity: 1;
      visibility: visible;
      transform: translateY(0);
    }
  }
  .vec-dropdown-container.open .vec-dropdown-menu {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
  }
  body.dark-theme .vec-dropdown-menu {
    box-shadow: 0 10px 30px rgba(0,0,0,0.5);
  }
  
  .vec-dropdown-item {
      padding: 12px 20px;
      display: flex !important;
      align-items: center !important;
      justify-content: flex-start !important;
      text-align: left !important;
      gap: 12px;
      text-decoration: none;
      color: var(--text-main) !important;
      font-weight: 500;
      font-size: 14px;
      border: none !important;
      outline: none !important;
      transition: background 0.2s, color 0.2s;
    }
  .vec-dropdown-item i {
    color: var(--text-main);
    font-size: 16px;
    width: 20px;
    text-align: center;
    transition: color 0.2s;
  }
  .vec-dropdown-item:hover, .vec-dropdown-item:hover i {
    background: rgba(37, 99, 235, 0.05) !important;
    color: var(--primary-base) !important;
  }
  
  /* Right Side */
  .vec-icon-btn {
    background: transparent;
    border: 1px solid transparent;
    border-radius: 50%;
    width: 38px;
    height: 38px;
    color: var(--text-muted);
    font-size: 18px;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: 0.2s;
  }
  .vec-icon-btn:hover {
    background: rgba(150,150,150,0.1);
    color: var(--primary-base);
  }
  .vec-dropdown-container.right-align .vec-dropdown-menu {
    left: auto;
    right: 0;
  }
  
  @media (max-width: 768px) {
    .vec-nav-links { 
      display: flex; /* Change from none to flex to allow animation */
      pointer-events: none; /* Prevent clicks when hidden */
      position: absolute;
      top: 100%; /* Drop right below topbar */
      left: 0;
      width: 100%;
      height: auto !important; /* Fix background clipping */
      background: var(--bg-card, #ffffff);
      flex-direction: column;
      border-bottom: 1px solid var(--border-strong, #e2e8f0);
      padding: 8px 0;
      box-shadow: 0 10px 25px rgba(0,0,0,0.15);
      z-index: 999;
      opacity: 0;
      visibility: hidden;
      transform: translateY(-10px);
      transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
    }
    .vec-nav-links.show-mobile {
      pointer-events: auto; /* Re-enable clicks */
      opacity: 1;
      visibility: visible;
      transform: translateY(0);
    }
    
    .vec-nav-link {
      padding: 14px 24px;
      width: 100%;
      height: auto !important; /* Fix active underline */
      box-sizing: border-box;
      justify-content: flex-start;
      font-size: 15px;
      color: var(--text-main);
      transition: background 0.2s ease, padding 0.2s ease;
    }
    .vec-nav-link i {
      margin-right: 12px;
      width: 20px;
      text-align: center;
    }

    /* Disable all sticky hover states on mobile to prevent "blue on tap" */
    .vec-sidebar-toggle {
      -webkit-tap-highlight-color: transparent;
    }
    .vec-sidebar-toggle:hover, .vec-sidebar-toggle:active, .vec-sidebar-toggle:focus {
      background: transparent !important;
      color: var(--text-main) !important;
      border-color: var(--border-strong) !important;
      outline: none !important;
      box-shadow: none !important;
    }
    .vec-nav-link:hover:not(.active) {
      color: var(--text-main) !important;
    }
    .vec-nav-links .vec-dropdown-item:hover {
      color: var(--text-muted) !important;
      background: transparent !important;
    }
    
    /* Standard Active State on Mobile (No bar) */
    .vec-nav-link.active::after {
      display: none; /* Hide horizontal blue line */
    }
    .vec-nav-link.active {
      color: var(--primary-base) !important;
      font-weight: 600;
      background: transparent;
      border: none;
      padding-left: 24px; /* Reset to normal padding */
    }
    
    /* Rotate Chevron on Dropdown Open */
    .vec-nav-link .fa-chevron-down {
      transition: transform 0.3s ease;
    }
    .vec-dropdown-container.open .vec-nav-link .fa-chevron-down {
      transform: rotate(180deg);
    }
    
    /* Dropdown inside the mobile menu */
    .vec-nav-links .vec-dropdown-container {
      width: 100%;
      display: flex;
      flex-direction: column;
      align-items: flex-start;
    }
    .vec-nav-links .vec-dropdown-menu {
      position: static;
      box-shadow: none;
      border: none;
      background: rgba(0, 0, 0, 0.02); /* Slight tint to differentiate */
      opacity: 1;
      visibility: visible;
      transform: none;
      padding: 0;
      display: none;
      align-items: flex-start;
      justify-content: flex-start;
      width: 100%;
      flex-direction: column;
    }
    body.dark-theme .vec-nav-links .vec-dropdown-menu {
      background: rgba(255, 255, 255, 0.03); /* Subtle light tint for dark mode */
      border: none;
    }
    body.dark-theme .vec-nav-links {
      border-bottom: 1px solid rgba(255, 255, 255, 0.1);
      box-shadow: 0 10px 25px rgba(0,0,0,0.5);
    }

    .vec-nav-links .vec-dropdown-container.open .vec-dropdown-menu {
      display: flex;
      animation: slideDown 0.2s ease forwards;
    }
    @keyframes slideDown {
      from { opacity: 0; transform: translateY(-5px); }
      to { opacity: 1; transform: translateY(0); }
    }
    
    .vec-nav-links .vec-dropdown-item {
      font-size: 14px;
      padding: 12px 24px 12px 46px; /* Indent child items */
      color: var(--text-muted);
      width: 100%;
      box-sizing: border-box;
      transition: color 0.2s;
    }
    .vec-nav-links .vec-dropdown-item:hover {
      color: var(--primary-base);
    }

    /* Ensure the hamburger icon is visible */
    .vec-sidebar-toggle { 
      display: flex !important;
    }
  }


/* Dark mode overrides */
body.dark-theme .vec-topbar {
  border-bottom: 1px solid rgba(255, 255, 255, 0.08) !important;
}

/* CSS Theme Icon Toggle (No JS Flash) */
.icon-dark-mode { display: none !important; }
body.dark-theme .icon-dark-mode { display: inline-block !important; }
body.dark-theme .icon-light-mode { display: none !important; }



/* =================== SCROLLBAR =================== */
::-webkit-scrollbar {
  width: 6px;
  height: 6px;
}
::-webkit-scrollbar-thumb {
  background: var(--border-strong, #d7dfe3);
  border-radius: 3px;
}
::-webkit-scrollbar-thumb:hover {
  background: var(--text-muted, #8b939a);
}
::-webkit-scrollbar-track {
  background: var(--bg-base, #f9f9fb);
}




/* --- TYPOGRAPHY REFACTOR --- */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-academic);
}