:root {
  --bg-light: #FFFBDE;
  --text-light: #4682A9;
  --primary: #91C8E4;
  --secondary: #749BC2;
  --accent: #4682A9;
  --border-main: #749BC2;
  --border-bottom: #91C8E4;
  --animated-gradient: linear-gradient(90deg, #91C8E4, #749BC2, #4682A9, #91C8E4);
}

body {
  font-family: 'Roboto', sans-serif;
  background-color: #91C8E4; /* Đổi màu nền ngoài khung */
  color: var(--text-light);
  min-height: 100vh;
  margin: 0;
  overflow-x: hidden; /* prevent horizontal scrolling */
  height: 100vh; /* lock to viewport height */
}

/* Ensure main layout fits viewport and only right panel scrolls vertically */
.main-layout {
  display: flex;
  align-items: stretch;
  width: 100vw;
  min-height: 100vh;
  box-sizing: border-box;
  padding: 0;
  margin-left: 0;
  height: 100vh;
  overflow: hidden; /* contain scroll to right panel only */
}

.left-panel {
  background: var(--bg-light);
  border-radius: 0 0 16px 16px;
  border: 2px solid var(--border-main);
  position: sticky;
  top: 0;
  height: 100vh;
  overflow: visible; /* allow active button to overlap right panel */
  z-index: 10; /* ensure left panel/buttons sit above right panel */
  display: flex;
  flex-direction: column;
  min-height: 100vh;
  margin: 0;
  box-sizing: border-box;
  flex: 0 0 20vw;
  max-width: 20vw;
  min-width: 180px;
  align-items: flex-start;
  padding: 32px 0 32px 0;
  border-bottom: 8px solid var(--border-bottom);
  border-radius: 0 0 0 16px;
}

.profile-header {
  width: 100%;
  padding: 0 24px 16px 24px;
  text-align: left;
}

.profile-header h2 {
  margin: 0;
  font-size: 1.5rem;
  color: var(--accent);
  font-family: 'Pacifico', cursive;
}

.side-btn-group {
  width: 100%;
  display: flex;
  flex-direction: column;
  gap: 12px;
  padding: 0 24px;
}

.side-btn {
  width: 100%;
  padding: 14px 0 14px 0;
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--accent);
  background: var(--primary);
  border: none;
  border-radius: 8px 0 0 8px; /* rounded on left side as original */
  cursor: pointer;
  box-shadow: 0 2px 8px rgba(72,130,169,0.08);
  position: relative;
  z-index: 11; /* ensure buttons are above right panel */
  transition: background 0.2s, color 0.2s, transform 0.2s, border-radius 0.2s;
}

.side-btn:hover, .side-btn.active {
  background: var(--accent);
  color: var(--bg-light);
  transform: scale(1.03);
}

/* Nút đang chọn có góc trái lỏm */
.side-btn.active {
  border-top-left-radius: 32px;
  border-bottom-left-radius: 32px;
  margin-left: 0;   /* remove any left protrusion */
  margin-right: -14px; /* nhỏ lệch sang phải để chồng lên khung phải */
  box-shadow: 2px 0 12px -4px var(--accent);
  z-index: 12;
}

/* Khung phải sát khung trái */
.right-dynamic-panel {
  flex: 1 1 0;
  background: var(--bg-light);
  border-radius: 0 0 16px 0;
  border: 2px solid var(--border-main);
  border-bottom: 8px solid var(--accent);
  min-height: 100vh;
  box-sizing: border-box;
  padding: 32px 24px;
  margin: 0;
  display: flex;
  align-items: flex-start;
  justify-content: flex-start;
  position: relative;
  height: 100vh;
  overflow-y: auto;
  overflow-x: hidden;
  z-index: 1; /* keep below left-panel buttons */
}

/* Grid home */
.home-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 18px;
  width: 100%;
  margin-top: 6px;
  box-sizing: border-box;
}

.home-card {
  background: linear-gradient(180deg, var(--primary), var(--secondary));
  color: var(--bg-light);
  padding: 8px 20px; /* top padding giảm để "dính trên" */
  border-radius: 12px;
  min-height: 240px; /* doubled from 120px */
  display: flex;
  flex-direction: column; /* title top, buttons below */
  align-items: center; /* căn giữa theo ngang */
  justify-content: flex-start; /* dính trên (vertical start) */
  text-align: center;
  box-shadow: 0 6px 18px rgba(72,130,169,0.08);
  transition: box-shadow 0.18s ease;
  cursor: default;
  border: 1px solid rgba(0,0,0,0.03);
  padding-bottom: 16px;
}

.home-card h3 {
  margin: 6px 0 8px;
  font-family: 'Pacifico', cursive;
  font-size: 1.25rem; /* tăng cỡ chữ 1 chút */
  color: #FFFBDE; /* requested color */
  -webkit-text-stroke: 0; /* remove previous stroke */
  text-shadow: 2px 2px 4px #4682A9; /* requested shadow */
}

/* Grid of 9 buttons inside each card (3 columns) */
.btn-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 8px;
  width: 100%;
  max-width: 260px; /* limit width so buttons look neat */
  margin-top: 6px;
}

/* small buttons */
.card-btn {
  padding: 6px 8px;
  font-size: 0.95rem; /* slightly larger text */
  background: rgba(255,255,255,0.06);
  color: #ffffff; /* Test texts white */
  border: 0.5px solid rgba(255,255,255,0.18); /* siêu mỏng, viền đục */
  border-radius: 6px;
  cursor: pointer;
  /* remove dark text stroke so buttons remain clean white */
  text-shadow: 0 0 1px rgba(0,0,0,0.25);
  transition: background 0.15s, transform 0.12s;
}

.card-btn:active { transform: translateY(1px); }
.card-btn:hover { background: rgba(255,255,255,0.10); }

/* Exercises styles */
.exercise-container {
  display: flex;
  flex-direction: column;
  gap: 18px;
  width: 100%;
  box-sizing: border-box;
}

.q-card {
  background: linear-gradient(180deg, #ffffff, #f6fbff);
  border: 1px solid rgba(0,0,0,0.06);
  padding: 14px;
  border-radius: 10px;
  box-shadow: 0 6px 18px rgba(72,130,169,0.04);
}

.q-card h4 { margin: 0 0 8px; color: var(--accent); font-size: 1rem; }

.two-col {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  align-items: start;
}

/* Multiple choice */
.mc-options { display: flex; flex-direction: column; gap: 8px; margin-top: 8px; }
.mc-option {
  text-align: left;
  padding: 8px 10px;
  background: rgba(145,200,228,0.14);
  border: 0.5px solid rgba(0,0,0,0.06);
  border-radius: 8px;
  cursor: pointer;
  color: var(--accent);
}
.mc-option.selected {
  background: var(--accent);
  color: var(--bg-light);
  box-shadow: 0 6px 14px rgba(72,130,169,0.08);
}

/* Reading pane */
.reading-pane {
  background: rgba(145,200,228,0.06);
  padding: 10px;
  border-radius: 8px;
  font-size: 0.95rem;
  color: var(--text-light);
}

/* Fill-in */
.fill-input {
  display: inline-block;
  min-width: 80px;
  border: 0.5px solid rgba(0,0,0,0.08);
  border-radius: 6px;
  padding: 6px 8px;
  background: #fff;
  color: #111;
}

/* Drag & Drop */
.drag-area { display: flex; gap: 12px; flex-wrap: wrap; align-items: flex-start; margin-top: 8px; }
.drop-zone {
  min-height: 40px;
  min-width: 100%;
  border: 1px dashed rgba(70,130,169,0.18);
  border-radius: 8px;
  padding: 8px;
  background: rgba(255,255,255,0.9);
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
}
.drop-zone.inline { min-width: 0; flex: 1 1 auto; }
.drag-pool { display:flex; gap:8px; flex-wrap:wrap; margin-top:8px; }
.draggable {
  padding: 6px 10px;
  border-radius: 6px;
  background: linear-gradient(180deg, var(--primary), var(--secondary));
  color: #fff;
  cursor: grab;
  user-select: none;
  border: 0.5px solid rgba(255,255,255,0.12);
  font-size: 0.95rem;
}
.draggable:active { cursor: grabbing; transform: translateY(1px); }

/* exercises header (centered) */
.ex-header {
  display:flex;
  align-items:center;
  justify-content:center;
  gap:12px;
  margin-bottom:6px;
}
.ex-title { margin:0; font-size:1.1rem; color:var(--accent); }
.ex-test-btn {
  background:var(--primary);
  color:var(--bg-light);
  border:none;
  padding:6px 10px;
  border-radius:8px;
  cursor:pointer;
}

/* center the check button area */
.ex-controls { margin-top: 10px; display:flex; gap:8px; justify-content:center; }

/* result overlay full screen - darker to "tối hết cả màn hình" */
.result-overlay {
  position: fixed;
  inset: 0;
  display:flex;
  align-items:center;
  justify-content:center;
  background: rgba(0,0,0,0.85); /* darker */
  z-index: 99999; /* very high to block everything */
}

/* result card layout: place Close and Retry side by side */
.result-card {
  background: var(--bg-light);
  padding: 28px;
  border-radius: 12px;
  text-align: center;
  border: 2px solid var(--border-main);
  min-width: 320px;
  display:flex;
  flex-direction:column;
  gap:12px;
  align-items:center;
}

/* controls row */
.result-card .result-controls {
  display:flex;
  gap:12px;
  margin-top:8px;
}

/* Styled Check button (explicit selector) */
#check {
    background: linear-gradient(135deg, #4682A9, #749BC2);
    color: #fff;
    border: none;
    padding: 12px 24px;
    border-radius: 10px;
    font-size: 16px;
    font-weight: bold;
    cursor: pointer;
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.2);
    transition: transform 0.2s ease, background 0.3s ease;
}

#check:hover {
    transform: scale(1.05);
    background: linear-gradient(135deg, #91C8E4, #4682A9);
}

/* reuse #check style for Retry and Close via class */
.result-card .btn-check-like {
    background: linear-gradient(135deg, #4682A9, #749BC2);
    color: #fff;
    border: none;
    padding: 12px 24px;
    border-radius: 10px;
    font-size: 16px;
    font-weight: bold;
    cursor: pointer;
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.2);
    transition: transform 0.2s ease, background 0.3s ease;
}
.result-card .btn-check-like:hover {
    transform: scale(1.05);
    background: linear-gradient(135deg, #91C8E4, #4682A9);
}

/* Responsive adjustments */
@media (max-width:900px) {
  .two-col { grid-template-columns: 1fr; }
}

@media (max-width: 900px) {
  .main-layout {
    flex-direction: column;
    width: 100vw;
    min-height: 100vh;
  }
  .left-panel {
    max-width: 100vw;
    min-width: 0;
    border-radius: 0 0 16px 16px;
    min-height: unset;
    flex: unset;
  }
  .right-dynamic-panel {
    border-radius: 0 0 16px 16px;
  }
  .home-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 480px) {
  .home-grid {
    grid-template-columns: 1fr;
  }
}
/* make builder buttons look like Check button globally */
.btn-check-like {
  background: linear-gradient(135deg, #4682A9, #749BC2);
  color: #fff;
  border: none;
  padding: 10px 20px;
  border-radius: 10px;
  font-size: 14px;
  font-weight: 700;
  cursor: pointer;
  box-shadow: 0 6px 14px rgba(72,130,169,0.12);
  transition: transform 0.18s ease, background 0.2s;
}
.btn-check-like:hover {
  transform: scale(1.03);
  background: linear-gradient(135deg, #91C8E4, #4682A9);
}

/* ensure fill-input inside q-card is full width and doesn't overflow */
.q-card .fill-input {
  display: block;
  width: 100%;
  box-sizing: border-box;
  margin-top: 8px;
}

/* spacing between q-cards so they don't overlap */
#builderArea .q-card {
  margin-bottom: 14px;
}

/* ensure two-col in builder has balanced columns */
#builderArea .two-col {
  grid-template-columns: 1fr 1fr;
}

/* make delete button consistent on small screens */
#builderArea .del-q {
  background: transparent;
  border: 1px solid rgba(0,0,0,0.06);
  padding: 6px 8px;
  border-radius: 6px;
  cursor: pointer;
}