/* 🌞 ===== TOÀN BỘ GIAO DIỆN ===== */
.reveal .backgrounds {
  background: linear-gradient(135deg, #fdfdfd 0%, #f6f8fa 100%);
}

.reveal section {
  color: #020a44;
  font-family: "Segoe UI", "Helvetica Neue", Arial, sans-serif;
  font-size: 26px;
  line-height: 1.6;
  text-shadow: none;
  letter-spacing: 0.3px;
  transition: color 0.3s;
}

/* 🌸 KHUNG SLIDE CHUNG – có viền và đổ bóng nhẹ */
.reveal .slides section {
  max-width: 100% !important;
  width: 100% !important;
  height: auto;
  background: #ffffff;
  border-radius: 10px;
  box-shadow: 0 0 20px rgba(243, 5, 40, 0.08);
  padding: 20px;
  box-sizing: border-box;
}

/* ✨ TIÊU ĐỀ CHÍNH */
.reveal h1, .reveal h2, .reveal h3 {
  color: #004aad;
  font-weight: 700;
  letter-spacing: 0.5px;
}

/* ===== KHUNG CÂU HỎI ===== */
.question, .summary-box {
  background: #fff;
  border: 1px solid #e0e0e0;
  border-radius: 10px;
  padding: 18px 22px;
  width: 96%;
  max-height: 82vh;
  overflow-y: auto;
  margin: 12px auto;
  box-shadow: 0 2px 8px rgba(0,0,0,0.05);
  box-sizing: border-box;
   color: #03631e;
   font-size: 22px;
}

/* Hình ảnh trong câu hỏi */
.question img, .summary-box img {
  max-width: 100%;
  height: auto;
  display: block;
  margin: 12px auto;
  border-radius: 8px;
  box-shadow: 0 2px 6px rgba(0,0,0,0.1);
}

/* ===== TRẮC NGHIỆM ===== */
.options-row, .option-row {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 10px;
  flex-wrap: wrap;
}

.option-label, .option-row label {
  display: flex;
  align-items: center;
  gap: 10px;
  cursor: pointer;
  padding: 10px 14px;
  border: 1px solid #d0d0d0;
  border-radius: 8px;
  background: #fdfdfd;
  transition: all 0.25s;
  box-shadow: 0 1px 2px rgba(0,0,0,0.05);
}

.option-label:hover, .option-row:hover {
  background: #e8f1ff;
  border-color: #0074d9;
}

.option-letter {
  font-weight: bold;
  color: #0074d9;
}

.icon {
  font-size: 20px;
  margin-left: 8px;
}

/* ===== NÚT KIỂM TRA ===== */
.answer-check {
  margin-top: 14px;
  text-align: left;
}

.answer-check button, .check-btn {
  background: #0074d9;
  color: white;
  border: none;
  border-radius: 6px;
  padding: 8px 16px;
  cursor: pointer;
  font-size: 16px;
  font-weight: 500;
  transition: background 0.3s, transform 0.2s;
}

.answer-check button:hover {
  background: #0059b2;
  transform: translateY(-1px);
}

/* ===== Ô NHẬP CÂU TRẢ LỜI NGẮN ===== */
.answer-check input[type="text"] {
  padding: 6px 10px;
  border: 1px solid #bbb;
  border-radius: 6px;
  width: 240px;
  font-size: 16px;
  margin-right: 10px;
}

/* ===== MENU SLIDE ===== */
.slide-menu {
  position: fixed;
  top: 0;
  left: -400px;
  width: 350px;
  height: 100vh;
  background: #fefefe;
  box-shadow: 4px 0 12px rgba(0,0,0,0.15);
  z-index: 1000;
  transition: left 0.3s ease;
  border-right: 3px solid #0074d9;
  overflow-y: auto;
}

.slide-menu.active {
  left: 0;
}

.menu-header {
  padding: 16px;
  background: #0074d9;
  color: white;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.menu-header h3 {
  margin: 0;
  font-size: 18px;
}

.close-btn {
  background: none;
  border: none;
  color: white;
  font-size: 24px;
  cursor: pointer;
}

.menu-content {
  padding: 10px;
}

.slide-item {
  padding: 10px 15px;
  border: 1px solid #ddd;
  border-radius: 6px;
  background: #f9fafc;
  cursor: pointer;
  color: #111;
  transition: 0.2s;
}

.slide-item:hover {
  background: #e7f1ff;
  border-color: #0074d9;
}

.slide-item.active {
  background: #0074d9;
  color: white;
  border-color: #0056b3;
  font-weight: bold;
}

/* ===== NÚT MỞ MENU ===== */
.menu-toggle {
  position: fixed;
  top: 30px;
  right: 10px;
  z-index: 999;
  background: #0074d9;
  color: white;
  border: none;
  border-radius: 50%;
  font-size: 20px;
  width: 50px;
  height: 50px;
  cursor: pointer;
  box-shadow: 0 3px 10px rgba(0,0,0,0.25);
  transition: transform 0.25s, background 0.25s;
}

.menu-toggle:hover {
  background: #0059b2;
  transform: scale(1.1);
}

/* ===== TOOLBAR VẼ ===== */
#drawCanvas {
  position: fixed;
  top: 0; left: 0;
  width: 100vw; height: 100vh;
  z-index: 10;
  pointer-events: none;
}

#toolbar {
  position: fixed;
  top: 50%; left: 5px;
  transform: translateY(-50%);
  z-index: 20;
  display: flex; flex-direction: column;
  background: rgba(255,255,255,0.95);
  padding: 4px;
  border-radius: 10px;
  box-shadow: 0 2px 6px rgba(0,0,0,0.2);
}

#toolbar button, #toolbar select {
  margin: 4px 0;
  width: 38px; height: 38px;
  font-size: 14px;
  border: none;
  border-radius: 6px;
  background: #f2f2f2;
  color: #111;
  cursor: pointer;
  transition: 0.2s;
}

#toolbar button:hover {
  background: #0074d9;
  color: white;
}

/* ===== NÚT TOÀN MÀN HÌNH ===== */
.fullscreen-btn {
  position: fixed;
  bottom: 20px;
  right: 20px;
  z-index: 900;
  padding: 10px 14px;
  background: #0074d9;
  color: white;
  border-radius: 50%;
  border: none;
  font-size: 22px;
  cursor: pointer;
  box-shadow: 0 2px 8px rgba(0,0,0,0.3);
}

.fullscreen-btn:hover {
  background: #0056b3;
}
/* ===== THANH TIÊU ĐỀ NGANG CỐ ĐỊNH ===== */
.topbar {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 40px;
  background: linear-gradient(90deg, #004aad, #0074d9, #00b4d8);
  color: #fff;
  font-family: "Segoe UI", sans-serif;
  font-size: 24px;
  font-weight: 600;
  text-align: center;
  line-height: 60px;
  letter-spacing: 1px;
  text-transform: uppercase;
  box-shadow: 0 2px 10px rgba(0,0,0,0.2);
  z-index: 2000;
  border-bottom: 3px solid rgba(255,255,255,0.3);
}

.topbar-title {
  animation: titleGlow 3s ease-in-out infinite alternate;
}

@keyframes titleGlow {
  0% { text-shadow: 0 0 8px #fff, 0 0 14px #00b4d8; }
  100% { text-shadow: 0 0 15px #fff, 0 0 25px #0074d9; }
}

/* ===== ĐỒNG HỒ (góc phải thanh) ===== */
.clock {
  position: absolute;
  right: 30px;
  top: 0;
  font-size: 22px;
  font-weight: 500;
  letter-spacing: 1px;
  color: #fff;
  text-shadow: 0 0 6px rgba(0,0,0,0.5);
}

/* Dời phần trình chiếu xuống dưới thanh tiêu đề */
.reveal {
  margin-top: 38px !important;
}

/* ===== CÁC KIỂU TRÌNH BÀY TOÁN HỌC - PHIÊN BẢN CẬP NHẬT ===== */

/* 🌟 ĐỊNH NGHĨA */
.definition-box {
  background: linear-gradient(135deg, #e3f2fd 0%, #bbdefb 100%);
  border-left: 5px solid #1976d2;
  border-radius: 8px;
  padding: 20px;
  margin: 20px 0;
  box-shadow: 0 2px 8px rgba(25, 118, 210, 0.15);
  position: relative;
}

.definition-icon {
  display: inline-block;
  margin-right: 10px;
  color: #1976d2;
}

.definition-content h3 {
  color: #1976d2;
  font-weight: 700;
  margin-bottom: 15px;
  border-bottom: 2px solid #1976d2;
  padding-bottom: 8px;
}

.styled-list {
  list-style: none;
  padding-left: 0;
}

.styled-list li {
  margin: 12px 0;
  padding: 10px;
  background: rgba(255, 255, 255, 0.7);
  border-radius: 6px;
  border-left: 3px solid #28a745;
}

/* 🎯 CHÚ Ý & PHƯƠNG PHÁP */
.note-box {
  background: linear-gradient(135deg, #fff8e1 0%, #ffecb3 100%);
  border-left: 5px solid #ffa000;
  border-radius: 8px;
  padding: 20px;
  margin: 20px 0;
  box-shadow: 0 2px 8px rgba(255, 160, 0, 0.15);
}

.note-header {
  display: flex;
  align-items: center;
  margin-bottom: 15px;
}

.note-icon {
  color: #ffa000;
  margin-right: 10px;
  font-size: 20px;
}

.note-title {
  font-weight: 700;
  color: #ffa000;
  font-size: 18px;
}

.note-content ul {
  list-style: none;
  padding-left: 0;
}

.note-content li {
  margin: 10px 0;
  padding: 8px;
  background: rgba(255, 255, 255, 0.6);
  border-radius: 4px;
}

/* 🔍 PHƯƠNG PHÁP GIẢI */
.solution-steps {
  background: rgba(255, 255, 255, 0.8);
  border-radius: 6px;
  padding: 15px;
  margin: 15px 0;
}

.solution-steps ol {
  padding-left: 20px;
}

.solution-steps li {
  margin: 10px 0;
  padding: 8px;
  background: rgba(232, 245, 232, 0.5);
  border-radius: 4px;
  border-left: 3px solid #388e3c;
}

/* 📊 DẠNG TOÁN */
.problem-type {
  background: linear-gradient(135deg, #e8eaf6 0%, #c5cae9 100%);
  border-left: 5px solid #303f9f;
  border-radius: 8px;
  padding: 20px;
  margin: 20px 0;
  box-shadow: 0 2px 8px rgba(48, 63, 159, 0.15);
}

.problem-header {
  display: flex;
  align-items: center;
  margin-bottom: 15px;
  border-bottom: 2px solid #303f9f;
  padding-bottom: 10px;
}

.problem-number {
  background: #303f9f;
  color: white;
  width: 30px;
  height: 30px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: bold;
  margin-right: 15px;
}

.problem-header h3 {
  color: #303f9f;
  margin: 0;
  font-weight: 700;
}

/* 📝 VÍ DỤ */
.example {
  background: linear-gradient(135deg, #fff3e0 0%, #ffe0b2 100%);
  border-left: 5px solid #f57c00;
  border-radius: 8px;
  padding: 20px;
  margin: 20px 0;
  box-shadow: 0 2px 8px rgba(245, 124, 0, 0.15);
}

.example-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 15px;
  border-bottom: 2px solid #f57c00;
  padding-bottom: 10px;
}

.example-header h3 {
  color: #f57c00;
  margin: 0;
  font-weight: 700;
}

.tag {
  background: #f57c00;
  color: white;
  padding: 4px 12px;
  border-radius: 20px;
  font-size: 14px;
  font-weight: 500;
}

.example-question {
  background: rgba(255, 255, 255, 0.7);
  padding: 15px;
  border-radius: 6px;
  margin-bottom: 15px;
  border-left: 3px solid #f57c00;
}

/* 💡 LỜI GIẢI */
.solution {
  background: linear-gradient(135deg, #fce4ec 0%, #f8bbd9 100%);
  border-left: 5px solid #c2185b;
  border-radius: 8px;
  padding: 20px;
  margin: 15px 0;
  display: none; /* Ẩn ban đầu, hiện khi click */
}

.solution h4 {
  color: #c2185b;
  font-weight: 700;
  margin-bottom: 15px;
  border-bottom: 2px solid #c2185b;
  padding-bottom: 8px;
}

.solution-conclusion {
  background: rgba(255, 255, 255, 0.8);
  padding: 12px;
  border-radius: 6px;
  border-left: 4px solid #c2185b;
  font-weight: 600;
  margin-top: 15px;
}

/* Nút xem lời giải */
.btn.solution-toggle {
  background: #0074d9;
  color: white;
  border: none;
  padding: 10px 20px;
  border-radius: 6px;
  cursor: pointer;
  font-weight: 500;
  transition: background 0.3s;
  margin: 10px 0;
}

.btn.solution-toggle:hover {
  background: #0059b2;
}

.mr-2 {
  margin-right: 8px;
}

/* Hình ảnh */
.image-container {
  text-align: center;
  margin: 15px 0;
}

.image-container img {
  max-width: 100%;
  height: auto;
  border-radius: 8px;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.2);
}

/* Tiêu đề section */
.doc-section {
  margin: 30px 0;
}

.article-subtitle {
  color: #004aad;
  font-weight: 700;
  border-bottom: 3px solid #004aad;
  padding-bottom: 10px;
  margin-bottom: 20px;
}

/* Công thức toán */
.math {
  font-size: 24px;
  margin: 10px 0;
}

/* Responsive */
@media (max-width: 768px) {
  .definition-box,
  .note-box,
  .problem-type,
  .example,
  .solution {
    padding: 15px;
    margin: 15px 0;
  }
  
  .example-header {
    flex-direction: column;
    align-items: flex-start;
  }
  
  .tag {
    margin-top: 8px;
  }
  
  .math {
    font-size: 20px;
  }
}
/* Cho phép cuộn slide dài */
.reveal .slides section {
  overflow-y: auto !important;
  max-height: 100vh !important;
  scroll-behavior: smooth;
  padding-bottom: 2rem;
}

/* Không giới hạn chiều cao các box */
.definition-box,
.theorem-box,
.method-box,
.example,
.note-box,
.formula,
.procedure {
  max-height: none !important;
  overflow: visible !important;
}

/* Box lồng nhau thu nhỏ nhẹ */
.box .box {
  font-size: 0.9em;
  padding: 0.8em;
}
/* ==== FIX: ensure reveal controls & progress visible above canvas ==== */
.reveal .controls,
.reveal .progress,
.reveal .slide-number {
  z-index: 10005 !important;
  pointer-events: auto !important;
}

/* Ensure toolbar stays above controls but below toggleMenu */
#toolbar { z-index: 10010 !important; }
#toggleMenu { z-index: 10030 !important; }

/* Canvas should not block interactions when not in draw mode */
#drawCanvas { pointer-events: none; }


/* ==== Thanh công cụ chọn đề, đăng nhập, tính điểm ==== */
.topbar-controls {
  position: fixed;
  top: 8px;        /* khoảng cách từ mép trên */
  right: 80px    /* lệch phải tránh nút ☰ */
  z-index: 99999;  /* nằm trên Reveal và Canvas */
  display: flex;
  gap: 8px;
  align-items: center;
  background: rgba(0, 0, 0, 0.4);
  padding: 4px 8px;
  border-radius: 8px;
  backdrop-filter: blur(4px);
}

.topbar-controls select,
.topbar-controls button {
  background: rgba(255, 255, 255, 0.25);
  color: #fff;
  border: 1px solid rgba(255, 255, 255, 0.4);
  border-radius: 6px;
  padding: 3px 6px;
  font-size: 14px;
  cursor: pointer;
  transition: background 0.3s;
}

.topbar-controls select:hover,
.topbar-controls button:hover {
  background: rgba(255, 255, 255, 0.5);
  color: #000;
}

/* canva
/* ==== Canvas và Toolbar ==== */
#drawCanvas { 
  position: fixed;
  top: 0;
  left: 0;
  z-index: 9998;
  touch-action: none;
}

.toolbar {
  position: fixed;
  top: 70px;
  left: 10px;
  background: white;
  border-radius: 10px;
  box-shadow: 0 4px 12px rgba(0,0,0,0.2);
  padding: 6px;
  z-index: 10000;
  display: flex;
  flex-direction: column;
  gap: 4px;
  width: 48px;
  align-items: center;
}

.toolbar button,
.toolbar select,
.toolbar input[type="color"],
.toolbar input[type="range"] {
  width: 100%;
  font-size: 10px;
  padding: 2px;
  height: 28px;
  box-sizing: border-box;
}

/* ==== Nút 3 gạch ☰ ==== */
#toggleMenu {
  position: fixed;
  top: 45px;
  left: 40px;
  z-index: 99999 !important;
  font-size: 22px;
  background: rgba(0,0,0,0.45);
  color: #fff;
  border: none;
  border-radius: 6px;
  padding: 3px 8px;
  cursor: pointer;
}
#toggleMenu:hover {
  background: rgba(255,255,255,0.25);
}