/* =================================
   RESET VÀ FONT
   ================================= */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    line-height: 1.6;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: #2d3748;
    min-height: 100vh;
    padding: 20px;
}

/* =================================
   CONTAINER CHÍNH
   ================================= */
.container {
    max-width: 1200px;
    margin: auto;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    padding: 30px;
    border-radius: 20px;
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.1);
    border: 1px solid rgba(255, 255, 255, 0.2);
}

/* =================================
   HEADINGS
   ================================= */
h1, h2 {
    color: #2d3748;
    text-align: center;
    margin-bottom: 20px;
    font-weight: 700;
}

h1 {
    font-size: 2.5rem;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: 30px;
}

h2 {
    font-size: 1.8rem;
    color: #4a5568;
    border-bottom: 3px solid #e2e8f0;
    padding-bottom: 10px;
    margin-bottom: 25px;
}

.task h2 {
    text-align: left;
    border-bottom: 2px solid #e2e8f0;
    color: #2d3748;
}

/* =================================
   TASK CONTAINERS
   ================================= */
.task {
    background: linear-gradient(145deg, #ffffff 0%, #f7fafc 100%);
    border: 1px solid #e2e8f0;
    border-radius: 16px;
    padding: 30px;
    margin-bottom: 30px;
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.08);
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
}

.task::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: linear-gradient(90deg, #667eea 0%, #764ba2 100%);
}

.task:hover {
    transform: translateY(-2px);
    box-shadow: 0 15px 35px rgba(0, 0, 0, 0.12);
}

/* =================================
   QUESTION GROUPS
   ================================= */
.question-group {
    margin-bottom: 20px;
    padding: 15px;
    background: #ffffff;
    border-radius: 12px;
    border: 1px solid #e2e8f0;
    transition: all 0.2s ease;
}

.question-group:hover {
    border-color: #cbd5e0;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.05);
}

/* =================================
   FORM ELEMENTS
   ================================= */
select, input[type="text"] {
    background: #ffffff;
    border: 2px solid #e2e8f0;
    border-radius: 8px;
    padding: 5px 5px;
    font-size: 1rem;
    transition: all 0.2s ease;
    margin-left: 10px;
    min-width: 75px;
    max-width: 95%;
}

select:focus, input[type="text"]:focus {
    outline: none;
    border-color: #667eea;
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
}

select.inline-select {
    width: auto;
    max-width: 25%;
    margin-left: 8px;
    margin-right: 8px;
}

/* =================================
   BUTTONS
   ================================= */
button {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 14px 28px;
    border: none;
    border-radius: 12px;
    cursor: pointer;
    font-size: 16px;
    font-weight: 600;
    margin: 8px;
    transition: all 0.3s ease;
    box-shadow: 0 4px 15px rgba(102, 126, 234, 0.3);
    position: relative;
    overflow: hidden;
}

button::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
    transition: left 0.5s;
}

button:hover::before {
    left: 100%;
}

button:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(102, 126, 234, 0.4);
}

button:active {
    transform: translateY(0);
}

button#resetBtn, .back-to-main, .back-to-selection {
    background: linear-gradient(135deg, #718096 0%, #4a5568 100%);
    box-shadow: 0 4px 15px rgba(113, 128, 150, 0.3);
}

button#resetBtn:hover, .back-to-main:hover, .back-to-selection:hover {
    box-shadow: 0 8px 25px rgba(113, 128, 150, 0.4);
}

/* =================================
   FEEDBACK
   ================================= */
.feedback, .item-feedback {
    margin-left: 12px;
    font-weight: 600;
    font-size: 1.1em;
    padding: 4px 8px;
    border-radius: 6px;
    display: inline-block;
}

.correct {
    color: #059669;
    background: #d1fae5;
    border: 1px solid #a7f3d0;
}

.incorrect {
    color: #dc2626;
    background: #fee2e2;
    border: 1px solid #fecaca;
}

/* =================================
   RESULTS
   ================================= */
.result {
    text-align: center;
    font-size: 1.8em;
    font-weight: 700;
    margin: 30px 0;
    padding: 20px;
    border-radius: 16px;
    background: linear-gradient(145deg, #ffffff 0%, #f7fafc 100%);
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.08);
    border: 2px solid #e2e8f0;
}

/* Kết quả từng task (Listening) */
.part-result {
    text-align: center;
    margin-top: 12px;
    padding: 10px 12px;
    border-radius: 10px;
    background: linear-gradient(145deg, #ffffff 0%, #f7fafc 100%);
    border: 2px solid #e2e8f0;
    font-weight: 600;
    color: #4a5568;
}

/* Hide final result by default, only show when there's content */
#finalResult {
    display: none;
    margin: 20px 0;
}

#finalResult:not(:empty) {
    display: block;
}

.result.correct {
    border-color: #059669;
    background: linear-gradient(145deg, #d1fae5 0%, #a7f3d0 100%);
    color: #065f46;
}

.result.incorrect {
    border-color: #dc2626;
    background: linear-gradient(145deg, #fee2e2 0%, #fecaca 100%);
    color: #991b1b;
}

/* LISTENING CONTEXT */
.listening-context {
    background: #f8fafc;
    border: 1px solid #e2e8f0;
    border-radius: 12px;
    padding: 16px;
    margin-bottom: 16px;
}
.listening-context .context-line {
    margin: 6px 0;
    color: #4a5568;
    line-height: 1.6;
}

/* MOBILE ORDERING INTERFACE */
.mobile-ordering-container {
    display: flex;
    flex-direction: column;
    gap: 15px;
    margin: 20px 0;
}

.mobile-slot {
    background: linear-gradient(145deg, #ffffff 0%, #f7fafc 100%);
    border: 2px solid #e2e8f0;
    border-radius: 12px;
    padding: 15px;
    display: flex;
    align-items: center;
    gap: 10px;
    transition: all 0.3s ease;
}

.mobile-slot:hover {
    border-color: #cbd5e0;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.05);
}

.mobile-slot .slot-number {
    font-weight: 700;
    color: #4a5568;
    font-size: 1.1em;
    min-width: 30px;
}

.mobile-slot .fixed-sentence {
    color: #059669;
    font-weight: 600;
    flex: 1;
    padding: 8px;
    background: #d1fae5;
    border-radius: 8px;
}

.mobile-slot .sentence-select {
    flex: 1;
    padding: 10px;
    border: 2px solid #e2e8f0;
    border-radius: 8px;
    font-size: 14px;
    background: white;
    transition: all 0.2s ease;
}

.mobile-slot .sentence-select:focus {
    outline: none;
    border-color: #667eea;
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
}

.mobile-result {
    margin-top: 15px;
    padding: 12px;
    border-radius: 10px;
    font-weight: 600;
    text-align: center;
    border: 2px solid;
}

/* =================================
   BUTTON CONTAINERS
   ================================= */
.button-container {
    text-align: center;
    margin-top: 30px;
    padding: 20px;
    background: rgba(255, 255, 255, 0.8);
    border-radius: 16px;
    backdrop-filter: blur(10px);
}

/* Sticky button container for final controls */
#final-controls {
    position: sticky;
    bottom: 0;
    z-index: 1000;
    margin-top: 30px;
    padding: 20px;
    background: #f8f9fa;
    border-top: 1px solid #e9ecef;
    box-shadow: 0 -2px 10px rgba(0, 0, 0, 0.1);
}

/* Top back button container */
.top-back-container {
    position: sticky;
    top: 0;
    z-index: 1001;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid #e9ecef;
    padding: 10px 0;
    margin-bottom: 20px;
    text-align: left;
}

.back-to-selection-top {
    background: #6c757d;
    color: white;
    border: none;
    padding: 8px 16px;
    border-radius: 8px;
    cursor: pointer;
    font-size: 14px;
    font-weight: 500;
    transition: all 0.3s ease;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
}

.back-to-selection-top:hover {
    background: #5a6268;
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
}

#test-buttons, #skill-buttons, #mode-buttons {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 15px;
    margin: 20px 0;
}

#skill-buttons button {
    padding: 25px 40px;
    font-size: 1.3em;
    min-width: 200px;
}

/* =================================
   DRAG AND DROP
   ================================= */
.drag-drop-container {
    display: flex;
    gap: 40px;
    margin: 30px 0;
    flex-wrap: wrap;
}

.sentences-list, .slots-container {
    flex: 1;
    min-width: 350px;
}

.sentences-list h3, .slots-container h3 {
    color: #4a5568;
    margin-bottom: 20px;
    font-size: 1.3em;
    font-weight: 600;
}

.draggable-sentence {
    background: linear-gradient(145deg, #f7fafc 0%, #edf2f7 100%);
    border: 2px solid #e2e8f0;
    border-radius: 12px;
    padding: 16px;
    margin: 12px 0;
    cursor: grab;
    transition: all 0.3s ease;
    user-select: none;
    font-size: 1rem;
    line-height: 1.5;
}

.draggable-sentence:hover {
    background: linear-gradient(145deg, #edf2f7 0%, #e2e8f0 100%);
    border-color: #cbd5e0;
    transform: translateY(-2px);
    box-shadow: 0 8px 20px rgba(0, 0, 0, 0.1);
}

.draggable-sentence.dragging {
    opacity: 0.8;
    transform: scale(1.02) rotate(2deg);
    box-shadow: 0 12px 30px rgba(0, 0, 0, 0.2);
}

.draggable-sentence.disabled {
    opacity: 0.5;
    cursor: not-allowed;
    pointer-events: none;
}

.slot {
    background: linear-gradient(145deg, #ffffff 0%, #f7fafc 100%);
    border: 2px dashed #cbd5e0;
    border-radius: 12px;
    padding: 20px;
    margin: 15px 0;
    min-height: 70px;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
}

.slot:hover {
    border-color: #a0aec0;
    background: linear-gradient(145deg, #f7fafc 0%, #edf2f7 100%);
}

.slot.correct {
    border-color: #059669;
    background: linear-gradient(145deg, #d1fae5 0%, #a7f3d0 100%);
}

.slot.incorrect {
    border-color: #dc2626;
    background: linear-gradient(145deg, #fee2e2 0%, #fecaca 100%);
}

.slot-number {
    font-weight: 700;
    color: #4a5568;
    margin-right: 15px;
    font-size: 1.1em;
    min-width: 30px;
}

.slot-text {
    color: #718096;
    font-style: italic;
    flex: 1;
}

.slot[data-position="1"] {
    background: linear-gradient(145deg, #e6fffa 0%, #b2f5ea 100%);
    border: 2px solid #38b2ac;
    color: #234e52;
}

.slot[data-position="1"] .slot-text {
    color: #234e52;
    font-style: normal;
    font-weight: 600;
}

.drag-drop-result {
    text-align: center;
    margin-top: 20px;
    padding: 15px;
    border-radius: 12px;
    font-weight: 600;
    font-size: 1.1em;
    background: linear-gradient(145deg, #ffffff 0%, #f7fafc 100%);
    border: 2px solid #e2e8f0;
}

/* =================================
   READING TEXT
   ================================= */
.reading-text {
    background: linear-gradient(145deg, #f7fafc 0%, #edf2f7 100%);
    border-left: 4px solid #667eea;
    padding: 20px;
    margin-bottom: 25px;
    border-radius: 0 12px 12px 0;
    line-height: 1.7;
    font-size: 1.05em;
}

/* =================================
   RESPONSIVE DESIGN
   ================================= */
@media (max-width: 768px) {
    body {
        padding: 10px;
    }
    
    .container {
        padding: 20px;
        border-radius: 16px;
    }
    
    h1 {
        font-size: 2rem;
    }
    
    h2 {
        font-size: 1.5rem;
    }
    
    .task {
        padding: 20px;
        margin-bottom: 20px;
    }
    
    .drag-drop-container {
        flex-direction: column;
        gap: 20px;
    }
    
    .sentences-list, .slots-container {
        min-width: auto;
        width: 100%;
    }
    
    .draggable-sentence {
        padding: 12px;
        margin: 8px 0;
        font-size: 0.95rem;
    }
    
    .slot {
        padding: 15px;
        margin: 10px 0;
        min-height: 60px;
    }
    
    button {
        padding: 12px 20px;
        font-size: 14px;
        margin: 5px;
    }
    
    #skill-buttons button {
        padding: 18px 25px;
        font-size: 16px;
        min-width: 150px;
    }
    
    .question-group {
        padding: 12px;
        margin-bottom: 15px;
    }
    
    select.inline-select {
        max-width: 20%;
        font-size: 14px;
    }
    
    .reading-text {
        font-size: 0.95rem;
        padding: 15px;
    }
    
    .result {
        font-size: 1.4em;
        padding: 15px;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 15px;
    }
    
    h1 {
        font-size: 1.8rem;
    }
    
    .task {
        padding: 15px;
    }
    
    button {
        padding: 8px 16px;
        font-size: 13px;
        margin: 3px;
    }
    
    #skill-buttons button {
        padding: 15px 20px;
        font-size: 15px;
        min-width: 120px;
    }
    
    .draggable-sentence {
        padding: 10px;
        font-size: 0.9rem;
    }
    
    .slot {
        padding: 12px;
        min-height: 50px;
    }
}

/* =================================
   ANIMATIONS
   ================================= */
@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.task {
    animation: fadeIn 0.6s ease-out;
}

@keyframes slideIn {
    from {
        opacity: 0;
        transform: translateX(-20px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

.question-group {
    animation: slideIn 0.4s ease-out;
}

/* =================================
   SCROLLBAR STYLING
   ================================= */
::-webkit-scrollbar {
    width: 8px;
}

::-webkit-scrollbar-track {
    background: #f1f1f1;
    border-radius: 4px;
}

::-webkit-scrollbar-thumb {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: linear-gradient(135deg, #5a67d8 0%, #6b46c1 100%);
}