css
/* ===========================
   PAGE
=========================== */

body{

    background:#f5f7fb;

    font-family:'Segoe UI',sans-serif;

}

/* ===========================
   MAIN CARD
=========================== */

.converter-card{

    max-width:1200px;

    margin:auto;

    background:white;

    border-radius:25px;

    padding:40px;

    box-shadow:0 10px 30px rgba(0,0,0,.08);

}

/* ===========================
   TITLE
=========================== */

h1{

    font-size:46px;

    font-weight:700;

    color:#2563eb;

}

/* ===========================
   SUMMARY CARD
=========================== */

.summary-card{

    display:flex;

    justify-content:space-between;

    align-items:center;

    background:#f8fafc;

    border:1px solid #e5e7eb;

    border-radius:15px;

    padding:20px 25px;

    margin-bottom:20px;

    font-size:18px;

}

/* ===========================
   FILE LIST
=========================== */

#fileListContainer .card{

    border:none;

    border-radius:15px;

    margin-bottom:12px;

    box-shadow:0 2px 10px rgba(0,0,0,.05);

}

#fileListContainer .card-body{

    padding:18px 25px;

}

.file-row-name{

    font-size:18px;

    font-weight:600;

}

.file-row-name i{

    color:#dc2626;

    font-size:24px;

    margin-right:10px;

}

/* ===================================
   UPLOAD AREA
=================================== */

.upload-area {

    background: #eff6ff;

    border: 2px dashed #2563eb;

    border-radius: 20px;

    padding: 50px 30px;

    text-align: center;

    cursor: pointer;

    transition: all .3s ease;

}

.upload-area:hover {

    background: #dbeafe;

    border-color: #1d4ed8;

}

.upload-area.dragover {

    background: #bfdbfe;

    border-color: #1e40af;

    transform: scale(1.02);

}

.upload-icon {

    font-size: 70px;

    color: #2563eb;

    margin-bottom: 20px;

}

.upload-area h3 {

    color: #1d4ed8;

    font-size: 1.7rem;

    font-weight: 700;

    margin-bottom: 10px;

}

.upload-area p {

    color: #475569;

    margin-bottom: 8px;

}

.upload-area .btn-primary {

    background: #2563eb;

    border: none;

    border-radius: 10px;

    padding: 12px 30px;

    font-weight: 600;

}

.upload-area .btn-primary:hover {

    background: #1d4ed8;

}

.upload-area .btn-outline-primary {

    border: 2px solid #2563eb;

    color: #2563eb;

    border-radius: 10px;

    padding: 12px 30px;

    font-weight: 600;

}

.upload-area .btn-outline-primary:hover {

    background: #2563eb;

    color: #ffffff;

}

/* ===========================
   BUTTONS
=========================== */

.btn-primary{

    background:linear-gradient(
        90deg,
        #2563eb,
        #7c3aed
    );

    border:none;

}

.btn-primary:hover{

    opacity:.9;

}

#convertBtn{

    width:320px;

    height:55px;

    font-size:18px;

    font-weight:600;

}

/* ===========================
   PROGRESS
=========================== */

.progress{

    height:30px;

    border-radius:50px;

    overflow:hidden;

    background:#e5e7eb;

}

.progress-bar{

    font-weight:700;

    font-size:15px;

    transition:width .25s linear;

}

/* ===========================
   RESULT HEADER
=========================== */

.result-header{

    background:#f8fafc;

    border:1px solid #e5e7eb;

    border-radius:15px;

    padding:15px;

    margin-bottom:15px;

}

/* ===========================
   RESULT FILES
=========================== */

#convertedFilesContainer .card{

    border:none;

    border-radius:15px;

    margin-bottom:12px;

    box-shadow:0 2px 10px rgba(0,0,0,.05);

}

#convertedFilesContainer .card-body{

    padding:18px 25px;

}

/* ===========================
   RESULT SUMMARY
=========================== */

.result-summary{

    margin-top:20px;

    padding:15px;

    background:#f8fafc;

    border:1px solid #e5e7eb;

    border-radius:15px;

    text-align:center;

    font-size:16px;

    font-weight:600;

}

/* ===========================
   PDF PREVIEW
=========================== */

#previewFrame{

    width:100%;

    height:700px;

    border:none;

}

/* ===========================
   DARK MODE
=========================== */

.dark-mode{

    background:#111827;

    color:white;

}

.dark-mode .converter-card{

    background:#1f2937;

    color:white;

}

.dark-mode .summary-card{

    background:#374151;

    border-color:#4b5563;

}

.dark-mode .card{

    background:#374151;

    color:white;

}

.dark-mode .upload-area{

    background:#374151;

    border-color:#60a5fa;

}

.dark-mode .result-header{

    background:#374151;

    border-color:#4b5563;

}

.dark-mode .result-summary{

    background:#374151;

    border-color:#4b5563;

}

.dark-mode .modal-content{

    background:#1f2937;

    color:white;

}
/* ===================================
   TABLET (768px - 991px)
=================================== */

@media (max-width:991px){

    .converter-card{
        padding:30px;
        margin-bottom:100px;
    }

    h1{
        font-size:38px;
        text-align:center;
    }

    .summary-card{
        font-size:16px;
        padding:16px 20px;
    }

    .upload-area{
        padding:40px 20px;
    }

    .upload-icon{
        font-size:60px;
    }

    .upload-area h3{
        font-size:22px;
    }

    .file-row-name{
        font-size:16px;
    }

    .result-header{
        display:none;
    }

    #previewFrame{
        height:550px;
    }

    #convertBtn{
        width:100%;
    }
}

/* ===================================
   MOBILE (576px - 767px)
=================================== */

@media (max-width:767px){

    .container{
        padding-left:15px;
        padding-right:15px;
    }

    .converter-card{
        padding:20px 15px;
        border-radius:18px;
        margin-bottom:100px;
    }

    h1{
        font-size:30px;
        text-align:center;
    }

    .summary-card{
        flex-direction:column;
        gap:10px;
        text-align:center;
        font-size:15px;
        padding:15px;
    }

    .upload-area{
        padding:30px 15px;
        border-radius:16px;
    }

    .upload-icon{
        font-size:50px;
    }

    .upload-area h3{
        font-size:20px;
    }

    .upload-area p{
        font-size:14px;
    }

    .upload-area .btn{
        width:100%;
    }

    /* Upload File Card */

    #fileListContainer .card{
        border-radius:14px;
    }

    #fileListContainer .card-body{
        padding:15px;
        text-align:center;
    }

    .file-row-name{
        font-size:15px;
        margin-bottom:8px;
        word-break:break-word;
    }

    .file-row-size{
        font-size:13px;
        margin-bottom:12px;
    }

    #fileListContainer .btn{
        width:100%;
        margin-bottom:10px;
    }

    /* Convert Button */

    #convertBtn{
        width:100%;
        height:50px;
        font-size:16px;
    }

    /* Result Cards */

    .result-header{
        display:none;
    }

    #convertedFilesContainer .card{
        border-radius:14px;
        margin-bottom:15px;
    }

    #convertedFilesContainer .card-body{
        padding:15px;
        text-align:center;
    }

    .result-file-name{
        font-size:15px;
        font-weight:700;
        margin-bottom:12px;
        word-break:break-word;
    }

    .result-info{
        display:grid;
        grid-template-columns:1fr 1fr;
        gap:10px;
        font-size:13px;
        margin-bottom:15px;
    }

    .result-actions{
        display:flex;
        flex-direction:column;
        gap:10px;
    }

    .result-actions .btn{
        width:100%;
    }

    .result-summary{
        font-size:14px;
        line-height:1.7;
    }

    #previewFrame{
        height:500px;
    }

    .modal-dialog{
        max-width:98%;
        margin:10px auto;
    }
}

/* ===================================
   SMALL MOBILE (320px - 575px)
=================================== */

@media (max-width:575px){

    .converter-card{
        padding:15px 12px;
        margin-bottom:100px;
    }

    h1{
        font-size:26px;
    }

    .summary-card{
        font-size:14px;
        padding:12px;
    }

    .upload-area{
        padding:25px 10px;
    }

    .upload-icon{
        font-size:42px;
    }

    .upload-area h3{
        font-size:18px;
    }

    .upload-area p{
        font-size:13px;
    }

    .file-row-name{
        font-size:14px;
    }

    .file-row-size{
        font-size:12px;
    }

    .result-info{
        grid-template-columns:1fr;
        text-align:center;
    }

    .result-actions .btn{
        font-size:14px;
    }

    .result-summary{
        font-size:13px;
    }

    #previewFrame{
        height:400px;
    }
}

/* ===========================
   UPLOAD SECTION FREEZE
=========================== */

.upload-section.converting{

    pointer-events: none;

    -webkit-user-select: none;

    -moz-user-select: none;

    -ms-user-select: none;

    user-select: none;

    opacity: .65;

}

/* ===========================
   PROGRESS SECTION
=========================== */

.progress-section{

    max-width:700px;

    margin:50px auto;

}

.progress-section h5{

    font-weight:700;

    color:#2563eb;

}

.progress-section p{

    color:#6b7280;

    font-size:16px;

}

/* ===========================
   DISABLED BUTTONS
=========================== */

button:disabled{

    cursor:not-allowed;

    opacity:.65;

}

/* ===========================
   HIDE UPLOAD AREA
=========================== */

.hide-during-convert{

    display:none !important;

}

/* ===========================
   DARK MODE PROGRESS
=========================== */

.dark-mode .progress{

    background:#374151;

}

.dark-mode .progress-section p{

    color:#d1d5db;

}