.container {
    max-width: 900px;
    margin: 40px auto;
    padding: 0 15px;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
}
h1 { text-align: left; color: #2c3e50; margin-bottom: 15px; font-size: 2em; }
.intro-text { font-size: 1.1em; color: #555; margin-bottom: 30px; text-align: left; line-height: 1.6; }


.time-calculator-block {
    background-color: #f8f9fa;
    border: 1px solid #dee2e6;
    padding: 20px 25px;
    border-radius: 8px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.05);
}


.operation-selector {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    margin-bottom: 25px;
    background-color: #ffffff;      
    border: 1px solid #dee2e6;    
    padding: 10px;                 
    border-radius: 10px;           
}
.operation-selector .op-link {
    padding: 10px 18px;
    border: 1px solid #ced4da; 
    border-radius: 20px;
    cursor: pointer;
    background-color: #f1f3f5; 
    color: #333;
    text-decoration: none;
    transition: all 0.2s ease-in-out;
    font-size: 1em;
    user-select: none;
}
.operation-selector .op-link:hover {
    border-color: #adb5bd;
    background-color: #e9ecef;
}
.operation-selector .op-link.selected {
    background-color: #3498db;
    color: white;
    border-color: #2980b9;
    font-weight: 500;
}


.time-input-row-wrapper { display: flex; align-items: flex-end; margin-bottom: 15px; gap: 10px; }
.time-input-row-wrapper .row-operator { font-size: 1.8em; color: #555; width: 25px; text-align: center; padding-bottom: 5px; }
.time-input-row-wrapper .row-label { font-size: 1em; font-weight: 500; min-width: 60px; padding-bottom: 10px; }
.time-inputs { display: grid; grid-template-columns: repeat(4, 1fr); flex-grow: 1; gap: 8px; }
.time-inputs > div { display: flex; flex-direction: column; }
.time-inputs label { font-size: 0.8em; color: #666; margin-bottom: 3px; text-align: center; }
.time-inputs input[type="number"] { width: 100%; padding: 10px 5px; font-size: 1rem; border: 1px solid #ced4da; border-radius: 4px; text-align: center; -moz-appearance: textfield; }
.time-inputs input[type="number"]::-webkit-outer-spin-button, .time-inputs input[type="number"]::-webkit-inner-spin-button { -webkit-appearance: none; margin: 0; }


.scalar-input-group { display: flex; align-items: flex-end; gap: 10px; margin-bottom: 15px; }
.scalar-input-group label { font-size: 1em; font-weight: 500; padding-bottom: 10px; }
.scalar-input-group input[type="number"] { width: 120px; padding: 10px 5px; font-size: 1rem; border: 1px solid #ced4da; border-radius: 4px; }
.remove-row-btn { padding: 8px 12px; font-size: 0.9rem; background-color: #e9ecef; border: 1px solid #ced4da; color: #495057; border-radius: 4px; cursor: pointer; transition: background-color 0.2s; margin-bottom: 1px; }
.remove-row-btn:hover { background-color: #dee2e6; }


#inputValidationError { color: #e74c3c; text-align: center; margin-top: 5px; margin-bottom: 15px; min-height: 1.2em; font-size: 0.9em; }
.button-container { display: flex; justify-content: center; gap: 15px; margin-top: 20px; margin-bottom: 10px; flex-wrap: wrap; }
#addRowBtn, #calculateTimeBtn { border: none; border-radius: 5px; cursor: pointer; font-weight: bold; transition: background-color 0.2s, transform 0.1s; }
#addRowBtn:hover, #calculateTimeBtn:hover { transform: translateY(-1px); }
#addRowBtn { padding: 10px 20px; font-size: 1em; background-color: #6c757d; color: white; }
#addRowBtn:hover { background-color: #5a6268; }
#calculateTimeBtn { padding: 12px 25px; font-size: 1.2rem; background-color: #2c3e50; color: white; }
#calculateTimeBtn:hover { background-color: #1a252f; }


.result-area-wrapper {
    display: flex;
    flex-direction: column; 
    align-items: center;    
    gap: 15px;
    margin-top: 25px;
}
#resultIcon {
    font-size: 6em;
    color: #3498db;
    line-height: 1;
}
#timeResultDisplay {
    width: 100%; 
}
.result-blocks-container {
    display: grid;
    grid-template-columns: repeat(4, 1fr); 
    gap: 10px;
    background-color: #e9ecef;
    border: 1px solid #ced4da;
    border-radius: 6px;
    padding: 8px;
}
.result-block {
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 10px;
    border-radius: 4px;
    background-color: #fff;
    box-shadow: 0 1px 3px rgba(0,0,0,0.05);
}
.result-label {
    font-size: 0.85em;
    color: #555;
    margin-bottom: 5px;
}
.result-value {
    font-size: 2em;
    font-weight: bold;
    color: #333;
}
.result-message-area {
    padding: 10px;
    font-size: 1.2em;
    font-weight: 500;
    background-color: #e9ecef;
    border: 1px solid #ced4da;
    border-radius: 6px;
    text-align: center;
    word-break: break-all;
    margin-top: 20px; 
}
.result-message-area.error {
    color: #721c24;
    background-color: #f8d7da;
    border-color: #f5c6cb;
}



.content-section {
    margin-top: 40px;
    padding: 0;
    background: transparent;
    border: none;
}
.content-section h2 {
    color: #333;
    margin-top: 0;
    padding-bottom: 10px;
    margin-bottom: 20px;
    border-bottom: 1px solid #eee;
}



@media (max-width: 600px) {
    h1 { font-size: 1.8em; }
    .time-inputs { grid-template-columns: repeat(2, 1fr); }
    .operation-selector .op-link { flex-grow: 1; text-align: center; }

    #resultIcon {
        font-size: 5em; 
    }

    
    .result-blocks-container {
        grid-template-columns: repeat(2, 1fr);
    }
    .result-value {
        font-size: 1.5em;
    }
}