:root {
    --spacer: 1rem;
    --multiply-index: 0.25;
    --bright-red: #f00;
    --dark-red: #842029;
    --light-red: #f8d7da;
    --form-input-text: #495057;
    --white: #fff;
    --form-border: #ced4da;
    --form-input-focus: #7490b8;
    --button-focus: rgba(0, 123, 255, .25);
    --background-button: #354a7b;
    --background-button-hover: #3858a1;
    --border-button-hover: #1d47a6;
    --background-button-secondary: #6c757d;
    --background-button-secondary-hover: #5a6268;
    --border-button-secondary-hover: #545b62;
    --background-button-delete-hover: rgba(132, 32, 41, 0.89);
    --border-button-delete-hover: #981c26;
    --shadow: rgba(108, 117, 125, .5);
}

body {
    margin: 0;
    font-family: Arial, sans-serif;
    background-color: #f0f2f5;
    color: #333;
}

.container {
    max-width: 900px;
    margin: 2rem auto;
    padding: 1rem 2rem;
    background-color: var(--white);
    border-radius: 12px;
    box-shadow: 0 4px 12px var(--shadow);
}

.button {
    padding: calc(var(--spacer) * var(--multiply-index) * 2)
             calc(var(--spacer) * var(--multiply-index) * 3);
    background: var(--background-button);
    color: var(--white);
    border: 1px solid var(--background-button);
    border-radius: 8px;
    font-size: 15px;
    font-weight: 600;
    cursor: pointer;
    transition: background .15s ease, border-color .15s ease, opacity .15s ease;
    box-shadow: 0 3px 6px var(--shadow);
}

.button:hover {
    background: var(--background-button-hover);
    border-color: var(--border-button-hover);
}

.button:active {
    opacity: .85;
    box-shadow: 0 2px 4px var(--shadow);
}

.button:focus {
    outline: none;
    box-shadow: 0 0 0 0.18rem var(--button-focus);
}

.button:focus:not(:focus-visible) {
    box-shadow: none;
}

.button:disabled {
    opacity: 0.55;
    cursor: not-allowed;
    box-shadow: none;
}

h1 {
    text-align: center;
    margin-bottom: 2rem;
}

.selectors {
    display: flex;
    gap: var(--spacer);
    margin-bottom: 2rem;
}

select {
    padding: 0.5rem 1rem;
    font-size: 1rem;
    border: 1px solid var(--form-border);
    border-radius: 6px;
    background-color: var(--white);
    color: var(--form-input-text);
    transition: all 0.2s ease;
    cursor: pointer;
}

select:focus {
    outline: none;
    border-color: var(--form-input-focus);
    box-shadow: 0 0 5px var(--form-input-focus);
}

#faculty-select {
    flex: 1;
}

#speciality-select {
    flex: 2;
}

#course-select {
    flex: 1;
}

.filter-row-flex {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    justify-content: space-between;
    align-items: center;
}

.filter-row-flex select,
.filter-row-flex button {
    flex: 1 1 0;
}

.flex-row-full {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    justify-content: space-between;
    align-items: center;
}

.flex-row-full select,
.flex-row-full button {
    flex: 1 1 0;
}

.top-controls {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    align-items: center;
    justify-content: space-between;
    margin-top: 1rem;
    font-size: 1rem;
}

.top-controls input[type="number"] {
    flex: 1 1 80px;
    padding: 0.5rem 0.75rem;
    border-radius: 6px;
    border: 1px solid var(--form-border);
    font-size: 1rem;
    min-width: 60px;
}

.top-controls .small-btn {
    flex: 1 1 100px;
    padding: 0.5rem 0.75rem;
    border-radius: 6px;
    border: 1px solid var(--background-button);
    background: var(--background-button);
    color: var(--white);
    font-size: 1rem;
    cursor: pointer;
    text-align: center;
}

.top-controls .small-btn[disabled] {
    opacity: .6;
    cursor: not-allowed;
}

table {
    width: 100%;
    border-collapse: collapse;
    margin-top: 1rem;
}

th, td {
    padding: 0.75rem 1rem;
    border-bottom: 1px solid #ddd;
    text-align: left;
}

th {
    background-color: var(--background-button-secondary);
    color: var(--white);
}

tr:nth-child(even) {
    background-color: #f8f9fa;
}

.shift-up {
    color: green;
}

.shift-down {
    color: red;
}

#loader {
    border: 6px solid #f3f3f3;
    border-top: 6px solid var(--background-button);
    border-radius: 50%;
    width: 40px;
    height: 40px;
    animation: spin 1s linear infinite;
    margin: 2rem auto;
}

.hidden {
    display: none;
}

.top-mark {
    background: linear-gradient(90deg, #e6f7ea, #dff0d8);
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

.percent-wrapper, .apply-btn-wrapper {
    width: 100%;
}

.range-row {
    width: 100%;
    display: flex;
    gap: 0.5rem;
}

.text-input {
    width: 100%;
    box-sizing: border-box;
}

.top-controls input[type="number"] {
    width: 100%;
    box-sizing: border-box;
}

.header {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 1rem;
    margin-bottom: 2rem;
}

h1 {
    margin: 0;
    text-align: center;
}

.share-btn {
    background: transparent;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
}

.share-btn:disabled {
    opacity: 0.55;
    cursor: not-allowed;
}

.apply-btn-wrapper{
    width: 100% !important;
}

.button{
    width: 100% !important;
}

@media (max-width: 768px) {
    #filter-row.flex-row-full {
        flex-direction: column;
    }

    #filter-row select,
    #filter-row button {
        flex: 1 1 100%;
    }

    .top-controls {
        flex-direction: column;
        gap: 0.5rem;
    }

    .top-controls input[type="number"] {
        flex: 1 1 100%;
    }

    .top-controls .small-btn {
        flex: 1 1 100%;
    }

    .top-controls .range-row {
        display: flex;
        gap: 0.5rem;
        width: 100%;
    }

    .top-controls .range-row input[type="number"] {
        flex: 1 1 50%;
    }

    .top-controls .apply-btn-wrapper {
        width: 100%;
    }

    .top-controls .apply-btn-wrapper button {
        width: 100%;
    }

    .percent-wrapper {
        width: 100%;
    }
    .text-input {
        width: 100%;
    }

    .header {
        flex-direction: column;
        gap: 0.5rem;
        align-items: center;
    }

    .container {
        max-width: 100%;
        margin: 1rem;
        padding: 1rem;
    }

    #students-table-container {
    width: 100%;
    overflow-x: auto;
}

#students-table-container table {
    width: 100%;
    min-width: 400px; 
    border-collapse: collapse;
}

}