:root {
    --primary-color: #38bdf8;
    --bg-gradient-start: #0f172a;
    --bg-gradient-end: #1e1b4b;
    --card-bg: #1e293b;
    --border-color: #334155;
    --text-main: #f1f5f9;
    --danger-color: #ef4444;
    --success-color: #10b981;
}

/* =========================================================================
   STRUCTURAL CLASSES (Wrapper, Container Components, Semantics)
   ========================================================================= */

body {
    font-family: 'Montserrat', sans-serif;
    color: var(--text-main);
}

.wrapper {
    display: flex;
    flex-direction: column;
    min-height: 100vh;
    width: 100%;
    background: linear-gradient(135deg, var(--bg-gradient-start) 0%, var(--bg-gradient-end) 100%);
}

.header__container,
.todo__container,
.footer__container {
    width: 100%;
    max-width: 45rem;
    margin: 0 auto;
    padding: 0 1.25rem;
    box-sizing: border-box;
}

.header {
    padding-top: 2.5rem;
    width: 100%;
    flex-shrink: 0;
}

.main {
    flex-grow: 1;
    width: 100%;
    display: flex;
    flex-direction: column;
}

.todo {
    width: 100%;
    display: flex;
    flex-direction: column;
    padding-top: 0.625rem;
    padding-bottom: 3.75rem;
}

.todo__container {
    display: flex;
    flex-direction: column;
}

.footer {
    width: 100%;
    height: auto;
    padding-bottom: 1.25rem;
    margin-top: auto;
    flex-shrink: 0;
}

/* =========================================================================
   MAIN PAGE AND APPLICATION STYLES
   ========================================================================= */

.todo-app {
    background: var(--card-bg);
    border: 0.0625rem solid var(--border-color);
    border-radius: 1.5rem;
    padding: 1.875rem;
    width: 100%;
    box-shadow: 0 1.25rem 2.5rem -0.9375rem rgba(0, 0, 0, 0.7);
    box-sizing: border-box;
}

.app-header {
    font-size: 1.75rem;
    font-weight: 800;
    text-align: center;
    margin-bottom: 0.9375rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: #ffffff;
    text-shadow: 0 0 0.625rem rgba(56, 189, 248, 0.3);
}

.theme-panel {
    background: rgba(0, 0, 0, 0.2);
    border-radius: 1rem;
    padding: 0.9375rem 1.25rem;
    margin-bottom: 1.5rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    border: 0.0625rem solid var(--border-color);
}

.theme-panel__info {
    display: flex;
    flex-direction: column;
    gap: 0.25rem;
}

.theme-panel__title {
    font-size: 0.875rem;
    font-weight: 700;
    color: var(--primary-color);
}

.theme-panel__counter {
    font-size: 0.75rem;
    color: #94a3b8;
}

.theme-panel__input {
    -webkit-appearance: none;
    -moz-appearance: none;
    appearance: none;
    width: 2.5rem;
    height: 2.5rem;
    background: transparent;
    border: none;
    cursor: pointer;
}

.theme-panel__input::-webkit-color-swatch {
    border-radius: 50%;
    border: 0.1875rem solid #ffffff;
}

.task-form {
    display: flex;
    flex-direction: column;
    gap: 0.875rem;
    margin-bottom: 1.875rem;
}

.task-form__row {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 0.875rem;
}

.task-form__group {
    display: flex;
    flex-direction: column;
    gap: 0.375rem;
}

.task-form__label {
    font-size: 0.6875rem;
    font-weight: 700;
    color: #94a3b8;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.task-form__input,
.task-form__select {
    background: rgba(0, 0, 0, 0.2);
    border: 0.125rem solid var(--border-color);
    border-radius: 0.625rem;
    padding: 0.625rem 0.875rem;
    font-family: inherit;
    font-size: 0.875rem;
    color: #ffffff;
    outline: none;
    transition: border-color 0.2s;
}

.task-form__input:focus,
.task-form__select:focus {
    border-color: var(--primary-color);
}

.task-form__btn {
    background: var(--primary-color);
    color: #000000;
    border: none;
    border-radius: 0.625rem;
    padding: 0.75rem;
    font-family: inherit;
    font-size: 0.8125rem;
    font-weight: 800;
    cursor: pointer;
    transition: opacity 0.2s;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.section-title {
    font-size: 0.875rem;
    font-weight: 800;
    color: #94a3b8;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-top: 1.5rem;
    margin-bottom: 0.75rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.section-title--completed {
    color: var(--success-color);
    border-top: 0.0625rem dashed var(--border-color);
    padding-top: 1.25rem;
}

.sort-panel {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 0.9375rem;
    padding-bottom: 0.625rem;
    border-bottom: 0.0625rem solid var(--border-color);
    flex-wrap: wrap;
    gap: 0.625rem;
}

.sort-panel__controls {
    display: flex;
    gap: 0.5rem;
}

.sort-panel__select {
    background: #334155;
    color: #ffffff;
    border: 0.0625rem solid var(--border-color);
    border-radius: 0.5rem;
    padding: 0.375rem 0.75rem;
    font-family: inherit;
    font-size: 0.75rem;
    font-weight: 700;
    outline: none;
    cursor: pointer;
}

.sort-panel__select:focus {
    border-color: var(--primary-color);
}

.task-list {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
    padding: 0;
    margin: 0;
}

.task-item {
    background: rgba(255, 255, 255, 0.02);
    border: 0.0625rem solid var(--border-color);
    border-radius: 0.75rem;
    padding: 0.875rem 1.125rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 0.9375rem;
    transition: border-color 0.3s, box-shadow 0.3s;
    word-break: break-word;
}

.task-item--overdue {
    border-color: var(--danger-color);
    background: rgba(239, 68, 68, 0.03);
    box-shadow: inset 0 0 0.625rem rgba(239, 68, 68, 0.1);
}

.task-item--completed {
    opacity: 0.6;
    border-color: rgba(16, 185, 129, 0.2);
    background: rgba(16, 185, 129, 0.01);
}

.task-item--completed .task-item__text {
    text-decoration: line-through;
    color: #94a3b8;
}

.task-item__content {
    display: flex;
    flex-direction: column;
    gap: 0.375rem;
    flex-grow: 1;
    min-width: 0;
}

.task-item__text {
    font-size: 0.9375rem;
    font-weight: 700;
    line-height: 1.4;
}

.task-item__meta {
    font-size: 0.75rem;
    color: #94a3b8;
    font-weight: 600;
}

.task-item__overdue-label {
    color: var(--danger-color);
    font-weight: 800;
    margin-left: 0.375rem;
    text-transform: uppercase;
}

.task-item__badge {
    display: inline-block;
    padding: 0.125rem 0.375rem;
    border-radius: 0.25rem;
    font-size: 0.625rem;
    font-weight: 800;
    text-transform: uppercase;
    margin-left: 0.5rem;
    vertical-align: middle;
}

.task-item__badge--low {
    background: #4ade80;
    color: #000000;
}

.task-item__badge--medium {
    background: #f59e0b;
    color: #000000;
}

.task-item__badge--high {
    background: #ef4444;
    color: #ffffff;
}

.task-item__actions {
    display: flex;
    gap: 0.5rem;
    flex-shrink: 0;
}

.task-item__btn {
    border: 0.0625rem solid var(--border-color);
    border-radius: 0.5rem;
    padding: 0.5rem 0.875rem;
    font-family: inherit;
    font-size: 0.75rem;
    font-weight: 700;
    cursor: pointer;
    background: transparent;
    color: #ffffff;
    transition: background 0.2s, border-color 0.2s;
    white-space: nowrap;
}

.task-item__btn--done {
    border-color: var(--success-color);
    color: var(--success-color);
}

.task-item__btn--undo {
    border-color: #f59e0b;
    color: #f59e0b;
}

.task-item__btn--edit {
    border-color: #38bdf8;
    color: #38bdf8;
}

.task-item__btn--delete {
    border-color: #f87171;
    color: #f87171;
}

.app-footer {
    margin-top: 0.9375rem;
    text-align: center;
    font-size: 0.8125rem;
    color: black;
    font-weight: 600;
    line-height: 1.6;
    width: 100%;
}

.app-footer__author {
    color: var(--primary-color);
    font-weight: 700;
    font-size: 0.75rem;
    letter-spacing: 0.03em;
}

/* =========================================================================
   DESKTOP ONLY HOVER EFFECTS (Prevents hover sticky styles on mobile)
   ========================================================================= */
@media (hover: hover) {
    .task-form__btn:hover {
        opacity: 0.9;
    }

    .task-item__btn--done:hover {
        background: rgba(16, 185, 129, 0.15);
    }

    .task-item__btn--undo:hover {
        background: rgba(245, 158, 11, 0.15);
    }

    .task-item__btn--edit:hover {
        background: rgba(56, 189, 248, 0.1);
    }

    .task-item__btn--delete:hover {
        background: rgba(239, 68, 68, 0.1);
    }
}

/* =========================================================================
   MEDIA QUERY FOR MOBILE DEVICES (Screens under 540px)
   ========================================================================= */
@media (max-width: 33.75rem) {
    .task-form__row {
        grid-template-columns: 1fr;
    }

    .sort-panel {
        flex-direction: column;
        align-items: flex-start;
        gap: 0.75rem;
    }

    .sort-panel__controls {
        width: 100%;
        flex-direction: column;
        gap: 0.5rem;
    }

    .sort-panel__select {
        width: 100%;
        padding: 0.625rem 0.75rem;
        font-size: 0.8125rem;
    }

    .task-item {
        flex-direction: column;
        align-items: flex-start;
        gap: 0.875rem;
        padding: 1rem;
    }

    .task-item__actions {
        width: 100%;
        justify-content: flex-start;
        gap: 0.5rem;
    }

    .task-item__btn {
        flex-grow: 1;
        text-align: center;
        padding: 0.625rem;
    }
}