:root {
    --bg-color: #f3f4f6;
    --text-color: #1f2937;
    --card-bg: #ffffff;
    --border-color: #e5e7eb;
    --primary-color: #3b82f6;
    --shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
}

@media (prefers-color-scheme: dark) {
    :root {
        --bg-color: #111827;
        --text-color: #f9fafb;
        --card-bg: #1f2937;
        --border-color: #374151;
        --primary-color: #60a5fa;
        --shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.5);
    }
}

/* Telegram WebApp integration */
body.tg-theme {
    --bg-color: var(--tg-theme-bg-color, #f3f4f6);
    --text-color: var(--tg-theme-text-color, #1f2937);
    --card-bg: var(--tg-theme-secondary-bg-color, #ffffff);
    --primary-color: var(--tg-theme-button-color, #3b82f6);
    --border-color: var(--tg-theme-hint-color, #e5e7eb);
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    font-family: 'Inter', sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    height: 100vh;
    display: flex;
    flex-direction: column;
    overflow: hidden;
}

header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 16px 20px;
    background: rgba(var(--card-bg), 0.8);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-color);
    z-index: 10;
}

h1 {
    font-size: 1.2rem;
    font-weight: 600;
}

button {
    background-color: var(--primary-color);
    color: #fff;
    border: none;
    padding: 8px 12px;
    border-radius: 6px;
    font-size: 0.9rem;
    cursor: pointer;
    font-weight: 500;
    transition: opacity 0.2s;
}

button:active {
    opacity: 0.8;
}

.loading {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    flex-grow: 1;
}

.spinner {
    width: 40px;
    height: 40px;
    border: 4px solid var(--border-color);
    border-top: 4px solid var(--primary-color);
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin-bottom: 16px;
}

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

.hidden {
    display: none !important;
}

.board {
    display: flex;
    gap: 16px;
    padding: 20px;
    overflow-x: auto;
    overflow-y: hidden;
    height: calc(100vh - 60px);
    align-items: flex-start;
}

.column {
    background-color: var(--card-bg);
    min-width: 280px;
    width: 280px;
    border-radius: 12px;
    display: flex;
    flex-direction: column;
    max-height: 100%;
    border: 1px solid var(--border-color);
}

.column-header {
    padding: 16px;
    font-weight: 600;
    font-size: 1rem;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
}

.column-count {
    background: var(--border-color);
    padding: 2px 8px;
    border-radius: 12px;
    font-size: 0.8rem;
}

.column-cards {
    padding: 12px;
    overflow-y: auto;
    flex-grow: 1;
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.card {
    background-color: var(--bg-color);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 16px;
    box-shadow: var(--shadow);
    cursor: grab;
    transition: transform 0.2s, box-shadow 0.2s;
}

.card:active {
    cursor: grabbing;
}

.card:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
}

.card-header {
    display: flex;
    justify-content: space-between;
    margin-bottom: 8px;
    font-size: 0.85rem;
    color: var(--primary-color);
    font-weight: 500;
}

.card-title {
    font-size: 0.95rem;
    font-weight: 500;
    line-height: 1.4;
    margin-bottom: 12px;
}

.card-footer {
    display: flex;
    justify-content: space-between;
    font-size: 0.8rem;
    color: var(--text-color);
    opacity: 0.8;
}

/* Scrollbar styling */
::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}

::-webkit-scrollbar-track {
    background: transparent;
}

::-webkit-scrollbar-thumb {
    background: var(--border-color);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--primary-color);
}