/* ══════════════════════════════════════════════════════════════
   MIDNIGHT AGENDA — Premium Task Manager
   Color Palette: Obsidian Black, Silver, Crimson Red, Night Sky Blue
   ══════════════════════════════════════════════════════════════ */

@import url('https://fonts.googleapis.com/css2?family=Space+Grotesk:wght@400;500;600;700&family=JetBrains+Mono:wght@400;500&display=swap');

:root {
    /* Core Colors */
    --obsidian: #0a0a0b;
    --charcoal: #141416;
    --graphite: #1c1c1f;
    --silver-mist: #8a8a94;
    --silver-bright: #c4c4cc;
    --pearl: #e8e8ec;
    
    /* Accent Colors */
    --crimson: #dc2626;
    --crimson-glow: rgba(220, 38, 38, 0.15);
    --night-blue: #1e3a5f;
    --sky-deep: #0c4a6e;
    --aurora: #38bdf8;
    
    /* Functional */
    --success: #059669;
    --success-soft: rgba(5, 150, 105, 0.12);
    
    /* Effects */
    --border-subtle: rgba(255, 255, 255, 0.06);
    --border-hover: rgba(255, 255, 255, 0.12);
    --glow-red: 0 0 40px rgba(220, 38, 38, 0.2);
    --glow-blue: 0 0 40px rgba(56, 189, 248, 0.15);
}

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

html {
    font-size: 16px;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: 'Space Grotesk', -apple-system, BlinkMacSystemFont, sans-serif;
    background: var(--obsidian);
    color: var(--pearl);
    min-height: 100vh;
    display: flex;
    justify-content: center;
    padding: 3rem 1.5rem;
    position: relative;
    overflow-x: hidden;
}

/* Subtle ambient gradient */
body::before {
    content: '';
    position: fixed;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: 
        radial-gradient(ellipse at 20% 20%, var(--night-blue) 0%, transparent 50%),
        radial-gradient(ellipse at 80% 80%, rgba(220, 38, 38, 0.08) 0%, transparent 40%);
    pointer-events: none;
    z-index: 0;
}

/* ═══════════════════════════════════════════
   MAIN CONTAINER
   ═══════════════════════════════════════════ */

.container {
    position: relative;
    z-index: 1;
    width: 100%;
    max-width: 580px;
}

/* ═══════════════════════════════════════════
   HEADER — Asymmetric Title Block
   ═══════════════════════════════════════════ */

header {
    margin-bottom: 3rem;
    padding-left: 0.25rem;
}

h1 {
    font-size: clamp(2.5rem, 8vw, 3.5rem);
    font-weight: 700;
    letter-spacing: -0.04em;
    line-height: 1;
    color: var(--pearl);
    position: relative;
    display: inline-block;
}

/* Red accent line */
h1::before {
    content: '';
    position: absolute;
    left: -1rem;
    top: 50%;
    transform: translateY(-50%);
    width: 4px;
    height: 60%;
    background: var(--crimson);
    border-radius: 2px;
}

.subtitle {
    margin-top: 0.75rem;
    font-size: 0.95rem;
    color: var(--silver-mist);
    font-weight: 400;
    letter-spacing: 0.02em;
}

/* ═══════════════════════════════════════════
   INPUT SECTION — Floating Input Bar
   ═══════════════════════════════════════════ */

.input-group {
    display: flex;
    gap: 0;
    margin-bottom: 2.5rem;
    background: var(--charcoal);
    border: 1px solid var(--border-subtle);
    border-radius: 8px;
    overflow: hidden;
    transition: all 0.3s ease;
}

.input-group:focus-within {
    border-color: var(--aurora);
    box-shadow: var(--glow-blue);
}

input[type="text"] {
    flex: 1;
    background: transparent;
    border: none;
    outline: none;
    padding: 1.15rem 1.25rem;
    font-family: inherit;
    font-size: 1rem;
    color: var(--pearl);
    letter-spacing: 0.01em;
}

input[type="text"]::placeholder {
    color: var(--silver-mist);
    opacity: 0.6;
}

input[type="text"].shake {
    animation: shake 0.4s ease;
}

@keyframes shake {
    0%, 100% { transform: translateX(0); }
    20% { transform: translateX(-6px); }
    40% { transform: translateX(6px); }
    60% { transform: translateX(-4px); }
    80% { transform: translateX(4px); }
}

button.add-btn {
    background: var(--crimson);
    border: none;
    padding: 1.15rem 1.75rem;
    font-family: inherit;
    font-size: 0.875rem;
    font-weight: 600;
    color: white;
    cursor: pointer;
    letter-spacing: 0.05em;
    text-transform: uppercase;
    transition: all 0.2s ease;
}

button.add-btn:hover {
    background: #b91c1c;
}

button.add-btn:active {
    transform: scale(0.97);
}

/* ═══════════════════════════════════════════
   TASK LIST — Clean Rows with Hover States
   ═══════════════════════════════════════════ */

.task-list {
    list-style: none;
    display: flex;
    flex-direction: column;
}

.task-item {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 1.1rem 0;
    border-bottom: 1px solid var(--border-subtle);
    transition: all 0.25s ease;
    position: relative;
}

.task-item:last-child {
    border-bottom: none;
}

.task-item:hover {
    background: linear-gradient(90deg, transparent 0%, rgba(255,255,255,0.02) 50%, transparent 100%);
}

/* Completed State */
.task-item.completed {
    opacity: 0.5;
}

.task-item.completed .task-text {
    text-decoration: line-through;
    text-decoration-color: var(--silver-mist);
}

.task-item.completed .checkbox {
    background: var(--success);
    border-color: var(--success);
}

.task-item.completed .checkbox::after {
    opacity: 1;
    transform: scale(1) rotate(0deg);
}

/* ═══════════════════════════════════════════
   TASK CONTENT — Checkbox + Text
   ═══════════════════════════════════════════ */

.task-content {
    display: flex;
    align-items: center;
    gap: 1rem;
    flex: 1;
    cursor: pointer;
    padding-right: 1rem;
}

.checkbox {
    width: 22px;
    height: 22px;
    border: 2px solid var(--silver-mist);
    border-radius: 6px;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
    transition: all 0.2s ease;
    position: relative;
}

.checkbox::after {
    content: '✓';
    font-size: 12px;
    font-weight: 700;
    color: white;
    opacity: 0;
    transform: scale(0.5) rotate(-20deg);
    transition: all 0.2s ease;
}

.task-item:hover .checkbox {
    border-color: var(--aurora);
}

.task-text {
    font-size: 1rem;
    color: var(--silver-bright);
    font-weight: 400;
    line-height: 1.4;
    transition: all 0.2s ease;
}

.task-item:hover .task-text {
    color: var(--pearl);
}

/* ═══════════════════════════════════════════
   DELETE BUTTON — Minimal Icon
   ═══════════════════════════════════════════ */

.delete-btn {
    background: transparent;
    border: none;
    color: var(--silver-mist);
    cursor: pointer;
    padding: 0.5rem;
    border-radius: 6px;
    opacity: 0;
    transform: translateX(8px);
    transition: all 0.2s ease;
    display: flex;
    align-items: center;
    justify-content: center;
}

.delete-btn svg {
    width: 18px;
    height: 18px;
}

.task-item:hover .delete-btn {
    opacity: 1;
    transform: translateX(0);
}

.delete-btn:hover {
    background: var(--crimson-glow);
    color: var(--crimson);
}

/* ═══════════════════════════════════════════
   EMPTY STATE
   ═══════════════════════════════════════════ */

.empty-state {
    text-align: center;
    padding: 4rem 2rem;
    color: var(--silver-mist);
    font-size: 0.95rem;
    opacity: 0.7;
    border: 1px dashed var(--border-subtle);
    border-radius: 8px;
    margin-top: 0.5rem;
}

/* ═══════════════════════════════════════════
   PARTICLE EFFECT
   ═══════════════════════════════════════════ */

.particle {
    position: fixed;
    width: 6px;
    height: 6px;
    pointer-events: none;
    border-radius: 50%;
    z-index: 1000;
    animation: particleFade 0.7s ease-out forwards;
}

@keyframes particleFade {
    0% {
        transform: translate(0, 0) scale(1);
        opacity: 1;
    }
    100% {
        transform: translate(var(--tx), var(--ty)) scale(0);
        opacity: 0;
    }
}

/* ═══════════════════════════════════════════
   SCROLLBAR — Custom Minimal Style
   ═══════════════════════════════════════════ */

::-webkit-scrollbar {
    width: 6px;
}

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

::-webkit-scrollbar-thumb {
    background: var(--graphite);
    border-radius: 3px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--silver-mist);
}

/* ═══════════════════════════════════════════
   RESPONSIVE
   ═══════════════════════════════════════════ */

@media (max-width: 480px) {
    body {
        padding: 2rem 1rem;
    }
    
    h1 {
        font-size: 2rem;
    }
    
    h1::before {
        left: -0.75rem;
        width: 3px;
    }
    
    .input-group {
        flex-direction: column;
    }
    
    button.add-btn {
        padding: 1rem;
    }
    
    .task-item {
        padding: 1rem 0;
    }
    
    .delete-btn {
        opacity: 0.6;
        transform: translateX(0);
    }
}

/* ═══════════════════════════════════════════
   SELECTION STYLE
   ═══════════════════════════════════════════ */

::selection {
    background: var(--crimson);
    color: white;
}