:root {
    --bg-main: #0d0d0f; /* Deep dark plum */
    --bg-card: rgba(28, 28, 30, 0.55);
    --text-main: #f0fdfa;
    --text-muted: #a1a1aa;
    --primary: #2dd4bf; /* Rose red */
    --primary-hover: #5eead4;
    --secondary: rgba(255, 255, 255, 0.08);
    --secondary-hover: rgba(255, 255, 255, 0.15);
    --accent: #38bdf8; /* Amber */
    --border: rgba(45, 212, 191, 0.25);
    --error: #ef4444;
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: 'JetBrains Mono', monospace;
}

body {
    background-color: var(--bg-main);
    background-image: 
        radial-gradient(circle at 0% 0%, rgba(45, 212, 191, 0.22) 0%, transparent 45%),
        radial-gradient(circle at 100% 100%, rgba(56, 189, 248, 0.18) 0%, transparent 45%),
        radial-gradient(circle at 50% 50%, rgba(6, 182, 212, 0.12) 0%, transparent 60%);
    background-attachment: fixed;
    color: var(--text-main);
    line-height: 1.6;
    min-height: 100vh;
}

.app-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2.5rem 2rem;
}

header {
    text-align: center;
    margin-bottom: 4rem;
    animation: fadeInDown 1s cubic-bezier(0.16, 1, 0.3, 1);
}

header h1 {
    font-size: 3.5rem;
    font-weight: 900;
    background: linear-gradient(135deg, #67e8f9, #2dd4bf, #06b6d4);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
    margin-bottom: 0.5rem;
    letter-spacing: -1.5px;
    filter: drop-shadow(0px 8px 16px rgba(45, 212, 191, 0.35));
}

header p {
    color: var(--text-muted);
    font-size: 1.15rem;
    max-width: 650px;
    margin: 0 auto;
    font-weight: 400;
}

.module {
    background: var(--bg-card);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border: 1px solid var(--border);
    border-top: 1px solid rgba(45, 212, 191, 0.4);
    border-radius: 24px;
    padding: 2rem 2.5rem;
    margin-bottom: 2.5rem;
    box-shadow: 0 12px 40px rgba(0, 0, 0, 0.4), inset 0 1px 0 rgba(255,255,255,0.1);
    transition: transform 0.3s cubic-bezier(0.16, 1, 0.3, 1), box-shadow 0.3s ease;
}

.module:hover {
    box-shadow: 0 16px 50px rgba(45, 212, 191, 0.2);
    transform: translateY(-3px);
}

h2 {
    font-size: 1.4rem;
    font-weight: 700;
    margin-bottom: 1.5rem;
    border-bottom: 2px solid var(--border);
    padding-bottom: 0.75rem;
    display: inline-block;
    color: #fff1f2;
    letter-spacing: -0.5px;
}

.input-group {
    display: flex;
    gap: 1rem;
    margin-bottom: 1.5rem;
    flex-wrap: wrap;
}

input[type="text"], input[type="number"] {
    flex: 1;
    padding: 0.9rem 1.4rem;
    border-radius: 14px;
    border: 1px solid var(--border);
    background-color: rgba(18, 18, 20, 0.6);
    color: var(--text-main);
    font-size: 1.1rem;
    min-width: 250px;
    transition: all 0.3s cubic-bezier(0.16, 1, 0.3, 1);
    font-family: 'JetBrains Mono', monospace;
    box-shadow: inset 0 2px 4px rgba(0,0,0,0.2);
}

input[type="text"]:focus, input[type="number"]:focus {
    outline: none;
    border-color: var(--accent);
    box-shadow: 0 0 0 4px rgba(56, 189, 248, 0.25), inset 0 2px 4px rgba(0,0,0,0.2);
    background-color: rgba(18, 18, 20, 0.8);
}

input[type="text"]::placeholder {
    color: #115e59;
}

button {
    padding: 0.9rem 1.8rem;
    border-radius: 14px;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 1px;
    font-size: 0.9rem;
    cursor: pointer;
    transition: all 0.25s cubic-bezier(0.16, 1, 0.3, 1);
    border: none;
}

.primary-btn {
    background: linear-gradient(135deg, #2dd4bf, #38bdf8);
    color: white;
    box-shadow: 0 6px 20px rgba(45, 212, 191, 0.4);
    text-shadow: 0 1px 2px rgba(0,0,0,0.2);
}

.primary-btn:hover {
    background: linear-gradient(135deg, #5eead4, #7dd3fc);
    transform: translateY(-2px) scale(1.02);
    box-shadow: 0 8px 25px rgba(56, 189, 248, 0.5);
}

.secondary-btn {
    background-color: var(--secondary);
    color: var(--text-main);
    border: 1px solid var(--border);
}

.secondary-btn:hover {
    background-color: var(--secondary-hover);
    border-color: var(--primary-hover);
    transform: translateY(-2px);
}

.icon-btn {
    width: 48px;
    height: 48px;
    padding: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: var(--secondary);
    color: white;
    border-radius: 50%;
    font-size: 1.3rem;
    border: 1px solid var(--border);
    transition: all 0.25s cubic-bezier(0.16, 1, 0.3, 1);
}

.icon-btn:hover:not(:disabled) {
    background-color: var(--secondary-hover);
    transform: scale(1.1);
    border-color: var(--accent);
    color: var(--accent);
    box-shadow: 0 4px 15px rgba(56, 189, 248, 0.3);
}

.icon-btn:disabled {
    opacity: 0.3;
    cursor: not-allowed;
    transform: none;
    border-color: transparent;
}

.primary-icon-btn {
    background: linear-gradient(135deg, #2dd4bf, #06b6d4);
    border: none;
    box-shadow: 0 4px 15px rgba(6, 182, 212, 0.4);
}

.primary-icon-btn:hover:not(:disabled) {
    background: linear-gradient(135deg, #5eead4, #22d3ee);
    box-shadow: 0 6px 20px rgba(6, 182, 212, 0.6);
    color: white;
}

.palette {
    margin-top: 2rem;
    background: rgba(0,0,0,0.15);
    padding: 1.5rem;
    border-radius: 16px;
    border: 1px dashed rgba(45, 212, 191, 0.3);
}

.palette h3 {
    font-size: 0.95rem;
    color: var(--text-muted);
    font-weight: 600;
    margin-bottom: 1rem;
    text-transform: uppercase;
    letter-spacing: 1px;
}

.palette-buttons {
    display: flex;
    flex-wrap: wrap;
    gap: 0.85rem;
}

.palette-btn {
    background: rgba(45, 212, 191, 0.1);
    border: 1px solid rgba(45, 212, 191, 0.3);
    color: #fff1f2;
    padding: 0.65rem 1.25rem;
    font-size: 0.95rem;
    border-radius: 10px;
    font-family: 'JetBrains Mono', monospace;
    text-transform: none;
    font-weight: 600;
}

.palette-btn:hover {
    background: rgba(56, 189, 248, 0.2);
    border-color: var(--accent);
    color: #fff;
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(56, 189, 248, 0.3);
}

.module-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1.5rem;
}

.module-header h2 {
    border-bottom: none;
    margin-bottom: 0;
    padding-bottom: 0;
}

input[type="range"] {
    accent-color: #38bdf8;
    cursor: pointer;
    height: 8px;
    border-radius: 4px;
    background: rgba(0,0,0,0.4);
}

.canvas-container {
    background: rgba(15, 4, 12, 0.7);
    border: 2px solid rgba(45, 212, 191, 0.3);
    border-radius: 16px;
    padding: 1rem;
    display: flex;
    flex-direction: column;
    align-items: center;
    min-height: 480px;
    position: relative;
    overflow: hidden;
    box-shadow: inset 0 4px 20px rgba(0,0,0,0.6);
}

canvas {
    max-width: 100%;
    cursor: grab;
}

canvas:active {
    cursor: grabbing;
}

.step-info {
    margin-top: 1.5rem;
    padding: 1rem 1.5rem;
    background: linear-gradient(90deg, rgba(45, 212, 191, 0.2), rgba(45, 212, 191, 0.05));
    border-left: 5px solid var(--primary);
    border-radius: 6px 12px 12px 6px;
    width: 100%;
    text-align: center;
    font-weight: 600;
    color: #fff1f2;
    letter-spacing: 0.5px;
    box-shadow: 0 4px 15px rgba(0,0,0,0.2);
}

.string-list {
    list-style: none;
    display: flex;
    flex-wrap: wrap;
    gap: 0.85rem;
    margin-top: 1.5rem;
}

.string-list li {
    background: linear-gradient(135deg, rgba(45, 212, 191, 0.15), rgba(6, 182, 212, 0.1));
    padding: 0.75rem 1.5rem;
    border-radius: 20px;
    border: 1px solid rgba(56, 189, 248, 0.3);
    font-family: 'JetBrains Mono', monospace;
    font-size: 1.1rem;
    color: #f0fdfa;
    font-weight: 500;
    transition: all 0.25s cubic-bezier(0.16, 1, 0.3, 1);
}

.string-list li.empty-state {
    background: none;
    border: 2px dashed rgba(45, 212, 191, 0.3);
    color: var(--text-muted);
    font-family: inherit;
    font-size: 1.05rem;
    border-radius: 12px;
    padding: 1.5rem 2.5rem;
}

.string-list li:hover:not(.empty-state) {
    border-color: #38bdf8;
    background: linear-gradient(135deg, rgba(56, 189, 248, 0.2), rgba(45, 212, 191, 0.2));
    color: #fff;
    box-shadow: 0 4px 15px rgba(56, 189, 248, 0.4);
    transform: translateY(-3px) scale(1.02);
}

.result-box {
    margin-top: 1.5rem;
    padding: 1.5rem;
    border-radius: 16px;
    display: none;
    font-weight: 700;
    font-size: 1.1rem;
    text-align: center;
    letter-spacing: 0.5px;
}

.result-box.success {
    display: block;
    background: linear-gradient(135deg, rgba(16, 185, 129, 0.2), rgba(16, 185, 129, 0.05));
    border: 2px solid #34d399;
    color: #6ee7b7;
    box-shadow: 0 8px 25px rgba(16, 185, 129, 0.2);
}

.result-box.error {
    display: block;
    background: linear-gradient(135deg, rgba(45, 212, 191, 0.2), rgba(45, 212, 191, 0.05));
    border: 2px solid var(--primary);
    color: #fda4af;
    box-shadow: 0 8px 25px rgba(45, 212, 191, 0.2);
}

@keyframes fadeInDown {
    from {
        opacity: 0;
        transform: translateY(-30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}